Introduction

No truly great book needs an explanation of its aim and purpose. A great book just grows, as has this Book of Wonders. It began with the attempt of a father to answer the natural questions of the active mind of a growing boy. It developed into a nightly search for plain, understandable answers to such questions as “What makes it night?” “Where does the wind begin?” “Why is the sky blue?” “Why does it hurt when I cut my finger?” “Why doesn’t it hurt when I cut my hair?” “Why does wood float?” “Why does iron sink?” “Why doesn’t an iron ship sink?” on through the maze of thousands of puzzling questions which occur to the child’s mind. It has grown until the answers to the mere questions cover practically the entire range of every-day knowledge, and has been arranged in such a form that any child may now find the answer to his own inquiries. As the mind of the child matures, the questions naturally drift toward the things which the genius of man has provided for his comfort and pleasure. We have become so accustomed to the use and benefits of these wonders produced by man that we generally leave out of our books the stories of our great industries, and yet the mind of the child wonders and inquires about them. We have so long worn clothes made of wool or cotton, that we have forgotten the wonder there is in making a bolt of cloth. Every industry has a fascinating story equal to that of the silkworm, which moves its head sixty-five times a minute while spinning his thousand yards of silk. Can you tell What happens when we telephone? How a telegram gets there? What makes an automobile go? How man learned to tell time? How a moving-picture is made? How a camera takes a picture? How rope is made? How the light gets into the electric bulb? How glass is made? How the music gets into the piano? and hundreds of others that embrace the captivating tales of how man has made use of the wonders of nature and turned them to his advantage and comfort? The Book of Wonders does this with illuminating pictures which stimulate the mind and give a bird’s-eye view of each subject step by step. Where shall such a book begin? Shall it begin with the Story of How Man Learned to Light a Fire--he could not cook his food, see at night, or keep warm without a fire; or should it begin with How Man Learned to Shoot--he could not protect himself against the beasts of the forest, and, therefore, could not move about, till the soil or obtain food to cook until he knew how to shoot or destroy. What was the vital thing for man to know before he could really become civilized? Some means, of course, by which the things he learned--the knowledge he had acquired--could be handed down to those who came after him so that they might go on with the intelligence handed down to them. This required some means of recording his knowledge. Man had to learn to write. Without writing there could be no Book of Wonders, and the book, then, begins naturally with the Story of Mow Man Learned to Write. THE EDITOR. [Illustration: WRITING BY MEXICAN INDIANS THOUGHT TO BE MORE THAN TEN THOUSAND YEARS OLD.] How Man Learned to Write It is a long time between the day of the cave-dwellers, with their instruments of chipped stone, and the present day of the pen. Yet wide apart as are these points of time, the trend of development can with but few obstacles be traced. The story of the pen is a natural sequence of ideas between the first piece of rock scratched upon rock by prehistoric man, and the bit of metal which now so smoothly records our thoughts. There was a time in the unwritten history of man when necessity prompted the invention of weapons, and the minds of these primitive men were concentrated upon this point. But the arts of war did not take up their entire time; some time must have been given to other pursuits. As the mind developed, and as an aid to memory, we find them carving, engraving, incising upon the rocks their hieroglyphics, which took the form of figures of men, habitations, weapons, and the animals of their period. [Illustration: THE STYLUS] How Did Writing First Come About? An apparently difficult question to answer, since without writing there can be no record of its origin, and without records no facts; yet the deduction is so clear that the answer is simple. Somewhere far, far back in the dawn of the world, back in the beginning of human history, in the epoch which we have now named the Quaternary Period, man lived in a dense wilderness surrounded by the wildest and most ferocious beasts. His home was a cave, exposed to the dangers incidental to that time and his surroundings, and he was of necessity compelled to look about for means of defense. With this idea in mind, he found that by striking one stone against another he knocked off chips, which chips could be used as arrow-heads, spears and axes. Following along these lines he discovered that by rubbing one of these chips against another there was left a mark, which was the first imitation of writing; that the sharper the edge of the chip, the deeper was the scratch, and consequently the more distinct the mark. [Illustration: EARLIEST WAYS OF WRITING THE FIRST IMITATION OF WRITING] Next it was discovered that certain stones, such as flint, serpentine and chalcedony, marked more readily than others; that the elongated chip was handled with more facility; that by rubbing one stone against another the finest possible points and edges might be obtained. Thus in the Age of Stone was the long, tapering instrument of stone, the first pen, the Stylus, originated. Then came the time, known as the Bronze Age, when men learned to hammer metal into shapes, and metal having many advantages over stone, the stylus of stone gave way to one of iron. So we find that in the time of the Egyptians, about fourteen or fifteen centuries B.C., an iron stylus was in use for marking on soapstone, limestone and waxed surfaces. An improvement in this metal stylus was that the blunt end was convex and smooth, the purpose of which was to erase and smooth over irregularities. In some cases it was pointed with diamonds, which gave it greater cutting properties. The iron stylus was also used by the Egyptians of that period, as well as in later times, with a mallet, after the manner of the modern chisel (which indeed it resembled) for cutting out inscriptions on their monuments. [Illustration: THE BRUSH] ~WRITING FLUIDS HELPED DEVELOPMENT~ In course of time a marking fluid was discovered, and this made necessary a writing instrument which could spread characters on parchment, tree-bark, etc. Thus it was found that by putting together a small bunch of hairs, arranging them in the shape of an acute cone, and fastening them together in some manner, an instrument could be made which would carry fluid in its path, and thus make a mark of the desired shape. The hair best adapted for the purpose was found to be camel’s hair, while that of the badger and sable was also used. A tube cut from a stalk of grass answered for a holder. The hairs were held together by a piece of thread which was then drawn through the tube, thus making the first writing instrument to be used in conjunction with ink, the Brush. [Illustration: HOW THE CHINESE IMPROVED METHODS] Just when the Brush came into existence is not definitely known, but with this instrument the great Chinese philosopher Confucius wrote his marvelous philosophy. The Brush as a writing instrument is generally associated with the Chinese, because the Chinese use this instrument even to the present day, it being especially adapted to their letters and mode of writing. We have now a pen (brush), as well as an ink, but the material upon which the people of that age wrote, in lieu of paper, was still very crude, parchment and tree-bark being most commonly used. [Illustration: THE QUILL] ~THE EARLIEST FORMS OF PAPER~ Just as the discovery of an ink wrought a change from the Stylus to the Brush, so the advent of papyrus, a paper made from the papyrus plant, which was much finer and more economical than parchment, brought with it a pen better adapted for this material. It was found that the Reed, or Calamo, as it was called, which grew on the marshes on the shores of Egypt, Armenia and the Persian Gulf, if cut into short lengths and trimmed down to a point, made an admirable pen for this newly discovered paper. This was the true ancient representative and precursor of the modern pen. The use of the Reed can be traced to a remote antiquity among the civilized nations of the East, where Reeds are in use now as instruments for writing. [Illustration: HOW THE MONKS DID THEIR WRITING] The introduction of a finer paper rendered necessary a finer instrument of writing, and the quill of the goose, swan, and, for very fine writing, of the crow, was found to be well adapted. Immense flocks of geese were raised, chiefly for their quills. The earliest specific allusion to the quill occurs in the writings of St. Isadore de Seville, seventh century, although it is believed to have been in use at an earlier period. The quill was used for many centuries. Most of the writing during its reign was done in the monasteries by the monks, and in the eighteenth century, when quill-making became quite an art, every monk and every teacher was expected to be proficient in the art of making a pen from a quill. The preliminary process of preparing the quills was first to sort them according to their quality, dry in the hot sand, then clean them of the outer skin, and harden by dipping in a boiling solution of alum and diluted nitric acid. During the last century many efforts were made to improve the quill, its great defect being speedy injury from use. Ruby points were fitted to the nib, but this was found impracticable on account of the delicacy of the work. Joseph Bramah devised, in 1809, a machine for cutting the quill into separate nibs for use in holders, thus making several pens from one quill and anticipating the form of the modern pen. [Illustration: THE STEEL TUBE PEN] [Illustration: THE FIRST STEEL PEN] The quill held sway as writing instrument for many years, and with it the greatest masterpieces in literature have been written. Many attempts, however, had been made to supersede the quill by a pen not so easily injured by use, but it was not until about 1780 that, after much experimenting and numerous failures, Mr. Samuel Harrison introduced the first metallic pen. ~THE INVENTION OF THE PEN~ This pen was made as follows: A sheet of steel was rolled in the form of a tube. One end was cut and trimmed to a point after the manner of the quill, the seam where both edges of the tube met forming the slit of the pen. This was soon after improved upon by cutting a rough blank out of a thin sheet of steel, which blank was filed into form about the nib, rounded, and with a sharp chisel marked inside where the slit was to be in the finished pen. After tempering, the nib was ground and shaped to a point suitable for fine or broad writing, as required. [Illustration: THE MODERN STEEL PEN] [Illustration: THE MODERN WRITING PEN] Once started, the steel pen made rapid strides in improvement. Mr. James Perry, in 1824, started in England the manufacture of pens on a large scale, and to him as well as Gillott is due the many improvements which followed. Perry was the first to manufacture “slip” steel pens, up to this time the pen and holder being one piece. “In times of yore, when each man cut his quill With little Perryian skill; What horrid, awkward, bungling tools of trade Appeared the writing instruments, home made!” ~THE MODERN WAY OF WRITING~ The steel pen of the present day has reached the pinnacle of perfection, and the method of manufacture of this little but mighty instrument of writing, though of extreme interest, is practically unknown by the general public. To explain in detail the development from the rough steel to the finished pen would needs make a book in itself. And as it has been our intention to dwell, not upon the manufacture of the pen, but to trace its history and development from its most crude form, the Stylus, to the perfect and smooth-writing steel pen of to-day, we will close our story with the well-worn epigram of old, grim Cardinal Richelieu: “Beneath the rule of men entirely great, The Pen is mightier than the Sword!” How a Steel Pen is Made In the picture on the following page, we see the various processes required in making a steel pen, together with a description of each process: [Illustration: HOW A STEEL PEN IS MADE N^o. 1. ROLLED STEEL. N^o. 2. SCRAP. N^o. 3. BLANKS. N^o. 4. MARKING. N^o. 5. PIERCING. N^o. 6. ANNEALING. N^o. 7. RAISING. N^o. 8. HARDENING. N^o. 9. TEMPERING. N^o. 10. SCOURING. N^o. 11. GRINDING. N^o. 12. SLITTING. N^o. 13. No. 1. COLLEGE PEN No. 5. SCHOOL PEN. (FINISHED PENS.) COLORING AND VARNISHING. The pictures herewith printed are by the courtesy of the Spencerian Pen Company _Raw Material._--The sheet steel is cut into strips of a convenient length and width, and then rolled cold to the exact gauge necessary, according to the pen to be manufactured. _Cutting the Blank._--This is a mechanical operation, and is effected with the aid of a screw press, in which a pair of tools corresponding with the shape of the pen has been fixed. On pulling a lever the screw descends, driving the punch into the bed, which cuts a blank with a scissors-like action, from the strip of steel. _Marking the Name._--This is done by means of a punch fixed in the hammer of a stamp, worked by the foot. The blanks are rapidly introduced between guides fixed on the bed of the stamp, and as soon as the hammer has fallen the blank is thrown out and a new one introduced. _Piercing._--The tools for this operation are of a delicate character. The blanks are fed by hand, as above explained, and the hole punched by a screw press. This is a most important process; the pierce hole and slide slits determine the elasticity and regulate the flow of the ink on the pen. _Annealing or Softening._--The blanks are still moderately hard and before raising, it is necessary to soften them by heating to a dull red, and allowing them to gradually cool. _Raising._--The operator places one of the soft blanks on a die to which guides are affixed to keep it in position; then by moving the handle of the press, the screw descends, forcing a die which rounds the blank into the form of a pen. _Hardening._--The pen is now too soft, and is hardened by heating and the immersing in oil while hot, after which it is thoroughly cleansed from all grease. _Tempering._--The pens are now hard but very brittle, and in order to correct this defect they are placed in an iron cylinder, and kept revolving over a gas or charcoal fire until they acquire a proper temper. _Scouring._--After soaking in diluted sulphuric acid, the pens are placed in iron cylinders containing fine stone and water, or fine sand, and revolved for several hours. When taken from these cylinders they are bright and smooth. _Grinding._--This is a process performed by hand on a “bob,” or wooden wheel covered with leather and dressed with emory, revolving at high speed. A light touch on the emory wheel grinds off the surface between the pierce hole and the point, to obtain proper action and to assist the flow of ink. _Slitting._--This is a hand process performed with a press, the cutters being as sharp as razors. The pen is placed in position by means of guides, and must be cut with utmost precision from the pierce hole to the point, the point must be divided exactly in the middle, the least variation making the pen defective. _Coloring and Varnishing._--The pens having been polished to a bright silver color are placed in an iron cylinder and kept revolving over a gas or charcoal fire until the tint required is produced. They are then immersed in a bath of shellac varnish, and afterwards dried in an oven. _Examination._--Every steel pen passing through the factory is most carefully examined before being boxed, and should the least fault be found, it is at once rejected.] Why Does a Pencil Write? You can use a pencil to write with or to make marks, because the pencil wears off if you are scratching it on a surface that is rough enough to make it do so. Writing, you know, is only a way of making marks in such a manner as to make them mean something. You cannot write with a pencil on a pane of glass, because the glass is so smooth that when you move the pencil over its surface, the pencil will not wear off. To prove to yourself that the tip of the pencil constantly wears off when you write, you have only to recall that when you write with it a pencil keeps getting shorter and shorter. A slate-pencil will wear down short by merely writing with it, but a lead-pencil must be sharpened--that is, you must keep cutting away the wood in order to get at the lead inside. Why Can’t I Write on Paper With a Slate-pencil? You cannot do so, because it takes something with a rougher surface than paper to wear off the point of a slate-pencil. A slate is used to write on with slate-pencils, because slate wears off the end of the pencil easily, and also because you can rub out the writing on a slate with water. Lead-pencils are used for writing on paper, but you must have a rough surface on the paper to write on even with a lead-pencil. Some kinds of papers have such a smooth surface that you cannot write on them with a lead-pencil. How Does a Pen Write? Writing with a pen, however, is quite different from writing with any kind of pencil, because in writing with ink we do not wear off the end of the pen, but have the ink flow from the pen. For this purpose we must have a surface that will absorb the ink from the pen, and draw the ink down off the pen and make it flow. A slate has no power of absorption and therefore cannot draw the ink. A piece of blotting paper is the best kind of paper for absorbing ink, but it is too much so for writing purposes. For writing with ink we need a comparatively hard surfaced paper that has absorbent qualities, but not too absorbent. How Does a Blotter Take Up the Ink of a Blot? It is because the blotter has a very excellent ability to absorb some liquids. The thinner the liquid the more easily the blotter will absorb it. Ink is thin--being mostly water--the blotter is of a loose texture and has a rough surface. This gives the blotter the ability to pick up the ink, just as a sponge would do. A sponge has what is called the power of capillary attraction and so has the blotter. Where Does Chalk Come From? Deposits of chalk are found on some shores of the sea. A piece of chalk such as the teacher uses to illustrate something on the blackboard at school consists of the remains of thousands of tiny creatures that at one time lived in the sea. All of their bodies excepting the chalk--called carbonate of lime in scientific language--has disappeared and the chalk that was left was piled up where it fell at the bottom of the ocean, each particle pressing against the other with the water pressing over it all until it became almost solid. It took thousands of years to make these chalk deposits of the thickness in which they are found. Later on, through changes in the earth’s surface, the mountain of chalk was raised until it stood out of the water and thus became accessible to man and school teachers. How Did Men Learn to Talk? Talking and the words used came into being through the desire of men to communicate with each other. Before words became known and used man talked to those about him by the use of signs, gestures and other movements of the body. Even to-day when men meet who cannot talk the same language they will be seen trying to come to an understanding by the use of signs and gestures and generally with fair results. The need of more signs and gestures to express a constantly increasing number of objects and thoughts led to the introduction of sounds or combination of sounds made with the vocal cords to accompany certain signs and gestures. In this way man eventually developed a very considerable faculty for expressing himself. Sign by sign, gesture by gesture and sound by sound language was slowly developed. A man would be trying to explain something to another by sign or gesture and to make it more clear would make a sound or combination of sounds to put more expression into his efforts. Finally the other man would understand what was meant and he would tell some one else, using the same signs, gestures and sounds. Later on it would develop that to express thus any certain thought, act or the name of a thing, all of the people in the community would make this same combination of sounds, signs and gestures to express the same thing. Finally the gestures and signs would be dropped and it was found that people understood perfectly what was meant when only the sound or combination of sounds was produced. That made a word. All the other words were made in the same way, one at a time, until we had enough words to express all the ordinary things and the combination of words became a language. The children learned the language by hearing their parents talk it, and that is how men learned to talk. How Did Shaking the Head Come to Mean “No”? The origin of this method of indicating “No” is found in the result of the mother’s efforts in the animal kingdom of trying to feed her young. A mother animal would be trying to get her young to accept the food she brought them and tried to put it in their mouths. Perhaps, however, the young animal had had sufficient food or did not fancy the kind of food offered. The natural thing to do under the circumstances would be to close the mouth tight and shake the head from side to side to prevent the mother from forcing the food into the mouth. Thus we get the closed lips and the shaking the head from side to side to mean “No.” In other words, that kind of a way of saying “No” came from an effort to say “I don’t want any.” How Did a Nod Come to Mean “Yes”? The idea of nodding to mean “Yes” comes from the opposite of the action which, as just described, indicates a “No.” When the young animal was anxious to accept the offered food, it made an effort to get at the food quickly. Hence, the pushing forward of the head and the open mouth (always more or less opened when you nod to indicate “Yes”) and an expression of gladness. You will notice if you see anyone nod the head to indicate “Yes” that the lips are open rather than closed, and that there is always a smile or an indication of a smile to accompany it. In other words, the nod to mean “Yes” is only another way of saying “I shall be pleased.” Why Do We Count in Tens? When man even in his uncivilized state found it necessary to count, the only implements at hand were his fingers and toes, and as he had ten toes and ten fingers, he naturally began counting in tens, and has been doing so ever since. When we to-day count on our fingers we confine ourselves to our fingers leaving our toes stay in our shoes, where they naturally belong. But the first men who counted used both fingers and toes, and so he was able to count twenty before he had to begin over again, while little children to-day, when they count with their fingers, must begin where they started after they reach ten. What Does Man Mean by Counting Himself? The expression “counting himself” was originated by the first man who counted. Such a man would count all of his fingers and toes and the result would be twenty. Then, so that he would remember the number of times he had counted himself, he made a mark some place each time he reached twenty. The mark he made was a mere scratch in the dirt or on a hoe or something else. To make a scratch you merely, of course, score the surface of whatever you happen to be scratching on, and that is how it happened that the word “score” in our language to-day means as a term in counting, twenty. There has been a great effort made to change our system of counting in tens to one where you count in twelves. That would fit in very well with our system of measuring which is based on the foot of twelve inches, and of our calendar for recording the passage of time which has twelve months. There are many arguments in favor of this change, among the principal of which is the fact that it would make our problems of division much easier, for our ten can be evenly divided by but two of our single figures, two and five, whereas twelve can be evenly divided by four of our single figures, viz., two, three, four and six. It is believed that sooner or later the system of counting by twelve instead of ten will be adopted by the entire world for counting everything. As it is now we do part of our counting by one system and part of it by another. Where Did All the Names of People Originate? There is no scientific plan by which people get their names. There is not much except curious interest to be gleaned from the study of how people got their names. In the earliest days of the world, or at least as soon as men had learned to speak by sounds, all known persons, places and groups of human beings must have had names by which they could be spoken of or to, and by which they were recognized. The study of these names and of their survival in civilization enables us in certain instances to tell what tribes inhabited certain parts of the earth now peopled by descendants of an entirely different race and of another speech altogether. We learn such things from the names of mountains and other things, for instance, which still cling to them. The story of personal names is very complex, but comes from very simple beginnings. The oldest personal names were those which indicated a group of people rather than individuals who may have been actually related to each other or even bound together for reasons of protection or other convenience. In the races of Asia, Africa, Australia and America examination shows that groups of people who considered themselves to be of the same relationship, attached to themselves the name of some animal or other object, whether animate or inanimate, from which they claimed to be descended. This animal or object was called the “totem,” and thus the earliest and most widely spread class and family names are totemistic. Such groups called themselves by names from wolves, turtles, bears, suns, moons, birds, and other objects, and these people wore badges with pictures of the animal or object from which they took their names to identify them to other people. When, then, we come to investigate the giving of personal names among the tribes, we see that most uncivilized races gave a name to each new-born infant derived from some object or incident. So a new-born member of the “Sun” tribe would be named “Dawn,” and would be known as “Dawn” of the “Sun” tribe; or perhaps a new-born son of the tribe of “Wolf” would be called “Hungry,” and be known as “Hungry Wolf.” A member of the “Cloud” tribe would be named “Morning,” because he was born in the morning. He would always be known as “Morning Cloud.” Later, as society became more established and paternity became recognized, we find the totem name give way to a gentile name. Among the Greeks and Romans the system was early adopted and proved satisfactory. Thus we have Caius Julius Caesar. Caius indicates that he is Roman; Julius is the gentile name given him and the Caesar a sort of hereditary nickname. On the other hand, the early Greeks began the system of introducing a local name instead of the gentile name. Thus Thucydides (obtained from the grandfather), the son of Olorus, of the Deme (township) of Halimusia. ~HOW DIFFERENT NAMES ORIGINATED~ This was all right and suited the purposes of the Greeks and Romans, who had plenty of time to give full explanations in this way. But in Europe, for instance, civilization demanded more speed, and the increase of population demanded more names, so that nicknames and names indicating personal descriptions and peculiarities came into use. Such names as Long, Short, Small, Brown, White, Green and others of the same kind came from this source, and as families grew these surnames stuck to the family and parents gave their children Christian names to further distinguish them as individuals. Other surnames such as Fowler, Sadler, Smith, Farmer, etc., became attached to people because of the occupations in which they were engaged, and yet other names were derived from places. The owner of an extensive estate would be designated by a Christian name which might be George (after his King) and then to indicate his landownership, von (meaning of) Wood, making the combination of George von Wood, meaning George, the owner of the place called Wood. On the other hand, he might have working for him a laborer who lived at the place and, if his name was Hiram, they would, to indicate where he belonged, put the Wood after the Hiram; but, lest there be confusion as to his class, they would put an At before the Wood and make him Hiram Atwood, indicating his Christian name, where he worked and the fact that he was not a landowner. Many other names were invented in similar manner. When Adams became so common that there would likely be confusion on account of there being so many of them, a son of one of the Adams family would add to the name the fact that he was a son by writing his name Adamson, and thus start a new family name. Thus, in the same way also came Willson, Clarkson, and other names of that kind. For a long time the Jews had only one word for a name, such as Isaac, Jacob, Moses, etc. They became so numerous that it was impossible to distinguish them, and so a commission was named to give surnames to all the Jews in addition to their other names. As the race was then, as now, held in derision by the rulers of many nations into which the tribe had become scattered, the people who had charge of the naming of the Jews took advantage of the opportunity to make sport of them, and gave them such names as Rosenstock (Rose bush), Rosenszweig (Rose twig), Rosenbaum (Rose tree), Blumenstock (Flower bush), Blumenthal (Flower valley), etc., etc. Our Christian names are from similar sources, and while many of them are well selected because of their beautiful meanings, there are many of them which mean nothing as words as they were only invented for the purpose of giving a new name to a new child. Why Can You Blow Out a Candle? When you light a candle it burns, because the lighted wick heats the wax sufficiently to turn it into gases, which mix with the oxygen in the air and produce fire in the form of light. You know it is not easy to light a candle quickly. You must hold the lighted match to the wick until the wax begins to melt and change to gases. As long as the wax continues hot enough to melt and turn to gas the candle will burn until all burned up; but if there is a break in the continuous process of changing the wax to gas, the light will go out. Now, when you blow at the lighted candle, you blow the gases which feed the flame away from the lighted wick, and this makes a break in the continuous flow of gas from the wax to taper, and the light goes out. [Illustration] The Story in a Photograph How Does a Camera Take a Picture? When we look upon the surface of a mirror we see the image of ourself and our surroundings. The extent of the view depends upon the size of the mirror and the distance we are standing from it. If we hold the mirror close to our face we see only the face, or perhaps but a portion of it, and the farther away we are the more the mirror will reflect, only, of course, the various images will be smaller. The mirror reflecting exactly what the eye sees, without doubt had a great influence in inducing the experiments that resulted in the process we call photography. The taking of a photograph with a camera may in a way be compared with the action of your eyes, when you gaze upon your reflection in a mirror, or look at any object or view. Any object in a light strong enough to render it visible will reflect rays of light from every point. Now, the eye contains a lens very similar in form to that used in a camera. This lens collects the rays of light reflected from the object looked at and brings them to a focus in the back of the eye, forming an image or picture of whatever we see, just as the mirror collects the rays of light and reflects them back through the lens of the eye. Certain nerves transmit the impression of the image so focused in the back of the eye to the brain and we experience the sensation of sight. What Is the Eye of the Camera? The lens is the eye of the camera, and the process we call photography is the method employed to make permanent the image the eye or lens of the camera presents to a sensitive surface within the camera. Fig. 1 shows a simple form of camera, it being merely a light tight box with a lens fitted to the front, and a means for holding a sensitive plate at the back, the plate being placed at just the right distance to focus the rays of light admitted through the lens in exactly the same manner as the rays of light pass through the lens of the eye and come to a focus in the back part of the eye. Now, if we could look inside the camera we would note that the image was inverted, or upside down. Fig. 2 will explain this. The rays of light from “A” pass in a straight line through the lens “B” until they are interrupted by “C,” upon which they strike, forming an upside down image of the object “A.” But, you exclaim, “we do not see things upside down.” No, we do not, because some mental process readjusts this during the passing of the impression from the eye to our brain. Let us suppose we have our camera loaded with its sensitive plate or film. We select some object or view we wish to photograph, uncover the lens for an instant, and let the light impress the image upon the sensitive surface of the plate or film. Now, how are we going to make this image permanent? If we were to examine the creamy yellow strip of film upon which the picture was taken there would seemingly be no difference between its present appearance and before the snapshot was made. Now let us suppose that this strip of film is a little trundle bed, and in it tucked securely away from the light are many hundreds of little chaps called silver bromides, little roly-poly fellows lying just as close together as possible, and protected by a coverlet of pure white gelatine. ~HOW A PHOTOGRAPH IS DEVELOPED~ Until the sudden flash of light in their faces when the picture was taken, they have been content to lie still and sleep soundly. Now they are seized with a strange unrest, and each little atom is eager to do his part in showing your picture to the world. Alone they are powerless, but they have, all unbeknown to them, some powerful chemical friends, who, organized and aided by the photographer, will bring about their transformation. These chemicals, with the help of the photographer, form themselves into a society called the developer. The photographer takes just so many of the tiny feathery crystals of pyro, just so many of the clear little atoms of sulphite of soda, and just so many little crystals of carbonate of soda, and tumbles them all into a beaker of clear cold water. Unaided by each other, any one of these chemicals would be powerless to help their little bromide of silver friends. The first of these chemicals to go to work is the carbonate of soda. He tiptoes softly over to the trundle bed and gently begins turning back the gelatine covers over the little bromide of silver chaps, so that Pyro can find them in the dark. It is Pyro’s mission to transform the little silver bromides into silver metal, but he is rather an impulsive chap, so he is accompanied by sulphite of soda, who warns him not to be too rough, and whose sole mission is to strain his eagerness to help his friends. “Go slow now,” says Sulphite, “don’t frighten the little silver bromides, or else you’ll make them cuddle up in heaps, and the picture won’t be as nice as if you wake them up gently and each little bromide stayed just where he belonged.” After all the little silver bromides that the light shone on have been transformed into metallic silver by the developer, another chemical friend has to step in and carry away all the little bromides that were not awakened by the flash of light. This friend’s name is “Hypo,” and in a few minutes he has carried away all the little bromides that are still sleeping, so that the trundle bed with the now awakened and transformed silver bromides will, after washing and drying, be called a negative, and ready to print your pictures from. If we take this negative, as it is called, and hold it up to the light, we will see that everything is reversed, not only from right to left, but also that whatever is white or light in color is dark in the negative, and that what would correspond to the darker parts of our picture are the lightest in the negative, and it is from these facts that we give it the name negative. Now, to get our picture as it should be, we must place this negative in contact with a sheet of coated paper that is also sensitive to light. So we place the negative and the sheet of sensitive paper in what is called a printing frame, with the negative uppermost, so that the light may shine through the negative, and impress the image upon the sheet of sensitive paper. Now, it stands to reason that if the lightest parts of our picture are the darkest in the negative that less light can pass through such portions of the negative in a given time, so that with the proper exposure to light the image upon the sheet of sensitive paper will be a correct picture of whatever the lens saw. [Illustration: The swiftest thing that the human race has ever put into motion is the steel projectile of a twelve-inch gun. No human eye can follow its flight. Released at a pressure of forty thousand pounds to the square inch--in a heat at which diamonds melt and carbon boils--it hurls through the air at the rate of twenty-five miles a minute, and reaches the mark _ahead of its own sound_! (Pictures and story by courtesy of McClure’s Magazine.)] TWENTY-FIVE MILES A MINUTE AN EXCLUSIVE STORY, ILLUSTRATED WITH A SERIES OF REMARKABLE PHOTOGRAPHS TAKEN WITH THE FASTEST CAMERA IN THE WORLD BY CLEVELAND MOFFETT ~HOW SHOOTING SHELLS ARE PHOTOGRAPHED~ One of the most progressive branches of our military service is the Department of Coast Defenses, which, under the far-seeing guidance of General E. M. Weaver, holds our shores and harbors in a state of alert preparedness against foreign aggression. At Hampton Roads sits the Coast Artillery Board, composed of officers and consulting engineers to whom are referred all problems relating to coast artillery, and who have the responsibility of testing all new instruments proposed for artillery use. The purpose of this article is to describe one among several notable achievements of the Hampton Roads Coast Artillery School, this particular work having been done by Captain F. J. Behr of the Coast Artillery Corps, who, after years of effort, has recently developed a system that makes it possible to take pictures of the swiftest moving bodies, the great steel projectiles of our biggest guns--to seize them with the camera’s eye as they hurl through the air at enormous velocities or at the very moment of their emergence from the gun muzzles, and to preserve these images, never seen before, for military study and comparison. Captain Behr was ably assisted in this work by Engineer J. A. Wilson. [Illustration: THE FASTEST CAMERA IN THE WORLD The big gun, equipped with the fastest camera shutter in the world, about to be fired and the shell photographed. For years a young officer of the Coast Artillery has been trying to devise a camera so incredibly swift that it will record every stage of this lightning flight from the gun-barrel to the target. At last he has succeeded. His photographs--some of them taken one hundred thousandth of a second apart--have revealed remarkable and unsuspected facts to the military world. The story of his invention had never before been told.] Reckoning in Millionths of a Second. Some of the increments and decrements of time involved in the series of photographs herewith published (several of them for the first time) are as small as one ten-thousandth part of a second. And Captain Behr has devised a method of taking photographs of projectiles as they arrive at a steel target and penetrate the target, inch by inch, that involves increments or decrements of time as small as the one hundred-thousandth part of a second. To the uninitiated it seems incredible that such infinitesimal divisions of time can be used in practical calculations; but every trained physicist knows that in wireless work scientists of to-day speak casually of experiments that take account of _two-tenths or one-tenth of a millionth part of a second_! [Illustration: THE PROJECTILE EMERGING FROM MORTAR In this photograph--the first of a remarkable series showing five stages of a moving projectile--the half-ton projectile seems to be standing still, but really it is traveling at the rate of 900 miles an hour. The gunners here work in concrete pits 34 feet high. Underneath the mounts are the powder magazines. Each pit has four mortars usually served by an entire Coast Artillery Company. The projectiles are the same as those used in the twelve-inch guns, but less powder is required because mortar projectiles are hurled high in the air, not straight at a vessel, and deliver their destructive blows downward from a great height.] [Illustration: THE SMOKE RINGS WHICH APPEAR This second photograph shows the projectile almost entirely out of the mortar. Its sharp nose may be seen above the “gas-ring” forming at its upper end. These “gas-rings,” or “smoke-rings,” come without warning, and only occasionally, perhaps once in eight or ten shots. They rise swiftly to the height of fifty or a hundred feet, growing larger and larger, and giving forth a weird, shrieking sound like a second projectile. Some insist that these “smoke-rings” are as hard as steel, owing to the enormous compression of their composing gases, and the story is told of a bird caught in the path of one of them and torn to pieces.] What happened to the projectile after it leaves the gun, or after the discharge of the gun, and before the projectile has had time to issue from the gun-barrel? What is the action at the muzzle of gases generated? What shape do these gases assume as they leave the gun? What causes the much-discussed “gas-rings” that sometimes form when a mortar is fired, and oftener do not form? What phenomena attend the arrival of the projectile at a solid steel target? Is the steel actually fused by the heat of impact? Is it vaporized? Or what? These are some of the questions that Captain Behr set himself to solve, or to help in solving, as he worked out his methods of rapid photography. His aims were strictly military, but his results make fascinating appeal to the general imagination. Fancy doing anything in the one hundred-thousandth part of a second! [Illustration: THE PROJECTILE HIDDEN BY THE SMOKE CONE In the third photograph the smoke-cone is almost perfect and gives the famous “powder-puff” effect. It still hides the projectile, although the latter is traveling at a velocity that would take it from New York to Chicago in one hour. At night the “gas-rings” present a startling and fascinating appearance, burning with a reddish orange glow, and whirling with a complicated double motion, strange opalescent balls, like rings of Saturn. A study of these photographs--the first record ever made of the “gas-rings”--has led some experts to the conclusion that the cause of the rings is defective ramming of the projectile.] [Illustration: THE PROJECTILE EMERGING FROM SMOKE CONE The fourth photograph shows the projectile emerging from the smoke-cone about thirty feet above the muzzle of the mortar. The men who fire these mortars from the mortar-pits never see the distant target or vessel they are firing at, but point their mortars according to directions transmitted to them (usually by telephone) from observers at distant stations. And so great a degree of precision has been attained that, on certain practice occasions at Hampton Roads, a record of nine hits out of ten shots has been scored on a moving target five miles out in the ocean. This picture shows the smoke-cone as first seen by the human eye.] Captain Behr’s general idea was to utilize some phenomena connected with the discharge to actuate, by electrical connections, a mechanism that would work a rapid shutter in a properly placed camera. The phenomenon of concussion was tried first--the smash of air against a little swinging door; but this was much too slow. The projectile was hundreds of yards away before the camera had registered its picture. And that chance was gone! [Illustration: THE PROJECTILE HIGH IN THE AIR In the fifth photograph the projectile is seen entirely clear of the smoke-cone and well started on its long flight. Climbing into the sky at this steep angle, it will reach a height of from three to six miles before it begins to descend. There are harbors on our coasts guarded by so many guns and mortars that if these were fired simultaneously they could hurl against a given small area a converging rain of projectiles aggregating more than fifty tons in their combined mass. A minute later they could hurl another fifty tons against the same small area; and so on as long as the ammunition lasted.] In the next trial, several months later, Captain Behr arranged to have the electrical connections made or broken by the movement of the gun-carriage itself in recoiling; but the result was unsatisfactory. Nor was he more fortunate at the succeeding target practice, when, having placed the apparatus farther forward on the parapet, he had the camera demolished by the force of the concussion and several blades of the rapid shutter broken. He was satisfied, now, that his effort to actuate the camera mechanism from the gun-carriage would never give the requisite precision in results, and he saw that he must work with a device functioning more reliably. In the months that followed before the next target practice, the Captain did some experimenting, and finally determined making the projectile itself displace a length of piano-wire fixed across the muzzle of the gun, and thus actuate the electrical system and operate the shutter. In this way he eliminated troublesome variables of recoil, elasticity of the carriage, etc., leaving to determine only the time element of the electrical system to function. This result was admirable, and, after taking several similar pictures, the captain found that he could now operate with great precision--that is, he could get the same phase of the discharge with almost identical shapes of gas-cone and smoke-cloud, and he could get these every time. In the fall of 1912 Captain Behr succeeded in obtaining a series of extremely rapid photographs showing a twelve-inch mortar battery in action. In taking these pictures the camera was placed on an elevation about ten feet above the concrete floor and about sixty feet back of the mortars. The electrical device for working the shutter was actuated by the mortar itself in its recoil. These pictures were taken in about one five-thousandth of a second--which is the more remarkable as the last two were taken in the shade after 4.30 A.M. The first three were taken about noon, in the sunshine, as the shadows show. So great was the precision of the electrical device as to render possible the photographic recording of these mortar projectiles, moving at great velocities, in almost any desired position after the discharge, say two feet away from the muzzle, or six feet away, or twenty feet away, or right at the muzzle, as shown in the first mortar picture, where the great projectile has been caught in its flight half way out of the mortar. Pictures Never Seen By the Human Eye. ~A CAMERA THAT IS FASTER THAN THE EYE~ It is interesting to note that of these five mortar pictures, representing five phases of the firing, only the last two are ever seen by the human eye. The far swifter camera, acting in about one five-thousandth of a second, has caught all these phases as reproduced here; but, to the ordinary observer standing by, the first visible impression after firing is that of the smoke-cone as developed in Number Four. The strange “powder-puff” effect shown in Number Three is never seen; nor the earlier effects in Numbers One and Two. Nor is any sound heard by an observer or by the gun crew until the third or fourth phase has been reached. This is a matter of simple calculation. Sound travels through the air very slowly as compared with light, and in Numbers One, Two, and Three, although the crashing explosion has taken place and the projectile is already started on its long journey, the men (even the lanyard man, who is nearest), have heard nothing, since the sound-waves have not yet had time to reach their ears. Nor has the mortar itself had time to recoil, as it does presently, down into the well in the floor of the pit. The men aboard the towing vessels that drag the floating targets during gun and mortar practice would seem to be in a dangerous position, since the tow-line is not more than two hundred yards long for guns and five hundred yards long for mortars, and a very slight error in aim or adjustment might cause a deviation of several hundred yards when the range is eight or ten thousand yards. As a matter of fact, such errors do not occur, and a gun-pointer who would make a right or left deviation from the target of ten yards, or at the most fifteen yards at a distance of five miles, would be considered unfit for his job. In one or two rare instances a towing vessel has been struck when a projectile has fallen short and then ricochetted to the right, as it invariably does owing to its rotation in that direction. The rifling of the gun-barrel causes this rotation. [Illustration: This shows one of Captain Behr’s earliest efforts to photograph the projectile from a twelve-inch gun. The man on the platform has been adjusting the electrical connections that actuate the camera mechanism. The halo effect at the muzzle of the gun is due to compressed air caused by the forward rush of the projectile. The projectile has not yet emerged from the muzzle of the gun. On the right is the place where the “Merrimac” and the “Monitor” had their famous fight.] Sometimes these great projectiles ricochet several times, and go bounding over the water as a pebble skips along the surface of a mill-pond, only there may be the distance of a mile or more between these giant leaps. The Projectile Travels Faster Than the Sound It Makes. A strange phenomenon is witnessed by the observer on a towing vessel as he looks, rather uneasily perhaps, toward the distant shore battery, that seems to be firing straight at him. First there is a flash and a puff of smoke; then nothing for a period of seconds, while the projectile is on its way; then suddenly a great splash as the mass of iron strikes the water. Up to this moment there has been no sound of the discharge, no sound of the projectile, since it travels faster than the sound-waves; but now, _after_ it has buried itself in the ocean, is heard its own unmistakable voice, a low, buzzing _um-m-m-m_ approaching from the shore. The projectile itself has arrived _before_ the sound that it makes in transit, and the sound arrives afterward. Last of all is heard the boom of the discharge. [Illustration: A GUN THAT PHOTOGRAPHED ITS OWN SHOT In this beautiful picture the hurling projectile was itself the photographer: that is, in passing out of the gun-barrel, it broke a length of piano-wire stretched across the muzzle and thus automatically closed an electrical circuit that actuated the camera mechanism. And so rapid was the shutter that the great shot hurled forth in the discharge photographed here has not yet had time to issue from the smoke-cone, where it is still hidden.] Owing to the great velocity of gun projectiles, it is almost impossible for an observer near the target to see them as they approach; but a trained eye can discern the slower moving mortar projectiles as they drop out of the sky, shrieking as they come, curving downward from a height of four or five miles, half a ton falling from a height of four or five miles. [Illustration: EXPLODING A SUBMARINE MINE This photograph illustrates another important form of coast defense--the submarine mine. A target about 5 by 5 feet, with a red flag at its apex, is towed across the mine-field, the mines being exploded electrically from a shore station several miles away. The methods of laying and exploding these mines are carefully kept secrets. In this case a charge of five hundred pounds of the newest explosive was used. Fragments of the shattered target and mine-buoy are seen at the right of the picture. Tons of water are hurled into the air by these explosions, and hundreds of fish are killed or stunned.] It is difficult to realize what an enormous force is released when one of these twelve-inch guns is discharged. The pressure inside of the gun behind the projectile is between thirty-five and forty thousand pounds to the square inch. No engine or machine made by man produces anything like this pressure. The boiler pressure in steam-engines, or in big turbines driven by superheated steam, does not exceed two hundred or three hundred pounds to the square inch. The huge hydraulic presses that would crumple up a steel girder do not exert a pressure of more than one thousand pounds to the square inch. The only reason a gun-barrel can resist this pressure (forty thousand pounds to the square inch) is that it is built up in a series of concentric steel hoops or tubes shrunk one over the other until there is a resistance capacity of from seventy thousand to ninety thousand pounds to the square inch. Even at rest, the barrels of these great guns are under such enormous compression, from being thus squeezed within these outer steel coverings, that, if the retaining steel jackets were suddenly cut, the tubes would blow themselves into pieces from the violent reaction of release. Not only does this smokeless powder, burning inside these guns, produce enormous pressure, but it generates inconceivably great heat. Water boils at 100° Centigrade; iron melts at 1400°; platinum and the most resistant metals at 2900°; while the hottest thing on earth is the temperature of the electric arc, in which carbon boils. This temperature is between 3000° and 4000° Centigrade, and is believed to be the same as that of these great powder chambers when the gun is fired. Thus a diamond, the hardest substance known, would melt in the barrel of a twelve-inch gun at the moment of discharge. The consequence is that at each discharge of a big gun a thin skin of metal inside the barrel is literally fused, and this leads to rapid erosion of the softened surfaces under the tearing pressure of gases generated. The rifling is worn away; the band over the projectile becomes loose-fitting; and soon the huge gun, that has cost such a great sum, is rendered unfit for service. The life of a twelve-inch gun is only 450 rounds, that is, the gun would be worn out if fired every three minutes for a single day. After that a new life may be given it by boring out the inner tube and putting in a new steel lining. A Secret for Which Foreign Governments Would Pay Millions. A few words may be added about the formidable smokeless powder used in these great guns. This powder, in spite of its terrible power, is of innocent appearance, and a small stick of it may be held safely in the hand while it burns with a vivid yellowish flame. There is no danger of its exploding or detonating like gun-cotton, and yet it is made from gun-cotton, treated by a colloiding process that is one of our jealously guarded military secrets. There are foreign governments that would give millions to know exactly how this powder is made and how it is preserved for years without deterioration. The recent destruction of two ships of the French navy was due, it is believed, to deterioration of their smokeless powder. [Illustration] Why Do Some Eyes In a Picture Seem to Follow Us? If a person’s picture is taken with the eyes of the person looking directly into the lens or opening of the camera, then the eyes in the picture will always be directly on and appear to follow whoever is looking at it. This is also true of paintings. If a subject being painted is posed so as to look directly at the painter, and the artist paints the picture with the eyes so pointed, then the eyes of the picture will follow you. When you are looking at a picture of a person and the eyes do not follow you, you will know at once that he was not looking at the camera or artist when the picture was being taken or painted. [Illustration] Where Does a Light Go When It Goes Out? ~WHY YOU CAN BLOW OUT A CANDLE~ To understand the answer to this question fully you will first have to learn what light is, and particularly that it is not the flame from the gas jet or of the lamp or candle that is actually the light, but that light consists of rays or waves in the ether, which is constantly in all space and even in our bodies, coming from the something that is burning. This in the instance above mentioned would be the gas burning as it comes out of the gas jet, the oil in the lamp as it comes up through the wick or the flame of the candle. We are apt to call a lighted gas jet a lamp, or a candle, light, because it is steady. Really, however, there is no such thing as keeping light in a room in an actual sense, for rays of light travel from the substance which produces them faster than anything else we know of in the world. The first thing a light wave does when it is once created is to go some place, and it does this at the rate of 186,000 miles per second. If it cannot penetrate the walls of the room it is either reflected back in the direction from which it came or transformed by the objects which it strikes into some other kind of energy. When you look at the rays coming from a gas jet, you do not see one ray for more than, say the millionth part of a second, but because these rays of light come so fast one after the other from the burning jet and spread in all directions, they seem to be continuous. So you see that the rays of light are going away as fast as they are coming from the gas jet. They either go on as light or, as said above, are changed into other forms of energy when they strike things they cannot penetrate in the form of light, or rather one thing, which is heat. A large part of it goes into the air in the room in the form of heat, as you well know, now that it is called to your attention. Some of it goes into the furniture and some of it is changed into another form of heat, which, combining with the chemicals in other things it mixes with, changes their appearance and usefulness. As, for instance, the carpets and hangings in the room, the colors of which become faded when exposed to light rays too much. The heat from the light rays is responsible for the fading of colors in our garments as well. When you “put out the light,” as we say, or turn off the gas, you cut off the source of light. Really, then, our expression that “the light goes out” is only true while the gas is lighted, for from the flaming gas jet the light is going out all the time, whereas when the gas is turned off no light is being produced, and when you turn off the gas you do not turn out the light, but only that which makes light. Why Does a Fire Go Out? Fire will go out naturally when there is nothing left to burn, or it will go out if it cannot secure enough oxygen out of the air to keep it going. In the first case it dies what we might call a “natural death,” and in the latter case the fire practically suffocates. The fire in the open fireplace, if it has plenty of air, will burn up everything burnable that it can reach. The stones of the fireplace or other parts of a stove will not burn, because they have already been burned, and you cannot burn anything a second time, if all of the oxygen in it was burned out of it the first time. Now, then, to burn up a thing, you must first start a fire under it, and then keep a constant draft of air playing on it from beneath, or the fire will die out. The more difficult a thing is to burn, the more important it is that you have plenty of draft. If the ashes accumulate under the fire the air cannot go through them in sufficient quantity and the fire will go out. Other things which prevent the current of air from going up through the fire will cause it to go out. That is why we close the lower door of the furnace, to keep the fire from burning out. When we shut off the draft of air from below, the fire in the furnace burns slowly, i. e., it just hangs on, so to speak. Why Does a Lamp Give a Better Light With the Chimney On? When a lamp is burning without a chimney it generally smokes. That is because the oil which is coming up through the wick is being only partially burned. The carbon, which is about one-half of what the oil contains, is not being burned at all, and goes off into the air in little black specks with the gases which are thrown off. The reason the carbon is not burned when the chimney is off is that there is not sufficient oxygen from the air combining with it, as it is separated from the oil in the partial combustion that is going on. To make the carbon in the oil burn you must mix it with plenty of oxygen at a certain temperature, and this can only be done by forcing sufficient oxygen through the flame to bring the heat of the flame to the point where the carbon will combine with it and burn. When you put the chimney on the lamp you create a draft which forces more oxygen through the flame, brings the heat up to the proper temperature and enables the carbon to combine with it and burn. When you take the chimney off again the heat goes down, when the draft is shut off and the lamp smokes again. The chimney also protects the flame of the lamp from drafts from the sides and above, and helps to make a brighter light, because a steady light is brighter than a flickering one. The draft created by the chimney also forces the gases produced by the burning oil up and away from the flame. Some of these gases have a tendency to put out a light or a fire. Does Light Weigh Anything? To get at the answer to this question we must go back to the definition of light. Light is a wave in the ether and contains no particles of matter. It, therefore, does not weigh anything at all. When men had studied light thoroughly, however, they came to the conclusion that it must have the power of pressure, which, from the standpoint of results, would amount to the same thing as having weight. They reasoned that if you had a perfect balance and let sunlight shine down on one of the sides of the balance, that side should go down under the pressure of light. In their first experiments along this line men failed to show that under such conditions the side of the balance on which the light shone did go down, but by continuous experiments it was proved finally that the light did exert a sufficient pressure to cause the scales to go down, and in effect this is the same as having weight; but this has been found to be a common property of rays of various kinds, including heat, and we, therefore, do not speak of this quality as weight, but as the power of radiating pressure. Why Does a Stick Seem to Bend When Put in Water? When light passes from one medium to another, as for example from glass or water to air, or from air or glass to water, the rays of light change their course, thus making them seem to be bent or broken. The rays of light from the part of the stick in the water take a different direction from the rays from the part which is out of the water, giving the appearance of breaking or bending at the place where the air and water meet. It is, of course, the light rays which are bent and not the object itself. This bending or changing of the path of light rays is called refraction. If you place a coin in a glass of water so that it may be viewed obliquely, you can apparently see two coins, a small one through the surface of the water and another apparently magnified through the side of the glass. This is due only to the absolute principle that rays of light change their direction in passing from one thing to another, and on this principle of the rays of light our optical instruments, including the microscope, the telescope, the camera and eyeglasses are based. What Makes the Stars Twinkle? I might tell you, just to show how clever I am, that stars do not twinkle at all, and leave you with that for an answer. But since they really do seem to twinkle, and that is what causes your question, I will tell you. As we have already learned in our talks about the stars and the sky in general, the stars are suns which are constantly throwing off light, just as our sun gives us light, and when this light strikes the air which surrounds the earth it meets many objects--little particles of dust and other things always floating about in it. The light comes to us in the form of rays from the stars and some of these rays strike particles of various kinds in the air and are thus interfered with. If you are looking at a lighted window some distance away and there are a lot of boys and girls or men and women running past the window, one after the other, rapidly, it will make the light in the window appear to twinkle. The twinkling is due to the interference which the rays of light encounter while traveling toward the eye. Why Does an Onion Make the Tears Come? That is nature’s way of protecting the eyes from the smarting which the onion would cause in your eyes if the tears did not come quickly and overcome the bad effect so produced. Tears are provided for washing the ball of your eyes. Every time you wink a little tear is released from under the eyelid, and the wink spreads it all over the eyeball. This washes down the front of the eyeball and cleanses it of all dust and other things that fly at the eye from the air. Then the tear runs along a little channel, much like a trough, at the lower part of the eye, and out through a little hole in the eye, and in this case the tear is really only an eye-wash. Many things, but more often sadness or injured feelings, start the tears coming so fast from under the eyelid that the little trough at the bottom and the hole in the corner of the eye are too small to hold them or carry them off, so they roll over the edge of the lower eyelid and down the face. These are what we call tears. Among other things that will cause tear-glands to cause an over-supply of eye-wash to come down, are onions. What they give off is very trying to the eyes, and so, just as soon as the something which an onion throws off hits the eyeball, the nerves of the eye telegraph the brain to turn on the tears quickly, and they come in a little deluge and counteract the bad effect of the onion. [Illustration: SOME REMARKABLE PICTURES WITH A FAST CAMERA] [Illustration] [Illustration] [Illustration] [Illustration] [Illustration: THE CAVE MAN OF PREHISTORIC TIMES WHO UNCONSCIOUSLY INVENTED AMMUNITION] The First Missile ~HOW MAN LEARNED TO SHOOT~ A naked savage found himself in the greatest danger. A wild beast, hungry and fierce was about to attack him. Escape was impossible. Retreat was cut off. He must fight for his life--but how? Should he bite, scratch or kick? Should he strike with his fist? These were the natural defences of his body, but what were they against the teeth, the claws and the tremendous muscles of his enemy? Should he wrench a dead branch from a tree and use it for a club? That would bring him within striking distance to be torn to pieces before he could deal a second blow. There was but a moment in which to act. Swiftly he seized a jagged fragment of rock from the ground and hurled it with all his force at the blazing eyes before him; then another, and another, until the beast, dazed and bleeding from the unexpected blows, fell back and gave him a chance to escape. He knew that he had saved his life, but there was something else which his dull brain failed to realize. He had invented arms and ammunition! In other words, he had needed to strike a harder blow than the blow of his fist, at a greater distance than the length of his arm, and his brain showed him how to do it. After all, what is a modern rifle but a device which man has made with his brain permitting him to strike an enormously hard blow at a wonderful distance? Firearms are really but a more perfect form of stone-throwing, and this early Cave Man took the first step that has led down the ages. This strange story of a development has been taking place slowly through thousands and thousands of years, so that today you are able to take a swift shot at distant game instead of merely throwing stones. [Illustration: THE SLING MAN IN ACTION PRACTICE DEVELOPED SOME WONDERFUL MARKSMEN AMONG THE USERS OF THIS PRIMITIVE WEAPON] We do not know the name of the man who invented the sling. Possibly he did not even have a name, but in some way he hit upon a scheme for throwing stones farther, harder, and straighter than any of his ancestors. The men and women in the Cave Colony suddenly found that one bright-eyed young fellow, with a little straighter forehead than the others, was beating them all at hunting. During weeks he had been going away mysteriously, for hours each day. Now, whenever he left the camp he was sure to bring home game, while the other men would straggle back for the most part empty-handed. Was it witchcraft? They decided to investigate. Accordingly, one morning several of them followed at a careful distance as he sought the shore of a stream where water-fowl might be found. Parting the leaves, they saw him pick up a pebble from the bank and then to their surprise, take off his girdle of skin and place the stone in its center, holding both ends with his right hand. Stranger still, he whirled the girdle twice around his head, then released one end so that the leather strip flew out and the stone shot straight at a bird in the water. The mystery was solved. They had seen the first slingman in action. The new plan worked with great success, and a little practice made expert marksmen. We know that most of the early races used it for hunting and in war. We find it shown in pictures made many thousands of years ago in ancient Egypt and Assyria. We find it in the Roman Army where the slingman was called a “funditor.” Surely, too, you remember the story of David and Goliath when the young shepherd “prevailed over the Philistine with a sling and with a stone.” Yet slings had their drawbacks. A stone slung might kill a bird or even a man, but it was not very effective against big game. What was wanted was a missile to pierce a thick hide. Man had begun to make spears for use in a pinch, but would you like to tackle a husky bear or a well-horned stag with only a spear for a weapon? No more did our undressed ancestors. The invention of the greatly desired arm probably came about in a most curious way. Long ages ago man had learned to make fire by patiently rubbing two sticks together, or by twirling a round one between his hands with its point resting upon a flat piece of wood. [Illustration: THE “LONG BOW” IN SHERWOOD FOREST ONE OF ROBIN HOOD’S FAMOUS BAND ENCOUNTERS A SAVAGE TUSKER AT CLOSE RANGE] In this way it could be made to smoke, and finally set fire to a tuft of dried moss, from which he might get a flame for cooking. This was such hard work that he bethought him to twist a string of sinew about the upright spindle and cause it to twirl by pulling alternately at the two string ends, as some savage races still do. From this it was a simple step to fasten the ends of the two strings to a bent piece of wood, another great advantage since now but one hand was needed to twirl the spindle, and the other could hold it in place. This was the “bow-drill” which also is used to this day. But bent wood is apt to be springy. Suppose that while one were bearing on pretty hard with a well-tightened string, in order to bring fire quickly, the point of the spindle should slip from its block. Naturally, it would fly away with some force if the position were just right. [Illustration: DEER STALKING WITH THE CROSSBOW THIS COMPACT ARM WITH ITS SMALL BOLT AND GREAT POWER WAS POPULAR WITH MANY SPORTSMEN] There was one man who stopped short when he lost his spindle, for a red-hot idea shot suddenly through his brain. Once or twice he chuckled to himself softly. Thereupon he arose and began to experiment. He chose a longer, springier piece of wood, bent it into a bow, and strung it with a longer thong. He placed the end of a straight stick against the thong, drew it strongly back, and released it. The shaft whizzed away with force enough to delight him, and lo, there was the first Bow-and-Arrow! Armed with his bow-and-arrow, man now was lord of creation. No longer was it necessary for him to huddle with his fellows in some cave to avoid being eaten by prowling beasts. Instead he went where he would and boldly hunted the fiercest of them. In other words, his brain was beginning to tell, for though his body was still no match for the lion and the bear, he had thought out a way to conquer them. Also he was better fed with a greater variety of game. And now, free to come and go wherever he might find it, he was able to spread into various lands and so to organize the tribes and nations which at last gave us civilization and history. A new weapon now came about through warfare. Man has been a savage fighting animal through pretty much all his history, but while he tried to kill the other fellow, he objected to being killed himself. Therefore he took to wearing armor. During the Middle Ages he piled on more and more, until at last one of the knights could hardly walk, and it took a strong horse to carry him. When such a one fell, he went over with a crash like a tin-peddler’s wagon, and had to be picked up again by some of his men. Such armor would turn most of the arrows. Hence invention got at work again and produced the Crossbow and its bolt. We have already learned how the tough skin of animals brought about the bow; now we see that man’s artificial iron skin caused the invention of the crossbow. What was the Crossbow? It was the first real hand-shooting machine. It was another big step toward the day of the rifle. The idea was simple enough. Wooden bows had already been made as strong as the strongest man could pull, and they wished for still stronger ones--steel ones. How could they pull them? At first they mounted them upon a wooden frame and rested one end on the shoulder for a brace. Then they took to pressing the other end against the ground, and using both hands. Next, it was a bright idea to put a stirrup on this end, in order to hold it with the foot. Still they were not satisfied. “Stronger, stronger!” they clamored; “give us bows which will kill the enemy farther away than he can shoot at us! If we cannot set such bows with both arms let us try our backs!” So they fastened “belt-claws” to their stout girdles and tugged the bow strings into place with their back and leg muscles. Who First Discovered the Power of Gunpowder? Probably the Chinese, although all authorities do not agree. Strange, is it not, that a race still using crossbows in its army should have known of explosives long before the Christian Era, and perhaps as far back as the time of Moses? Here is a passage from their ancient Gentoo Code of Laws: “The magistrate shall not make war with any deceitful machine, or with poisoned weapons, or with cannons or guns, or any kind of firearms.” But China might as well have been Mars before the age of travel. Our civilization had to work out the problem for itself. It all began through playing with fire. It was desired to throw fire on an enemy’s buildings, or his ships, and so destroy them. Burning torches were thrown by machines, made of cords and springs, over a city wall, and it became a great study to find the best burning compound with which to cover these torches. One was needed which would blaze with a great flame and was hard to put out. Hence the early chemists made all possible mixtures of pitch, resin, naphtha, sulphur, saltpeter, etc.; “Greek fire” was one of the most famous. Many of these were made in the monasteries. The monks were pretty much the only people in those days with time for study, and two of these shaven-headed scientists now had a chance to enter history. Roger Bacon was the first. One night he was working his diabolical mixture in the stone-walled laboratory, and watched, by the flickering lights, the progress of a certain interesting combination for which he had used pure instead of impure saltpeter. Suddenly there was an explosion, shattering the chemical apparatus and probably alarming the whole building. That explosion proved the new combination was not fitted for use as a thrown fire; it also showed the existence of terrible forces far beyond the power of all bow-springs, even those made of steel. Roger Bacon thus discovered what was practically gunpowder, as far back as the thirteenth century, and left writings in which he recorded mixing 11.2 parts of the saltpeter, 29.4 of charcoal, and 29 of sulphur. This was the formula developed as the result of his investigations. Berthold Schwartz, a monk of Freiburg, studied Bacon’s works and carried on dangerous experiments of his own, so that he is ranked with Bacon for the honor. He was also the first one to rouse the interest of Europe in the great discovery. [Illustration: THE “KENTUCKY RIFLE” WITH ITS FLINT-LOCK WAS ACCURATE BUT MUST BE MUZZLE-CHARGED] ~THE FIRST REAL FIRE ARMS~ And then began the first crude, clumsy efforts at gunmaking. Firearms were born. Hand bombards and culverins were among the early types. Some of these were so heavy that a forked support had to be driven into the ground, and two men were needed, one to hold and aim, the other to prime and fire. Improvements kept coming, however. Guns were lightened and bettered in shape. Somebody thought of putting a flash pan, for the powder, by the side of the touch-hole, and now it was decided to fasten the slow-match in a movable cock upon the barrel, and ignite it with a trigger. These matches were fuses of some slow-burning fiber, like tow, which would keep a spark for a considerable time. Formerly they had to be carried separately, but the new arrangement was a great convenience and made the match-lock. The cock, being curved like a snake, was called the “serpentine.” About the time sportsmen were through wondering at the convenience of the match-lock, they began to realize its inconvenience. They found that they burned up a great deal of fuse, and were hard to keep lighted. Both statements were true, so inventors racked their brains again for something better. They all knew you could bring sparks with flint and steel, and that seemed an idea worth working on. A Nuremberg inventor, in 1515, hit on the wheel-lock. In this a notched steel wheel was wound up with a key like a clock. Flint or pyrite was held against the jagged edge of the wheel by the pressure of the serpentine. You pulled the trigger, then “whirr,” the wheel revolved, a stream of sparks flew off into the flash-pan, and the gun was discharged. [Illustration: WHEEL-LOCK RIFLE] This gun worked beautifully, but it was expensive. Wealthy sportsmen could afford them, and so for the first time firearms began to be used for hunting. Some of these sixteenth and seventeenth century nabobs had such guns of beautiful workmanship, so wrought and carved and inlaid, that they must have cost a small fortune. You will find them in many large museums to this day. But now the robbers had their turn. There are two stories of the invention of the flint-lock. Both deal with robbers, both have good authority, and both may be true, for inventions sometimes are made independently in different places. One story runs that the flint-lock which was often styled “Lock à la Miquelet,” from the Spanish word, “Miquelitos”--marauders--told its origin in its name. The other is, that the flint-lock was invented in Holland by gangs of thieves, whose principal business was to steal poultry. In either case the explanation is easy. The match-lock showed its fire at night and wouldn’t do for thieves, the wheel-lock was too expensive, so again necessity became the mother of a far-reaching invention. Everybody knows what the flint-lock was like. You simply fastened a flake of flint in the cock and snapped it against a steel plate. This struck off sparks which fell into the flash-pan and fired the charge. It was so practical that it became the form of gun for all uses; thus gunmaking began to be a big industry. Invented early in the seventeenth century, it was used by the hunters and soldiers of the next two hundred years. Old people remember when flint-locks were plentiful everywhere. In fact, they are still being manufactured and are sold in some parts of Africa and the Orient. One factory in Birmingham, England, is said to produce about twelve hundred weekly, and Belgium shares in their manufacture. Some of the Arabs use them to this day in the form of strange-looking guns with long, slender muzzles and very light, curved stocks. There were freak inventors in the flint-lock period just as there are to-day. Some of them wrestled with the problem of repeating guns, and put together a number of barrels, even seven in the case of one carbine. Others tried revolving chambers, like our revolvers, and still others, magazine stocks. Pistols came into use in many interesting shapes, but these were too practical to be considered freaks. ~WHY WE CALL THEM PISTOLS~ Pistols, by the way, are named from the town of Pistola, Italy, where they are said to have been invented and first used. We must not forget that rifling was invented about the time that the wheel-lock appeared, and had a great deal to do with the improvement of shooting. Austrians claim its invention for Casper Zollner, of Vienna, who cut straight grooves in the barrel’s bore. His gun is said to have been used for the first time in 1498, but the Italians seem to have still better warrant as these significant words appear in old Latin Italian, under date of July 28th, 1476, in the inventory of the fortress of Guastalla: “Also one iron gun made with a twist like a snail shell.” The rifling made the bullet spin like a top as it flew through the air, thus greatly improving its precision. In the year 1807 the Rev. Alexander John Forsythe, LL.D., got his patent papers for something far better than even the steady old flint. He had invented the percussion system. In some form this has been used ever since. Which is to say that when the hammer of your gun falls, it doesn’t explode the powder, although it seems to. Instead it sets off a tiny portion of a very sensitive chemical compound called the “primer,” and the explosion of this “primer” makes the powder go off. Of course, the two explosions come so swiftly that your ear hears only a single bang. Primers were tried in different forms called “detonators,” but the familiar little copper cap was the most popular. No need to describe them. Millions are still made to be used on old-fashioned nipple guns, even in this day of fixed ammunition. But now we come to another great development, the Breech-loader. [Illustration: THE MODERN AUTOMATIC RIFLE THE MODERN SPORTSMAN WITH HIS AUTOMATIC RIFLE IS PREPARED FOR ALL EMERGENCIES] Perhaps you have had to handle an old muzzle-loader. It was all right so long as you knew of nothing better, but think of it now that you have your beautiful breech-loader. Do you remember how sometimes you overloaded, and the kick made your shoulder lame for a week? Or how, when you were excited you shot away your ramrod? The gun fouled too, and was hard to clean, the nipples broke off, the caps split, and the breeches rusted so that you had to take them to a gunsmith. Yes, in spite of the game it got, it was a lot of trouble, now you come to think of it. How different it all is now! [Illustration: ASSEMBLING REPEATING SHOTGUNS AND RIFLES] Breech-loaders were hardly new. King Henry VIII of England, he of the many wives, had a match-lock arquebus of this type dated 1537. Henry IV of France even invented one for his army, and others worked a little on the idea from time to time. But it wasn’t until fixed ammunition came into use that the breech-loader really came to stay--and that was only the other day. You remember that the Civil War began with muzzle-loaders and ended with breech-loaders. [Illustration: ASSEMBLING AUTO SHOTGUNS] [Illustration: SOME OF THE SHOOTING TESTS] Houiller, the French gunsmith, hit on the great idea of the cartridge. If you were going to use powder, ball and percussion primer to get your game, why not put them all into a neat, handy, gas-tight case? THE FIRST AMERICAN MADE GUNS ~HOW THE FIRST AMERICAN GUN WAS MADE~ Two men, a smith and his son, both named Eliphalet Remington, in 1816, were working busily one day at their forge in beautiful Ilion Gorge, when, so tradition says, the son asked his father for money to buy a rifle, and met with a refusal. The request was natural for the surrounding hills were full of game. The father must have had his own reasons for refusing, but it started the manufacture of guns in America. Eliphalet, Jr., closed his firm jaws tightly, and began collecting scrap iron on his own account. This he welded skillfully into a gun-barrel, walked fifteen miles to Utica to have it rifled, and finally had a weapon of which he might well be proud. [Illustration: TYPES OF CARTRIDGES] In reality, it was such a very good gun that soon the neighbors ordered others like it, and before long the Remington forge found itself hard at work to meet the increasing demand. Several times each week the stalwart young manufacturer packed a load of gun-barrels upon his back, and tramped all the way to Utica where a gunsmith rifled and finished them. At this time there were no real gun-factories in America, although gunsmiths were located in most of the larger towns. All gun-barrels were imported from England or Europe. A VISIT TO A CARTRIDGE FACTORY ~HOW AMMUNITION IS MADE~ One of the first shocks you get when you start your visit through a cartridge factory is the matter-of-fact way in which the operatives, girls in many cases, handle the most terrible compounds. We stop, for example, where they are making primers to go in the head of your loaded shell, in order that it may not miss fire when the bunch of quail whirrs suddenly into the air from the sheltering grasses. That grayish pasty mass is wet fulminate of mercury. Suppose it should dry a trifle too rapidly. It would be the last thing you ever did suppose, for there is force enough in that double handful to blow its surroundings into fragments. You edge away a little, and no wonder, but the girl who handles it shows no fear as she deftly but carefully presses it into moulds which separate it into the proper sizes for primers. She knows that in its present moist condition it cannot explode. [Illustration: INSPECTING METALLIC SHELLS] [Illustration: EXAMINING PAPER SHELLS] [Illustration: WEIGHING BULLETS] Or, perhaps, we may be watching one of the many loading machines. There is a certain suggestiveness in the way the machines are separated by partitions. The man in charge takes a small carrier of powder from a case in the outside wall and shuts the door, then carefully empties it into the reservoir of his machine, and watches alertly while it packs the proper portions into the waiting shells. He looks like a careful man, and needs to be. You do not stand too close. [Illustration: SHOOTING ROOM OF BALLISTICS DEPARTMENT] [Illustration: CHRONOGRAPH FOR MEASURING] The empty carrier then passes through a little door at the side of the building, and drops into the yawning mouth of an automatic tube. In the twinkling of an eye it appears in front of the operator in one of the distributing stations, where it is refilled, and returned to its proper loading machine, in order to keep the machine going at a perfectly uniform rate; while at the same time it allows but a minimum amount of powder to remain in the building at any moment. Each machine has but just sufficient powder in its hopper to run until a new supply can reach it. Greater precaution than this cannot be imagined, illustrating as it does that no effort has been spared to protect the lives of the operators. [Illustration: PUTTING METAL HEADS ON PAPER SHOT SHELLS] It is remarkable that, in an output of something like four million per day, every cartridge is perfect. Such things are not accidental. The secret is, inspection. ~TESTING MATERIALS AND PRODUCTS~ Let us see what that means. It means laboratory tests to start with. Here are brought many samples of the body paper, wad paper, metals, waterproofing mixture, fulminate of mercury, sulphur, chlorate of potash, antimony sulphide, powder, wax, and other ingredients, and even the operating materials such as coal, grease, oil, and soaps. In the laboratory we see expert chemists and metallurgists with their test-tubes, scales, Bunsen burners, retorts, tensile machines, microscopes, and other scientific looking apparatus, busily hunting for defects. For example, one marker is examining a supply of cupro-nickel, such as is used in jacketing certain bullets. A corner of each strip is first bent over at right angles, then back in the other direction until it is doubled, then straightened. It does not show the slightest sign of breaking or cracking, in spite of the severe treatment, therefore it is perfect. Let but the least flaw appear, and the shipment is rejected. [Illustration: WHAT A SHOT TOWER LOOKS LIKE SHOT TOWER--TALLEST BUILDING IN CONNECTICUT] [Illustration: LARGEST CARTRIDGE EQUALS MORE THAN 1,000,000 OF SMALLEST (HELD ON HAND)] Two large iron cylinders descend in the center, coming down through the ceiling from above; we are invited to look through an open port in one of these. We see nothing but the whitened opposite wall, against which a light burns. It appears absolutely empty, though within it is raining such a swift shower of invisible metal that if we were to stretch our hands into the apparently vacant space they would be torn from our arms. A large water tank below is churned into foam with the impact of the falling shot, and as we look downward we make out finally the haze of motion. It is so interesting that we take the elevator and rise ten stories to the source of the shower. Here high in the air are the large caldrons where many pigs of lead, with the proper alloy, are melted into a sort of metallic soup. This is fed into small compartments containing sieves or screens, through the meshes of which the shining drops appear and then plunge swiftly downward. But this only begins the process. Taken from the water tanks and hoisted up again, the shot pellets, in a second journey down, through complicated devices, are sorted, tumbled, polished, graded, coated with graphite, and finally stored. The pictures shown in this story were prepared especially to illustrate this story of “How Man Learned to Shoot” by the Searchlight Library for the Remington Arms Company. [Illustration: FORGING A MONSTER GUN Photo by Bethlehem Steel Co. This photograph shows gun ingots after being “stripped” and “cored.”] [Illustration: Photo by Bethlehem Steel Co. This photograph shows a gun ingot in the process of being forged under forging press.] [Illustration: Photo by Bethlehem Steel Co. This photograph shows a gun being fired at the Proving Grounds for test.] The Parts of a Big Gun ~THINGS TO KNOW ABOUT A BIG GUN~ Before going into a description of the manufacture of a big gun it would be well to understand the following definitions: The “breech” of a gun is its rear-end, or that end into which the projectile and powder charge are loaded. The “muzzle” of a gun is its forward end. By “calibre” is meant the inside diameter of the gun in inches. A 5-inch gun is one of “minor calibre,” and one of 14-inches a gun of “major calibre.” The length of a gun is never expressed in inches or feet, but in the _number of times_ that its calibre is divisible into its length; thus, when we say a 12-inch 50-calibre gun, we mean a gun of 12 inches in diameter, and 12 times 50, or 600 inches long. The “bore” is the hole extending through the center of the gun, from the rear face of the liner to its forward end. The “powder chamber” is the rear part of the bore, and extends from the face of the breech plug when closed to the point where the “rifling” begins. The powder chamber is slightly larger in diameter than the rest of the bore. The “rifling” is the name given to the spiral grooves which are cut into the surface of the bore of the gun, and give to the projectile its rotary motion when the gun is fired. With the advent of “iron-clads” and heavily armored fortresses, it became necessary to increase the power of the guns in use, until to-day a 14-inch gun of 45 calibres fires a projectile weighing 1400 pounds, with an initial velocity of 2600 feet per second. An idea of this initial velocity may be better obtained by comparison when you realize that a train going sixty miles an hour is only traveling at the rate of 88 feet per second. Now, in order to produce such wonderful power in a gun, great pressure must be generated in the bore, and it was soon found that a one-piece gun, whether cast or forged, could not withstand such pressures. To begin with, we may consider this one-piece gun, or any gun, as a tube which must withstand a great pressure from within, so that when a gun is designed care must be taken to see that the material from which it is constructed is strong enough to withstand this pressure. And not only must the gun be sufficiently strong, but it must not be too heavy, so that you see you cannot go on forever increasing the thickness of the walls of this tube. Besides, it is generally acknowledged that a simple tube or cylinder cannot be made with walls of sufficient thickness to withstand from within a _continued_ pressure per square inch greater than the tenacity of a square-inch bar of the same material; in other words, if the tensile strength of a metal is only twelve tons per square inch, no gun of that metal, however thick its walls, could withstand a pressure of twenty tons per square inch, and the modern big guns are tested at that great a pressure. And if we look further into this matter of pressures we find that when a gun is fired the pressure exerts itself in two ways; it tends to burst the gun longitudinally or down the middle, and it tends to pull the gun apart in the direction of its length. Of course, some method of strengthening this one-piece gun was sought after, with the result that to-day guns are either “_built-up_” or “_wire-wound_.” A “built-up” gun is one made of several layers, each layer being separately constructed and then assembled together. The order of assemblage differs somewhat with the different calibres, but the method of assemblage is essentially the same, that is, the outside layers are heated and shrunk on the inner ones. This question will be treated at greater length later on. A “wire-wound” gun is one in which the necessary additional strength is obtained by winding wire around an inner tube of steel, each layer being wound with a different tension of the wire; this type of gun has found great favor with foreign manufacturers. In this country, however, the “built-up” system is used almost exclusively, and so this description will deal with the manufacture of a “built-up” gun. [Illustration: HOW A BIG GUN WOULD LOOK IF YOU WERE TO CUT IT IN TWO Sketch Showing Construction of a Modern “Built-up” Gun. _A_, HOOP; _B_, HOOP; _C_, JACKET; _D_, TUBE; _E_, LINER; _F_, HOOP.] A modern “built-up” gun is composed of a _liner_, a _tube_, a _jacket_ and _hoops_. The _liner_ is in one piece and extends the entire length of the bore and carries the “rifling” and the powder chamber. The _tube_ is in one piece and envelops the liner for its entire length. Formerly the _tube_ carried the “rifling” and powder chamber, but due to the wearing out of the “rifling” with constant firing, a liner was decided on, so that now when the “rifling” becomes worn, the liner can be removed and a new one substituted. The _jacket_ is usually in two pieces and is shrunk on the tube; it extends the entire length, and its rear end is threaded in the inside for the attachment of the “breech bushing.” _Hoops_ are shrunk on over the jacket and in a big gun are sometimes as many as six or seven in number. The liner, tube, jacket and hoops are made of the finest quality of open hearth steel, and the steel must conform to specifications set by the government. [Illustration: Photo by Bethlehem Steel Co. This photograph shows a mould for a gun ingot under hydraulic press for fluid compression.] The chemical composition having been determined, the necessary elements are weighed out and the whole charged into an open hearth furnace. When the furnace is ready to be tapped the molten metal is run into a large ladle, which in turn is taken by a crane to the casting pit, where the mould is filled. The ingots for the large calibre guns run from 42-inch to 48-inch in diameter, and after being poured they are immediately run under a hydraulic press, where they are subjected to a pressure of about six tons per square inch to drive out the gases, and then lowered to about 1500 pounds pressure per square inch for a certain length of time during the cooling. This pressure tends to make the ingot solid, by expelling the gases, which would cause blow-holes, and by preventing “piping” and “segregation.” When a metal cools, the top and sides cool first, and this outer layer shrinks and pulls away from the centre, with the result that a cavity or “pipe” would be formed, but the hydraulic pressure forces fluid metal into this cavity and so prevents the “pipe.” The cooling also causes the various elements to solidify separately, and they tend to break away from the mass and collect at the centre; this is called “segregation,” and is also partially prevented by fluid compression. A solid ingot, however, is obtained, and this is absolutely necessary. After the ingot has cooled sufficiently it is “_stripped_,” that is, it is removed from the mould, and then it is sent to the shop to have the “discard,” or extra length, cut off. When the ingot is cast, an extra amount of metal is poured into the mould to permit this discard, the theory being that the poorer metal, together with gases and other impurities, rise to the top. The government specifications require that there shall be a 20% discard from the upper end and a 3% discard from the lower end. The discard having been cut off, the ingot is “cored,” that is, its centre is bored out, the diameter of the hole depending on the size of the ingot. [Illustration: TAKING THE BORE OF A BIG GUN Photo by Bethlehem Steel Co. This photograph shows gun ingot in boring mill being cored.] The ingot is now ready for the “forge,” and on its receipt in the forge shop it is placed in a furnace to be heated; and here great care must be exercised to prevent setting up any additional strains in the ingot. When the ingot was cooling just after casting the metal tended to flow from the centre; the interior is still in a condition of strain, and if the cold ingot is now placed in a hot furnace, cracks are apt to form in the centre, causing the forging to later break in service. However, the ingot having been properly heated, it is ready for either the forging hammer or the press. The present-day practice, though, is to forge the ingot under a press forge, as the working of the metal causes a certain flow, and as a certain amount of time is necessary for this flow, the continued pressure and slow motion of the press allows the molecules of the metal to adjust themselves more easily, and a better and more homogeneous forged ingot is produced than if the forging had been done with a hammer. When forging a hollow ingot, a mandrel, merely a cylindrical steel shaft, is placed through the hole in the ingot and the ingot forged on the mandrel, thereby not only is the outside diameter of the ingot decreased, but the length of the ingot is increased. The usual practice is to continue the forging until the original thickness of the walls of the ingot is decreased one-half and until the ingot is within two inches of the required finished diameters. The ingot is now known as a “forging,” and the lower end of each ingot as cast will be the breech end of the forging that is made from it. The next process is that of “annealing.” This consists in heating the forging to a red heat and then allowing it to cool very slowly, and is usually done by hauling the fires in the furnace after the correct temperature has been attained and permitting both to cool off together. This process is to relieve the strains set up in the metal during forging, and further, it alters the molecular condition of the steel, making a finer and more homogeneous forging. [Illustration: HOW THE GUN TUBE IS TEMPERED Photo by Bethlehem Steel Co. This photograph shows a gun tube ready to be lowered into oil bath for “oil tempering.”] After annealing, the forging is ready to go to the machine shop to be rough bored and turned. The forging is set in a lathe, the breech end being held by jaws on the face-plate and the muzzle end by a “pot-centre,” a large iron ring having several radial arms screwed through it. The lathe can now be turned and the forging centered by screwing in or out on the jaws of the face-plate or the radial arms of the “pot-centre.” When centered, several surfaces are turned on the forging for “steady rests” and then all is in readiness for the turning and boring. In both operations of “turning” and “boring,” the work revolves while the cutting tools are fed along. Turning is very simple and usually several tools are cutting at the same time, but boring is a more delicate operation, because the workman cannot see what he is doing. And in boring, either a “hog bit” or a “packed bit” is used; a “hog bit” is a half cylinder of cast iron fitted with one cutting tool and used for rough cuts, while a “packed bit” is a full cylinder of wood with metal framing and carrying two tools 180° apart and used for finishing cuts. The forging, having been rough machined, is now ready to receive its heat treatment in order to give to the steel its required physical characteristics. Every piece of steel used in gun manufacture must conform to certain specifications as regard both its physical and chemical characteristics. The chemical analysis was made at the time the ingot was cast; now for the treatment of the forging, prior to the physical test as to its tensile strength, elastic limit, elongation and contraction. The “tensile strength” of a metal is the unit-stress required to break that metal into parts. If a round bar ten inches in cross-section area will fracture under a strain of 120 tons, its tensile strength is 120 ÷ 10 or 12 tons per square inch. Tensile strength is usually expressed in pounds per square inch. The “elastic limit” of a metal is the unit-stress required to first produce a permanent deformation of the metal. If a bar of metal be subjected to an increasing strain, up to a certain point that metal will be perfectly elastic, resuming its normal shape when the strain is removed; at the first permanent set or deformation, however, the elastic limit of that metal has been reached. Elastic limit is expressed in pounds per square inch. By “elongation” is meant the increase in length in a bar when its tensile strength is reached. If a bar 10 inches long after rupture measures 11.8 inches, its elongation is 18%. By “contraction” is meant the decrease in cross-section area in a bar when its tensile strength is reached. If a bar 1 square inch in area after rupture is only .75 of a square inch in area, its contraction is 25%. These definitions being understood, a brief description of the heat treatment can be taken up, because it is after this treatment that standard bars are taken from the forgings to undergo the physical tests. The first step consists in “tempering” or hardening the metal. The piece to be tempered is placed in an upright position in a high furnace and uniformly heated to the required temperature. It is then lifted from the furnace through an opening in the top and carried by a crane to an oil tank of suitable depth and plunged into the oil. This rapid cooling or “tempering in oil” is facilitated by having the oil tank surrounded by a water bath, so arranged that a supply of cold water is constantly in circulation to carry the heat from the mass as quickly as possible. This operation produces exceeding toughness, increases the tensile strength and raises the elastic limit of the metal. Now the forging is again annealed, so as to relieve any strains set up by tempering and to soften up the metal to the degree required by the specifications. It also increases materially the elongation and contraction. Great care must be exercised in the heat treatment, as the acceptance or rejection of the forging depends upon whether or not the test bars pass the required specifications. The forging is now submitted for test and the test bars taken. In the manufacture of a big gun, four test bars are taken from the breech end and four from the muzzle end of each forging and these bars sent to the physical laboratory. Quite an elaborate testing machine is provided, and if the bars pass the required tests the forging is accepted and is sent to the machine shop for finish-boring and turning. ~SEARCHING FOR POSSIBLE DEFECTS~ Frequently during finish-boring the work is examined to see that the bit is running true, and great care must be exercised to prevent its running out of alignment. After finish-boring every forging is “bore-searched,” that is, the bore is carefully examined for any cracks, flaws, streaks or discoloration. A special instrument called a “bore-searcher” is used and consists of a long wooden handle which has a mirror inclined at 45° at one end, together with a light to illuminate the bore, and so shielded as to obscure the light from the observer. (See sketch.) [Illustration] The bore is also inspected by the foreman after each boring, but the final “bore-searching” is done by an inspector. Now to measure accurately the inside diameters of long cylinders, such as are used in gun work, a special measuring device called a “star-gauge” is used. Its name is derived from the fact that it has three measuring points set at 120° apart and two measurements are taken, one [Illustration] and the other [Illustration], making a star [Illustration]. Every forging is “star-gauged” after being finish-bored and also the liner of the _gun_ after each assemblage operation. ~PUTTING THE PARTS OF A “BUILT-UP” GUN TOGETHER~ In preparation for the assembling of the different parts, the tube is the forging to be finished. It is bored and turned to exact dimensions and carefully “bore-searched” and “star-gauged.” With the data at hand a sketch is made showing the external diameters of the liner under the tube, due allowance being made for the shrinkage when assembling. The liner is next bored to within .35 of an inch of the finished diameter, and turned to the dimensions required by the sketch above. This extra metal in the bore is left until the gun is completely assembled and is removed in the finish-boring. The liner is then carefully “bore-searched” and “star-gauged” and liner and tube are ready for assembling. The liner is now taken to the shrinking pit and carefully aligned in an upright position with the breech end down. The shrinking pit is merely a well of square section with room enough to permit workmen to move freely about the gun when it is in position, and equipped with a movable table at its bottom upon which the gun rests. In the meantime the tube, with breech end down, is being heated in a hot-air furnace. This furnace is a vertical cylinder built of fire-brick and asbestos and so constructed that air which has been passed in pipes over petroleum burners can enter at the bottom, pass around and through the tube and out through the top to be reheated. This service permits a uniform heat to be transmitted to the tube and when the desired temperature has been attained the tube is lifted from the furnace by a crane, carried to the shrinking pit and carefully lowered over the liner. Great care must be exercised in this operation to prevent the tube from sticking while being lowered into place. Should it happen, the tube should be hoisted off at once, allowed to cool, any roughing of the liner be smoothed off, the tube reheated and a second trial made. When the tube is properly in place a cold spray may be turned upon any particular section where it is desired the tube should first grip the liner. The tube is then left to cool by itself, but cold water is constantly circulating through the liner. When the gun is sufficiently cool for handling purposes, it is hoisted out of the shrinking pit and taken to the shop for careful measurement, the liner being “star-gauged” to note the compression due to the shrinking on of the tube. The same procedure is followed in the case of the jackets and hoops, until the entire gun is assembled. The gun is considered completely “built-up” when the last hoop has been shrunk on and is now ready to be finished. The gun is now finish-bored, as .35 of an inch of metal was left in the liner in the first boring. “Packed bits” are used and the greatest care is exercised to keep the bit properly centered and running true. After this step the gun is finish-turned and the powder chamber is bored. Following this operation the gun is “bore-searched” for any defects that may have shown up in the finish-boring and chambering, and then carefully “star-gauged.” The gun is then ready to be “rifled.” [Illustration: RIFLING A BIG GUN Photo by Bethlehem Steel Co. This photograph shows a gun in the Rifling Machine in the process of being rifled.] The “rifling” of a gun consists in cutting spiral grooves in the surface of the bore from the powder chamber to the muzzle end, and is done from the muzzle end. Rifling is a very difficult operation, and great care must be exercised that the cutting is uniform. The grooves are separated by raised portions called “lands,” and after “rifling,” these grooves and “lands” are carefully smoothed up to remove the rough edges or burrs caused by the cutting tools of the “rifling” machine. The necessary holes are now drilled for fitting the breech mechanism and the breech block fitted. This operation usually takes some little time, as quite a bit of hand work is necessary to insure a perfect fit. The “yoke,” really another “hoop,” is now put on at the breech end and the gun is complete. The centre of gravity of gun and breech mechanism is now determined by balancing on knife edges and the whole then weighed. The breech mechanism is also weighed and the two weights marked on the rear faces of the gun and breech mechanism. The gun is now fitted in its “slide,” that part of the mount which carries the trunnions and through which the gun recoils when it is fired, and after it is adjusted, all is in readiness for the “proof-firing” or testing of the gun. What Is Motion? There are practically but two things we see when we use our eyes. One of them is matter, which is a term we apply to the things we see, speaking of them as objects only, and the other is motion which we observe some of the matter to possess. Some of the things we see confuse us, if we bear in mind that everything is either matter or motion. For instance, we see light and know it is not matter and are confused until we understand that light is a movement of the ether which surrounds us and is in and outside of everything. In the same way we feel heat and may think it is matter thrown off by the fire, when it is only another kind of motion of this same ether. When we understand these things we see that motion is a very important and real part of the world. When a motion is started it will keep on going forever unless some other force which is able to overcome the motion stops it. When a ball is thrown in the air it would go on forever were it not for the law of gravitation which pulls it to the earth and the friction of the air on the ball as it goes through the air. When you stop a thrown ball you sometimes realize that motion is a real thing because it stings your hands. We do wonderful things with motion. Many things when you add motion to them acquire qualities which they did not possess before. For instance, an ordinary icicle thrown against a wooden door will break, but if you put it into a gun and give it sufficient motion, it will go right through the door. There is a story of how a man killed another by using an icicle as a bullet. The icicle entered the man’s body and killed him. Then, of course, the ice melted and no one could tell how the man received his wound, for no trace of anything like a bullet could be found. A piece of paper has no cutting qualities, but if you arrange a circular or square piece of paper with a rod or stick through the center and revolve it fast enough, you can cut many things while it is whirling. The motion gives it the cutting qualities. You can take a piece of strong rope and, by tying the ends together, making a circle of it, you can make it roll down the street like a steel hoop if you catch it just the right way and set it spinning fast enough before starting it on its way. A steam engine has no power to pull the train of cars until the wheels are set in motion. So we see that motion is a very important thing in the world. Motion is the cause of movements of all kinds, the power which takes things from one place to another. Is Perpetual Motion Possible? Perpetual motion will never be possible unless some one discovers a way to overcome the law of gravitation and also the certainty that materials will eventually wear out. Many men have tried to make a machine that would keep on moving forever without the application of any power, the consumption of fuel within itself, the fall of weights or the unwinding of a spring; such a machine would be absolutely impossible, although many people have been fooled into investing money in machines that appeared to have this power within themselves. How Can an Explosion Break Windows That Are at a Distance? An explosion is a sudden expansion of a substance like gunpowder or some elastic fluid or other substance that has the power to explode under certain conditions with force, and usually a loud report. Some explosions are comparatively mild and accompanied by a very mild noise, while others are very powerful and accompanied by a very loud noise. When an explosion occurs, the air and everything surrounding the thing that explodes is very much disturbed. The air surrounding the thing that explodes is thrown back in air waves which are powerful in the exact proportion in which the explosion is powerful. These air waves can be so suddenly thrown back against the objects in the vicinity that not only the windows in the buildings are broken, but often the entire building blown away. The explosion acts in all directions at once with equal force. A great hole may be torn in the earth beneath the explosion. If there is anything over the explosion, that is blown away unless its power of resistance is sufficient to withstand the power of the explosion. Then, also, the air surrounding on all sides is forced back against everything in its path. Very often this air which is suddenly forced back by the power of the explosion is thrown against houses at a distance. These houses may be so strongly built as to be able to withstand the effect of the explosion, but still certain parts of them, such as the windows and the bricks of the chimney, may not be able to withstand this sudden pressure of air against them and they are forced in. The wind from such an explosion acts on the outside of the windows just the same as though you stood on the outside with your hands against the windows and pushed them in. Anything that is thrown against a window with more force than the window glass can resist will break the window, and even slight explosions may be so powerful as to throw the air back and away from them with such force as to break windows at a great distance--even a mile or more away. Why Do Some Things Bend and Others Break? When an outside force is applied to some objects, some of them will bend and others break. It is due to the fact that in some things the particles have the faculty of sticking together or hanging on to each other, and it is very difficult to break them away from each other. In such instances, as in the case of a wire, the article will bend when we apply the power to it and it will not break, because the particles which make up the wire have the faculty of hanging on to each other. A piece of glass, however, can be broken right in two by the application of no more force than was used to bend the wire, because the particles which make up the glass haven’t the faculty to hang on to each other. If you continue to bend a wire back and forth, however, at the same point, it will finally break apart, because you eventually overcome the ability of the particles in the wire to hang on to each other. It all depends upon the hanging-on ability. Sometimes in undergoing different processes an article which will ordinarily only bend will become very brittle or breakable. A steel wire may bend but if you make a steel wire very hard it becomes brittle. On the other hand, glass is very brittle ordinarily, but if you make it very hot, you can bend it into any shape you wish, and thus the glass-worker makes different shapes to various dishes; lamp chimneys, bottles, etc., by heating glass and then bending it. When it becomes cool again, it also becomes brittle or breakable as before. Why Does a Ball Bounce? When you throw a ball against the floor in order to make it bounce the ball gets out of shape as soon as it comes in contact with the floor. As much of it as strikes the floor becomes perfectly flat, and because the ball has a quality known as elasticity, which means the ability to return to its proper shape, it returns to its shape immediately and in doing so forces itself back into the air and that is the bounce. Of course, the first thing we think of when we consider something that bounces is a ball, and in most cases a rubber ball. We are more familiar with the bouncing qualities of a rubber ball. Other balls, like standard baseballs, are not so elastic as a rubber ball filled with air, but a solid-rubber ball is more elastic and some golf balls are much more elastic than a solid-rubber ball. The principle is the same, when you drive a golf ball, excepting that when you bounce a ball on the floor the floor does the flattening and when you drive a golf ball, the golf club does the flattening. A baseball flies away from the bat for the same reason. When you meet a fast-pitched ball squarely on the nose with a good swing, it goes farther and faster than when you hit a slow-pitched ball with an equal swing, because in the case of the fast-pitched ball you flatten the ball out more, and it has so much more to do to recover its proper shape that it bounces away from the bat at much greater speed and goes much further unless caught than a slow-pitched ball under the same circumstances. What Makes a Ball Stop Bouncing? A bouncing ball, when you first throw it against the wall bounces back at you about as fast as you throw it, but if you do not catch it on the rebound, it goes to the floor again, because the law of gravitation which is the pulling power of the earth, pulls it down again. When it strikes the floor it is again flattened to a certain extent and bounces up again, but does not come back so high. It goes on striking the floor and bouncing back into the air again each time a shorter distance, until the force of gravity has actually overcome its tendency to bounce back. When you bounce a ball on the floor and it bounces up again, the motion of the ball through the air is affected by the friction that the contact with the air produces and this friction of the air overcomes part of the bouncing ability in the ball also. What Makes a Cold Glass Crack if We Put Hot Water Into It? Hot water will not always cause a cold glass to crack, but is very apt to, especially a thick glass. The very thin glasses will not crack. The test tubes used by chemists are made of very thin glass, and will not crack when hot liquids are poured into them. When a glass cracks after you have poured a hot liquid into it, it does so because, as soon as the hot liquid is put in, the particles of glass which form the inside of the glass become heated and expand. They begin to do this before the particles which form the outside of the glass become heated, and in their efforts to expand the inside particles of glass literally break away from the particles which form the outside, causing the crack. The same thing happens if you put cold water into a hot glass, excepting in this instance the inside particles of the glass contract before the particles which form the outside of the glass have had time to become cool and do likewise. What Causes the Gurgle When I Pour Water from a Bottle? The air trying to get in causes the gurgle. Air has one strong characteristic which stands out above everything else. It wants to go some place else all the time. When it learns of a place where there is no air it wants to go there above all things, and goes at it with a rush. Now, when you turn a bottle full of water upside down, the water comes out if the cork is out, of course, and as soon as the water starts out the air strives to get in, and every time you hear a gurgle you know the air is getting in. Every gurgle is a battle between the water and the air. Sometimes the air comes and pushes the water back enough to let it slide into the bottle; sometimes the water pushes the air back, and thus they fight back and forth. The water always gets out and the air always gets in. In doing so they make the gurgle. Where Does the Part of a Stocking Go That Was Where the Hole Comes? Perhaps this is a foolish question, but many boys and girls have been puzzled for an answer to it. When you put your stockings on they have no holes in the feet, and at night, when you take them off, there are often quite large holes in them. The answer is the same as in the case of the lead in the lead-pencil. The lead in the pencil wears away. You can see it wear away because that is what makes the marks. When a hole is coming into your stocking, the stocking on your foot is being rubbed between your foot and something else (probably some part of your shoe) and this constant rubbing will wear through the yarns with which the stocking is knitted. Of course, the yarns in the stocking are stretched somewhat when it is on your foot and the rubbing finally cuts through the threads and releases the tension of the threads of yarn, so that not always is as much stocking lost as the size of the hole. But, if you were to look carefully at your foot and inside your shoe, when you first take the stocking off and see the hole, you would find little particles of yarn all about. Why Do Coats Have Buttons On the Sleeves? The practice of putting buttons on coat sleeves, which serve no useful purpose at all and do not add to the beauty of the coat, is a relic of very old days. There was a time when people did not use handkerchiefs, and it was common practice for men to wipe their noses on their sleeves. They had coats also in those days, but they did not have buttons on the sleeves. One of the old kings finally developed the idea of dressing his soldiers in fancy uniforms and, as he sat in his palace and reviewed his troops, he noticed many of them using the sleeves of their coats as handkerchiefs. He immediately issued a decree that all sleeves should have a row of buttons sewed on them, but at a point directly opposite to where they are now on the sleeves. This was done to remind the soldiers that the sleeves of their beautiful uniforms were not to be used as handkerchiefs, and those who attempted to draw their sleeves in front of the nose were quickly reminded of the decree by the buttons which scratched them. And so the buttons really had a quite useful purpose at one time, and so also all sleeves had buttons sewed on to them at this place. Later on, however, when the unsightly practice had been cured and people had learned to use handkerchiefs, the buttons remained as a decoration, but their former purpose was lost sight of. Then some tailor or leader of fashion had the buttons set on the under side of the sleeves for a change, and it became the fashion to have them there, and the tailors have been sewing them there ever since. Why Has a Long Coat Buttons on the Back? The buttons on the back of a long coat, i. e., one with skirts, had a more sensible reason originally. At one time the skirts of such coats were made very long, and when the wearer moved quickly the tails of the coat flapped about the legs and interfered with progress. So an ingenious gentleman had buttons sewed on to the back and buttonholes made in the corner of his coat-tails. Then when he was in a hurry he simply buttoned up his skirts and went his way comfortably. [Illustration: TELEPHONE DISPLAY BOARD Showing in outline the apparatus necessary to complete the simplest kind of a telephone call--to a number in the same exchange] The Story in the Telephone ~WHAT HAPPENS WHEN WE TELEPHONE~ Mrs. Smith, at “Subscriber’s Station No. 1,” desires to telephone to Mrs. Jones at “Subscriber’s Station No. 2.” When she lifts her receiver, the movement causes a tiny white light to appear instantly on the switchboard at the Central Office. Directly beneath this light is another and larger lamp, which glows in a way to attract the operator’s attention immediately. The operator inserts a “plug” in a little hole on the switchboard called a “jack,” directly above the tiny light which appeared when Mrs. Smith lifted the receiver. This connects her to Mrs. Smith’s line. Then she pushes a listening key on the board, connecting her telephone set to the line. “Number, please?” she calls. Mrs. Smith gives the number; the operator repeats it to be sure there is no mistake, places another “plug” in a “jack” corresponding to the number of Mrs. Jones’ telephone and makes the connection. Each subscriber’s telephone has a particular signal on the switchboard to which it is connected by a pair of wires. Mrs. Smith’s wires run from her instrument to the nearest “cable terminal,” a gathering point for the wires of various telephones in her neighborhood. Here they form part of a group of wires going to the Central Office. These groups, called cables, are made up of from 50 to 600 pairs of wires, according to the telephone needs of the district the “terminal” serves. When the wires reach the Central Office they pass through the “cable vault” to the “main distributing frame,” which is the Central Office terminal of the cable. When the wires come to this frame they are in numbered order in the cable. Subscribers living next door to Mrs. Smith may have entirely different call numbers and yet use consecutive wires. It is the task of the main frame to redistribute these wires, so that they will be arranged according to their call numbers and to make it possible to connect Mrs. Smith’s line with the line of any other subscriber with the least possible delay. This frame has two parts: the “vertical side” and the “horizontal side.” Before the wires are redistributed they are taken to pairs of springs equipped with devices for protecting the lines against outside currents. [Illustration: ASKING FOR A NUMBER] After leaving the main frame they are taken to the “intermediate distributing frame,” the central connecting point for various branches of the lines going to the switchboard, signaling and other apparatus. From the “horizontal side” of this frame, wires go to the switchboard, where they terminate in little holes known as “multiple jacks.” They also connect with the line and position message registers, where the calls from each Line and the calls handled at each operator’s position at the switchboard are recorded. The “multiple jacks” are additional terminals placed at necessary intervals throughout the switchboard, where they can be used by operators to make connections with any other line on the board. From the “vertical side” of the intermediate frame Mrs. Smith’s wires reach the “line and cut-off relay,” an electrically controlled switch which turns on the light signal that appears on the switchboard when she lifts the receiver from the hook. This “line relay” also extinguishes the light when the operator makes the connection, or when Mrs. Smith returns the receiver to the hook. [Illustration: A TYPICAL POLE LINE, WITH CROSS ARMS, IN THE COUNTRY] The swift moving electric current that was set in motion when Mrs. Smith began the call, instantaneously passes through all these devices for safeguarding and protecting the subscriber’s telephone service. The light announcing Mrs. Smith’s desire to make a call is called the “line lamp,” and is flashing on the switchboard. Directly beneath it is the “pilot lamp,” which glows whenever any “line lamp” lights. With the “line lamp” is a “jack” or terminal, where connection can be made with Mrs. Smith’s line. This is the “answering jack.” [Illustration: THE CABLE VAULT INTO WHICH THE CABLES PASS WHEN THEY ENTER THE EXCHANGE AND FROM WHICH THEY ARE LED UPWARD TO THE MAIN DISTRIBUTING FRAME] When the operator sees the flashing signal of Mrs. Smith’s “line lamp,” she inserts one end of a pair of “connecting cords,” which are on the board before her, in the “answering jack” for Mrs. Smith’s line. These “connecting cords” are flexible conductors that put the wires of subscribers in electrical connection. Then she pushes forward the “operator’s key” directly in front of her and is connected with Mrs. Smith’s line. The operator ascertains the number wanted and places the other “connecting cord” in the “jack” corresponding to Mrs. Jones’ line. If she finds she cannot herself connect with Mrs. Jones’ “jack,” because it is on another part of the board out of her reach, she makes a connection with another operator who can reach Mrs. Jones’ line. The second operator then makes the connection with Mrs. Jones’ “multiple jack” and places her line in connection with Mrs. Smith’s line at the first operator’s position. At the same time the first operator pushes the operator’s key back, thus ringing Mrs. Jones’ bell. “Supervisory lamps” on the board before her, connected with the “connecting cords,” tell the operator when Mrs. Jones answers the summons. They flash when the connection is made and one goes out just as soon as Mrs. Jones takes the receiver from the hook to answer. If one of these lamps flashes and dies out alternately it tells the operator that either Mrs. Smith or Mrs. Jones is trying to attract her attention and she connects herself and ascertains the party’s wishes. When both subscribers “hang up,” both lights flash to indicate the end of the conversation. The operator then disconnects the cords from the subscribers’ “jacks” and presses the “message register” button recording the call against Mrs. Smith. [Illustration: ROUTINE OF A TELEPHONE CALL The subscriber, after looking up in the directory the desired number, takes the telephone off the hook, which causes a tiny electric light to glow in front of the operator assigned to answer his calls. (In some exchanges equipped with a magneto system, a drop is released by the turning of a crank.)] [Illustration: The arrow indicates the light as it appears on the switchboard. Each operator can connect a caller with any subscriber in that exchange, but she is assigned to answer the calls of only a limited number of subscribers whose signals are these lights showing at her particular position.] [Illustration: She takes up a brass-tipped cord, inserts the tip, or “plug,” into the hole, or “jack,” just above the light, at the same time throwing a key with the other hand in order to switch her transmitter line into direct communication with the caller, and says: “Number?”] [Illustration: The caller replies by giving the name of the exchange and the number he wants, as for example, “Main 1268.” The operator repeats the number, “One-two-six-eight,” pronouncing each digit with clear articulation, to insure its correctness, and, if it be from a subscriber in the Main Exchange, she--] [Illustration: Takes up the cord which is the team mate, or “pair,” of the one with which she answered the caller, locates the jack numbered 1268, and “tests” the line by tapping the tip of the plug for a moment on the sleeve of the “jack” to ascertain if the line is “busy.” If no click sounds in her ear she--] [Illustration: Pushes in the plug and with her other hand operates a key on the desk. The first action connects the line of the subscriber called; the second rings his bell. When either party hangs up his receiver, a light glows on the switchboard desk, showing the operator that the conversation is ended.] [Illustration: THE CENTRAL TERMINAL OF YOUR TELEPHONE A MULTIPLE SWITCHBOARD] [Illustration: THE BACK OF A MULTIPLE SWITCHBOARD] [Illustration: THE BIRTHPLACE OF THE TELEPHONE, 109 COURT STREET, BOSTON On the top floor of this building, in 1875, Prof. Bell carried on his experiments and first succeeded in transmitting speech by electricity] How the Telephone Came to Be. It is hard to realize that there was once a time, not so very many years ago, when the telephone was regarded as a scientific toy and hardly anyone could be found willing to invest any money in the development of the telephone business. [Illustration: ALEXANDER GRAHAM BELL IN 1876] [Illustration: THOMAS A. WATSON IN 1874] The story of Professor Alexander Graham Bell’s wonderful invention is full of romantic interest and the early days of its exploitation were replete with dramatic incidents. ~THE MEN WHO MADE THE TELEPHONE~ Young Bell had come to America in 1870 in search of health, the family settling at Brantford, Canada. He numbered among his forebears many distinguished professional men. For three generations the Bells had taught the laws of speech in the universities of Edinburgh, Dublin and London. He himself was an accomplished elocutionist and an expert in vocal physiology. During the year spent in Canada in regaining his health, Bell taught his father’s method of visible speech to a tribe of Mohawk Indians and began to think about the “harmonic telegraph.” In 1871 young Alexander Bell accepted an offer from the Boston Board of Education to teach the “visible speech” method in a school for deaf mutes in that city. For two years he devoted himself to the work with great success. He was appointed a professor in the Boston University and opened a school of “Vocal Physiology” which was at once successful. He might have continued his career as a teacher had it not been that his active brain still clung to the “harmonic telegraph” idea and his inventive genius demanded an outlet. [Illustration: PROF. BELL’S VIBRATING REED] So we find him in 1874 working out his idea of the “harmonic telegraph,” the perfection of which meant a fortune to the young inventor. That he never realized his goal was due to the fact that while experimenting, he made a discovery which led to a far greater invention and one that was fraught with more benefit to mankind than the “harmonic telegraph” could ever have been. It was while working with his faithful man Friday, Thomas A. Watson, in the dingy little workrooms on Court Street, Boston, that Bell got the inspiration which made him turn from the “harmonic telegraph” to devote himself to the invention which was destined to make his name famous--the speaking telephone. ~THE FIRST SOUND OVER A WIRE~ Mr. Watson has dramatically described the incident as follows: “On the afternoon of June 2, 1875, we were hard at work on the same old job, testing some modification of the instruments. Things were badly out of tune that afternoon in that hot garret, not only the instruments, but, I fancy, my enthusiasm and my temper, though Bell was as energetic as ever. I had charge of the transmitters, as usual, setting them squealing one after the other, while Bell was retuning the receiver springs one by one, pressing them against his ear as I have described. One of the transmitter springs I was attending to stopped vibrating and I plucked it to start it again. It didn’t start and I kept on plucking it, when suddenly I heard a shout from Bell in the next room, and then out he came with a rush, demanding, ‘What did you do then? Don’t change anything. Let me see!’ I showed him. It was very simple. The make-and-break points of the transmitter spring I was trying to start had become welded together, so that when I snapped the spring the circuit had remained unbroken while that strip of magnetized steel by its vibration over the pole of its magnet, was generating that marvelous conception of Bell’s--a current of electricity that varied in intensity precisely as the air was varying in density within hearing distance of that spring. That undulatory current had passed through the connecting wire to the distant receiver which, fortunately, was a mechanism that could transform that current back into an extremely faint echo of the sound of the vibrating spring that had generated it, but what was still more fortunate, the right man had that mechanism at his ear during that fleeting moment, and instantly recognized the transcendent importance of that faint sound thus electrically transmitted. The shout I heard and his excited rush into my room were the result of that recognition. The speaking telephone was born at that moment. Bell knew perfectly well that the mechanism that could transmit all the complex vibrations of one sound could do the same for any sound, even that of speech. That experiment showed him that the complex apparatus he had thought would be needed to accomplish that long-dreamed result was not at all necessary, for here was an extremely simple mechanism operating in a perfectly obvious way, that could do it perfectly. All the experimenting that followed that discovery, up to the time the telephone was put into practical use, was largely a matter of working out the details. We spent a few hours verifying the discovery, repeating it with all the differently tuned springs we had, and before we parted that night Bell gave me directions for making the first electric speaking telephone. I was to mount a small drumhead of gold-beater’s skin over one of the receivers, join the center of the drumhead to the free end of the receiving spring and arrange a mouthpiece over the drumhead to talk into. His idea was to force the steel spring to follow the vocal vibrations and generate a current of electricity that would vary in intensity as the air varies in density during the utterance of speech sounds. I followed these directions and had the instrument ready for its trial the very next day. I rushed it, for Bell’s excitement and enthusiasm over the discovery had aroused mine again, which had been sadly dampened during those last few weeks by the meagre results of the harmonic experiments. I made every part of that first telephone myself, but I didn’t realize while I was working on it what a tremendously important piece of work I was doing. [Illustration: WHAT THE FIRST TELEPHONE LOOKED LIKE ALEXANDER GRAHAM BELL’S FIRST TELEPHONE] The First Telephone Line. “The two rooms in the attic were too near together for the test, as our voices would be heard through the air, so I ran a wire especially for the trial from one of the rooms in the attic down two flights to the third floor where Williams’ main shop was, ending it near my work bench at the back of the building. That was the first telephone line. You can well imagine that both our hearts were beating above the normal rate while we were getting ready for the trial of the new instrument that evening. I got more satisfaction from the experiment than Mr. Bell did, for shout my best I could not make him hear me, but I could hear his voice and almost catch the words. I rushed upstairs and told him what I had heard. It was enough to show him that he was on the right track, and before he left that night he gave me directions for several improvements in the telephones I was to have ready for the next trial.” Then followed many heart-breaking months of experimenting and it was not until the following March that the telephone was able to transmit a complete, intelligible sentence. [Illustration: TELEPHONE APPARATUS PATENTED IN 1876 BY PROF. BELL, PHOTOGRAPHED FROM THE ORIGINAL INSTRUMENTS IN THE PATENT OFFICE AT WASHINGTON] On February 14, 1876, Professor Bell filed at Washington his application for patents covering the telephone which he described as “an improvement in telegraphy” and on March 3, of the same year, the patent was allowed. That was the year of the Centennial Exposition at Philadelphia and Professor Bell had a working model of the telephone on exhibition. Tucked away in an obscure corner it had attracted but little attention, until on June 25th an incident occurred which had a tremendous effect in giving to the new invention just the sort of publicity it needed. Professor Bell himself describes the incident in the following interesting manner: “Mr. Hubbard and Mr. Saunders, who were financially interested in the telephone, wanted this instrument to be exhibited at the Centennial Exhibition. In those days--and I must say even up to the present time I am afraid to say it is true--I was not very much alive to commercial matters, not being a business man myself. I had a school for vocal physiology in Boston. I was right in the midst of examinations. “I went down to Philadelphia, growling all the time at this interruption to my professional work, and I appeared in Philadelphia on Sunday, the 25th. I was an unknown man and looked around upon the celebrities who were judges there, and trotted around after the judges at the exhibition while they examined this exhibit and that exhibit. My exhibit came last. Before they got to that it was announced that the judges were too tired to make any further examinations that day and that the exhibit could be examined another day. That meant that the telephone would not be seen, for I was not going to come back another day. I was going right back to Boston. ~HOW AN EMPEROR SAVED THE TELEPHONE~ “And that was the way the matter stood--when suddenly there was one man among the judges who happened to remember me by sight. That was no less a person than His Majesty Dom Pedro, the Emperor of Brazil. I had shown him what we had been doing in teaching speech to the deaf in Boston, had taken him around to the City School for the Deaf and shown him the means of teaching speech, and when he saw me there he remembered me and came over and shook hands and said: ‘Mr. Bell, how are the deaf mutes of Boston?’ I said they were very well and told him that the next exhibit on the program was my exhibit. ‘Come along,’ he said, and he took my arm and walked off with me--and, of course, where an Emperor led the way the other judges followed. And the telephone exhibit was saved. [Illustration: THE FIRST TELEPHONE SWITCHBOARD USED. EIGHT SUBSCRIBERS.] An Emperor Wonders. “Well, I cannot tell very much about that exhibit, although it was the pivotal point on which the whole telephone turned in those days. If I had not had that exhibition there it is very doubtful what the condition of the telephone would be today. But the Emperor of Brazil was the first one to bring that situation about at that time. I went off to my transmitting instrument in another part of the building, and a little iron box receiver was placed at the ear of the Emperor. I told him to hold it to his ear, and then I heard afterward what happened. I was not present at that end of the line. I went to the other end and was reciting, ‘To be or not to be, that is the question,’ and so on, keeping up a continuous talk.” “I heard afterward from my friend, Mr. William Hubbard, that the Emperor held it up in a very indifferent way to his ear, and then suddenly started and said, ‘My God! it speaks!’ And he put it down; and then Sir William Thomson took it up and one after another in the crowd took it up and listened. I was in another part of the building shouting away to the membrane telephone that was the transmitter. Suddenly I heard a noise of people stamping along very heavily, approaching, and there was Dom Pedro, rushing along at a very un-Emperor-like gait, followed by Sir William Thomson and a number of others, to see what I was doing at the other end. They were very much interested. But I had to go back to Boston and couldn’t wait any longer. I went that very night.” “Now, it so happened there, that, although the judges had heard speech emitted by the steel disc armature of this receiving instrument, they were not quite convinced that it was electrically produced. Some one had whispered a suspicion that it was simply the case of the thread telegraph, the lovers’ telegraph, as it was known in those days, and that the sound had been mechanically transmitted along the line from one instrument to the other. Of course, I did not know about it at that time; but when the judges asked permission to remove the apparatus from that location I said, ‘Certainly, do anything you like with it.’ But I could not remain to look after it; they had to look after it themselves.” “My friend, Mr. William Hubbard, who had kindly come up from Boston to help me on this celebrated Sunday, June 25, said he would do his best to help them out, although he was not an electrician. He knew nothing whatever about the apparatus, beyond being in my laboratory occasionally, knowing me well. But he undertook to remove this apparatus and set up the line under the direction of the judges themselves. So they had an opportunity finally of satisfying themselves that speech had really been electrically reproduced.” “Sir William Thomson’s announcement was made to the world in England, before the British Association, and the world believed--and from that time dates the popular interest in the telephone.” In October, 1876, the first outdoor demonstration, in which conversation was carried on over a private telegraph wire, borrowed for the occasion, took place between Boston and Cambridge, a distance of two miles. In April, 1877, the first telephone line was installed between Boston and Somerville. A month later an enterprising Boston man put up a crude switchboard in his office and connected up five banks, using the system for telephoning in the day-time and as a protection against burglars at night. This was the beginning of the exchange system, all previous telephoning having been between two parties on the same circuit. ~NINE MILLION TELEPHONES IN U. S.~ Soon after exchanges sprang up in several cities, and by August of that year there were 778 Bell telephones in use. From this modest beginning the telephone has grown until on January 1, 1914, there were 13,500,000 telephones in the world, nearly 9,000,000, or over 64 per cent being in the United States. [Illustration: MODERN DISTRIBUTING FRAME When the wires come to this frame they are in numbered order in the cable. The main frame redistributes these wires so that they are arranged according to their call numbers, making it possible to connect any wire with any other wire anywhere that telephone service is installed.] [Illustration: HOW THE WIRES ARE PUT UNDERGROUND Breaking Up the Asphalt Pavement. First Step in Laying an Underground Cable.] [Illustration: Laying Multiple Duct Tile Subway Through Which the Cables Will Run.] [Illustration: Feeding Cable Into Duct as It is Being Pulled Through Subway from the Other End.] [Illustration: A CABLE TROUBLE] The use of the telephone instrument is common, but it affords no idea of the magnitude of the mechanical equipment by which it is made effective. ~UNSEEN FORCES BEHIND YOUR TELEPHONE~ To give you some conception of the great number of persons and the enormous quantity of materials required to maintain an always-efficient service, various comparisons are here presented. [Illustration: TELEPHONES. Enough to string around Lake Erie--8,000,000, which, with equipment, cost at the factory $45,000,000.] [Illustration: WIRE. Enough to coil around the earth 621 times--15,460,000 miles of it, worth about $100,000,000, including 260,000 tons of copper, worth $88,000,000.] [Illustration: LEAD AND TIN. Enough to load 6,600 coal cars--being 659,960,000 pounds, worth more than $37,000,000.] [Illustration: CONDUITS. Enough to go five times through the earth from pole to pole--225,778,000 feet, worth in the warehouse $9,000,000.] [Illustration: POLES. Enough to build a stockade around California--12,480,000 of them, worth in the lumber yard about $40,000,000.] [Illustration: SWITCHBOARDS. In a line would extend thirty-six miles--55,000 of them, which cost, unassembled, $90,000,000.] [Illustration: BUILDINGS. Sufficient to house a city of 150,000--more than a thousand buildings, which, unfurnished, and without land, cost $44,000,000.] [Illustration: PEOPLE. Equal in numbers to the entire population of Wyoming--150,000 employes, not including those of connecting companies.] The poles are set all over this country, and strung with wires and cables; the conduits are buried under the great cities; the telephones are installed in separate homes and offices; the switchboards housed, connected and supplemented with other machinery, and the whole system kept in running order so that each subscriber may talk at any time, anywhere. Where Does Sound Come From? Somebody or something causes every sound we hear. Sounds are the result of disturbances in the air. Sound is produced by waves in the air. The buzz of the bumble-bee is caused by the quick movement of his wings in the air. The wings themselves do not make the sound, but their motion causes waves or vibrations in the air which produce the sound of buzzing. Every motion made by anybody or anything produces waves in the air just like the waves you see in the water--a big movement makes a big wave and a tiny movement a tiny wave. When you clap your hands you make a disturbance in the air which causes a sound--the harder you clap the louder the sound. You can hear this sound and anybody else near can hear it. If there were no air about us, however, we would hear no sound, even if we could live in such a condition of things, for it is the air waves produced striking against the drum of our ears that enable us to discern sounds. When we talk we make air waves also and thus produce sound. If you were deaf, and talked, you could not hear any sound, because even when there are air waves they must still strike against a sounding board in order to be recognized as sound--and the drum of our ear is our sounding board for hearing sounds. When the air waves produced are regular we call the sound musical, and when they are irregular we call it noise. Some people can make musical sounds when they sing, while others cannot. If you take a piece of thin wire and stretch it tightly, fastening it at both ends, and then pull it with your finger and let go, you will hear a musical sound, because the vibrations produced will be regular and will continue for some time. If you shorten the distance on the wire where it is fastened at both ends and pull it as before, the sound produced will be in a higher key. If you take a guitar and snap the big G string you will produce the bass note of G. If the other G string (the smaller one) is in tune (if you watch the smaller one closely while you strike the larger one) you will notice the smaller one vibrate also. Sound waves of the same tone, although in different octaves, produce the same sounds, although in different keys. This is the principle on which the piano is made to produce music. Inside the piano are wires of different lengths and the keys of the piano are arranged to operate certain little hammers, each of which strikes a certain wire. Every time you strike a piano key you cause one of the little hammers to hit its wire--the wire then makes vibrations which cause air waves. The air waves strike against the sounding board which is located behind the wires, and being thrown back into the air, strike against the drum of our ears, and we can hear the note. Why Can We Make Sounds With Our Throats? The sounds we make when we talk are produced in exactly the same way with the exception of the little hammers. In our throats are two cords which we call our vocal cords. When we talk we cause these cords to vibrate and thus we make the sounds of our voices. The most wonderful part of this voice of ours is that with only two vocal cords or wires, we can produce practically all the notes that can be made with a piano, which has a wire or cord for every note, excepting that we cannot make so many at one time. The human throat is so wonderfully constructed that we can lengthen or shorten our vocal cords at will and produce, with two strings, in our throats as many notes as it takes the piano many more strings to produce. Why Does the Sound Stop When We Touch a Gong that Has Been Sounded? When we touch the gong we stop the sound waves which the gong gives off when it is struck. These sound waves continue after the gong has been struck in continuous vibrations until something stops them. When you touch the vibrating gong, you stop its vibrating. If you only touch your finger to the vibrating gong you can feel the vibrations which cause a little tickling sensation. Naturally when you stop these vibrations you stop the air waves which the vibrations cause, and thus also the sound of these air waves striking your ear are stopped and the sound ceases. How Can Sound Come Through a Thick Wall? A sound will come through a thick or thin wall only if the wall is a good conductor of sound. Some things are good conductors of sound and others are not, just as some things are good conductors of electricity and others are not. If a wall is built of materials all of which are good conductors of sound, the sound will come through it no matter how thick. Wood is an especially good conductor of sound. It is even better than air. You can stand at one end of a long log and have another person at the other end hold up his watch in the air, and you cannot hear the watch tick, but if the watch is “going” as we say, and you ask the person holding it to put the watch against his end of the log, and you then put your ear to the other end, you can hear the watch ticking almost as well as if you had it to your own ear. In like manner you can hear the scratching of a pin at the other end of the log. When you put your ear against a telegraph pole you can hear the hum of the wires while you cannot hear it through the air. All sound is produced by sound waves and many solids are better conductors of sound waves than the air. Sound waves, however, will sometimes not be heard as plainly through a wall, because of the fact that the wall may be made of materials which are not equally good conductors of sound. When a sound wave strikes a poor conductor it loses some of its power and the sound, although it may be heard through the wall, will be fainter. What Is Meant by Deadening a Floor or a Wall? By deadening a floor, for instance, we mean inserting between the ceiling of the room below and the floor above, or in the instance of a deadened wall, between the two sides of the wall, some substance like felt, paper or other non-conductor of sound, which will prevent the sound waves from passing through. This deadens them to the passing of sound or makes them sound-proof. What Makes the Sounds Like Waves in a Sea Shell? The sounds we hear when we hold a sea shell to the ear are not really the sound of the sea waves. We have come to imagine that they are because they sound like the waves of the sea, and knowledge that the shell originally came from the sea helps us to this conclusion very easily. What Are the Sounds We Hear in a Shell? The sounds we hear in the sea shell are really air waves or sounds made by air waves, because all sounds are produced by air waves. The reason you can hear these sounds in a sea shell is because the shell is so constructed that it forms a natural sounding box. The wooden part of a guitar, zither or violin is a sounding box. They have the faculty of picking up sounds and making them stronger. We call them “resonators,” because they make sounds resound. The construction of a sea shell makes an almost perfect resonator. A perfect resonator will pick up sounds which the human ear cannot hear at all and magnify them so that if you hold a resonator to the ear you can hear sounds you could not otherwise hear. Ear trumpets for the deaf are built upon this principle. Sometimes when you, with your ear alone, think something is absolutely quiet, you can pick up a sea shell and hear sounds in it. But the sea shell will magnify any sound that reaches it. It would be possible, of course, to take a sea shell to a place where it would be absolutely quiet and then there would be no sounds. There are such places, but very few of them. A room can be built which is absolutely sound proof. [Illustration: SIBERIAN LAMBS IN SOUTH DAKOTA] The Story in a Suit of Clothes Where Does Wool Come From? We could not write the story of a suit of clothes without dealing largely with the sheep, for it is only from the wool of the sheep that the best, warmest and most lasting garment can be made. In order that we may properly understand the development of the great wool and clothing industry in America we must supply a brief history of our sheep industry, for the sheep must always come before the clothing. Who Brought the First Sheep to America? The sheep is not a native of America, but it came here with the first white men. History records that Columbus on his way to this country stopped at the Canary Islands to take on stores. Among other things he loaded a number of sheep, some of which were later landed on the new continent. What became of this early importation history does not record, but it is probable that most, if not all, of them perished from the attack of wild animals or at the hands of the natives. However, when settlers began pouring into the new world many of them brought along their sheep, so that from the earliest colonial days the sheep constituted our most numerous domestic animals. This, indeed, was necessary, for if the colonist was to survive the rigor of our climate he must have an abundant supply of woolen clothing. In those days clothing materials were limited to wool, flax and the skins of animals, and, as may be supposed, wools were in very great demand. England and most European countries prohibited the exportation of wool, in order to increase the demand for the clothing which she manufactured. However, as our new colonist had ample time and but little money, he desired to make his own clothing rather than send such funds as he had to the mother country. Therefore, the new settler, as a matter of necessity, was forced to increase the domestic supply of wools. Who Started to Make Clothing from Wool in America? Early records reveal that shortly after the year 1600 many of the colonies passed laws for the purpose of encouraging the sheep industry. In fact, some of them went so far as to prohibit the transportation of sheep or wool from one colony to another. However, our new sheep industry prospered, and well it should, for it had the backing of every prominent patriot of the early days. Washington, Jefferson, Madison, and Franklin all were enthusiastic advocates of sheep husbandry, for they knew that unless a people had a large domestic supply of wool they could not long remain independent or hope to gain independence from foreign countries. In fact, at one time Washington owned as many as one thousand sheep, and if he lived in the present day he would be regarded as a sheep baron. Wool, next to food, is the most vital necessity of a people, for when wars come wool becomes a contraband, and all foreign supplies are shut off. Thus, in stimulating a domestic wool supply the great wisdom of our early patriots was vindicated with the coming of the Revolutionary War. When that great struggle came our foreign wool supply was shut off, but on account of the foresight of these patriots in encouraging home production, our colonists had a supply ample for most of their needs. We not only had the wool, but the housewife had learned the art of manufacturing wool into clothing by means of the spinning wheel, so that when our soldiers went forth in that great struggle, which was to bring to us independence, they were clad in garments made of American grown wool and manufactured by the good housewife during her hours of leisure. When affairs became tranquil, following the close of the Revolution, settlement, which had largely been confined to the Atlantic coast, pushed westward farther and farther into the wilderness. Each of these settlers took with him his supply of sheep, for the purpose of furnishing wool for clothing and meat for food. In the early days wool was not grown for the purpose of sale, but to be used entirely by the family of the producer. However, when settlement reached the Mississippi River, conditions changed. Wool manufacturing had then been established in the land, and it became customary to raise wool to sell to these manufacturers, who had located along the Atlantic seaboard. Why Does the Sheep Precede the Plow in Civilizing a Country? In all countries the sheep has been the pioneer of civilization. They have settled and developed practically all new lands. In fact, so firmly established has been this rule that it seems almost necessary that the sheep should precede the plow, and thus prepare land for agriculture. The reason for this is that the sheep is a tractable animal and depends on man to guide its every step. It can endure hardships that would destroy other forms of animal life. However, the maintenance of a sheep industry requires an abundance of labor, and in this way settlement always follows the sheep. So has it been in foreign countries, and so was it in this country. Where Does Most of Our Wool Come From? Sheep came into our western states early in the seventies, at a time when these states were thinly settled, but following the sheep came the labor incident to its care, and thus the railroads, stores, cities and schoolhouses found their way into the land. Originally all of our sheep industry was east of the Mississippi River. Then for a time it was east of the Missouri River. To-day west of the Missouri River we have about 23,000,000 aged sheep, or more than one-half of the total in the United States. In the pioneer days the western sheep skirmished on the range for most of the food that it obtained. To-day conditions are different, and, while the sheep is on the range for a short time each year, it spends its summer in the National Forest, for which grazing a fee is paid to the Federal Government. Its winters are spent largely around the hay-stack of the farmer, and about fifty to sixty cents’ worth of hay is fed to each sheep in the West each winter. With the coming of spring the western sheep are divided into bands of about 1500, and each two bands are placed in care of three caretakers, who care for and protect the sheep either on the deeded land of the owner or on the land rented from the Federal Government. [Illustration: SHEEP COMING OUT OF FOREST] How Much Wool Does America Produce Yearly? So much for the history of our sheep. A few words now about wool. The total wool crop of the United States is approximately 300,000,000 pounds per year. The value of this crop is around $60,000,000 annually. How Do We Get the Wool Off the Sheep? With the coming of spring our sheep are driven to large central plants, where they are shorn by the use of machines driven by electricity or steam power. One man shears about one hundred and fifty sheep per day. For this he receives eight cents per head. When the wool is taken off the sheep it is gathered up and carefully tied with string made of paper. The tied fleece is then dropped into an elevator, and is carried up about ten feet, where it is dropped into a large sack about three feet in diameter and seven feet long. In this sack there is always a wool tramper, who keeps tramping the fleeces down, so that about forty fleeces are finally put into each sack, making the weight of the sack approximately three hundred pounds. As these sacks are filled they are carefully stored in a dry shed, and, when shearing is completed, are hauled to the railroad station and shipped to the great wool centers of Boston or Philadelphia. While the bulk of the wool in the United States is produced west of the Missouri River, that territory manufactures very little wool. So the western sheepman, who is thus forced to grow his wool in the western states, pays about two cents a pound freight on it back to the eastern market, where it is sold and later manufactured into cloth. A part of this same clothing is then shipped west, to be sold to the very man, in some instances, who produced the wool out of which it is made. American wool, taken as a whole, is the best wool grown in the world. It is not as soft as some Australian wool, but all of it possesses a greater strength than foreign wools, and it has long since been determined that clothing made of American wool will give better service than that made of foreign wool. Of the wool used in the United States for the manufacturing of clothing we produce about 70 per cent and import about 30 per cent. How Much Does the Wool In a Suit of Clothes Cost? It is customary for the person who buys clothing made of wool to believe that the value of the wool in the cloth is what makes the clothing seem expensive. However, if we take a man’s suit made of medium-weight cloth, such as is worn in November, we find that it requires about nine pounds of average wool to make the suit. For this wool the sheepman receives an average of seventeen cents per pound, so that out of the entire suit the man who produces the material out of which the suit is made receives a total of $1.53. A suit such as is here described would be of all wool and free from shoddy or any wool substitute. It would be a suit that would be sold by the storekeeper at $25.00, and if you had it made by the tailor he would charge you $35.00. Yet the wool-grower furnished all the material out of which the suit was made, and received as his share but $1.53. Thus it will be clear to the person who buys clothing and reads these lines that no longer can the blame for the high cost of clothing be laid at the door of the wool-grower. While the wool-using population of the world is increasing very rapidly, the number of wool-producing sheep in the world is decreasing. Ordinarily this would mean that a point would be reached where the supply of wool would be totally inadequate to meet the needs of the public. However, this unfortunate possibility is being averted by the energy and thrift of the sheepmen in breeding sheep that produce more and better wool than was the case in the past. The sheep which Columbus brought to this country, and, in fact, all the sheep of the world in that day, produced wool of very coarse, inferior quality, and but very little of it. One hundred years ago our sheep did not average three pounds of wool per head, but by careful breeding and better feeding we have brought the average fleece up to slightly more than seven pounds. Of course, some sheep produce decidedly more wool than this, but the fact that in one hundred years we have more than doubled the amount of wool that a sheep produces and increased its quality very materially speaks well for the ingenuity and determination of our sheep producers. Probably as time goes on the average fleece may be still further increased, so that in the next twenty-five years it is not too much to hope that our sheep will produce on an average of one pound more wool than they now do. Of course, as wool comes from the sheep, it naturally contains much dirt. The sheep have run on the range or in the open pasture during much of the year, and dust and dirt has settled into the wool. Then, besides producing wool, the sheep excrete into the wool a fatty substance known as wool fat. When the fleece is taken from the sheep and sent to the market the first thing that the manufacturer does with the fleece is to wash out all this foreign matter. The foreign matter is of a considerable quantity, for 60 per cent of wool as it comes from the sheep is dirt and grease, so that only 40 per cent of the sheep’s fleece represents wool fibres. This wool fibre is a very delicate affair, being made up of thousands of little cells, one laid on top of the other. On the surface of the fibre are a lot of scales arranged something like the scales on a fish. In the process of manufacturing the scales on one fibre lock with scales on another fibre, and in that way the fibres are held together in the piece of cloth. When wool is received at the factory it is in fleeces, and each fleece contains different kinds of fibres--long and short--coarse and fine, and it is necessary that these should be sorted into different kinds or grades, as may be desired--perhaps six or eight different kinds, according to the particular uses to which the different qualities are to be put. [Illustration: Copyright American Woolen Company WOOL SORTING] The fleece is spread out on a table, the center of which is covered with wire netting, and through this netting part of the dust and other matter from the wool falls while the sorting is going on. Sorters tear with the hands the different parts of the fleece from each other and separate them into piles, according to their different qualities. All unwashed wool contains a fatty or greasy matter called yolk, which is a secretion from the skin of the sheep. The effect of this yolk is to prevent the fibres of the wool from matting, except at the ends, where, of course, it collects dust, and, forming a sort of a coating, really serves as a protection to the rest of the fleece while on the sheep’s back. After the wool is sorted it is next cleansed or scoured, in order to remove all this yolk, dirt and foreign matter, and this is accomplished by passing the wool, by means of automatic rakes, through a washing machine, consisting of a set of three or four vats or bowls, which contain a cleansing solution of warm, soapy water, until all the grease and dirt have been removed. Each bowl has its set of rollers, which squeezes out the water from the wool before it passes into the next bowl. Having passed through the last bowl and set of rollers the wool is carried on an apron made of slats on chains, to the drying chamber, called the dryer, where is taken out most of the moisture. The wool is now blown through pipes or carried on trucks to the carding room. ~DIFFERENCE IN WOOLENS AND WORSTEDS~ From this point the wool follows one of two different processes of manufacture--that of making into worsteds or that of making into woolens. Speaking in a general way, worsted fabrics are made of yarns in which the fibres all lie parallel, and woolens are made of yarns in which the fibres cross or are mixed. Ordinarily, worsteds are made from long staple wools, and woolens from short staple wools. [Illustration: Copyright American Woolen Company WOOL SCOURING] By means of the comb the fibre is still further straightened out, the short stock and noil, or nibs, are removed, and when the sliver comes from the combs most of the fibres are parallel to each other. A number of the slivers taken from the comb are then put through two further operations of gilling, and wound into a large ball, which is called a finished top. The next process in the manufacture of worsteds is carding. In this process the wool is passed between cylinders and rollers, from which project the ends of many small wires. These cylinders revolve in opposite directions. The result is the opening, separating and straightening of the fibres; and the wool is delivered in soft strands, which are taken off by the doffer comb and wound upon a wooden roll into the shape of a large ball, known as a card-ball or card-sliver, or put into a revolving can. The sliver from a number of these balls or cans is now taken and put through what is known as the gilling machine, which to a degree straightens the fibres. From the gilling machine the wool comes off in soft strands. Four strands are then taken to the balling machine, where is made a large ball, ready for the combing. It takes eighteen of these balls to make a set or fill up the comb. The dyeing is done in three ways--in the top, in the thread or skein after being spun, or in the piece after it is woven. If the wool is to be stock dyed--that is, dyed in the top--it is sent to the dyehouse to be dyed the shade required, and afterwards returned to be gilled and recombed ready for the drawing. [Illustration: Copyright American Woolen Company WORSTED CARDING] Up to this point there has been no twist given to the wool, nor any appearance of a thread. The top, the soft untwisted end, is now run through the drawing machine, the process sometimes consisting of nine distinct operations, and is drawn and redrawn until reduced to the size required for its special purpose; and the stock is then delivered to the spinning room on spools, and is called roving. [Illustration: Copyright American Woolen Company GILLING AFTER CARDING] [Illustration: Copyright American Woolen Company COMBING] In the spinning the process of drawing continues until the twisted thread is reduced to the size required, which, either singly or twisted together in two, three or four strands, is to be used for weaving. The yarn is then very carefully inspected, and all imperfections which would show in the finished goods are removed, and, if it is to be dyed in the skein, the yarn is taken to a reel, where the skeins are made ready for the dyehouse. ~HOW CLOTH IS MADE FROM WOOL~ The threads must now be prepared for the loom, in order that the actual weaving may be done. The thread is used in two ways in weaving--as warp, which is the thread which runs lengthwise of the cloth, and as filling, or woof, which runs across the cloth from side to side. [Illustration: Copyright American Woolen Company GILLING AND MAKING TOP AFTER COMBING] The warp threads--the threads which run lengthwise of the cloth--are sized and wound upon large reels, and from these transferred to a large wooden roll called the warp beam, which holds all the warp threads, usually several thousands. The filling threads are put on shuttle bobbins and placed in the shuttles to be refilled by the operatives as required, and as the weaving progresses. The warp beam is then taken to the drawing-in room, where these several thousand threads are drawn through wire heddles in a frame called the harness, then drawn through a wire reed. The completed warp beam is now ready for the loom. The harnesses are placed in the loom, and by means of what is called the “head-motion,” part of the threads are raised and part are lowered. This allows the filling shuttles to pass above some threads and below others, filling out the pattern required. The cloth, having been made in such length as is desired, is taken from the loom, and, by what is known as burling and mending, any knots or threads woven in wrongly are removed, and any imperfections which have been discovered through a careful examination are corrected. The web or cloth is scoured or washed and the oil and any foreign matter removed. Undressed fabrics would now be fulled. This consists of running cloth through a fulling machine, where, moistened with a specially prepared soap, it is subjected to a great pressure and pounding, which aids in giving the required finish. There are different kinds of finishes which require different treatments, and it would be impracticable for us to dwell in detail upon this matter here. If dyed in the piece, the web or cloth is taken to the dyehouse and dyed. It is thoroughly rinsed, all moisture is extracted from it, and it is dried. After drying the cloth is run through a machine by which it is brushed and sheared, the brushing lifting the long fibres, and the shearing cutting them off at even length. The cloth is put through the press, which irons it out, giving it the lustre or the finish that is desired. It is examined again for further imperfections, and if such have occurred they are corrected. Measuring, weighing, rolling and tagging follow, and the cloth is packed and ready for the market. Woolens are made from short staple wools, known as clothing wools, and in the finished woolens the fibres of the yarns cross or are mingled together. In the case of woolens, after the scouring, it is frequently necessary to remove burrs or other vegetable matter from the wool. To accomplish this the wool is dipped in a bath of chloride of aluminum or sulphuric acid solution, then the moisture is extracted and the wool is put through a drier, where the temperature must be at least 212 degrees. This heat carbonizes the foreign substance, but has little effect on the animal fibres of the wool. [Illustration: FINISHING BOX ENGLISH DRAWING Copyright American Woolen Company GILLING ENGLISH DRAWING Copyright American Woolen Company] Next, an ingenious machine called the burr picker removes the burr. Sometimes there is to be a blend of the wool with other stocks, and in that case the several different wools are mixed together. [Illustration: GILLING, FIRST OPERATION ENGLISH DRAWING Copyright American Woolen Company REDUCER ENGLISH DRAWING Copyright American Woolen Company] ~HOW WOOLEN CLOTH IS DYED~ Dyeing of woolens is done in three ways--in the wool, in the thread after it is spun, or in the piece after it is woven. If the wool is to be “dyed in the wool” it is now conveyed to the dyehouse, dyed the shade required, then returned to the mixing room. During the process of scouring, when the yolk was removed, a large part of the natural oil of the wool was also eliminated, and, in order to restore this lubricant, the wool is sprinkled with an oil emulsion, and the mixing picker thoroughly blends the wools. From here the wool goes to the cardroom, and by means of the carding machine the fibres are carded and drawn and delivered to the finisher in a broad, flat sheet. By means of the condenser it is divided into narrow bands, and the wool--free as yet from twist--comes out in soft strands. These strands or threads are called roping. [Illustration: MENDING ROOM Copyright American Woolen Company BURLING RAISING KNOTS Copyright American Woolen Company MENDING PERCHING Copyright American Woolen Company] [Illustration: DRAWING IN WARP THREADS Copyright American Woolen Co. Copyright American Woolen Co. Copyright American Woolen Co. WEAVING AND SCOURING] Now comes the mule spinning. The roping passes through rolls by which it is drawn and twisted to the size required, and wound on paper cop tubes or bobbins. Such of the yarn as is to be used for warp is then spooled from the bobbins to dresser spools. It is sized and wound upon large reels: from these transferred to the warp beam, as in the case of worsteds. The processes of drawing-in, preparation for weaving, burling and mending are practically the same as in the case of worsteds. ~HOW THE CLOTH IS MADE PERFECT~ The finishing processes of woolens, like the finishing processes of worsteds, vary with different fabrics, some fabrics being scoured and cleansed in the washers before fulling, others going to the fulling mill without cleansing. After fulling, the cloth is again washed and rinsed, and if necessary to remove any vegetable fibres it is carbonized. Napping or gigging raises the fibres to the nap desired. Gigging is done by means of a wire napping machine or teasel gig, which raises the ends of the fibres on the face of the cloth. The teasel is a vegetable product about the shape of a pine cone, and it is interesting to note that no mechanical contrivance has ever been invented to equal it for the purpose. [Illustration: SPINNING THE WOOL Copyright American Woolen Company ENGLISH CAP SPINNING] The napping which has been raised by the teasel is sheared or cut to a proper length by machine. The cloth is pressed, and, if it is desired to finish it with lustre, it is wound upon copper cylinders and steam is forced through it at a high pressure. [Illustration: Copyright American Woolen Company RING TWISTING] [Illustration: Copyright American Woolen Company BEAMING--YARN INSPECTING] [Illustration: Copyright American Woolen Company WOOLEN MULE SPINNING] [Illustration: Copyright American Woolen Company FINISHER WOOLEN CARDING] Next the cloth is dyed, if it is to be piece-dyed--that is, dyed in the piece. If the cloth is a mixture, the wool was dyed immediately after the scouring. In worsteds the dyeing is done either just after it has been subjected to the first combing processes, or the yarn is dyed in the skein or hank. [Illustration: Copyright American Woolen Co. PIECE DYEING Copyright American Woolen Co. FULLING CLOTH Copyright American Woolen Company FINISH PERCHING] [Illustration: Copyright American Woolen Company FINISHED CLOTH, READY FOR THE TAILOR] In the dry finishing the cloth is finished with various kinds of finishes desired, and it is steamed, brushed, sheared and pressed. Another examination for any imperfections or defects follows; the cloth is measured, packed and tagged and is ready for the market. The difference between worsteds and woolens is principally that in the threads or yarns from which worsteds are made the fibres of the wool lie parallel, one to another, being made from combed wool, from which the short fibres have been removed; and woolens are made from yarns in which the fibres cross and are matted and intermixed. When finished the effect of worsteds and woolens is materially different. Upon examination it will be found that the worsted thread resembles a wire in evenness, while the woolen thread is uneven and irregular. A worsted fabric when finished has a clear, bright, well defined pattern, seems close and firmly woven, and is of a pronounced dressy effect; while woolen cloths are softer, they are more elastic, the colors are more blended, the threads are not so easily distinguishable and the general effect is duller. Why Can’t We See in the Dark? We cannot see in the dark because there is no light to see by. To understand this we must first understand that when we see a thing, as we generally say, we do not actually see the thing itself, but only the light coming from it. But we have become so used to saying that we see the thing itself that for all practical purposes we can accept that as true, although it is not scientifically exact. Scientifically speaking, we see that part of the sunlight or other light which is shining upon it, which the object is able to reflect. If there were no air about us we could not hear any sounds, no matter how much disturbance people or things created, because it requires air to cause the sound waves which produce sound, and air also to carry the sound waves to our ears. In the same way, if there is no light to produce light rays from any given object to our eyes, we can see nothing. It requires light waves to produce the reflections of objects to our eyes. Without light our eyes and their delicate organs are useless. You cannot see yourself in a mirror when the quicksilver which was once on the back of the glass has been removed, because there is then nothing to reflect the light. We can only see things when there is light enough about to reflect things to our eyes. When it is dark there is no light, and that is the reason we cannot see anything in the dark. Why Can Cats and Some Other Animals See in the Dark? They cannot see in the real dark any more than human beings. These animals can find their way in the dark and can see more than a human being, because of one distinct difference in their eyes, which may for them be considered an advantage. The pupils of their eyes can be made much larger, and they can, therefore, let more light into their eyes than people. The result is that when it is so dark that you cannot see a thing and you decide it is really dark, the cat can still see, because there is always a little more light left and she can open the pupils of her eyes and make them larger, thus letting in more light, and the little bit of light there is still left gets into her eyes and she is able to see. But in a really dark room a cat could see no more than you can. You see, our eyes open and shut more or less just like those of the cat, according to the intensity of the light. When you go out of the dark and shaded room into the bright sunlight and look at the sun, you naturally squint your eyes without deliberately intending to do so. This is nature’s way of preventing too much light getting into your eyes at one time. Gradually the pupils of your eyes contract and get smaller, until you can see, without squinting, anything in the sunlight. If, then, you were to go right back into a dark or shaded room, you would have to wait a moment or two before you could see things distinctly in the room--until the pupils of your eyes had dilated (become larger), so as to let in enough light to enable you to see normally. The eye automatically enlarges and contracts the pupil of the eye, to enable us to see distinctly in either light or less light places. Why Is It Difficult to Walk Straight with My Eyes Closed? The reason we cannot do this always is because when we walk naturally the steps taken by our right and left feet are not of equal length. This difference in the length of the steps is due to the fact that our legs are never exactly the same length. We think of them generally as of the same length, but they are not, and this will be proven if you measure them accurately. Now, then, the longer of the legs will always take a longer step than the shorter one, and so, if our eyes are shut, we walk in circles, unless we have something to guide us. When we walk with our eyes open, we are able to overcome the tendency to walk in circles, because our eyes help the brain to direct the legs on a straight course. Another reason which affects the matter is that our eyes are very necessary in keeping our bodies balanced on our feet, and it is very difficult to learn to keep the body balanced with the eyes closed. Now, when your eyes are closed and you attempt to walk in a straight line your body balances from one side to the other, and this fact, coupled with the first reason given, makes your course irregular. But, say you, the man on the tight-rope has his eyes bandaged and he walks a very straight line. Yes; but remember that he has a straight tight-rope to guide him, and all he needs is to maintain his balance. One can learn to walk in a straight line with the eyes closed, but it takes a good deal of practice, as you will learn if you try. Why Can’t We Sleep with Our Eyes Open? We cannot sleep with our eyes open, because to be asleep involves losing control of most of the functions of the body. When we sleep the brain sleeps also. Perhaps it would be stated more clearly to say that we cannot sleep while the part of the brain which controls our activities is awake. There is a part of the brain which has the power to open our eyes, i. e., lift the eyelids, and when that portion of the brain ceases to exercise its power to keep the eyes open, they go shut. Even when we are awake that part of our brain cannot keep our eyes from winking, because there is another part of the brain which sees to it that our eyes wink every so often. This is done for the purpose of washing the eye-ball, and is the answer to another of your questions which is given in another place in this book. When the engineer at the electric light plant shuts off the power all the lights go out, and when you go to sleep you automatically shut off the power that opens your eyes, and the eyes are shut. The brain is asleep also, and if it is not completely asleep, you are restless. Why Do Our Eyes Sparkle When We Are Merry? If you should watch very closely the eyes of a merry person when you see them sparkle you would probably notice that the eyelids move up and down more often under such conditions than ordinarily, and if you know what moving the eyelids up and down in front of the pupil of the eye does, you will have your answer. Every time the eyelid comes down it releases a little tear, which spreads over the eyeball and washes it clean and bright. It does this every time the eyelid comes down. Now, there is something about being merry which has the effect of making the eyelids dance up and down, and thus, every time the lid comes down, the ball of the eye is washed clean and bright, and gives it the appearance of sparkling, as we say. Why Do We Laugh When Glad? We laugh when glad because the things which make us laugh combine together to rouse those parts of the body which are involved in a good laugh to act in a certain harmony, and when this combination is arranged in a certain way it produces a laugh. Certain things in the world, whether they are funny, ludicrous, or other things that produce the laughing effect, cause the brain to work certain muscles and nerves in a combination that produces a laugh. The impression which reaches the brain causes these muscles and nerves to act involuntarily and the laugh comes. It works just like the keys of the piano. Some combinations of notes produce sad sounds and other combinations produce glad sounds, but the combination when once touched will always produce the same sound. It is the impressions made on the brain which start the proper combination, and it does this instantly. Just as a pin prick in the arm will at once send a “hurt” message to the brain and cause the brain to jerk the arm away, so a laugh-producing combination of sounds, or things we see, or feel, sends an impression to the brain which at once sends out the “laugh” order. Some things make some people laugh while they do not affect others at all. That is because our brains are not always the same in regard to recording impressions. Some things impress some brains one way and others entirely in a different way or not at all. You do not laugh so heartily the second time you hear a funny story, because the impression the brain receives when the story is told the second time is not so vivid. Why Do I Laugh When Tickled? Practically the same things happen when we are tickled, and explains why you laugh when tickled. When some one tickles the bottom of your feet or your ribs or another part of your body it produces, in most cases, the same effect on the brain as the laugh-producing sound or sight, and arouses the same combination of muscles and nerves to activity. It is just like pushing the button of an electric bell. When you push the button the contact produces the spark which sets the machinery of the bell in motion and the bell rings and will continue to ring as long as you keep your finger on the button, or until the spark-producing power of the battery is gone. Then, as in the case of the bell, you cease to laugh, because the spark that produced the laugh combination is gone. That is why some things tickle some people very much and do not affect others. Some are not so sensitive to the laugh-producing combination as others. After the thing that tickles you has been going on for some time you are not tickled into laughter any more, because the impression on the brain ceases to be as strong. Why Don’t I Laugh When I Tickle Myself? Your mind tells you there is no need to laugh when you tickle yourself. Your mind will not respond to the tickling sensation when it is aware that the cause of the tickle is yourself. The reflex action of the mind which causes laughter and squirming when some one else tickles you only acts when it is not conscious of the cause. The whole purpose of the sensitive organization of our skins is to give us information and cause action which will enable us to protect ourselves when any outside influence touches us. An injurious touch causes shock and pain, and the harmless tickle arouses the laughing and squirming sensation. What Happens When We Laugh? Laughter is what we call a reflex action. When something occurs to make us laugh, whether it is something we see, or feel, or hear, it is because certain sensory nerves receive an impression in one of three ways, carry it to the nerve centre and the nerve centre then sends the same impression along certain efferent nerves, which connect with certain muscles or glands, and excite them to activity. The action is practically the same as when you hold a light before a mirror. The rays from the light strike the surface of the mirror and are reflected back from the surface, lighting perhaps corners of the room, which the direct rays from the light could not reach, all depending upon the angle of reflection. Light will always reflect from a mirror that is exposed to it. Now, then, when you see, hear or feel anything that makes you laugh, the sensory nerves have only to receive the impression to bring on the explosion of laughter. Something touched the laugh nerves or the laugh trigger that caused it to go off. You can prove that it is a matter of impression entirely by noting that some people can listen to a perfectly funny story, even when told by a clever performer, and never crack a smile, while others burst into uncontrollable laughter, and he who does not even smile may be listening even more intently than the other--he may even be looking for a laugh. It all depends upon the impression that is made upon the nerves. The muscles have the power to express the state of gladness which is indicated by laughter when certain impressions pass along the nerves which operate them, just as they can be made to do other things when the proper cause for action is shown them. Why Do We Cry When Hurt? We cry when we are hurt for the same reason that we laugh when we are glad. The muscles and nerves, under the direction of the brain, produce the cry just as the muscles and nerves produce laughter, although they are probably, but not necessarily, a different set of muscles and nerves. When we are hurt in any part of our body or feelings the impression does not affect us until it reaches the brain. Then instantly, of course, the body and brain go to work to destroy the pain. The first thing, of course, is to give a warning to other parts of the body that there is a hurt, and our crying is a warning to other people that we are hurt. That is probably the only good that crying does. It does not remove the hurt--it only tells others of our troubles. We cry with the lower part of the brain--the only portion of the brain which is active in a little baby. This is why even a tiny baby can cry. Crying is the only thing a baby can do to give warning of its distress or discomfort. Later in life the upper part of the brain develops. This is the master of the lower part. Therefore, we do not always cry when hurt as we grow older, because the master brain sometimes tells the lower brain that to cry will not help matters in the least, even though we are inclined to cry. Sometimes the hurt or shock to older people is so great or sudden that we cry out before the controlling part of the brain has had time to get in its work of preventing the outcry, but we are able to stop crying when the master brain again secures control. Where Do Tears Come From? Tears are not made only when we cry. They seem to come only when you cry, because it is then that they spill over. A little part of you is making tears all the time, and your eyes are constantly washing themselves in them. You have often noticed how you wink every few seconds? You have often tried to keep from winking--to see how long you could keep from winking. Boys and girls often do that, and when you keep from winking what seems a long time, you notice how your eyes ache and feel very dry just before you have to let them wink, in spite of how hard you try not to, and just when you think you are not going to. I will tell you just what winking does for the eyes. All of the time your eyes are open the front, or the part you see things with, is exposed to the dust and dirt that fills the air at all times, although we cannot always see the dust. The wind, too, is constantly making them dry. But have you ever noticed that although you never wash the inside of the front of the eye, or pupil, it is always clean? Well, it is because your eye washes itself every time you wink. I will tell you how this is done. Up above each eye, inside, of course, there is a little gland called the tear-gland. This gland is busy all the time you are awake making tears. As soon as the front of your eye becomes dry, or if a particle of dust or anything else strikes it, the nerves you have there tell the brain, and almost at once the eyelid comes down with a tear inside of it, and so washes the front of your eye clean again. It does its work perfectly and as often as necessary. There is always a tear ready to be used in this way. Where Do the Tears Go? Let me show you. Look right down here at the inner corner of my eyelid, where you will see a little hole. That is where the tears get out of the eye, when they have washed your eyeball clean. Where do they go then? Did you ever notice how soon after you cry you have to blow your nose? The reason for that is that when the tears go through the little hole they run down into the nose. This making of tears and winking goes on all the time while you are awake, and after they wash your eye off they go on out through this little hole. But when you cry you make more tears come than you need, so many, in fact, that they cannot all get away through this little hole, and as there is no place else for them to go, and as there is no place to keep them inside the eye, they simply spill themselves right over the edge of your lower eyelid and run down your cheek. Story in a Barrel of Cement What Is Cement? The dictionary tells us that cement is “any adhesive substance which makes two bodies cohere.” Thus any material performing this function may be called cement, such, for example, as the cement used in mending broken china. Glue also is a form of cement. This story has to do with Portland cement, which is a structural or building material used in countless ways. Why Is Cement Called Portland Cement? After being wet with water it hardens into stone, and it was given the name “Portland” because, when first manufactured in England, and mixed with sand and stone, it resembled a celebrated building stone called Portland, which was obtained from the Isle of Portland. Compared with other American industries, the manufacture of Portland cement is of recent origin. Formerly all Portland cement was brought from foreign countries. After successful manufacture became established in this country, however, the industry advanced with great rapidity. A few years ago the entire United States did not use as much cement as is now used in any one of our large cities. At the time these facts were written (1914) the manufacturers were making more than 90 millions of barrels a year. What Is Cement Made Of? Portland cement is composed chiefly of lime, alumina and silica. It is manufactured from rocks, marl, clay and shale containing these ingredients. If any one of them is lacking in the raw material as it is taken from the earth, it is supplied during process of manufacture. The greatest cement district in America is in Pennsylvania, and is known as the “Lehigh District.” A rock containing proper constituents for making Portland cement was found there in vast quantities, and for a number of years the Lehigh District was the center of the industry. In time it was found that certain clays, marls and shale could also be manufactured into Portland cement, and thus mills have been erected in all sections of the United States. One of the largest companies in the United States found that cement could be manufactured from a combination of blast-furnace slag and limestone, and this is now made by the company in large quantities, the product being a true Portland cement. What Is Concrete? Portland cement is the strongest and most lasting of all modern mortars or binding materials. When mixed with sand and stone the resulting mixture is called concrete. Being a plastic material when first mixed, it cannot be used as we use brick or stone, but must be poured into molds or forms, which hold it in place until it hardens into rock. It may be cast in any form or shape, and thus it is useful for a vast number of purposes. It will harden under water, and time and exposure to the elements merely increase its strength. The most common form in which it is used, one familiar to everybody, is in the construction of sidewalks. It is used in all great engineering projects, such as the building of dams, bridges, retaining walls, sewers, subways and tunnels. Being fireproof, large quantities of it are used in buildings and likewise on our farms, where it is extremely valuable as an enduring and sanitary material. What Is Cement Used For? It has been said that concrete is a plastic material, meaning that it is soft and pliable in the sense that clay or putty are plastic. For this reason it is cast in forms or molds. Sometimes it is used in the form of plain concrete, and on other occasions it is reinforced, meaning that iron rods, steel bars or woven wire mesh are imbedded in the concrete. When we speak of a “reinforced” concrete building, imagine a huge wire bird cage encrusted within and without with concrete. Place a block, beam or column of concrete upon the ground and it will bear a tremendous load, meaning that it has great strength in compression. On the other hand, if we were to place a long beam upon supports at either end, leaving the greater length of it suspended and without support, it would carry but a small load compared with concrete in compression. Therefore, in making concrete beams or girders in a building, strong steel bars are embedded in the concrete to take up what are termed the tensile strains. [Illustration: WHAT A CEMENT MILL LOOKS LIKE This is a picture of a cement mill. Millions of dollars are invested in these great mills, which are now located in practically all sections of the country. Material is brought from the quarry to the mills, where it passes through various stages, such as grinding, burning and bagging. Expert chemists are employed to see that the cement is made exactly right. It is a very scientific matter to make a thoroughly good cement. There must be no guess work. Some mills are very large, the plant comprising a number of buildings, and some companies operate several mills in different localities. A single company supplied all of the cement used in the Panama Canal, which great project required more than six million barrels.] [Illustration: This picture shows a quarry in the famous Lehigh cement district. The giant steam shovel or excavator burrows into the hill like some great animal, and when the bucket is full it is dumped into the cars shown on the track, which convey the rock or the raw material to the mill.] [Illustration: WHERE THE MATERIAL IS OBTAINED This is an illustration of a method of excavating and loading marl and clay to be manufactured into Portland cement. The large bucket suspended over the cars does not gouge into the hillside as shown in the preceding picture, but descends like a huge steel hand, the metal parts opening and closing like fingers. The long derrick elevates the bucket and swings it over the train of cars.] [Illustration: This is a view of a powerful rock crusher, which is operated by the electric motor shown at the right. The cement rock is brought from the quarry and dumped into the machine, from which it issues in broken fragments, as shown in the illustration, this being the first or preliminary crushing process.] [Illustration: THE HUGE ROCK GRINDERS This is a view of the electric motors operating the grinding machines which reduce the raw material to a very fine powder. There are various types of mills or grinders, to which the material comes after going through the rock crusher. They grind it in preparation for the kilns.] [Illustration: The kiln is a very important feature of the cement plant. The finely ground raw material must be calcined or burned before it becomes Portland cement. These kilns range from 60 to 240 feet in length. They are slightly inclined and revolve upon rollers. The finely ground material enters the kiln at the upper end and travels throughout its length as the kiln slowly revolves. Powdered coal dust is fed into the kiln at the lower end, where it is ignited and generates intense heat. When the finely ground raw material comes into contact with the heat, which reaches 2800 degrees F., it is transformed into what is known as clinker, which issues from the lower end of the kiln and is passed on to other machinery, which grinds it into impalpable powder or Portland cement.] [Illustration: HOW CONCRETE IS MIXED This is an ingenious machine which bags and weighs the cement. The bags are suspended as shown, and when filled and weighed by the machine are placed in barrels and shipped to their destination. Every device of this kind that will save time and labor cheapens the cost of manufacture.] [Illustration: In mixing cement, sand and stone together in order that concrete may be obtained, it is customary to use, if the operation is a large one, what are known as mechanical mixers. These are large iron cylinders into which the three materials are put and water added. The cylinder or iron drum revolves until the contents are thoroughly mixed, when they issue from the mixer through a chute or spout. A mixer of this type is shown on a succeeding page describing the making of a concrete road. This picture shows mixing concrete by hand. The sand and cement are first thoroughly mixed in the dry state and subsequently the stone and water are added. Concrete should be thoroughly mixed in order that every grain of sand may be entirely coated with cement, and then these two combined make a rich mortar, which should surround entirely every piece of stone.] [Illustration: HOW CONCRETE BUILDINGS ARE MADE This picture shows how concrete houses or walls are built through the use of what are known as forms. In building a wall we have an inside and outside form, as shown in the picture, between which the concrete is placed. After it hardens the forms are removed. In some operations, such as the construction of a large factory building or great bridge, there is such a vast array of timber construction as to make the scene quite impressive, especially when bridge arches of great span and height are under construction.] [Illustration: This is a view of an arch built of concrete during the Jamestown Exposition. It is a striking illustration of how concrete may be used for both ornamental and practical purposes. In no field has concrete proved to be of more value and economy than in the construction of bridges, whether large or small. Some of the largest bridges in the world are built of concrete, and in many cases iron bridges are incased in concrete to keep them from rusting.] [Illustration: CONCRETE HOUSES CANNOT BURN This is a curious example of concrete construction. It is a coal pocket, from which locomotives are supplied with fuel. Railroad companies have adopted it because of its great strength and durability.] [Illustration: Just as mammoth structures are created with poured concrete, so we may produce the most delicate and ornamental patterns. These are usually cast in plaster molds and often in molds of wood or iron. Where undercut work is required, such as in the sun-dial shown, a wood or metal mold could not be removed without injury to the concrete, and so sculptors have invented the pliable glue mold, which can be easily removed and which will spring back to its original shape if necessary to use it a second time.] [Illustration: Concrete in dwelling construction means the elimination of fire danger and also cost of painting and repairs. This picture shows a solid concrete house, parts of which have been encrusted with beautiful tiles. Concrete has been successfully used in all types of dwellings, from the humble abode of the workingman to the palace of the multimillionaire. An entire house may be made of concrete, even to the roof and stairways, and where a dwelling is constructed of this material throughout, it is proof against fire and decay.] [Illustration: HOW THE FARMER USES CONCRETE This is an interesting example of concrete construction. It is a large water tower which will never warp, rust or decay. In this field concrete has been of great service, whether reservoirs are constructed in the form of towers or tanks. As already stated, water does not affect the life or strength of concrete, except to improve it.] [Illustration: This is a concrete silo. A silo made of concrete is merely a huge stone jar in which green food for cattle is preserved. The crop is gathered and placed in the silo, thus insuring abundance of green and wholesome food throughout dry seasons and during the winter. The contents of the silo is known as silage or ensilage, and is merely corn fodder cut when green. Concrete silos are both storm- and fire-proof.] [Illustration: It is usual to consider concrete in connection with great engineering enterprises, but nevertheless many millions of barrels are used each year by the farmers of the United States. This picture shows a clean, sanitary and durable concrete stable. In buildings of this character concrete is rapidly supplanting wood, which soon goes to decay, to say nothing of accumulation of filth.] [Illustration: HOW CONCRETE ROADS ARE BUILT MECHANICAL CEMENT MIXER] [Illustration: A CONCRETE ROAD Our two last pictures relate to an exceedingly important and rapidly increasing use of cement. It is the construction of concrete roads. The first picture shows a concrete road in course of construction. The mechanical mixer referred to above is shown in this picture. It is a self-propelling machine and mixes the concrete very rapidly. As it comes from the mixer in a wet and mushy mass it is placed between rigidly staked side forms, where it hardens into imperishable rock. The road is brought to its shape by working to and fro a long plank called a template, after which the surface of the road is troweled with wooden floats, giving it a texture which prevents horses and cars from slipping. The last picture shows a narrow concrete road in the state of Maryland. Wherever these roads have been built they mean much to the women and children of the community. They never grind up into mud or dust, and are as pleasant to walk upon as the sidewalks of the city. Children, especially, delight in them. In Wayne county, Mich., where they have the most celebrated concrete roads in the world, the children go to and from school on roller skates, and various games are played on the concrete road.] Why Don’t We Make Roads Perfectly Level? Roads are made with a curving upper surface, i. e., higher in the middle, in order that the rain will drain away from the road into the gutters or ditches which you find at the sides. You see water has the faculty of running only in one direction, and that is downward. If it cannot go down on one side or the other, it will collect in puddles and make the road impassable. For this reason we build our roads so they are higher in the middle than at the sides--not much higher; only about six inches or so--giving them just the gentle slope toward each side that is necessary to allow the water to run off gradually, but sufficiently sloping to keep the water from collecting in puddles in the road. Thus after the dust has been settled by the first rain that falls, most of the surplus rain that falls on the roads finally runs into the ditches at the side of the road. Why Are Some Roads Called Turnpikes? Undoubtedly the name turnpike as applied to some roads arose from the fact that pikes or gates were set across the roads by the keeper or toll-collector. In addition to collecting tolls, it was a part of the toll-keeper’s business to keep the road in repair. His wages and other expenses for doing this were received from the tolls collected from the people who used the road to ride on in carriages, wagons, etc. In the early days the toll-collector was armed with a pike, a long-handled weapon with a sharp iron head, which he used to prevent people who travelled his road from going by without giving up their toll. Later on a swinging gate was built across the road, which made it unnecessary to use the pike, though the name was retained, for no one could pass while the gate barred the way. When the passerby had paid his tolls, the toll-collector opened the gate and let him pass. If he did not pay the gate remained closed and the driver had to turn back or decide to pay. Hence comes the name turnpike. In some parts of the country they call these toll roads. What Is Dust? A large part of the dust we see in the roadway when the horses kick it up, or when an automobile passes, is made up of the pulverized dirt of the roadway. It becomes mixed with other things, such as the street deposits of animals, particles of carbon, etc. Particles of this dust get into our throats, and as there are many germs in it, they are very liable to cause sickness, especially the colds from which we suffer. What Becomes of the Dust? The dust of the roadway is generally blown away by the wind, to come down to earth again wherever the wind happens to carry it--on the lawns, the doorsteps or back to the road, perhaps. In any event, the rain which is certain to come sooner or later, washes this dust back into the soil, or into the sewers. Part of it mixes with the soil. The organic matter in dust helps to fertilize the soil, and is therefore useful. Other parts of the dust are oxidized and consumed by the air, through the heat of the sun. So you see the dust is continually changing from one thing to another. Are Stones Alive? Real stones are not alive. They do not become stones until they have been burned out--until they have become what is known as dead matter. This is meant entirely in the sense that we commonly think of the meaning of the word “alive,” which is to be able to breathe and grow. Stones can neither breathe nor grow. They belong to the inanimate kingdom of things on the earth. Particles of this dead matter, found in stones, etc., are in many cases taken up by things that are actually alive, and help to form the bodies of living things. The most common thing to be found in rocks and stones is what is called “silicon,” and we find this silicon in the straws of the wheat, oats and corn, and in many other things, but not in a way that can be detected except by chemical analysis. A great many of the things found in stones are found in living things, but rocks and stones are not alive in any sense. What and Why Is Smoke? Smoke is produced only when something which is being burned is burning imperfectly. If we were to put anything burnable into the fire and establish just the right amount of draft, and knew how to build our fires properly, there would be no smoke and very little ashes. In the case of the black coal smoke which we think of mostly when we think of smoke at all, the black portion is principally little unburned particles of coal which pass up the chimney with the gases which are thrown off when the coal is being burned. These gases would be invisible--they really are invisible--if it were not for the little particles of coal which are drawn up the chimney with them. If you look at the chimney from which a wood fire expels the gases you find the smoke very light in color--showing that not so much unburned matter is being thrown off. A charcoal fire makes no smoke, because the charcoal has had the unburnable things taken out of it beforehand, and the charcoal stove is almost perfect in construction from the standpoint of combustion. Of course, the thickness of the smoke from a coal fire is often increased by the fact that there are unburnable things mixed in with the coal, some of which also pass off through the chimney. Why Can’t We Burn Stones? We cannot burn anything that has already been burned, and a stone has already been burned. To understand how this is we must first find out what takes place when a thing is burned. When a thing is burning it means merely that that particular thing is taking into its system all of the oxygen of the air that it can combine with. When it has done this it cannot be burned any more. Of course, in doing this the thing originally burned changes its character. The elements in a candle when lighted mix with the oxygen in the air and disappear in the form of gases. The elements in coal mix when fired with oxygen and change into ashes, gases and smoke. A stone, however, is the result of a burning that has already taken place. The original element of most of the rocks and stones we see was silicon, and when that combines with oxygen, the result is some form of rock, which you may be able to break up or throw, but which you cannot burn again. What Is Fog? The fog which we generally think of when we speak this word is the fog at or on the sea or other body of water--the one that makes the ships stand by and blow their fog horns. A fog of this kind is nothing more nor less than a cloud, come right down to earth and spread out a little more. People who have gone up into the air in balloons and other airships through the clouds, say that the clouds are only fogs, and that above them it is as clear as it is on a sunshiny day on the water when there is no fog. There is another kind of fog which settles down over the land, especially in the cities. It is a damp mist which combines with the smoke and other impurities in the air and forms a black and dirty cloud about everything. This occurs when the upper air prevents the smoke which rises from a city with all its people and fires in the furnaces from passing up and away. The upper air acts like a blanket and keeps the misty, smoky air down, until the wind comes along and blows it away. What Becomes of the Smoke? There are a number of things in smoke, and when we know what they are, we will find a natural answer to this question. First, there are, of course, the little unburned particles of fuel which get carried up the chimney by its drawing power. These naturally fall to the ground of their own weight, once they get beyond the drawing power of the chimney and out of the current of air so formed. Some of the gases are already quite burned out when they pass up the chimney. There is a lot of carbonic acid gas which, of course, mixes with the air and eventually becomes food for the plants. Then there are some gases which are not entirely burned, and the air burns them still more until they, too, become carbonic acid gas, or water which is also thrown off by a burning fire. Why Does an Apple Turn Brown When Cut? The reason is that when you cut an apple, the exposure to the air of the inside of the apple causes a chemical change to take place, due to the effect the oxygen in the air has on what is scientifically known as the enzymes in the apple, or what are commonly called the “ferments.” When the peel is unbroken it protects the inside of the apple against this action by the oxygen. The brown color happens to be due to the chemical action. The action is similar to the action of the air on wet or damp iron or steel, in which case we call it rust. Why Does a Piece of Wood Float in Water? A piece of wood will float in water because it is lighter than the same amount of water. We do not mean that a piece of wood weighing one pound, for instance, would weigh any more than a pound of water, of course, but if you took the measurements of each you will find that it took less bulk to make a pound of water than of wood. If you had a piece of wood so shaped that it just filled a glass completely, and then took another glass and filled it with water, you would find that the glass containing the water weighed the most. Another name to give to this difference would be to say that the water was more dense than the wood. By the law of gravitation the denser thing will always go to the bottom, and as wood is less dense than water, it will stay at the top if put in water. The piece of wood has more air in it than the water. If you could expel the air from the piece of wood and then put it in water, it would sink. Why Does Iron Sink In Water? The explanation in regard to the piece of wood floating in water is the beginning of the answer to this question. A piece of iron is heavier than an equal bulk of water, and will therefore go to the bottom, as will all things which are more dense than water. A piece of iron has no air in it. The particles of a piece of iron are so close together that there is no room for air in it and it will therefore sink in water. A piece of wood from which all of the air had been expelled would also sink. Why Doesn’t an Iron Ship Sink? This is a very natural question for you to ask right after you were told why iron sinks in water. The explanation is that by making an iron ship in the way we do, we fix it so that it holds a lot of air in between the bottom and sides, making the combination of the two--the iron ship and the air in it--lighter than the water on which it sails. Men thought at one time that a ship would sink if made of iron, and therefore built all of their ships of wood. Finally one inventor made a ship of iron and it was one of the wonders of the world. When we found that iron ships would float if they were built to retain sufficient air to keep them from sinking, we made the hulls of most ships of iron for a time. Now, however, the best ships are made of steel, which is even better. If you bore a hole in the bottom of a ship, the water will run in if the ship is in the water, and the ship will sink, because the water coming in drives out the air; and when the ship is full of water, the water in it, with the ship itself, are heavier than the water on which it sails, and the ship will go down. Filling a ship with water makes the iron part of the ship just like a bar of iron, so far as its sinking qualities are concerned. Of course, an iron ship must be made long enough and broad enough so that when it is completed there will be sufficient air contained within the hull to make the combination lighter than water. Always, therefore, when a ship is to be built, competent engineers must go over the plans of the vessel and calculate the air capacity, so as to make sure she will float. Nowadays it would be difficult to sink a modern vessel by boring one small hole in the bottom, because the bottom and sides are lined with enclosed steel air-chambers, and a ship will keep afloat even if one or a number of holes are made. The reason is, of course, that when you bore a hole into one of these air-chambers the water rushing in will fill that air-chamber with water, but as there is no connection from the inside with the rest of the ship, the water can get no further. Why Does a Poker Get Hot at Both Ends if Left in the Fire? Both ends of the poker become heated because the poker is made of iron, and iron is a particularly good conductor of heat. To understand this we must look into the question of what a good conductor of heat is. In this case the particles of iron, which combined form the poker, are so close together that when those at the end of the poker which is in the fire get hot, the particles at that end hand the heat on to the particles next to them, and so on until the whole poker is hot. The difference between a thing which is a good conductor of heat and a thing which is not a good conductor, lies in the ability of the different particles which compose it to hand the heat on to the others. Did you ever notice that the handle of a solid silver spoon will become hot if the spoon is left in hot coffee? Solid silver is a good conductor of heat. A plated spoon is not a good conductor, however, and will not become hot if left in the cup of hot coffee as a solid silver spoon will. Would a Wooden Spoon Get Hot? A wooden spoon would not get hot, because wood is not a good conductor of heat. The atoms which compose the wood have not the power to transmit the heat to each other. This is strange, too, when we think that a poker is a good conductor of heat, but will not burn, while wood is not a good conductor, but will burn readily. Perhaps you have already discovered this in connection with a wood fire. One end of a stick of wood may be burning fiercely, and yet you can pick it up by the other end and find it is not even warm. This proves to you that wood is not a good conductor of heat, and explains why the handle of a wooden spoon in a bowl of hot soup will not get hot while the handle of a silver spoon will. Why Does Iron Turn Red When Red Hot? The answer is that the piece of iron has been heated to the point where it gives off light of its own. The red you see is only one stage in the development of iron to the point where it makes its own light. If you heat it still more it will make a white light. You know that it produces the light itself, because if you take a piece of iron into a perfectly dark room and heat it to a white heat it will show better than where there is other light. If you continue the process the iron will melt and change in form. Therefore, the “red hot” name for a piece of iron in that state is a perfect name. It is a warning that the iron is coming to a point where if the heating process is continued, it will change its form and in this state, when treated according to known methods, the iron is turned into steel, which has many characteristics that iron does not possess. Now, I can, of course, hear you ask why doesn’t an iron kettle get red hot? and I can answer that easily. If you treat the kettle the same way as you do the piece of iron, it will get red hot. The difference is that you are thinking of an iron kettle with water in it. As long as there is any water in the kettle, that keeps it from getting hot. The water inside keeps the kettle from becoming red hot. If you took a hollow rod of iron and filled it with water, it would not become red hot as long as any water remained in the hollow portion. How Did the Sand Get on the Seashore? The sand on the seashore is nothing more or less than ground-up sandstone. In dealing with the inanimate things in the world we find that a very important element of all of them has been given the name silicon. When the crust of the earth, which is the part we call the land and rocks, and includes the part under the sea, was a molten mass, this silicon was burned, combining with the oxygen which surrounded everything, and produced what is known as silica. Silica is the name given to the thing which is left after you burn silicon. A very large part of this silica was deposited in parts of the earth, and when the crust of the earth cooled off it was sand. By pressure and contact with other substances it became stuck together, just as you can take wet sand at the seashore to-day and make bricks and houses and tunnels, excepting that in the case we speak of it was something besides water that pressed and stuck the little particles of sand together. They stuck together more permanently. Then when the oceans were formed, as shown in another part of this book, much of the sandstone was found to be at the bottom and on the shores of the oceans. The action of the water continually washing against the sandstone gradually broke the sandstone up into the tiny particles of sand again, and this is what makes the sand on the seashore. What Makes a Soap Bubble? A bubble is merely a hollow ball of water with air inside. The air in coming up through the water in trying to rise out of the water is caught in the water in such a way as to form the bubble, and since the ability of the air inside of the bubble to rise is greater than that of the water which forms the bubble, and which has a tendency to pull it down, the bubble rises into the air. The water ball is very thin and keeps running down to the bottom of the ball, where you see it form into drops, and soon this makes the walls of the water bubble so thin that the air bursts through the ball of water, and that is What Makes the Bubble Explode? Sometimes we blow soap bubbles. We mix soap in the water and that makes the walls of the water ball which we produce a little tougher, and it requires a great deal more effort for the air to escape from it, as the soap keeps the water in the walls of the bubble from running down to the bottom for quite some time, and, therefore, soap bubbles will often travel in the air for some distance. The colors we see on soap bubbles are produced by the rays of sunlight, which strike the bubble and reflect them back to us in colors very similar to those of the rainbow. Why Are Bubbles Round? Bubbles are round because the air which forms the inside of the bubble exerts an equal pressure in all directions. It presses equally against all sides of the bubble at the same time. The Story in a Yard of Silk God’s Creation and Man’s Invention. ~WHERE DOES SILK COME FROM?~ Silk in its finished state is an ideal product. It is at once durable, magnificent to the eye, tender to the touch, and its rustle is soft music to the ear. Hence it is easy to understand why the silkworm, from the earliest times, has been an object of much consideration and concern from a commercial and industrial point of view. In this country alone, we annually expend as much for silk goods as we do for public education and thirty times as much as we do for foreign missions. Such an indomitable producer of wealth is the silkworm, and a producer of wealth it has been from an age as remote as when Joseph was down in old Egypt, interpreting the dreams of King Pharaoh’s butler and baker and later that of the King himself. To-day we speak of twenty centuries, and our minds can hardly comprehend such a lapse of time. What shall we think of the silkworm, that for twice twenty centuries has furnished practically all the raw material for the world’s silk supply? Because man’s ingenuity is at present actively engaged in the attempt to displace it by cheaper substitutes, the thought has come to us that, without going too minutely into mechanical processes, a good opportunity is presented to give some interesting information in regard to the silkworm as the creation of the Divine Hand, in contrast to the silkworm as the creation of man. According to Chinese authority, the use of silk dates from 2650 B.C., and it is generally conceded that, in point of age, it stands midway among the great textiles, wool and cotton having preceded it, while flax, hemp and other fibrous plants followed shortly in its train. The first patron of the silkworm was Hoang-Ti, Third Emperor of China, and his Empress, Si-Ling-Chi, was the first practical silkworm breeder and silk reeler. It is related of her that she was once walking in the palace gardens when she discovered a strange and repulsive looking worm. It was small, of a pale green color, and was feeding greedily on a mulberry leaf. She interested the Emperor in this strange creature, and, at the Emperor’s suggestion, took the fine silken web which the worm finally spun, and was the first to successfully reel the new filament and weave it into cloth. So beneficial to the nation was her work considered that her gratified subjects bestowed upon her the divine title of “Goddess of the Silkworms,” and to this day the Chinese celebrate in her honor the “Con-Con Feast,” which takes place during the season in which the silkworm eggs are hatched. In accounting for the presence of silkworms in the garden of this early empress, we can rightly conclude that certain parts of China have always abounded in forests of mulberry trees, and that the worms themselves had existed in great numbers in a wild state and attached their cocoons to the trees for ages before any use was discovered for their web. In fact, such wild silkworms not only abound in China to-day, but have also been found in Southern and Eastern Asia, inhabiting the jungles of India, Pegu, Siam and Cochin China, but the cocoons of these worms are, naturally, of a very inferior quality, and are only used for the crudest kind of work. [Illustration: Illustration by courtesy The Brainerd & Armstrong Silk Co. THE INTRODUCTION OF SILK INTO EUROPE Pilgrims brought silkworm eggs in their staffs, together with the branches of mulberry trees, from China to the Court of Justinian at Byzantine, A.D. 555. The penalty for taking silkworm eggs out of China was death. The accompanying illustration is a reproduction of a mural painting on rep in the Royal Textile Museum at Crefeld, Germany, one of the great silk textile centers of the world. The artist shows the pilgrims presenting the silkworm eggs and the mulberry branches to Justinian, beside whom, just in the act of rising, is his famous queen Theodora.] Silk culture from the time of Hoang-Ti became one of the cherished secrets of China. The headquarters of the industry was in the Province of Chen Tong, where was produced the silk for the royal family. In time the silk and stuffs of China became articles of export to various portions of Asia. Long journeys were made by caravans, occupying two-thirds of a year in going from the cities of China to those of Syria, but the price obtained there exceeded the expense of the journey, and thus left a large margin of profit to the merchants. In this manner, for one thousand years, the Chinese sent their silk to the Persians who, without knowing how or from what it was made, carried it to the Western nations. So carefully did the Orientals guard their secret, that there is reason to believe that Aristotle was the first person in the occidental world to learn the true origin of the wrought silk from Persia. In commenting on the silk which was brought from that country on the return of Alexander’s victorious army, he described the silkworm as a “horned insect,” passing through several transformations, which produced “bomby-kia,” as he called the silk. But the classics must convince one that Aristotle’s discovery did not at once become matter of current knowledge. In fact, for five hundred years after Aristotle’s time the common theory of the origin of silk among the Greeks and Romans was that it was either “a fleece which grew upon a tree” (thus confounding it with cotton), or a fibre obtained from the inner bark of a tree; and some, deceived by the glossy and silky fibres of the seed vessels of the plant that corresponds to our milk or silk weed, believed it to be the product of some plant or flower. So Virgil, in speaking of silk, says, “the Seres comb the delicate fleecings from the leaves.” In the Sixth Century, A.D., all the raw silk was still being imported from China by way of Persia, when the Emperor Justinian, having engaged in war with Persia, found his supply of raw silk cut off and the manufacturers in great distress. His foolish legislation did not help the situation, and a crisis was averted only by two Nestorian monks, who came from China with seed of the mulberry tree and a knowledge of the Chinese method of rearing worms. No one, on pain of death, was allowed to export the silkworm eggs from China, but Justinian bribed the monks to return to that country, and in 555 they came back, bringing with them a quantity of silkworm eggs concealed in their pilgrim’s staffs. And here let us say that there has only once since been an important importation of eggs from Asia. That was about 1860, when Dr. Pasteur was making a study of a germ disease which was threatening the industry. Consequently, it can truly be said that practically all the silkworms of the Western world are descended from those brought in the eggs by the monks to Constantinople. Justinian gave the control of the silk industry to his own treasurer. Weavers, brought from Tyre and Berytus, were employed to manufacture the silk, and the whole production was a monopoly of the emperor, he fixing its prices. Under his management, the cost of silk became eight times as great as before, and the Royal Purple was twenty-four times its former price. But this monopoly was not of long duration and, at the death of Justinian in 565, the monopoly ceased, and the spread of the industry commenced in new and diverse directions. While every detail of the growth of the industry has an unusual interest, as showing how such an insignificant thing as a worm may become a potent factor in Nature’s economy, the scope of this article will hardly allow us to more than sketch some of the other more salient points of the history of the silkworm. About the year 910, the silkworms made their appearance in Cordova, Spain, being brought there by the Moors. From Spain silk culture soon extended to Greece and Italy. ~WHEN SILK CULTURE WAS INTRODUCED IN AMERICA~ Silk was introduced on this continent through the Spanish Conquest of Mexico, and the first silkworm eggs sold for $60.00 an ounce. A century later royal orders were issued requiring mulberry trees to be planted in the Colony of Virginia, and a fine of twenty pounds of tobacco was imposed for neglect, and fifty pounds of tobacco was given as a bounty for every pound of reeled silk produced. Silk culture spread rapidly in the other Colonies, and to-day the story of the ineffectual attempts to profitably rear the silkworm in this country is as voluminous as it is interesting. Suffice it to say, as a sop to our inherent Yankee pride, that silk culture was introduced into Connecticut as early as 1737, the first coat and stockings made from New England silk being worn by Governor Law in 1747, and the first silk dress by his daughter, in 1750. This State, for the eighty-four years following, led all the others in the amount of raw silk produced. In Connecticut also, was built the first silk mill to be erected on this continent for the special purpose of manufacturing silk goods. This building was constructed in 1810 by Rodney and Horatio Hanks, at Mansfield, and is still standing as an heirloom which has come to us from the infant days of the industry. The silkworm has become domesticated, since, during the long centuries in which it has been cultivated, it has acquired many useful peculiarities. Man has striven to increase its silk producing power, and in this he has succeeded, for, by comparing the cocoon of the silkworm of to-day with its wild relations, the cocoon is found to be much larger, even in proportion to the size of the worm that makes it or the moth that issues from it. The moth’s loss of the power of flight and the white color of the species are probably the results of domestication. [Illustration: JAPAN THE NATURAL HOME OF THE SILK WORM GATHERING MULBERRY BRANCHES.[1] This picture shows a grove of mulberry trees from which branches are being gathered as food for the worms. This is often done by the children.] [Illustration: FEMALE MOTHS DEPOSITING EGGS.[1] The moths are placed upon pieces of cardboard, upon which they deposit their eggs. The cards with the eggs are kept in a cool place until the season for hatching arrives.] [Illustration: PREPARING COCOONING BEDS.[1] This picture shows two boys preparing a bed of twigs or branches upon which the worms may spin their cocoons.] [1] Illustrations by courtesy The Brainerd & Armstrong Co. [Illustration: HOW THE SILKWORMS ARE CARED FOR HATCHING THE EGGS. As the eggs hatch on the cards, the young worms are removed to other cards or trays, where they are fed and cared for.] [Illustration: REMOVING SILKWORMS FROM CARDS WHERE THEY WERE HATCHED. Every few days the young worms are changed to new and clean cards.] [Illustration: METHOD OF REELING RAW SILK. The cocoons are soaked in hot water in the basins shown in the front to loosen the gum. The silk threads then pass through the hands of the operators and are reeled on swifts in the cabinet shown in the rear. A more modern appliance for reeling the silk is shown on one of the following pages.] The foregoing pages and pictures by courtesy of Brainerd & Armstrong Silk Company, from their book entitled, “Silk, the Real versus the Imitation.” [Illustration: FULL GROWN LARVA--SHOWING POSITION IN MOLTING.[2]] [Illustration: MALE MOTH.[2]] [Illustration: FEMALE MOTH.[2]] [Illustration: SIDE VIEW OF CHRYSALIS.[2]] [Illustration: BOTTOM VIEW OF CHRYSALIS.[2]] [2] The cuts on this page and balance of cuts in the story of silk copyright by the Corticelli Silk Mills. The silk moth exists in four states--egg, larva, chrysalis, and adult. The egg of the moth is nearly round, slightly flattened, and closely resembles a turnip seed. When first laid it is yellow, soon turning a gray or slate color if impregnated. It has a small spot on one end called the micropyle, and when the worm hatches, which in our climate is about the first of June, it gnaws a hole through this spot. Black in color, scarcely an eighth of an inch in length, covered with long hair, with a shiny nose, and sixteen small legs, the baby worm is born, leaving the shell of the egg white and transparent. ~THE SILKWORM—HOW HE DOES HIS WORK~ Small and tender leaves of the white mulberry or osage orange are fed the young worm which simply pierces them and sucks the sap. Soon the worm becomes large enough to eat the tender portions between the veins of the leaf. In eating they hold the leaves by the six forward feet, and then cut off semi-circular slices from the leaf’s edge by the sharp upper portion of the mouth. The jaws move sidewise, and several thousand worms eating make a noise like falling rain. The worms are kept on trays made of matting, that are placed on racks for convenience in handling. The leaves are placed beside the worms, or upon a slatted or perforated tray placed above them, and those that crawl off are retained, while the weak ones are removed with the old leaves. The worms breathe through spiracles, small holes which look like black spots, one row of nine down each side of the body. They have no eyes, but are quite sensitive to a jar, and if you hit the rack they stop eating and throw their heads to one side. They are velvety, smooth, and cold to the touch, and the flesh is firm, almost hard. The pulsation of the blood may be traced on the back of the worm, running towards the head. The worm has four molting seasons, at each of which it sheds its old skin for a new one, since in the very rapid growth of the worm the old skin cannot keep pace with the growth of the body. The periods between these different molts are called “ages,” there being five, the first extending from the time of hatching to the end of the first molt, and the last from the end of the fourth molt to the transformation of the insect into a chrysalis. The time between the four “molts” will be found to vary, depending upon the species of worm. [Illustration: HOW THE SILKWORMS ARE REARED.[2]] When the worm molts it ceases eating, grows slightly lighter in color, fastens itself firmly by the ten prolegs, and especially by the last two, to some object, and holding up its head and the fore part of its body remains in a torpid state for nearly two days. By each successive molt the worm grows lighter, finally becoming a slate or cream white color, and the hair, which was long at first, gradually disappears. The gummy liquid which combines the two strands hardens immediately on exposure to the air. The worm works incessantly, forcing the silk out by the contraction of its body. The thin, gauze-like network which soon surrounds it gradually thickens, until, twenty-four hours after beginning to spin, the worm is nearly hidden from view. However, the cocoon is not completed for about three days. ~SIXTY-FIVE MOTIONS OF HIS HEAD A MINUTE~ The cocoon is tough, strong, and compact, composed of a firm, continuous thread, which is, however, not wound in concentric circles, but irregularly in short figure eight loops, first in one place and then in another. In doing this the worm makes sixty-five elliptical motions of his head a minute or a total of 300,000 in an average cocoon. The motion of the worm’s head when starting the cocoon is very rapid, and nine to twelve inches of silk flow from the spinneret in a minute, but later the average would be about half this amount per minute. [Illustration: SILKWORM EATING.[2]] [Illustration: SILKWORM—ONE OF THE WORLD’S GREATEST WORKERS SILKWORM PREPARING TO FORM ITS COCOON.] Having attained full growth, the worm is ready to spin its cocoon. It loses its appetite, shrinks nearly an inch in length, grows nearly transparent, often acquiring a pinkish hue, becomes restless, seeks a quiet place or corner, and moves its head from side to side in an effort to find objects on which to attach its guy lines within which to build its cocoon. The silk is elaborated in a semi-fluid condition in two long, convoluted vessels or glands between the prolegs and head, one upon each side of the alimentary canal. As these vessels approach the head they grow more slender, and finally unite within the spinneret, a small double orifice below the mouth, from which the silk issues in a glutinous state and apparently in a single thread. [Illustration: COCOON BEGUN--SILKWORM CAN STILL BE SEEN.] The color of the worm’s prolegs before spinning indicates the color the cocoon will be. This varies in different species, and may be a silvery white, cream, yellow, lemon, or green. [Illustration: COMPLETED COCOON.] ~WHEN THE SILKWORM’S WORK IS DONE~ When the worm has finished spinning, it is one and a quarter inches long. Two days later, by a final molt, its dried-up skin breaks at the nose and is crowded back off the body, revealing the chrysalis, an oval cone one inch in length. It is a light yellow in color, and immediately after molting is soft to the touch. The ten prolegs of the worm have disappeared, the four wings of the future moth are folded over the breast, together with the six legs and two feelers, or antennæ. It soon turns brown, and the skin hardens into a tough shell. Nature provides the cocoon to protect the worm from the elements while it is being transformed into a chrysalis, and thence into the moth. [Illustration: MOTHS EMERGING FROM COCOONS.] With no jaws, and confined within the narrow space of the cocoon, the moth has some difficulty in escaping. After two or three weeks the shell of the chrysalis bursts, and the moth ejects against the end of the cocoon a strongly alkaline liquid which moistens and dissolves the hard, gummy lining. Pushing aside some of the silken threads and breaking others, with crimped and damp wings the moth emerges; and the exit once effected, the wings soon expand and dry. [Illustration: COCOONS FROM WHICH THE MOTHS HAVE EMERGED.] The escape of the moth, however, breaks so many threads that the cocoons are ruined for reeling, and consequently, when ten days old, all those not intended for seed are placed in a steam heater to stifle the chrysalis, and the silk may then be reeled at any future time. The moths are cream white in color. They have no mouths, but do have eyes, which is just the reverse of the case of the worm. From the time it begins to spin until the moth dies, the insect takes no nourishment. The six forward legs of the worm become the legs of the moth. Soon after mating the eggs are laid. The male has broader feelers than the female, is smaller in size, and quite active. The female lays half her eggs, rests a few hours, and then lays the remainder. Her two or three days’ life is spent within a space occupying less than six inches in diameter. One moth lays from three to four hundred eggs, depositing them over an even surface. In some species a gummy liquid sticks the eggs to the object upon which they are laid. In the large cocoon varieties there are full thirty thousand eggs in a single ounce avoirdupois. It takes from twenty-five hundred to three thousand cocoons to make a pound of reeled silk. Do you wonder that, centuries ago, silk was valued at its weight in gold? Growers of silk in the United States, by working early and late every day during the season, which lasts from six to eight weeks, could scarcely average fifteen cents for a day’s labor of ten hours. Silk, once regarded as a luxury, is now considered a necessity. [Illustration: HOW THE COCOON IS UNWOUND REELING THE SILK FROM COCOONS BY FOOT POWER, CALLED “RE-REEL” SILK. The cocoons are first assorted, those of the same color being placed by themselves, and those of fine and coarse texture likewise. The outside loose silk is then removed, as this cannot be reeled, after which the cocoons are plunged into warm water to soften the “gum” which sticks the threads together. The operator brushes the cocoons with a small broom, to the straws of which their fibers become attached, and then carefully unwinds the loose silk until each cocoon shows but one thread. These three operations are called “soaking,” “brushing,” and “cleansing.” Into one or two compartments in a basin of warm water below the reel are placed four or more cocoons, according to the size of the thread desired. The threads from the cocoons in each compartment are gathered together and, after passing through two separate perforated agates a few inches above the surface of the water, are brought together and twisted around each other several times, then separated and passed upward over the traverse guide-eyes to the reel. The traverse moves to and fro horizontally, distributing the thread in a broad band over the surface of the reel. The rapid crossing of the thread from side to side of the skein in reeling facilitates handling and unwinding without tangling, the natural gum of the silk sticking the threads to each other on the arms of the reel, thus securing the traverse. Silk reeled by hand or foot power is known as “Re-reel” silk, while silk reeled by power machinery is called “Filature.”] [Illustration: A FILATURE--REELING THE SILK FROM COCOONS BY POWER MACHINERY.[2]] [Illustration: DRYING SKEINS OF SILK.] [Illustration: THE SILK IS WOUND ON SPOOLS WINDING FRAMES--WINDING THE SILK ON BOBBINS.] ~WHERE MAN’S WORK ON THE SILK BEGINS~ The raw silk is first assorted, according to the size of the fiber, as fine, medium, and coarse. The skeins are put into canvas bags and then soaked over night in warm soapsuds. This is necessary to soften the natural gum in the silk, which had stuck the threads together on the arms of the reel. Following the soaking, the skeins are straightened out and hung across poles in a steam-heated room, as shown in the accompanying photograph. When the skeins are dry, they are ready for the first process of manufacturing. The room we now step into is filled with “winding frames,” each containing two long rows of “swifts,” from which the silk is wound on to bobbins. The bobbins are large spools about three inches long. The bobbins filled with silk, as wound from the skeins, are next placed on pins of the “doubling frames”; the thread from several bobbins, according to the size of the silk desired, is passed upward through drop wires on to another bobbin. Should one of the threads break, the “drop wire” falls, which action stops the bobbin. By this ingenious device absolute uniformity in the size of silk is secured. The “doubling frame” is shown in one of the photographs herewith. [Illustration: DOUBLING FRAMES--THE SILK THREAD IS MADE UNIFORM.] The bobbins taken from the “doubling frame” are next placed on a “spinner.” Driven by an endless belt at the rate of over six thousand turns a minute, the bobbins revolve, the silk from them being drawn upward on to another bobbin. This spins the several strands brought together by the “doubling process” into one thread, the number of turns depending on the kind of silk--Filo silk being spun quite slack, and Machine Twist just the reverse. [Illustration: SPINNING SILK.[2]] [Illustration: TWISTING SILK.[2]] A transferring machine combines two or three of these strands; two for sewing silk and three for machine twist; and the bobbin next goes on to the “twisting machine”--a machine that is similar to a “spinner,” but the silk is twisted in the opposite direction from the spinning. To stand before these machines and watch how rapidly and how accurately they do the work assigned them is a revelation. No one realizes how nicely the parts are adjusted. If but one tiny strand breaks that part of the machinery is stopped by an automatic device which works instantaneously. After twisting, the silk is stretched by an ingenious machine called a “water-stretcher.” This smooths and consolidates the constituent fibers, giving an evenness to the silk not to be obtained by any other known process. The bobbins are placed in water and the silk is wound on to the lower of the two copper rolls. From the lower roll it passes upward to the upper roll, which turns faster than the lower one, thereby stretching the silk. From the upper roll it passes again on to a bobbin. [Illustration: SILK THREADS READY FOR THE WEAVER WATER STRETCHER--MAKING THE SILK THREAD SMOOTH.] The dyeing process is a very important one, and upon its success depends the permanency of the various colors. Vast tubs, tanks, and kettles surround you on every side, and the hissing steam seems to spring from all quarters. The “gum” of the silk is first boiled out by immersion in strong soapsuds for about four hours. The attendants, standing in heavy “clogs” (big shoes with wooden soles two inches thick), turn the silk on the sticks at intervals until the gum is removed. After the silk is dyed it is put into a “steam finisher,” a device looking like a long, narrow box with a cover opening on the side, set upright on top of an iron cylinder. The hanks of silk are placed upon two pins in the steam chest, the cover fastened, and the live steam rushes in around the silk. This brightens the silk, giving it the lustrous, glossy appearance. The editors are indebted to the Corticelli Silk Mills, Florence, Mass., for this story of how silk is made, as well as for permission to use their splendid life-like copyrighted photographs of the silkworm. Many teachers will be glad to know that they can obtain from the Corticelli Silk Mills, at slight expense, specimen cocoons and other helps for object lesson teaching. What Animal Can Leap the Greatest Distance? The galago, or flying lemur. This singular animal is a native of the Indian Archipelago. It is from 2 ft. to 3 ft. in length, and is furnished with a sort of membrane on each side of its body connecting its limbs with each other; this is extended and acts as a parachute while taking its long leaps, which measure about 300 ft. in an inclined plane. The kangaroo can leap with ease a distance of between 60 ft. and 70 ft. and can spring clean over a horse and take fences from 12 ft. to 14 ft. in height. The animals that can leap the greatest distance in proportion to their size are the flea and the grasshopper, the former being able to leap over an obstacle five hundred times its own height, while the grasshopper can leap for a distance measuring 200 times its own length. The springbok will clear from 30 ft. to 40 ft. at a single bound. The flying squirrel, in leaping from tree to tree often clears 50 ft. in a leap. This animal also has a broad fold of skin or membrane connecting its fore and hind legs. A steeplechase horse, called The Chandler, is reported to have covered 39 ft. in a single leap at Warwick some years ago. Some species of antelopes can make a leap 36 ft. in length and 10 ft. in height. A lion and a tiger each clear from 18 ft. to over 20 ft. at a bound while springing on their prey. A salmon often leaps 15 ft. out of the water in ascending the falls of rivers. Why Do We Call Voting Balloting? The term covers all forms of secret voting, as in early times such votes were determined by balls of different colors deposited in the same box, or balls of one color placed in various boxes. The Greeks used shells (ostrakon), whence we derive the term ostracism. In 139 B.C. the Romans voted by tickets. The ballot was first used in America in 1629, when the Salem Church thus chose a pastor. It was employed in the Netherlands in the same year, but was not established in England until 1872, although in Scotland it was used in cases of ostracism in the 17th century. In 1634 the governor of Massachusetts was elected by ballot, and the constitutions of Pennsylvania, New Jersey and North Carolina adopted in 1776, made this method of voting obligatory. The ballot progressed slowly in the Southern States, Kentucky retaining the viva voce method until a comparatively recent date. In certain states, the constitutions stipulate that the legislature shall vote viva voce, i. e., cast their votes orally. Since 1875 all congressmen have been elected by ballot. In 1888 the Australian ballot system, which requires the names of all the candidates for the various offices to be placed on one large sheet of paper, commonly known as a “blanket” ticket, was adopted in Louisville, Ky., and some sections of Massachusetts. It is now in very general use in this country. The voter, in the privacy of an individual booth, indicates his preference by making a mark opposite a party emblem or a candidate’s name. This system originated in 1851 with Francis S. Dutton, of South Australia, and Henry George, in a pamphlet, “English Elections,” published in 1882, was the first to advocate it in the United States. The first bill enacting it into a law here was introduced in the Michigan legislature in 1887, but it did not pass until 1889. Why Do We Call a Cab a Hansom? The term is applied usually to a public vehicle, known in England as a “two-wheeler,” or “Hansom” (from the name of the inventor), and drawn by one horse. In a hansom cab, the passenger or hirer of the vehicle sits immediately in rear of the dashboard, the driver sitting on an elevated perch behind, the reins being passed over the top. The term cab is sometimes also applied to a four-seated, closed or open carriage, drawn by one or two horses, the driver sitting in front. The term is also applied to the covered part of a locomotive, in which the engineer and fireman have their stations. The word cab is derived from the cabriolet, a light one-horse carriage, with two seats and a calash top. In London, England, the cab or hansom was called the “gondola” of the British metropolis by Disraeli. Where Did the Name Calico Come From? A fabric of cotton cloth, the name being derived from the city of Calicut, in Madras, where it was first manufactured, and in 1631 brought to England by the East India Company. Calico-printing, an ancient Indian and Chinese art, has become a great industry in this country and in Britain, as well as in Holland. Who Made the First Postage Stamp? The stick on postage stamps so generally used today was invented by an Englishman James Chalmers in 1834. The English Government passed a bill calling for uniform postage of One Penny in 1840 and furnished envelopes bearing stamps printed on them. The people did not like them, however, and the adhesive stamp invented by Chalmers was substituted. The first stamps used in America were introduced in 1847. People have, it seems, always preferred to lick their postage stamps. How Many Languages Are There? It is said that there are more than 3,400 languages, including dialects, in the world. Most of them belong, of course, to savage or uncivilized people. There are said to be more than 900 languages used in Asia, almost 600 in Europe, 275 in Africa and more than 1,600 languages and dialects which are American. What Is the Deepest Mine In the World? The mine that goes farther down than any other in the world is the rock salt mine near Berlin, Germany which is 4,175 feet. It is not, however, straight down but somewhat slanting. The Calumet Copper Mine near Lake Superior is at a depth in some places of 3,900 feet. The deepest boring in the world is an artesian well at Potsdam, Missouri, which is 5,500 feet deep or more than one mile straight down. What Is Color? ~WHAT PRODUCES THE COLORS WE SEE?~ What is termed the color-sense is the power or ability to distinguish kinds or varieties of light and their distinctive tints. We owe the faculty of doing this to the structure of the eye and its elaborate connecting nerve machinery. The eye in man is specially sensitive to light, and the sensations we feel through it enables us to distinguish the different colors. Over 1,000 monochromatic tints are said to be distinguishable by the retina of the eye, though these numerous tints are, in the main, merely blendings or combinations of the three primary color-sensations, the sense of red, of green and of violet. Each of these colors, it has been demonstrated, is produced by light of a varying wave length, while white light is only light in which the primary colors are combined in proper proportion. Colored light, on the other hand, as Newton proved, may be produced from white light in one of three ways: First, by refraction in a prism or lens, as observed in the rainbow; second, by diffraction, as in the blue color of the sky, or in the tints seen in mother-of-pearl; and third, by absorption, as in the red color of a brick wall, or in the green of grass--the white light which falls upon the wall being wholly absorbed, save by the red, and all that falls upon the grass being absorbed except the green. In art, color means that combination or modification of tints which is specially suited to produce a particular or desired effect in painting; in music, the term denotes a particular interpretation which illustrates the physical analogy between sound and color. Where Did the Term Dixie Originate? The term was applied originally to New York City when slavery existed there. According to a myth or legend, a person named Dixie owned a tract of land on Manhattan Island and had a large number of slaves. As Dixie’s slaves increased beyond the requirements of the plantation, many were sent to distant parts. Naturally the deported negroes looked upon their early home as a place of real and abiding happiness, as did those from the “Ole Virginny” of later days. Hence “Dixie” became the synonym for a locality where the negroes were happy and contented. In the South, Dixie is taken to mean the Southern States. There the word is supposed to have been derived from Mason and Dixon’s line, formerly dividing the free states from the slave states. It is said to have first come into use there when Texas joined the Union, and the negroes sang of it as Dixie. It has been the theme of several popular songs, notably that of Albert Pike, “Southrons, Hear Your Country Call”; that of T. M. Cooley, “Away Down South where Grows the Cotton,” and that of Dan Emmett, the refrain usually containing the word “Dixie” or the words “Dixie’s Land.” During the Civil War, the tune of “Dixie” was to the Southern people what “Yankee Doodle” had always been to the people of the whole Union and what it continued, in war times, to be to the Northern people, the comic national air. The tune is “catchy” to the popular ear and it was played by the bands in the Union army during the war as freely as by those on the other side. During the rejoicing in Washington over the surrender of Lee at Appomattox, a band played “Dixie” in front of the White House. President Lincoln began a short speech, immediately afterward, with the remark, “That tune fairly belongs to us now; we’ve captured it.” How Big Is the Earth? The third planet in order of distance from the sun, Mercury and Venus being nearer to it. It is in shape a sphere slightly flattened at the poles and bulged at the equator, hence it is called an oblate spheroid. The equatorial diameter or axis measures 7,926 miles and 1.041 yds., and the polar diameter is 7,899 miles and 1.023 yds. The earth revolves upon its axis, completing its diurnal or daily revolution in a sidereal day, which is 3 minutes and 55.9 seconds shorter than a mean solar day. It revolves around the sun in one sidereal year, which is 365 days, 6 hours, 9 minutes, and 9 seconds. Its orbit or path around the sun is an ellipse, having the sun in one of the foci. The earth’s mean distance from the sun is 93,000,000 miles. Its axis is inclined to the plane of its orbit at an angle of 23° 27′ 12.68″. The circumference at the equator measures 24,899 miles. The total surface is 196,900,278 sq. miles, and the solid contents is 260,000,000,000 cubic miles. As we descend into the earth the temperature rises at the rate of 1° Fahr. for every 50 ft. At the depth of 10 or 12 miles the earth is red-hot, and at a depth of 100 miles the temperature is such that at the surface of the earth it would liquefy all solid matter in the earth. What Causes Hail? Hail is the name given to the small masses of ice which fall in showers, and which are called hailstones. When a hailstone is examined it is found usually to consist of a central nucleus of compact snow, surrounded by successive layers of ice and snow. Hail falls chiefly in Spring and Summer, and often accompanies a thunderstorm. Hailstones are formed by the gradual rise and fall, through different degrees of temperature (by the action of windstorms), and they then take on a covering of ice or frozen snow, according as they are carried through a region of rain or snow. With regard to rain, it may be said, in popular language, that under the influence of solar heat, water is constantly rising into the air by evaporation from the surface of the sea, lakes, rivers, and the moist surface of the ground. Of the vapors thus formed the greater part is returned to the earth as rain. The moisture, originally invisible, first makes its appearance as cloud, mist or fog; and under certain atmospheric conditions the condensation proceeds still further until the moisture falls to the earth as rain. Simply and briefly, then, rain is caused by the cooling of the air charged with moisture. Why Does a Human Being Have To Learn to Swim? It is strange, isn’t it, that almost every animal, excepting man and possibly the monkey, knows how to swim naturally; others such as birds, horses, dogs, cows, elephants, can swim as soon as they can move about alone. The trouble with man in this connection is that his natural motion is climbing. He has been a climber ever since he was developed from the monkey, and when you throw him into the water before he has learned to swim, he naturally starts to climb and as a climbing motion won’t do, for swimming, the man will drown. This climbing motion is as much of an instinct in man and monkeys as the instinct in dogs which causes him to turn round once or twice before he lies down just as his forefathers used to do ages ago when, as wild dogs, they first had to trample the grass before they could lie down comfortably. Why Do I Get Cold in a Warm Room? I suppose you mean the instances when you get cold while in a warm room even when you are perfectly well. This will happen often when all of the moisture in the room outside of what is in your body, is evaporated by the heat in the room. The remedy is, of course, to keep a pan of water some place in the room as the air has become too dry. While heat is necessary to evaporate water, the process of evaporation produces cold. The quicker the evaporation the sharper the cold feeling produced. Now your body is continually evaporating the water from your body which comes out in the form of perspiration through the pores of the skin. This is one of nature’s ways of taking the impurities and waste out of the body. You know, of course, don’t you, that more than one-half the waste material which the body expels from the system comes out through the pores of the skin rather than through the canals. When the air in the room becomes too dry, the evaporation on the outside of the body proceeds faster and makes you cold. By keeping water in some vessel in the room you keep the air of the room from becoming too dry. Why Do They Call Them Wisdom Teeth? The wisdom teeth are the two last molar teeth to grow. They come one on each side of the jaw and arrive somewhere between the ages of twenty and twenty-five years. The name is given them because it is supposed that when a person has developed physically and mentally to the point where he has secured these last two teeth he has also arrived at the age of discretion. It does not necessarily mean that one who has cut his wisdom teeth is wise, but that having lived long enough to grow these, which complete the full set of teeth, the person has passed sufficient actual years that, if he has done what he should to fit himself for life, he should have come by that time at the age of discretion or wisdom. As a matter of fact these teeth grow at about the same age in people whether they are wise or not. What Makes Freckles Come? Freckles are generally caused by the exposure of unprotected parts of the body to the sun, but this will not cause freckles on all people. Only people with certain kinds of sensitive skins freckle. What happens when freckles are produced in this way is this: The sunlight shining on the face, neck or arms of anyone who has a tendency to freckle, has a peculiar action on certain cells of the skin which produces a yellowish brown coloring pigment, which remains for a time. Then again the skins of some people are so peculiarly sensitive the cells develop this kind of coloring matter in almost any kind of light and such people are, so to speak, apt to be freckled for life. [Illustration: First successful power-driven aeroplane. The Langley monoplane with steam engine, which flew over the Potomac River in 1896.] The Flying Boat When Did Man First Try to Fly? ~HOW MAN LEARNED TO FLY~ Man’s desire to conquer the air is older than recorded history. When a kite was flown for the first time the principle of aviation, or dynamic flight, was uncovered. For centuries man has sought the mechanical equivalents for the things that keep a kite flying steadily in the air,--the power that lies in the cord that keeps a kite headed into the wind; an equivalent for the wind’s own power; an equivalent for the tail which controls the kite’s lateral and longitudinal balance. Each separate part of the modern flying machine, or aeroplane, was worked out long ago, with the exception of the gas engine light enough and reliable enough to be used for this work. The present generation knows dynamic flight as a commonplace thing, not because we are so much more clever than previous generations in designing flying machines, but because of the development of the modern gasoline or internal combustion engine. Who Invented Flying? No one invented flying, nor did any one man invent all the separate parts of the flying machine. They are the result of evolution,--of the combined work and thought of hundreds of men, many of whose names are unrecorded. To attempt to find the true beginning of the modern flying machine would be as difficult as attempting to discover who planted the seed of the tree from which one has gathered a rose. But the tree from which all the flying machines, or aeroplanes, of today have sprung undoubtedly is Dr. Samuel Pierpont Langley, third secretary of the Smithsonian Institution. Some of the Men Who Helped. Taking the most conspicuous names of scientists who worked out various details of the aeroplane during the past century we find that a century ago Sir George Cayley built a machine on lines very similar to those accepted today, and he went so far as to foretell the necessity of developing the internal combustion engine before dynamic flight could be a success. Mr. F. H. Wenham, in 1866, also built a flying machine along conventional lines and tried to fly it with a steam engine, which of course, proved too heavy. [Illustration: One of Dr. Langley’s first models; a biplane with flexible wing-tips and twin propellers. 1889.] ~EARLY TYPES OF FLYING MACHINES~ M. A. Penaud, a Frenchman, in experimenting with models, seems to have been the first to discover the necessity of vertical and horizontal rudders in maintaining balance. Mr. Horatio Phillips, an Englishman, discovered, and patented, the use of curved instead of flat surfaces for the planes. Otto and Gustav Lilienthal are said to have been the first to attempt to balance aeroplanes by flexing or bending the wings. Various others, including Messrs. Richard Harte, Boulton, Mouillard, worked out ideas for balancing machines by the use of auxiliary planes which could be set at different angles with regard to the line of flight, thus forcing the machines to different positions by the force of the air rushing against them. Dr. Langley, trained in scientific investigation, conducted an elaborate series of experiments covering many years and costing thousands of dollars to test and prove the value of the claims of the earlier investigators. Some things which he thought he was the first to discover,--such as the effect of the vertical and horizontal rudders,--he later found had already been proven by others. Independently he covered the entire field of experiment and after building hundreds of small models he succeeded, in 1896, in making a machine weighing several pounds equipped with a very light steam engine which flew safely as long as the fuel lasted. For his early experiments Dr. Langley was afforded financial assistance by Mr. William Thaw of Pittsburg. After the success of his small machines Dr. Langley was asked to undertake the construction of a large, man-carrying machine, and Congress voted him $50,000 to carry on the work. A large share of this was spent on the development of a very light gasoline engine. The machine finally was completed, but was twice broken through defective launching apparatus. Congress and Dr. Langley were so ridiculed by the public press that the machine was temporarily abandoned. Not, however, until after Dr. Langley had successfully flown a steam driven machine much larger than many of the racing aeroplanes of today. But eight years after Dr. Langley’s death, which is said to have been due to the heart-breaking disappointment he suffered in trying to demonstrate the large machine, Glenn H. Curtiss, at the request of the Smithsonian Institution, rebuilt the old Langley machine and succeeded in making a flight with it at Hammondsport, N. Y., on May 28, 1914. [Illustration: THE FIRST MAN-CARRYING AEROPLANE First successful man-carrying aeroplane. Designed by Dr. Langley in 1898; flown by Glenn H. Curtiss at Hammondsport, N. Y., 1914.] [Illustration: Front view of big Langley machine in 1914.] While longer flights probably will be made with this machine none will attain greater importance, because this first flight with it was sufficient to establish for all time the fact that Dr. Langley built the first man-carrying machine equipped with a gasoline engine and able to fly and raise itself with its own power. This was considerably more than was accomplished by other machines for some time after Dr. Langley’s death. The Langley machine not only lifted the weight it was designed to fly with, but also carried pontoon and other fittings, added by Mr. Curtiss to make flight from the water possible, which added 340 pounds to the original weight of the machine. [Illustration: THE MACHINE WITH WHICH BLERIOT FLEW IN EUROPE Copy of early Langley model with which Bleriot made first circular flight in Europe.] The connection between Dr. Langley’s work and present machines is now very easy to trace, though not obvious until 1911, when the Smithsonian Institution published memoirs written by Dr. Langley in 1897, and some memoirs of Mr. Octave Chanute, a French engineer who resided in Chicago, and who forms one of the main connecting links. The chain is practically completed by notes left by the late Lieut. Thomas Selfridge, U. S. A., America’s first martyr to aviation. Dr. Langley’s knowledge is represented in modern aviation by three distinct lines. The central and most direct line is through Dr. Alexander Graham Bell, inventor of the telephone, to the Aerial Experiment Association, and thence to Mr. Glenn H. Curtiss, and finds its expression in what is known as the Curtiss type of machines. Another line is that carried by a Mr. A. M. Herring to Mr. Chanute and by him transmitted to Mr. Wilbur Wright, finding expression in the Wright type of biplane. The third line is that leading to the modern monoplane school; M. Bleriot having first copied in toto the tandem monoplane form, generally known as the Langley type, and later, with the development of better gasoline engines, developing into the monoplane as known today. With the exception of M. Bleriot it is doubtful if the others fully realized the source of their inspiration,--not to call it information. Dr. Bell was interested in Dr. Langley’s work for more than ten years before Dr. Langley gave up. He observed many of the trials, and his reports of the first successful flights are incorporated in the official publications of the Smithsonian Institution. Dr. Bell began some independent experiments, but following Dr. Langley’s death he formed the Aerial Experiment Association, to carry on the work left by Dr. Langley. The members of this organization were, Mr. Curtiss, at that time the most successful builder of light motors; Lieut. Thomas H. Selfridge, U. S. A.; Mr. J. A. D. McCurdy and Mr. F. W. Baldwin, two young Canadian engineers. Mrs. Bell financed the project, furnishing the sum of $35,000 for the experiments. ~WHAT TWO BROTHERS ACCOMPLISHED FOR FLYING~ The Wright Brothers, for Wilbur Wright was joined by his brother Orville in the experiments, were the first to reap success from the seeds of Dr. Langley’s sowing. Mr. Chanute had been experimenting with a biplane form of motorless glider with little success, because of lack of means for balancing the machines in the air, until he was joined by a former employe of Dr. Langley. He appears to have imparted to Mr. Chanute the secret of the stabilizing effect of the Penaud tail, or combination of vertical and horizontal rudders. Thereafter hundreds of successful gliding flights were made with the Chanute biplane, though Chanute seems not to have grasped the full significance of the rudders,--though it was well understood by Dr. Langley. To the Chanute machine, as described to him, Mr. Wright added first the idea of flexing or warping the wings, after the fashion set by the Lilienthals. He found, however, as Dr. Langley had found years before, that in attempting to correct lateral balance in this way caused the aeroplane to swerve to such an extent that the fixed vertical rudder, as originally employed, did not correct the upsetting tendency that was developed. Mr. Wright then arranged his rudder in such a way that when the wing was warped the rudder turned in a way to offset the swerve. This combination was patented all over the world and has resulted in much complicated litigation. To this machine the Wright Brothers added a gasoline motor in December, 1903, and with it made numerous flights during 1904-5. Their claims were not generally credited however until a later date for their experiments had been conducted with considerable secrecy, and during 1906, 1907 and until late in 1908 they did no more flying. In the meantime M. Bleriot had made a copy of one of the early Langley tandem monoplane models and made some fairly successful flights with it in Europe. Later, as gasoline motors developed in power for weight, he reduced the rear surface until the modern monoplane evolved. While Bleriot was working in Europe, Dr. Bell’s Aerial Experiment Association in America was evolving still another type of machine, and the members of the association made the first successful public flights in America. Mr. Curtiss won the Scientific American Trophy for the first time on July 4th, 1908, by a straightaway flight of more than a kilometer. The balancing system employed by the A. E. A. differed from that employed by the Wrights and by Bleriot in that small auxiliary planes took the place of warping planes for righting the machine. This they claimed to be a superior method, first, because it eliminated the use of the rudder as being absolutely essential to the balance of the machine; second, because it enabled them to make the main planes rigid throughout, and consequently stronger than the flexible planes. There are several other names that must be mentioned in connection with the early history of successful flight; these are the Frenchmen, Messrs. Henri Farman, Maurice Farman, the brothers Voisin, and Santos Dumont. These produced some of the first notably successful aeroplanes in Europe but seem to have discovered nothing which has had any marked effect upon the later development of flying machines. M. Farman adopted the auxiliary planes used by the A. E. A. and modified them to suit his ideas. ~WONDERFUL RECORDS OF AEROPLANES~ Volumes could be, in fact, have been written about the exploits of the first demonstrators of the practical heavier-than-air flying machines,--of the crossing of the English Channel by Bleriot, of the flights by Wilbur Wright at Rheims, France; of Mr. Curtiss’ winning of the first Gordon Bennet International speed trophy and his flight down the Hudson from Albany to New York; of Orville Wright’s flight at Fort Meyer, and the death of Lieut. Selfridge who was flying with him. The barest record of these interesting accomplishments would fill volumes. Of the aeroplane proper it is enough to say here that since 1908 its development has been too rapid for accurate recording. In strength, in speed, in reliability, in size and carrying capacity, it has developed at a remarkable rate. At this writing the speed record is about 130 miles per hour; the duration record is more than 24 hours, non-stop; the distance record is some 1,300 miles in one day; the altitude record some 26,000 feet. New records succeed the old ones with such rapidity that probably before this can be printed all these present records will have been greatly eclipsed. [Illustration: AEROPLANE “RED WING” HAMMONDSPORT, N.Y. FIRST AMERICAN PUBLIC FLIGHT, MAR 12 1908] [Illustration: The biplane in which G. H. Curtiss flew from Albany to New York in 1910.] Meantime the aeroplane has developed greatly in other directions. In flying over land with the early types of machines many fatal accidents occurred, particularly to the fliers who gave exhibitions everywhere during 1909, 1910 and 1911. A majority of these accidents were indirectly due to the fact that a very smooth surface is required for landing a fragile machine running at high speed. The obvious expedient was to develop machines capable of rising from and alighting upon the water. [Illustration: SOME FAMOUS FOREIGN MONOPLANES A modern German monoplane.] [Illustration: The machine in which Bleriot crossed the English Channel in 1909. A modified Langley type.] [Illustration: Rolland Garros and monoplane in which he flew across the Mediterranean Sea in 1914.] ~THE WONDERFUL FLYING BOAT~ During the winter of 1910 and 1911 Mr. Curtiss, who had continued independent experiments upon the disbandment of the Aerial Experiment Association, succeeded in producing the first machine to safely leave and return to the water. For the development and demonstration of this type of flying machine he was awarded the Aero Club of America Trophy, and when during 1912 he produced still another type of water flying machine, the Curtiss Flying Boat, he was again awarded the Aero Club Trophy and also voted a Langley Medal by the directors of the Smithsonian Institution. [Illustration: Different views of flying boat.] Not until the development of the flying boat did the general public begin to take a participative interest in aviation, but as soon as the comparative safety of this type of machine became apparent the new sport began to be taken up rapidly both in this country and in Europe. The experiences of naval fliers and amateurs alike went to show that water flying offered not only the fastest and most comfortable mode of rapid travel, but also the safest, for during 1913 several hundred thousand miles were flown by navy aviators and amateur enthusiasts in Curtiss water flying machines without a single serious accident. What aviation will mean to future generations,--even to this generation in the course of a few years,--it would be foolhardy to try to guess. Mr. Rodman Wanamaker already has agreed to furnish the financial support for Mr. Curtiss’ attempt to build a machine to fly across the Atlantic Ocean, from America to Europe. If the venture is successful it is expected the crossing will be made in a fraction of the time taken by the fastest Transatlantic liners. The discovery of new metals and new manufacturing methods will certainly result in the development of light motors that may be relied upon to run for days without stopping, and automatically stable aeroplanes seem to be not far away. This will result in overland flight as safe and sure as we now enjoy over water. [Illustration: INSIDE OF A MODERN FLYING BOAT Interior arrangement of modern flying boat, showing fuel tank and instrument board.] [Illustration: Six-passenger flying boat hull. This machine will fly 1,000 miles without stopping for fuel.] [Illustration: FUN IN A FLYING BOAT Flying at speed of a mile a minute.] [Illustration: Monoplane flying boat, built for R. V. Morris.] [Illustration: In a flying boat on pleasure bent.] ~GREATEST PRESENT VALUE OF AEROPLANE~ At present the greatest value of the aeroplane seems to be for military reconnaissance and all the great powers are striving their utmost to secure supremacy in the air. France, Germany, Russia and England have to date spent millions in developing aeroplane fleets. Only the government of the United States has failed as yet to appreciate the military significance of the flying machine. If the relative aeronautical strength of the world’s nations were represented alphabetically the U. S. would naturally scarce have to change its initial, U being slightly in advance of Z which would stand for Zululand. But even with its modest equipment the navy fliers of the United States proved the great worth of the aeroplane and the flying boat, when during the recent trouble in Mexico the air scouts gathered in a few minutes information that could only have been secured by days of cavalry scouting before the advent of the flying machine. Indeed, the name of Lieut. P. N. L. Bellinger, the most able of the naval fliers at Vera Cruz, has figured more prominently in the despatches from the front than that of any other officer connected with the expedition. Flying seems certain in the very near future to take its place as the fastest, safest and most comfortable mode of conveyance. The flying boat will render quickly accessible the vast country lying along the great rivers of South America, Africa, and Australia; it will bridge the great lakes and the oceans; bring near together the islands of the Pacific and Indian oceans. It will make imperative, because of the speed with which distances will be traversed, of a language common to all peoples; and treble man’s life without extending his years by making it possible to see and do three times as much in the same length of time. ~TEN YEARS OF FLYING~ Ten years ago on that day, December 17, 1913, Wilbur and Orville Wright made four flights on the coast of North Carolina near Roanoke Island, a spot historic in America’s history as the site of the first English settlement in the Western Hemisphere. [Illustration: Flying over military post in Curtiss biplane.] The first flight started from level ground against a 27-mile wind. After a run of 40 feet on a monorail track, the machine lifted and covered a distance of 120 feet over the ground in 12 seconds. It had a speed through the air of a little over 45 feet per second, and the flight, if made in calm air, would have covered a distance of over 540 feet. Altogether four flights were made on the 17th. The first and third by Orville Wright, the second and fourth by Wilbur Wright. The last flight was the longest, covering a distance of 852 feet over the ground in 59 seconds. After the fourth flight, a gust of wind struck the machine standing on the ground and rolled it over, injuring it to an extent that made further flights with it impossible for that year. [Illustration: 1900 1901 1902 1905 1904 1903] The gliding experiments of Lilienthal in 1896 led the Wright Brothers to become interested in flight. The next four years were spent in reading and theorizing. In the Fall of 1900 practical experiments were begun with a man-carrying glider. These experiments were carried on from the sand hills near Kitty Hawk, North Carolina. The first glider was without a tail, the lateral equilibrium and the right and left steering were obtained by warping of the main surfaces. A flexible forward elevator was used. This machine was flown as a kite with and without operator, and several glides were made with it. A second machine was designed of larger size, and many glides were made with it in 1901. This machine was similar to the one of 1900 but had slightly deeper curved surfaces. Experiments with this machine demonstrated the inaccuracy of all the recognized tables of air pressures, upon which its design had been based. In 1902 a third glider was constructed, based upon tables of air pressures made by the Wright Brothers themselves. The lateral control was maintained by warping surfaces, and a vertical rear rudder operated in conjunction with the surfaces. Nearly a thousand gliding flights were made with this machine. In 1903, the Wright Brothers designed a machine to be driven with a motor. They also designed and built their own motor. This had four horizontal cylinders, 4 in. by 4 in., and developed 12 h.p. Two propellers, turning in opposite directions, were driven by chains from the engine. After many delays the machine was finally ready and was flown on the 17th of December, 1903, as related above. In the Spring of 1904, power flights were continued near Dayton with a machine similar to the one flown in 1903, but slightly heavier. The first complete circle was accomplished on the 20th of September, 1904, in a flight covering a distance of about one mile. Altogether 105 flights were attempted during the year, the longest of which were two of five minutes each, covering a distance of about three miles. All of the flights were started from a monorail. After September a derrick and a falling weight were used to assist in launching the machine. [Illustration: 1908-9 1910 1910 MODEL R, 1910] ~INTERESTING GOVERNMENTS IN FLYING MACHINES~ It was not till 1908 that the Wright Brothers found purchasers for their invention. In that year they made a contract to furnish one machine to the Signal Corps of the United States Army and to sell the rights to their invention in France to a French company. In both cases they agreed to carry a passenger in addition to the operator, fuel sufficient for a flight of 100 miles, and to make a speed of 40 miles an hour. After making some preliminary practice flights at their old experiment grounds near Kitty Hawk in May, 1908, Wilbur Wright went to France to give demonstrations before the French Syndicate and Orville Wright to Washington to deliver the machine to the United States Signal Corps. The machines used by Wilbur Wright had been standing in bond in the warehouse at Havre since August of the year before. Owing to damage done to the machine in shipment, it was not ready for the official demonstrations until late in the year. Meanwhile Orville Wright in September, 1908, started demonstrations of the machine contracted for by the United States Government. On the 9th he made two flights, one of 57 minutes, and the other one hour and 2 minutes, world’s records. On the 10th and 11th, these records were increased and on the 12th a flight of 1 hour and 15 minutes was made. On the 17th, the tests were terminated by an accident in which Lieutenant Selfridge met his death and Mr. Wright was severely injured, so that he was not able to complete the tests until the following year. Four days after the accident, on the 21st of September, Wilbur Wright made a flight of 1 hour and 31 minutes at Le Mans, France, which record he improved several times during the following months, and on the 31st of December, won the Michelin Trophy by a flight, in which he remained in the air 2 hours and 24 minutes. Where Is the Wind When It Is Not Blowing? The answer is, of course, that there isn’t any wind then. To understand this perfectly we must study a little and find out what wind is. In plain words it is nothing more than moving air. If you make a hole in the bottom of a pail of water the water will run out slowly. If you knock the whole bottom out of the pail filled with water, the water will rush out before you know it. That is about what happens to make the wind. The air is constantly full of air currents, like the currents you can see in a river. Down the middle of the river you may notice a softly-flowing current going straight. Along the shores there will be little side currents going in all directions, and you may find some little whirlpools. That is exactly what we should see in the air if we could see air currents. Where Does the Wind Begin? The movement of these currents of air leaves many pockets of space where there is no air, and when one of these is uncovered the air rushes in and creates a wind in doing so. These air currents are continually pressing against each other to get some place else. They change their direction according to the pressure that is being applied to them. Sometimes the pressure will be very light in one part of the air, many miles away perhaps, and then the air in another part, which is under great pressure, will rush with great force into the part where the pressure is light, and thus form a big wind. When the pressure stops the wind stops. We have probably felt the wind which comes out of the valve of the automobile tire when the cap is taken off to pump up the tire. It is a real wind that comes out. The reason is that the air in the tube of the tire is under great pressure, and when the opportunity is given to get where the pressure is light it starts for that place with a rush and comes out of the valve a real wind. What Causes the Wind’s Whistle? The whistle of the wind is caused very much like the whistle you make with your mouth or the noise made by the steam escaping through the spout of the kettle. You do not hear the wind whistle when you are out in it. You can hear it when you are in the house and the wind is blowing hard. When the wind blows against the house it tries to get in through all the crevices, under the cracks of the doors, down the chimneys, wherever it finds an opening. And whenever it starts through an opening that is too small for it, it makes a noise like the steam coming out of the spout of the kettle, provided the opening is of a certain shape. Not all the noises made by the wind, however, are made in this way. The wind in blowing against things makes them vibrate like the strings of a piano or violin, and when things vibrate, as we have already seen, they produce sound waves, which, when they strike our ears, produce sounds of various kinds. The wind even on ordinary days makes the telegraph and telephone wires hum, as you can prove to yourself by placing your ear against a telegraph or telephone pole, and whenever the wind makes anything vibrate, a great many queer sounds are produced, which often frighten us more than they should. Why Does the Air Never Get Used Up? Simply because it is constantly being replenished. The three gases, oxygen, nitrogen and carbonic acid gas, which are found in the air about us, are constantly being used up. All living animal creatures are at all times taking oxygen out of the air to live on. Certain microbes are using up quantities of the nitrogen all the time, and the plants live on the carbonic acid gas. But while these different kinds of life between them use up the air, they give back something also. The plants give off oxygen. The bodies of the animals and plants when they die decompose, and as they are full of nitrogen, that is given back to the air in that way, and then all living creatures are always throwing off carbonic acid gas through their lungs, and thus everything that is taken out of the air is put back again. The plants live on carbonic acid gas, and give us back oxygen. The living creatures live on oxygen and give off carbonic acid gas, and when they die their bodies put back in the air the nitrogen which the microbes take out, and so, consumption and production are about equal all the time. Why Can’t We See Air? We cannot see air because it has no color and is perfectly transparent. If at times it appears that there is color in the air it is not the air you see, but some little particles of various substances in it. Sometimes you think when you look off toward a range of mountains or hills, for instance, that the air is blue. You know the grass and trees on the mountains are green, so it cannot be they that have turned blue, and so you think the air is blue. But it is only the sunlight reflected to your eyes from the little particles of dirt and other substances which fill the air at all times which makes the blue that you see, and not the air. Pure air is a mixture of gases without any color and is perfectly transparent. Air is nearly entirely composed of a gas called nitrogen--the remainder being oxygen with a little water and carbonic acid gas, which latter is thrown off in breathing. This is, however, but a very small percentage. Air has been and still can be reduced to a liquid state, and with the use of it in this form many seemingly wonderful things can be done, which are interesting to look at, but have not as yet become commercially practical. Why Does Thunder Always Come After the Lightning? This occurs simply because lightning or light travels so much more quickly than sound. Light travels at the rate of 186,000 miles per second, and sound travels only at the rate of 1090 feet per second when the temperature is at 32 degrees. Now, the thunder and lightning come at the same time and place in the air, but the light travels so much faster that you see the lightning often quite some seconds before you hear the thunder. In fact, you can tell quite accurately how far away from you the flash of lightning and clap of thunder are by taking a watch and noting the number of seconds which elapse between the flash of the lightning and the time when you hear the roll of the thunder. If as much as five seconds elapse you can figure that it was about a mile away from you, since sound travels only about 1100 feet per second and there are 5280 feet in a mile. When the thunder and lightning come close together you may know that it is near by, and when they come at the same time you may be sure it is very close. When, therefore, you see the lightning and then have to wait several seconds for the noise of the thunder, you may rest easy about the lightning hurting you, because you know then it is too far away to harm you, and when it is so close that the lightning and thunder come simultaneously, there is no use being afraid, because if you were to be struck you would have been struck at the same instant or before you would have had time to notice that the lightning and thunder come together. How Big Is the Sun? It is very difficult to gain a clear idea of how very large the sun really is. We know from the scientists who have measured it with their accurate measuring instruments that it is 865,000 miles through it, and that at its largest part it is 2,722,000 miles around. Now, you can see why I said it is very difficult to get a clear conception of the sun’s size. A mile is quite a long distance to walk on a hot day. Now, the earth is 8000 miles through. If there were a tunnel right through the earth, like the subway, and you started to walk it, it would take you 83¹⁄₃ days if you walked day and night without stopping to rest or eat, if you kept going at the rate of four miles every hour. This would be a long, hot walk, for, of course, the inside of the earth is hot, as we have already learned. It would take an automobile, going at the rate of 40 miles an hour night and day, about nine days to make the trip through such a subway from one side of the earth to the other. That makes it look like a pretty big old earth, doesn’t it? But let us see what would happen if we started to do the same thing on the sun. The sun is 865,000 miles through. If you were to walk through a similar tunnel on the sun at four miles per hour it would take you 20 years, not counting the stops, and an automobile going 40 miles an hour day and night would take two years and a half to make the trip one way. The sun is ninety million miles from the earth and an automobile travelling at the rate of forty miles per hour day and night on a straight road, without stopping, would be 257 years in getting there. When we stop to think of how big the bulk of the sun is it is altogether beyond us. We have a general idea that our earth is a pretty large affair as worlds go, and yet we cannot conceive how much the bulk of the earth amounts to. Still, the sun is so large that it could contain a million worlds like our own. How Hot Is the Sun? We think the sun is pretty hot in summer when the thermometer goes up to 90 degrees in the shade or out. We begin to get sunburned long before it reaches that high. But right on the sun’s surface it is between 10,000 and 15,000 degrees hot. That is, of course, a degree of heat which we cannot conceive. How much hotter still it is on the inside of the sun we don’t as yet know. It must be awfully hot there. Why Is It Warm in Summer? It is warm in summer because at that season of the year the heat rays of the sun strike our part of the earth through less air. The blanket of air which surrounds the earth is very much in comparison as to thickness like the peeling of an orange and surrounds the earth in just the same way. If you stick a pin straight into an unpeeled orange you only have to stick it in a little way before you reach the juicy part of the orange, but if you stick the pin in at an angle the pin will travel a much longer ways through pure peeling before it strikes the juicy part. Now, then, in summer the rays of the sun come down to us straight through the peeling of air, and less of the heat is lost by contact with the air, and that makes it warmer in summer. The explanation also accounts for your next question. Why Is It Cold in Winter? In winter the heat rays of the sun strike at our part of the earth at the angle at which you stick the pin into the orange when you wish to make it travel through the most peeling. In winter the rays strike the earth at such an angle that a great deal of the heat is lost in travelling through the air, because they have to come through so much more of the air. Of course, the sun’s rays strike some part of the earth straight down through the peeling of air at all times, and at the equator this occurs all the year round, so it is always summer there, while at the North and South Poles the rays always strike the earth at the greatest possible angle, and it is always very cold winter there. In between, when it is neither hot nor cold, we have spring and fall, due to the fact that the rays come down at an angle, but not so great an angle. Why Have We Five Fingers on Each Hand and Five Toes on Each Foot? All animals, it seems, from a study of nature were started with ten fingers and ten toes, the fingers originally having been the toes of the fore legs. In a good many cases the environment in which animals have lived has caused a change in the formation of the ends of the limbs as well as in the limbs themselves. The horse, for instance, has developed into a one toe or one finger animal, while a cow is a two finger animal. The hen has only three toes on each foot and a part of another. But if we go back into the history and examine how the horses’ foot used to look we will find that he originally had five toes. The same is true of the cow and also the hen. Something happened to cause the change, for the rule of five fingers and five toes on the end of each limb has been universal. If you examine a chicken in a shell just before it is ready to come out, you can distinctly count five toes on each foot and at the ends of the wings you will see five little points, which under other conditions would develop into fingers, perhaps. Some of these toes of the new-born chicken do not develop. It can be accepted as a rule that creatures were intended in the original plan to have five fingers on each hand and five toes on each foot, making our count of tens, which is the world’s basis for counting, and has always been. Why Do We Have Finger Nails? Finger nails and toe nails are only another phase of the development of man from the animal that originally walked on four feet. Animals that walk on all fours use the finger and toe coverings which in man is the nail, to scratch in the ground, to attack enemies, and to climb with, and our nails of the present day are what the development of man into a civilized being has changed them to. At that, there are still uses for finger nails and toe nails, or man in his changing to a higher plane would have found a way to develop away from them. They are useful to-day in making our fingers and toes firm at the end, and enable us to pick up things more easily. The time may come when man will have neither finger nails nor toe nails. Why Are Our Fingers of Different Lengths? There is no known reason why our fingers should be of different lengths to-day; in fact, it is thought by some people that the hand would be stronger if the fingers were all of the same length. Certainly, however, the hands would not then be so beautiful, and it might not be so useful. The human hand to-day is perhaps the most versatile thing in the world. You can do more things with the hand than with any other thing in the world. The probability is that the shape of the hand to-day and the length of the fingers are the result of the different things the human being has called upon the hand to do during man’s development up to the present time. We must go back to the time, however, when man walked on fours, for that is probably the real explanation. Originally man’s fingers were of different lengths because all four-footed animals had the same peculiarities. The shape and length of the toes and their arrangement were the ideal arrangement for giving the proper balance and support to the body, and in moving about and in climbing produced the best toe hold. Why Does It Hurt When I Cut My Finger? It hurts when you cut your finger, or, rather, where you cut it, because the place you have cut is exposed to the oxygen in the air, and as soon as it is so exposed a chemical action begins to take place, just as when you cut an apple and lay it aside you come back and find the cut surface all turned brown. If the apple could feel it would hurt also, because the chemical action is much the same. The apple has a skin which protects its inside from the oxygen in the air, and you have also a skin which protects you from the oxygen as long as it is unbroken. What happens, of course, is this: When you cut your finger you sever the tiny little veins and nerves which are in your finger. They are spread all over your body like a net-work under the skin, close to the surface in most places. The nerves when cut send a quick message to the brain, with which they are connected, telling that they are damaged, and the brain calls on the heart and other functions to get busy and repair the damage along the line. There may be some hurt while this process of repairing is going on, but the principal part of your hurt, outside of what we call your feelings, is due to the fact that the inside of you is thus exposed to the chemical action of the air. Then I can hear you say next: Why Don’t My Hair Hurt When It Is Being Cut? It does not hurt to cut anything that has no nerves. There are no nerves in the hair which the barber cuts. If he pulls out a hair it hurts, because the root of the hair has nerves, which telegraph notice of the damage to the brain. When a dentist takes out or kills the nerve in your tooth you cannot have any more toothache in that tooth, because there is no nerve there to send the message to the brain. You can cut your finger nails without feeling pain, because they have no nerves at the ends, but underneath, where they join the skin of the finger, there are a great many nerves, and it hurts very much to bruise the nails at that location. Of What Use Is My Hair? ~WHY WE HAVE HAIR~ Your hair is a relic of the days when the entire body was covered with hair, just like some animals to-day, to protect the body from the heat, cold and wet. Man has, however, for so long a time worn clothes over most of his body that the need of the hair to protect him from these elements has all but disappeared, and so also has the hair, excepting in such places as the top of the head and face and other exposed parts. If you were to go out into the woods without clothes and live a long time your body would probably again become covered with hairs. The time is coming, however, it is believed, when human beings will have no hair at all on their bodies. You have hair on your head, but if you were to wear a hat or cap all the time you would soon be bald. Hair is of no use to us to-day excepting to adorn our bodies and add to our appearance. This it seems to do to-day, probably because we are accustomed to seeing it, and will make no difference in our looks relatively if the time comes when we have no hair at all. Why Does My Hair Stand On End When I Am Frightened? It does this under certain conditions, because there is a little muscle down at the root of each hair that will make each hair stand up straight when this muscle pulls a certain way. It is difficult to say just how these muscles are caused to act in this way when we are frightened. We know that when thoroughly frightened our hair will sometimes stand straight up, and we know that it is this muscle at the root of each hair that makes it possible, but why it is that a big scare will make this muscle act this way we do not as yet know. What Makes Some People Bald? The chief cause of baldness is the lack of care of the hair. It is as necessary for the roots of the hair to have a free circulation of the blood and that the hair itself should have plenty of air as it is necessary for the brain to have a good circulation. A great many men become bald through wearing their hats most of the time. The hat pulled down tight over the head presses against the scalp and interferes with the circulation of the blood in the scalp. Then, also, many hats do not have any means of ventilation, and that keeps the pure air away from the hair. The hair then becomes sick and dies, just as flowers wilt if you keep them away from the air. You will notice that women do not become bald so easily. One reason is that even when the women wear large hats, as they often do, there is plenty of room for the air to circulate through the hair, even when the hat is on, and women’s hats are not pulled down tightly on the scalp. Therefore, they do not press on the arteries and veins in the scalp and interfere with the circulation of the blood. Another reason why women do not become bald is that the hair of women has long been their “crowning glory”; a man likes to see a fine head of hair on a woman, and as women have long tried to please men in every possible way, they take better care of their hair than men do, because they like to have the men consider it beautiful. What Makes Some Things in the Same Room Colder than Others? The objects in a room which has been kept at a given even temperature of heat will be all the same temperature, because heat spreads from one thing to another equally. Still, if you put your hands on various objects in such a room some of them will feel colder than others. You touch the tiling of the fireplace and that will feel cool to you. On the other hand, the upholstered furniture will feel quite warm. The piano keys feel cool, while the wood of the piano and case is warm. The difference is due to the fact that heat or cold will run through some objects more quickly than through others. It will run through the tiling on the hearth and the piano keys more quickly than through the upholstering on the furniture or the wood of the piano case. When you touch a thing with your finger you supply some of the heat of your body to the object through your finger. If the object is the tiling on the hearth or the keys of the piano the heat runs through it quickly and you get a cold impression in your finger. On the other hand, if you touch the upholstery on the furniture, through which the heat runs slowly, you get a warm feeling for the very same reason. Thus, anything which carries the heat away from our contact quickly we call a cold feeling object, and if the object touched does not carry the heat away so quickly we call it a warm feeling object. Why Does the Hair Grow After the Body Stops Growing? The hair on our bodies is one of the things that is continually wearing or falling away, and since, like the skin, it is necessary to protect certain portions of the body, the hair keeps on growing long after the grown up period has arrived. The skin is a very necessary protection of the whole body, but is constantly being worn away, and is all the time being replaced. Your hair falls out when it is not healthy. Unless proper care is given to it, it will fall out and not grow in again, and then we become bald. Will People All Be Bald Sometime? There is a theory that before many years have passed human beings will lose all of the hairs which now grow on different parts of their bodies, due to the fact that we wear so much clothing and keep so much of our bodies away from the sunlight. If that time comes we shall have a hairless race of men and women. THE STORY IN A LUMP OF SUGAR [Illustration: PREPARING THE GROUND.--PLOWING AND HARROWING WITH A CATERPILLAR ENGINE. Sugar beets require deep plowing, ten to fourteen inches, or twice the usual depth. When using horses, farmers are inclined not to plow deeply enough to secure maximum results, and some of the factories have put in power plows which turn six furrows and harrow the land at the same time. They plow and harrow the land of beet farmers for $2.50 per acre, which is about one-half of what it costs the farmers to plow equally deep with horses. The traction engines also are used for hauling train wagon loads of beets to the factory. In some localities farmers are banding together and purchasing engines for plowing and hauling beets. The outfit illustrated above costs about $4,500.] [Illustration: DRILLING THE SEED. Beets are drilled in rows, usually eighteen inches apart, 18 to 25 pounds of seed being drilled to each acre. Practically all the beet seed used in America is grown in Europe, principally in Germany, but it has been demonstrated that superior seed can be produced in the United States. Sugar-beet seed growing requires five years of the utmost skill, care and patience, from the planting of the original seed to the maturing of the commercial crop which is sold to the trade. The factories contract for their seed for three to five years in advance, sell it to farmers at cost price, and deduct the amount from the payment for beets.] [Illustration: HOW THE BEETS ARE GROWN BLOCKING AND THINNING. When the beets are up and show the third leaf they should be “thinned.” Unless thinned at the proper time the pulling up of the superfluous beetlets injures the roots of the remaining ones. Scientific experiments in Germany, where all other conditions were identical, showed that one acre thinned at the proper time yielded 15 tons; the next acre, thinned a week later, yielded 13¹⁄₂ tons; the third acre, thinned still a week later, yielded 10¹⁄₂ tons; and the fourth acre, thinned three weeks after the first, yielded 7¹⁄₂ tons. The men in the foreground are “blocking” the beets, leaving a bunch of them every eight inches. Those in the rear are “thinning,” or pulling up the superfluous beetlets, leaving one in a place, eight inches apart.] [Illustration: READY FOR THE HARVEST. This field of beets yielded 20 tons to the acre. Ex-Secretary of Agriculture James Wilson is convinced that when American farmers become expert in beet culture they will average to produce more than 20 tons per acre because of the superiority of our soils. The ideal factory beet weighs about two pounds, and a perfect “stand” of such beets, one every eight inches, in rows eighteen inches apart, would yield 43¹⁄₃ tons per acre. The present average yield in the United States is about 10 tons per acre, while the hitherto “worn-out soils” of Germany yield 14 tons per acre, or 40% more than is secured from our “virgin soils.”] [Illustration: HUGE BINS TO HOLD THE BEETS AT FACTORY TOPPING THE BEETS. After the beets are plowed out they are topped or cut off by hand and the tops are fed to stock, for which purpose they are worth $3.00 per acre. They are topped just below the crown and the factories require that they be so topped as to remove any portion which grew above the ground, as such portion of the beet contains but a small percentage of sugar. The beet will grow in length, and, if as a result of shallow plowing or coming in contact with a rock it cannot grow downward, it will grow upward and out of the ground, thus necessitating a deeper topping and consequent loss to the farmer.] [Illustration: DUMPING CARS AT FACTORY WITH HYDRAULIC JACK. Beets arriving at the factory by rail from receiving stations either are stored in bins until needed or are floated directly to the beet washers. If to be used at once, they are dumped, as shown above, and slide directly into a cement flume filled with warm water, which has been pumped to its upper end, and is flowing in the direction of the beet end of the factory. In whatever manner they may be received, they first are weighed, and as they are dumped, a basket is held under them to catch a fair sample of both beets and the loose dirt, which the car or wagon contains. These samples, properly tagged, are conveyed to the beet laboratory, where they are washed, and trimmed if not properly topped, and the difference in the weight of the sample beets as received and their weight when washed is called the “tare.” Whatever percentage this amounts to is applied to and deducted from the weight of the car or wagon load. A sample of these beets then is tested by the polariscope for its sugar content and its purity; farmers often being paid a stipulated price per ton for a beet of a given sugar content and 25 to 33¹⁄₃ cents per ton additional for each extra degree of sugar which they contain. The tare rooms and the beet-testing laboratories are open to any one, and in some localities the farmers’ associations employ experts to tare and analyze each sample of beets.] [Illustration: MILLIONS OF BUSHELS OF BEETS FACTORY BEET BINS FILLED TO CAPACITY. As they arrive by rail from receiving stations, or by team, or traction engines from the farm, beets are stored in bins or sheds, the capacity of which ranges from 6000 to 35,000 tons per factory, depending upon location and general climatic conditions. The bins are V shaped, about 3 feet wide at the bottom, 20 to 30 feet at the top, and they are 20 to 30 feet high. As beets are needed, beginning at one end of the bin the loose three-foot planks at the bottom are removed one at a time, and with hooks attached to long poles the beets are rolled into the flume or cement channel below, in which they are floated into the factory. This is not only to save labor, but to loosen up the dirt which attaches to the beets, thus partially washing them. The water which is used in the flumes is warm water from the factory.] [Illustration: TYPICAL AMERICAN BEET SUGAR FACTORY. These factories cost from half a million to three million dollars. They consume from 500 to 3,000 tons of beets per day, and during the “campaign,” which usually lasts about three months, will produce from 12 to 75 million pounds of granulated sugar. There are 73 of these factories, located in 16 States, from Ohio to California. During the operating season they give employment to from 400 to 1000 men each.] [Illustration: WASHING THE SUGAR BEETS CHEMICAL LABORATORY. In a beet-sugar factory each set of apparatus for performing a given process is termed a “station.” In the chemical laboratory the juices and products from each station are tested hourly to check up the correctness of the work and to determine the losses of sugar in each process in the factory.] [Illustration: CIRCULAR DIFFUSION BATTERY. After being floated in from the sheds the beets are elevated from the flume to a washer, where they are given an additional washing before being sliced. From the washer they are elevated and dropped into an automatic scale of a capacity of 700 to 1500 pounds. From the scale they pass to the slicers, where with triangular knives they are cut into long, slender slices, which look something like “shoestring” potatoes. These slices drop through the upright chute seen at the right side of the picture, and are packed tightly into cylindrical vessels holding from two to six tons each; the battery consisting of eight to twelve vessels arranged either in a straight line or in circular form. Warm water is run into these slices, and coaxes out the sugar as it passes from one vessel to the succeeding ones. After passing through the entire series of vessels the water has become rich in sugar, of which it contains from 12 to 15 per cent, depending upon the richness of the beets. It then is drawn off and is called diffusion juice or raw juice. This is carefully measured into tanks and recorded. As this juice is drawn off the vessel over which the water started is emptied of the slices from the bottom, the exhaust slices containing in the neighborhood of ¹⁄₄ to ¹⁄₃ per cent of sugar. These slices are carried out from the factory in the form of pulp and fed to stock, as explained later.] [Illustration: HOW THE SUGAR IS TAKEN FROM THE BEET CARBONATATION AND SULPHUR STATION. Warm raw juice is drawn into the carbonatation tanks and treated with about 10 per cent milk of lime--about like ordinary whitewash. This lime throws out impurities, sterilizes the juice and removes coloring matter. Carbonic acid gas from the lime kiln is forced through the lime juice in the tank, throwing out the excess of lime, converting it into a carbonate of lime or chalk. Tests are taken here by the station operator to show when the process is finished.] [Illustration: FILTER PRESSES. From the carbonatation tanks the juice is pumped or forced through filter presses consisting of iron frames so covered with cloth that the juice passes through the cloth as a clear liquid, leaving the lime and impurities precipitated by it, in the frame, in the form of a cake. This cake, after washing, is dropped from the presses and conveyed out of the factory. It contains from one to two per cent of its weight in sugar, which constitutes one of the large losses of the process. It also contains organic matter, phosphate and potash, besides the carbonate of lime, which makes it an excellent fertilizer, all of which is used in Europe on the farm, but so far to too small an extent in America.] [Illustration: EVAPORATING THE WATER FROM THE SUGAR EVAPORATORS. After a second, and sometimes a third carbonatation and filtration, the juice is carried to the evaporators, commonly called the “effects,” usually four (4) large air-tight vessels furnished with heating tubes running from 3000 to 7000 square feet in each vessel. A partial vacuum is maintained in these evaporators which makes the juice boil out at a low temperature, thus preventing discoloration, and to a large degree the destruction of sugar which will come about by high temperature. There always is, however, some unavoidable loss of sugar in this apparatus. The juice passes along copper pipes from first to last vessel, becoming thicker as it does so. It comes into the first vessel at 10% to 12% sugar and is pumped out of the last one so thick that it contains about 50% of sugar.] [Illustration: VACUUM PANS. After a careful filtration, the juice that comes from the evaporators, and is called thick juice, is pumped to large tanks high up in the building, and from these is drawn into vacuum pans. These are large cylindrical vessels from 10 to 15 feet in diameter and from 15 to 25 feet high, with conical top and bottom, built air-tight. Around the inner circumference they are furnished with 4- to 6-inch copper coils, which have a heating surface of 800 to 2000 square feet. Exhaust steam is used in the evaporators, live steam in the pans, the juice in both being boiled in a vacuum to prevent discoloration and reduce losses. After considerable thickening by this evaporation, minute crystals begin to form. When sufficient of these have formed, fresh juice is drawn in and the crystals grow, the operator governing the size of the crystals to suit the trade. If small crystals be desired, a large quantity of juice is admitted at the outset, while if large crystals are desired, a small quantity of juice first is admitted, and, as it boils to crystals, fresh juice gradually is added to the pan, and the crystals are built up to the desired size. The operator of this pan, known as the “sugar boiler,” is one of the must important men in the factory. The water furnished the condensers of these vacuum pans and the evaporator goes to the beet sheds and is used for floating in the beets. It amounts to from 3,000,000 to 8,000,000 gallons every 24 hours, depending upon the size of the factory, and must be very pure.] [Illustration: HOW SUGAR IS GRANULATED FRONT VIEW OF CENTRIFUGAL MACHINES. The mass of crystals with syrup around them and containing about 8 per cent to 10 per cent of water is let out of the vacuum pan into a large open vessel called a mixer, beneath which are the centrifugal machines. These are suspended brass drums perforated with holes and lined with a fine screen. They are made to revolve about 1000 times to a minute, and the crystal mass of sugar rises up the side like water in a whirling bucket. The centrifugals force the syrup out through the screen holes, leaving the white crystals of sugar in a thick layer on the inner surface. These are washed with a spray of pure warm water and then are ready for the dryer.] [Illustration: SUGAR GRANULATOR OR DRYER. The damp white crystals from the centrifugal machine are conveyed to horizontal revolving drums about 25 feet long by 5 to 6 feet in diameter. These drums are furnished with paddles on the inside circumference, the paddles picking the sugar up and dropping it in showers as the drum revolves. Warm dry air is drawn through and takes the moisture out of the sugar, which now is ready to be put in bags or barrels for the market.] [Illustration: BY-PRODUCTS OF THE SUGAR BEET CRYSTALLIZERS. The syrup that was thrown off from the crystals in the centrifugal machines is taken back to the vacuum pan, evaporated in the same manner as previously described, and from the vacuum pan goes into the crystallizers to carry the process of crystallization as far as it will go. These contain from 1000 to 1600 cubic feet of the crystallized mass which remains in them from 36 to 72 hours, during which time it is kept in constant motion by a set of slowly revolving paddles, or arms, to facilitate further crystallization. From the crystallizers it goes to the centrifugal machines, where the syrup is separated from the crystals as before. The crystals are remelted and go in with the thick juice for white sugar. The syrup, still containing a large amount of sugar, goes out to be sold as cattle feed or to an Osmose or Steffens process, where a portion of the remaining sugar may be recovered. This lost syrup constitutes the largest loss in the entire process. It contains all the impurities of the beet juice not removed by the lime. These impurities prevent more than one and one-half times their weight of sugar from crystalizing, and make what is called molasses.] [Illustration: A SEA OF BEET PULP. For a century the high feeding value of sugar-beet pulp has been recognized in Europe, but until a few years ago millions of tons of this valuable by-product rotted about American beet-sugar factories, as shown above, because American farmers could not be made to believe it possessed sufficient value to pay for hauling it back to the farm.] [Illustration: MACHINE THAT FILLS, WEIGHS AND SEWS THE BAGS OF SUGAR SACKING ROOM.--SHOWING AUTOMATIC SCALES AND SEWING MACHINE. After the moisture has been thoroughly removed in the granulators or dryers, the sugar drops directly to the sacking room through a chute, at the lower end of which the top of the double bag is attached. The sugar flows directly into the sack, the flow being cut off automatically with each 100 pounds, when an endless belt conveyor passes the upright sack past the sewing machine at the proper speed and the product is sealed ready for storage or shipment. While it requires from 400 to 1000 men to man a factory, not a human hand has touched either beets or product since the beets were topped in the field, and at no stage of the operation could flies or vermin or filth come in contact with the product, which from the beginning has been subjected to continuous high temperatures.] Pictures herewith by courtesy of United States Beet Sugar Industry. How Can We Smell Things? You do not need to be told what organ of the body we use in exercising the sense of smell. You can prove that easily to yourself by getting the nose within range of a distasteful smell. We do not use all of the nose to smell with, and the nose is useful to us in other ways besides this. We use the nose a great deal in the act of respiration or breathing, and it is also useful in helping us to make sounds, form words, and, though you may not have known it, helps our sense of taste. We smell things by means of the olfactory nerves which are located within the nose. The entire interior surface of the nose is covered with a membrane. The ends of olfactory nerves, or the nerves which give us the sensation of smell, are in this membrane, and the air, which is filled with the odor of things we smell, passes over this membrane, and thus the ends of the nerves feel the odor and cause sensation of smell in the brain. The nerves of smell do not, however, go all through this membrane. There are other nerves in the nose, however, besides those which give us the sensation of smell. These are also very sensitive and serve to make the nose exercise other functions when the inside of the nose is hurt or tickled. When a foreign substance, one of the many smaller particles which are constantly floating in the air, gets into the membrane in the nose, it irritates these nerves and often causes us to sneeze, which is only nature’s effort to drive out this foreign substance and clean out the nose. Smell is one of the lesser of the five senses which we possess. It is one of what has been called the chemical senses. The sense of smell does not act at any great distance. This sense could be made of more value to us if we developed it. Some people have a more highly developed sense of smell than others. The lower animals have a much keener sense of smell than people. A great many of them can follow a trail for miles merely by the smell of the foot-prints, and it is said that a deer will note the presence of man or any other animal that may subject him to danger even when miles away, the odor being carried to him through the air. How Do We Taste Things? The sense of taste is closely associated with the sense of smell. In fact we do a good deal of what we think is tasting by using our sense of smell. A cold in the nose will sometimes destroy almost altogether the taste of food, so that there is a very close connection between the sense of taste and the sense of smell. The sense of taste comes to us through the tongue, which is the principal organ of taste. The remainder of our sense of taste lies in the surface of the palate and in the throat. As in the case of the other senses, the sensation of taste is given us through nerves, the ends of which are all through those parts of the tongue, the palate and the throat, which contribute to this sense. More nerves of taste are located in the back part of the tongue than on the front, and it is said that when you have to swallow a bad dose of medicine it won’t taste so much if you put it on the front part of your tongue and then swallow, because there are so few tasting nerves there. The extreme tip of the tongue, however, is very thickly covered with the ends of the taste nerves. In like manner one could have the front end of the tongue cut off and still retain most of the sense of taste. Now, in order to produce the sensation of taste, the substance to be tasted must come in contact with something which mixes with it and causes the sensation of taste. This is what happens when we taste anything. The juices or liquids which are caused to flow when anything is put into the mouth act on the substances which enter and give the taste nerves a chance to taste them. Really the nerves of taste are so placed in the mouth as to be regular guards or inspectors of what shall go into the stomach. You can see how well they are arranged. In the tip of the tongue quite a few of them; in the back part of the tongue a great many nerves, for from there the food goes into the throat, which delivers it to the stomach; then those in the palate and in the throat. They are arranged so that the taste nerves have ample opportunity to test what comes in and to give warning to the brain of what is being sent to the stomach. Sometimes the things that come into the mouth are so distasteful to the nerves of taste that they refuse to hand it over to the stomach, but instead cause the distasteful substance to be thrown out again immediately. It is said that a good rule to follow in eating would be to swallow only such things as are pleasing to the sense of taste. On this principle many children would decide to eat nothing but candy, but do you know, if you tried that, the continuous tasting of sweets by our sense of taste nerves would cause them to repel further insertion of candy after a while. You know that too much of a good thing is bad for you, and that is what makes you feel badly when you have eaten too much of one thing. What Happens When We See? ~HOW WE SEE THINGS~ Of course, it is the eyes with which we see things. When we think of the things with which we see, we think only of eyes, which give us our sense of vision, but there are certain forms of animal life which have no eyes but which have what are called eye spots or eye points, which are sensitive to light and which are merely spots. These eye spots may be located in any part of the body, and are often found in great numbers on the same body. These rude eyes are, however, not real eyes. They are, as has already been said, sensitive to light, but are found only in some of the very low forms of animal life which live in the water. A real eye is an organ in which the parts are so arranged that optical images may be formed. As animal life becomes developed to a higher scale, the parts which contain the making of real eyes become more distinct although, of course, the eyes themselves are not so highly developed as in man. One of the first kinds of life which has eyes with a definite structural character are the worms, snails, etc., though their sense of vision is more or less dim. When we come to the family of mollusks, however, low down in the scale of life though they are, we find them to possess eyes which enable them to see almost as well as animals which have a backbone, although this kind of eyes is constructed in a very different manner than the eyes of vertebrate animals referred to. As we ascend the scale of animal life in the study of eyes, we come next to the crustaceous, which is an important division of animal life that embraces the crabs and lobsters, shrimps, crawfish, and insects such as sand-hoppers, beach-fleas, wood-lice, fish-lice, barnacles. The eyes of such animals are quite developed, but the number that each will have varies. Some have only a single eye and others two, four, six or eight, but only certain kinds of this class of life have more than two eyes. The spiders generally have the most. In vertebrates, which is the class of animal life to which we belong, the number of eyes is almost always two and no more. The eyes are formed in special sockets in the skull, which are called eye sockets or orbits. This arrangement of placing them in a socket is of great advantage because the eye is thus protected from chance of injury except from one direction--the front. These animals have also eyelids, eyebrows and eyelashes, which serve as a further protection to the eyes. The principal parts of the eye are arranged in a globe-like ball called the eyeball. This eyeball is movable in the socket under control of various muscles. The eyeball is almost surrounded by a membrane which is opaque in most parts, but very transparent at the front. This transparent portion of the surrounding membrane is called the cornea, and is quite hard. This is the outside coat of the eye. The second coat of membrane consists of parts of various names and contains the iris. The third coat is the retina, which is the end of the optic nerve entering the eye full from behind and expanded into a membrane which spreads out over the second coat. The retina or optic nerve receives optical impressions focused upon it by the crystalline lens. These impressions are carried along the optic nerve to the brain, and the brain then receives the sensation of seeing the image. The eyeball is hollow, and its three surrounding coats form what is practically the same as the interior of a camera. The crystalline lens of the eye acts the same as the lens in the camera. This crystalline lens is suspended within the eyeball right in front of the transparent opening in the front of the eyeball, and when the rays of light strike this lens it focuses them on the retina, which is the same as the film in your camera. Why Can We Hear? We can hear because nature has provided us with a very wonderful organ called the ear and which catches the sound waves that come through the air into the ear and make a part of the ear vibrate. In man and mammals the ear is generally found on the outside of the body, but the principal part of the ear is located within the skull. What we call ears are only the funnel-shaped extensions on the outside of the head which are not so very important so far as hearing is concerned, because they only help the real ear to hear more easily. The outside of the ear gathers in the sound waves and, because it is much larger than the little hole which takes the sounds in to the real ear, we can detect more sounds by having this funnel-shaped arrangement on the outside. The inside of the ear contains an eardrum or tympanum which is separated from the outside part of the ear by a membrane. Behind this eardrum is the real hearing part of the ear in a labyrinth containing the nerves of hearing. Now, when a sound wave strikes the membrane which hangs over the opening before the eardrum, the membrane vibrates and transmits the sound wave through the eardrum into the inner ear which contains the ends of the nerves by which we hear. These nerves, on receiving the sensation, transmit it to the brain which thus records the impression of sounds. As we descend the scale of animal life from the mammals downward, the ear becomes a more and more simple organ. In the vertebrates which are not mammals, there is no external ear at all, and we find great simplifications of the ear the lower down in the scale we go. What Is a Totem Pole For? Before people had individual names, the savage people who lived in clans or tribes referred to themselves in the name of some natural object, usually an animal which they assumed as the name or emblem of the clan or tribe. These names never applied to one individual more than another, but only to the clan or tribe, so that everyone in a tribe which had taken the “wolf” for its emblem was known as “Wolf.” Later on they began to distinguish individuals by giving them additional names characteristic of the individual, such as “Lonely Wolf,” “Growling Wolf,” or other names. The name of this animal was then the emblem of one tribe. They, therefore, placed this emblem upon their bodies, their clothes, utensils, etc. Through this, these emblems also became at times idols of worship and so they erected poles upon which their emblems were engraved. The word totem is a North American Indian word meaning “family token.” The tribes called themselves after animals from which they believed themselves descended. Where Does a Flower Get Its Perfume? The perfume or smell of the flower comes from within the plant itself. The perfume arises from an oil which the plant makes, and just as there are many kinds of flowers, so almost every flower has a different smell. Of course, flowers belonging to the same family or species are likely to develop different smells. The oils produced are what are known as the volatile oils, which means “flying oils,” because, if extracted from the flower and placed in a bottle and the cork left out, they will vanish into the air. Without this quality we could not, of course, smell them at all. Why Do Flowers Have Perfumes? Man uses these oils to provide himself with perfumes, but the plant or flower has another purpose than this. The perfume is not made for man’s use, but for the use of the plant itself. In the plant and flower world the smell of the plant which is in the flower is a part of the scheme whereby plants reproduce themselves. Every plant in order to reproduce itself must produce a seed. The flowers are in most cases the advance agent of the coming seed. Each flower produces within itself a little powder called the pollen, but as plants are like people--also male and female--they are dependent upon each other for the production of a perfect seed. Some of the pollen from the male plant must be mixed with the pollen of the female plant before a perfect seed results. How Do Flowers Produce Seeds? Naturally, the nearest male plant to a female plant may be quite some distance off. How, then, is the pollen from the male plant to mix with the pollen of the female plant? In some cases it is the wind which blows the pollen powder from one to the other, and this thus leaves the development of a perfect seed from a perfect flower open to chance. In the case of perfumed flowers, however, which are mostly low-growing plants, the wind cannot be depended upon. So nature gives to such plants the power to make the perfumed oil and the busy bee does the rest. The perfume being a flying oil rises up into the air and attracts the bee. He is gathering honey and visits in turn all the flowers to which he is attracted. He lights on a male flower and gathers in his honey, and incidentally acquires on his legs, without intending to do so, some of the pollen of the male flower. Then he flies about to the next flower, and to others, and sooner or later he will come across a female flower of the same kind as that from which he secured the pollen on his legs. When he thus enters the female flower, the pollen on his legs mixes with the pollen of the same kind of the female flower, and quite unintentionally the bee helps thus to make the perfect seed. It is not a part of a bee’s business to do this carrying. It only happens that he does this in connection with his regular business of gathering honey. It is a wonderful thing which may be noted here that the pollen from a male of any flower will not mix with the pollen of the female of any other kind of flower, but that the same kinds only have attractions for each other. Flowers are given these attractive perfumes in order that they may attract the bees and other insects in this way. The plants or flowers which grow closest to the ground have generally the strongest and most far-reaching smells. This is so that they will not be overlooked. Why Are Leaves Not All the Same Shape? Leaves are of different shapes because they belong to different families of plants or trees. They are a good deal like people in this respect. Hardly two people in the world look exactly alike, but there is a distinct family resemblance in members of the same family. It is difficult to say just what happens inside the tree to determine the shape of the leaf and that causes them to possess different shapes from others. The shape of the leaf is a mark of identification of the family to which the tree or plant belongs, just as you can tell from a dog’s ears and from other characteristics what his breeding has been. In the case of plants and trees however it is quite probable that the shape and texture of the leaves has been developed as the result of the conditions under which the plant grows. A plant or tree throws off oxygen and takes in carbonic acid gas through the surface of the leaves. To thrive and be healthy it must secure just the proper amount of this food and as the quantity of food taken in depends upon the amount of surface exposed through the leaves, each particular tree or plant has developed in its own direction in this respect until this feature of their structures has been adjusted properly to their needs. It is a good deal like the radiation of heat in your home. Why Are Some Radiators Longer Than Others? When the plumber gets ready to put in the radiators in the home he figures the cubic measurements of the room and then puts in a radiator, the outside surface of whose pipes, is in the right proportion to throw off sufficient heat to fill the room or heat all the air in the room. It requires a certain number of square inches of radiator surface to heat each cubic foot of air space and a good plumber can figure this to a nicety. If he puts in a radiator however that has not sufficient number of square inches on the outside of the pipes, the room will not be heated properly. In the same way, the trees, require that their leaves have a certain amount of square inches of surface space in proportion to the size of the tree, to enable them to do what is required of them and this is arranged by nature so that the trees grow naturally, and no doubt the shape of the leaves has something to do with this. What Makes Roses Red? All roses are not red. Some are white and others pink or of still another color. The color of the rose, and in fact the color of all flowers is due to the way they absorb and reflect the sunlight. In the case of the red rose, the something in the plant that determines the color, absorbs all the other colors in the sunlight and reflects the pure red rays and that makes the color of the red rose. You cannot see the color of any flower when it is perfectly dark. That is because they have no color of their own, but only the colors which they reflect when in the sunlight or some other light. The question of colors is more fully explained in another part of the book. Why Do Plants and Trees Grow Up Instead of Down? As a matter of fact plants and trees do grow downward as well as up. There is a part of each called the root whose business it is to grow down and take certain things necessary to the life of the tree out of the ground. But the part we see above the ground and which is the part we generally think of only when we think of plants or trees. The tree or plant, in order to grow properly, and eventually produce flowers and perfect seeds, must have sunshine and carbonic acid gas, and it is the business of the leaves and other parts above the ground to get these out of the air for the good of the plant or tree. So they start to grow toward the sun. It is easy to prove how a plant will turn toward the light. Take notice of the plants in the flower pots at home. Set one of them on the window sill inside the window where the sun can shine on it and notice how quickly the leaves and branches will be bent over against the window pane. Turn it completely around then so that the plant leans away from the sunlight and watch it for a day or two. Before long you will find that it has not only straightened itself completely out but started to lean toward the window glass again so as to get as near the sun as possible. Most plants, if kept where the sunlight cannot touch them, will die. The sunlight is a necessary part of their lives. What Becomes of the Plants and Flowers in Winter? A great many, in fact the large percentage of plants, live only during one season. This kind of plant actually dies completely after, in the natural course of growth and flowering, it has produced its seed which is the method by which such plants are reproduced. Other plants only appear to die in the winter. Parts of them, such as the leaves and flowers actually die, but the roots and stalks of such plants do not die in winter. The part that represents the life in them goes to sleep and lies dormant until the light and warmth of summer bring forth the leaves and flowers again. The flowers, however, always die and the same flowers never appear again but others just like them appear in their places. Even in hot countries where there is no winter, the plants must go through a period of rest or sleep, although this change is not so marked in plants which grow in these hot countries. How Can Some Plants Climb a Smooth Wall? To get at the answer to this question, we should pick out one kind of plant like the creeping ivy vine. If we examine same as it climbs a brick wall, we find that it sends out little shoots which attach themselves around the little rough places in the bricks of the wall which, if examined under a microscope are quite large apparently--at least they are large enough for the tiny creepers of the ivy to hold on to. Of course, if there were only one little “shoot” to reach out and take hold of the rough spots in the wall, the vine could not cling to the wall, but the vine puts out a great many of these shoots--which it would perhaps be best to call “clingers” and as each helps a little to hold on, the great number all holding on together enable a quite heavy vine to hang on to an apparently smooth wall. Some vines have actually the ability to send out little suckers which are made on the same principle as the boys’ sucker (a circular piece of leather with string attached to the middle with which a boy can pick up stones) and such plants can cling to and climb up an almost perfectly smooth wall. What Are the Thorns on Roses and Other Plants Good For? The thorns of roses and other plants which have thorns originally grew for the purpose of enabling the plants to fasten themselves on to other things thus helping them to climb. Many plants with thorns are permitted to grow now in places where they can use their thorns for climbing but many others with thorns are cut down by the gardener to make the plants shapely and to make them produce more flowers and less branches, but they keep on growing their thorns just the same. Do Plants Breathe? Yes, indeed, plants do breathe. To breathe is just as important to the life of a plant as it is to a boy or girl. Plants do not have lungs like boys and girls and grown up people, but they find it necessary to breathe. You know, of course, that fishes breathe, but they haven’t any lungs either, even though they belong to the animal kingdom. Fishes do not, however, breathe the air in the same form as we do because they must use the air which they find in the water. That is why we say fishes drown when on the land. They cannot breathe air in the form in which we are able to use it any more than people can breathe the air in the water. Breathing, however, is necessary to all living things and the gas which we take in when breathing is oxygen. There is oxygen in the water as well as in the air. Things which live in the air take their oxygen out of the air and things which live in the water get their oxygen out of the water. For this purpose it is necessary for plants and animals that live under the water to have a breathing apparatus especially adapted for getting oxygen out of the water. What Happens When Breathing Occurs? The act of breathing consists really of two actions. Taking something into the body and expelling something. Every living thing inhales and expels in breathing. We take in oxygen and expel it again but when it comes out it has added something to it and the combination or result is carbonic acid gas--so we take in oxygen and expel carbonic acid gas. How Do Plants Breathe? The lungs of a plant, or what the plant breathes with corresponding to our lungs, are located in the leaves of the plant. Under a magnifying glass we can see the lungs of the leaf quite clearly. In addition to this we know that plants breathe, because if we put them in a vacuum where there is no air they die very quickly. The plant needs air or it will suffocate just as any animal will suffocate under similar conditions. Plants, however, do not make use of the oxygen as they find it in the air. They live on the carbon which they find in the air mixed with oxygen. What happens then is this. The plants take in through their lungs in the leaves carbonic acid gas from which they take the carbon and use it as food, and throw off the oxygen which they cannot use. Human beings and other animals take the oxygen into their lungs and use it and expel carbonic acid gas. The result is that each kind of life is dependent upon the other. If it were not for the plant life, men and other animals would find it difficult perhaps to find sufficient oxygen in the air to keep them alive, and if it were not for the carbonic acid gas which the animals throw off, plants and other vegetable life would have great difficulty in finding sufficient carbonic acid gas to go around. Why Do Plants Need Sunlight? Most plants, if placed where no light from the sun can reach them, will die very quickly. To prove that a plant needs the sunlight we have only to place it in a dark corner of the cellar and notice how soon it dies. In fact if it were not for sunlight there would be no life on earth at all. The plant or tree drinks in sunlight through the surface of the leaves. In fact the ability to take in sunlight constitutes the real life of the tree or plant. Leaves grow thin and flat in order that as much surface as possible may be exposed to the sunlight. If a leaf were curled up like a hoop only a part of the outside surface would be exposed to the sunlight and the amount of life that a leaf could supply to the rest of the tree would be much less. The leaf is so constructed that when the sunlight strikes down upon its green surface, it changes the carbonic acid gas which it drinks in, into its elements, i.e., it takes out the carbon which goes into the body of the plant and combining with other food and water supplied by the roots causes the plant or tree to grow and then returns the oxygen part of the carbonic acid gas to the air. Why Does Milk Turn Sour? The milk turns sour because a little microbe, known as the milk microbe gets into it, and being very fond of the sugar which is in the milk, turns this sugar into an acid. If we could keep milk entirely away from the air after the cow is milked, it would not turn sour, but as soon as it is exposed to the air these microbes which are constantly in the air, drop into the milk. They are alive, although invisible to the naked eye. If when they drop into the milk it is warm enough for them to get in their work so to speak, they fall upon the sugar in the milk and turn it into the acid. Their attempt to sour the milk can be overcome by keeping the milk at a low temperature in the refrigerator, but as soon as the milk is taken out of the refrigerator and left out long enough to become warm, the microbe begins to work and the milk cannot be made sweet again. If the milk is boiled as soon or shortly after the cow is milked, the sugar in the milk is changed in such a way that the microbe cannot feed upon it. [Illustration: A PERSIAN RUG WEAVER AT WORK.[3]] [3] Pictures and descriptions by courtesy of Hartford Carpet Co. The Story in a Rug What Are Carpets and Rugs Made Of? The choicest wool of the world is used in the manufacture of carpet. In order to give satisfactory service carpet must be made of wool that is of a tough quality and has a long fiber. Such wool is not produced in America, and the markets of the distant lands that supply it are practically exhausted to supply the American manufacturers. Most of the wool used comes from Northern Russia, Siberia and China. It is shipped in bales. When it arrives at the mill there is much to be done before the wool is ready for any process of manufacturing. How Long Have People Used Carpets? The art of weaving stands foremost among the ancient industries. It came into being in the sunrise lands of the East where color has endless charm and variety and where figure is made to serve the purpose of fact and fancy. The art of weaving rugs is older than Egyptian civilization. Stone carvings made when Egypt was yet unborn were reproduced in rugs. At what period the loom was first used is impossible to tell. An ancient Jewish legend claims that Naamah, daughter of Tubal-Cain, was the inventor of the process of weaving threads into cloth. There are other indications that the ancient Hebrews were the first weavers. Mythology also tells of beautiful maidens weaving exquisite patterns for the gods. Most of us are familiar with the story of Jason who set sail on the Argo in search of the Golden Fleece, arrived at the kingdom of Aeetes, won the hand of Medea, the daughter of Aeetes, who eloped with him after he had secured the coveted fleece. The first hands busy at the weaving craft undoubtedly were those of women. Chaldean gossip, repeated in history relates that Sardanphulees, an ancient Greek king, was often seen in woman’s garb carding purple wool from which his wives wrought rugs for floor coverings for the palace. Homer shows Helen of Troy setting the tale of her people’s war in the woof of her web, and also tells with Virgil of rugs that were laid under the thrones of kings or upon chariot horses. Ancient Hindu hymns show that these people made their textile fabrics studies of great beauty. The woman in the Proverbs of Solomon says: “I have woven my bed with cords; I have covered it with painted tapestry from Egypt.” One learns from the writings of Pliny of the large money value of rugs in ancient times. He wrote at length of a vast rug displayed at a banquet of Ptolemy Philadelphius, the value of which was placed at a fabulous sum. A later writer tells of the love of Cleopatra for rich rugs and tapestries that were woven in her palace or in the countries to the East. On the occasions of her meeting with Cæsar and Antony, the Egyptian queen enveloped herself in a superb rug which she had woven especially for the purpose of showing her renowned beauty to the best advantage. Akhar, emperor of Hindostan, spread a knowledge of the art of weaving throughout India. The earlier phases of the art of weaving may be traced through the land of the Pharaohs to Northern Africa, Southwestern Asia, and finally into the dawn of the Aryan civilization. The loom has not been materially changed, and it may be seen to-day as it was in the time when the priests of Heliopolis decorated the shrines of their gods with magnificent carpets and when Delilah wove the hair of Samson with her web and fastened it with a wooden pin. The ancient weavers attained high artistic standards in their fabrics. Pliny tells of Babylonian couch covers that had all the beauty of paintings and sold for great fortunes to the ancient Asiatic kings. In all ages fine rugs have been used for religious purposes. Early writings describe the use of rugs on the holy cars of pilgrimage to Mecca, at the tomb of the prophet at Medinah and throughout the mosques of the Orient. The abbot Egelric gave to the church at Croyland, before the year 892, two large rugs to be laid before the high altar on great festivals. At later periods rugs were used for similar purposes in the cathedrals of Southern Europe. The Oriental people ever have been devoted to symbols and naturally wove them into their fabrics. Their textiles were made to reproduce mythological stories in which the fauna and flora of a country figured prominently. There was the symbolism of form, color and animal life, of trees and flowers, of faith, and earthly and heavenly existence. The symbols were made to illustrate the conflict between light and darkness, the evolution of life, the decay of death and the immortality that awaits the blessed in paradise. What Do the Designs in Rugs Mean? Since many of the figures of ancient rug-weaving are retained in modern rug designs, the following list of meanings of ancient Oriental symbols used in rug-weaving may be interesting as a key to the stories that are said to appear in many rugs of Oriental design: Asp--intelligence Bat--duration Bee--immortality Beetle--earthly life Blossom--life Boat--serene spirit Butterfly--soil Crescent--celestial virgin Crocodile--deity Dove--love Eagle--creation Egg--life Feather--truth Goose--child Lizard--wisdom Palm tree--immortality Sail of vessel--breath Wheel--deity Lion--power Ass--humility Butterfly--beneficence of summer Jug--knowledge Ox--patience Hawk--power Lotus--the sun Pine-cone--fire Zigzag--water Leopard--fame Sword--force Serpent--desire Bird--spirit Owl--wisdom Pig--kindness Such are the traditions that the makers of modern rugs must live up to. The art of the centuries has been revealed in the rugs of many nations, and the rug-maker of to-day must uphold the standards of an art that undoubtedly takes rank with the great arts. Where a valuable painting goes into the home of one millionaire, thousands of rugs made from an original design of unquestioned art and beauty go into homes the country over to give warmth, comfort and beauty, delighting housewives and imparting a sense of coziness and elegance. According to students of the art of weaving, the perfection of this art was attained about the sixteenth century, after many centuries of slow growth. Since then weaving as an art has been broadened and given a wider scope by means of processes invented for a cheaper production of rugs in all the beauty of their original designs. But there also has developed a modern school of rug and carpet designing that in itself represents no mean standard of art. Many of the less expensive grades of American rugs and carpets, for example, are of designs created by artists of this modern school of weaving designs whose work is of a high degree of artistic excellence. [Illustration: HOW OUR GRANDMOTHERS MADE RAG CARPETS MAKING THE OLD RAG CARPET.] A quarter of a century ago many homes had rugs woven by the housewives with their spinning-wheels, or no floor coverings, except crude cloths made of rags. These homes, of course, were those of families in moderate circumstances, which to-day can have their attractive and comfort-giving rugs of the less expensive grades of tapestry carpet, Axminster or of the various other grades of carpet manufactured at a range of prices within the financial reach of people of modest means. It is only a step from the ancient weaving of rugs, with all the color, glamor and romance that attached to rug-weaving in the ancient days, to the manufacture of rugs in America to-day. There is no romance attached to the making of rugs and carpets in America, except the romance of industrial achievement; but the American rug-maker is as careful of the quality and beauty of his product as was the ancient weaver, and the best standards of ancient weaving have been realized in the manufacture of rugs and carpets in America to-day. Why Did the Ancients Make Rugs? It is only a rug, several yards of woven threads, a design that few can understand--a simple thing, to be sure; yet what a lot of history and memories and traditions it carries! Merely a strip of carpet, with strange figures, beautiful though meaningless, a product of modern invention like many another, some may think. But the story of a rug may go back through many centuries to ancient times of opulent splendor, when wars were waged and kingdoms created and shattered for the beauty of a woman; when gorgeous palaces were raised and great spectacles of art were shown to inspire the world for thousands of years. Only a rug, but a relic of a rich and glowing past! For in those distant days of war and pageantry, an era more classic than our own, history and romance were woven into the rug. The patterns and designs told great stories of wars and loves that swept nations away and created great new empires and related vivid accounts of intrigue and tragedy that determined history and inspired the immortal works of poets and dramatists. The rug in the ancient times was also used for religious symbolism, and sacred doctrines were inscribed in the woven figures. Of all the arts none has been as close to the lives and history of the peoples of the earth as the art of weaving. Songs and stories of these peoples and their national achievements have been immortalized through their woven fabrics. Generations have learned of the great deeds of their forefathers through the historical accounts woven into rugs. And in the days of the early Greeks, Hebrews and Egyptians and on through the succeeding centuries until the middle ages the rug was used as a symbolical part of state, religious and romantic ceremonies. What Makes Some Rugs so Valuable? The reason many rugs are valued at so high a price in money is largely due to the skill of the artist or designer, just as a painting becomes valuable because the artist who painted it has succeeded in producing a remarkable result. The question of rarity also enters largely into the value of rugs. The great artist weavers of the past who worked for love of their art rather than for the money they might secure by disposing of their masterpieces, are dead, and they have had no successors. Then, also, the rug becomes valuable by reason of the amount of time and labor put into it. Many valuable rugs take years to produce, because the artist must do all his work by hand practically and tie his different colored yarns together just so, or the pattern will not come right. These knots may occur every inch or sometimes even less than an inch, and there will be thousands of hand knots in one rug. [Illustration: MAKING TURKISH RUGS.] [Illustration: THE OLDER THEY ARE THE MORE HIGHLY PRIZED The above is a typical Chinese rug, containing symbolical emblems. This is an antique and is of a class that sells sometimes as high as $5,000, its rarity of design, beauty in colors, and scarcity enhances its value.] [Illustration: This is an American machine-made interpretation of a Chinese rug. The ground is a rich gold coloring, the figures being in ecru, dark blue, terra cotta and light blue. It is a beautiful rug, and one of the finest examples of loom-tufted goods ever produced.] [Illustration: WHERE THE BEST PERSIAN RUGS ARE MADE This antique Persian was made in the district of Kurdistan, in Western Persia. The general effect is handsome, although the design is crude. The ground is of a deep rich red, and top colors of dark blue and ecru. The most valuable Persian rugs come from Kurdistan, Khurasan, Peraghan and Karman. The most highly prized come from Kurdistan. The pattern does not show a uniform ground of flowers or other objects, but looks more like a field of wild flowers in the spring, which is very appropriate as a design for anything that is to be walked upon. It is astonishing what wonderful artistic ability is displayed by some of the members of these wild nomadic Persian people. The carpets and rugs are woven on a simple frame on which the warp is stretched. The woof, or cross threads, consist of short threads woven into the warp with the fingers and without the use of a shuttle. Then a sort of comb is pressed against the loose row of cross threads to tighten it. The weaver sits with the back of the rug towards him, so that he depends entirely on his memory to produce a perfect pattern.] [Illustration: This rug is an American copy of a typical Kurdistan. It is marvellous how well the effect in colors and design are reproduced in this domestic rug.] [Illustration: HOW WE IMITATE POPULAR DESIGNS BY MACHINERY This Tabriz reproduction has all the characteristics of the genuine rug in both design and color. The ground is of a soft rose with figures olives, ivory and deep blue.] [Illustration: This is a copy of an old piece of a rug in the Kensington Museum, London, which is 500 to 600 years old. The design is very interesting on account of the symbolical figures which cover the ground.] [Illustration: WOOL-PICKING MACHINE.] The Making of Carpets How Are Modern Rugs and Carpets Made? The best way to learn of this is for us to take a brief visit to one of the largest carpet factories, where we will assume we have already arrived. There is a sharp whistle, then an outlet of steam, the clang of a bell and a locomotive rolls around the curve of the spur-track into the factory yard. Attached to it are several freight cars that only the day before received their cargoes at the New York docks fresh from steamships coming from foreign lands. Inside the yard, the engine comes to a stop alongside a warehouse. Sturdy men unlock the doors of the cars and begin pulling out bales of the imported wool. This is the first step in the evolution of a rug. Between the arrival of the rough wool at the warehouse and the placing in the stock room of the finished rug, splendidly woven after an artistic design shown in attractive colors, many interesting processes are followed. It is sufficient to state that few people looking at rugs of the Saxony, or Axminster or Tapestry type realize the high degree of mechanical science and artistic perception that have been brought to bear in the manufacture of these rugs. After the arrival of the wool there are many steps to be taken until the skeins of yarn receive their coloring treatment in the dye-house and, at the bidding of the great machine, assemble themselves in the beautiful designs that the artists have created. Though there are many details of work in the development of a rug, they have been so well mastered that the employes in charge of every stage of the rug’s evolution give to their work a nicety of attention in little time that careful training and scientific understanding alone can supply. The travel-stained covers of the bales are removed. The heavy bulk is broken and the tightly-compressed bales loosened. Then the wool is fed into the washing-machine, and after that goes into the picking-machine. The process of cleansing the wool is an elaborate one, for it is so full of dirt and grease that several waters and several operations are necessary to its final appearance in a white and fleecy condition. After the last washing the wool is lifted to a drying-room, where the heat from steam-coils is forced through it by means of blowers. The wool now passes to the sorting-room, where the blends are carefully made before it goes to the machine which tears the wool fibers apart, and gets them in shape for the carding and combing processes. Next the wool is blown into a spinning mill. The wool is now ready to be converted into yarn. It passes through a picking-machine, which blends the different grades of the raw material, selecting the strands as to fiber and color. Then it is refined and purified. [Illustration: CARDING MACHINE] Through tubes the wool is forced to the carding-room by means of air pressure. In passing through the cards it is carefully weighed to secure evenness in the yarn. Leaving the carding machine, the wool is taken to the floor above, where the big spools of yarn reach the combing machine for the next process. This machine separates the long from the short fibers. The strands of wool are still thick and must go through another process before they are ready to be made into yarn. They are finally united and given sufficient strength to stand the weaving process. As the visitor sees the strands of yarn first appear on the machine they resemble rolls of smoke. [Illustration: DYEING THE YARN] ~HOW THE YARN FOR CARPETS IS DYED~ The yarn next appears on rows of spindles in the mule-room, six hundred feet long, where the yarn is twisted and brought to its final stage. The yarn now is ready for the dye-house. Here the atmosphere is very dense. Clouds of steam rise from the many vats of boiling dyes. The yarn receives the coloring for which it is intended, or is bleached in an adjoining department, and then is transferred on poles to the drying-room, after passing through a steaming process which sets the color. Next it passes on an electric conveyor to the weave-shop. Considerable skill is required in the weaving process. The assembling of the yarns and matching of colors require expert attention. The skeins of yarn are wound on spools, which are put in sets back of the looms, each color or set representing one “frame” of color in the rug. By the famous Jacquard motion of cards each color wanted in the surface of the rug is pulled up in its proper place, the other frame color laying in the back of the rug. The mechanical process is a remarkable sight. As the pattern forms itself from the mechanical devices, the onlooker is struck with the wonder of it. [Illustration: HOW A CARPET IS WOVEN BY MACHINERY WEAVING A RUG BY MACHINERY] [Illustration: 10,000,000 YARDS OF CARPET PER YEAR FROM ONE FACTORY This picture shows the plant of one of the largest carpet factories in the United States at Thompsonville, Conn. From the looms of these mills are annually produced ten-million yards of the twenty-five different grades of carpet manufactured by this concern. Imagine a strip of carpet across the United States at its widest part, the Forty-second latitude--a strip of “Hartford Saxony”, say, stretching from the Atlantic seaboard to the Pacific coast; and then another carpet strip the length of the United States, where this country is the longest--i. e., from the Northern boundary of the state of Minnesota to the Southern boundary of the state of Texas; then imagine one more strip stretching from Chicago to New Orleans, and finally a connection between the two latter strips at about the vicinity of St. Louis. With a mental picture of this vast country thus stripped with carpet, you wonder if there is that much carpet in the world. It seems incredible that this great sweep of land could be measured with carpet--and yet enough material comes every year from the looms of one carpet factory alone in this country to strip the United States East and West, and North and South as indicated above.] The weave is now completed; the rug comes out. But it is rough and has to be finished. It is passed through a machine that removes the roughness of the face as a lawn-mower cuts away the top-grass. The ends are finished, and the carpet is complete. ~SOME DESIGNS STAMPED ON YARN BEFORE WEAVING~ The pattern of tapestry carpet is obtained by printing the colors to appear in the design on the yarn which forms the face before the weaving is started, by means of large drums. After all rugs leave the weave-shop a force of skilled women examine them carefully to make sure that there are no defects. Every yard of the annual output of carpet and rugs is inspected five times before it leaves the factory. [Illustration: EXAMINING AND REPAIRING] [Illustration: PACKING FOR SHIPMENT] Why Do I Yawn? When you yawn, you do so because you have not been breathing quite properly and for some reason or other your blood supply has not been getting sufficient oxygen through the air which has been taken into your lungs. Nature’s way, in this instance, is to call for a big intake of air all at one time, and since it is important at such times that a large quantity of air should be supplied to the lungs at once, nature has so arranged matters that certain muscles shall cause you to open your mouth wide and take in as much air as you can at one time, and also has arranged so that it is almost impossible to keep from yawning when the demand for it is once made. The yawn is controlled by a part of our nerve structure which looks after the breathing apparatus. The satisfaction we feel after a wholesome yawn is due to the fact that having replied to nature’s demand that we bring in more air, our blood secures the oxygen which it needs and we feel the effect of better blood in our arteries at once. A peculiar thing about the process of yawning is that one person in a room yawning will quite likely set all or nearly all the others to yawning also. There seems to be no explanation of this excepting that when a number of people are in one room and one of them begins to yawn, the others do so, not because they perceive the first yawn so much as the probable fact that the air in the room has become so poor that there is not enough good air for all the people in it, breathing normally, and many of them are forced to yawn at about the same time. Where Do Living Things Come From? This is a big subject, but a very interesting one. To understand it fully we must begin at the very beginning of the world. God made first of all the rocks, the mountains, the sun, the moon, the stars, the soil, and put the water in the lakes, rivers and oceans. This took a long time, but they had to be there before the living things could begin to be. What is Inorganic Matter? This thing we have spoken of is called inorganic matter, which means “without life,” and everything in the world which has no life is called inorganic matter. These things do not die, and for that reason do not have to be replaced. The form and appearance of inorganic matter and its location is often changed by man or other causes, but even when man burns the coal which he has dug up out of the ground in the furnace, no part of it is destroyed. Some of it is turned into smoke and gas and some of it is turned into ashes, while every other particle which went to make up the coal originally is still in existence. It remains as inorganic matter in some form or other. Where Did Life Begin on Earth? After the inorganic things had been made and the earth was ready for life, the different kinds of living things which we find on the earth began to exist. These are called organic objects, which means objects “with life.” The first living things to appear were the bushes, the grass, the garden vegetables, the flowers, trees, and all the kinds of life which we ordinarily think of as growing things. This division of living things makes up what we call the vegetable kingdom, and in a general way of classing it is the kind of life which cannot move about from place to place and which has not a sense of feeling, or any of the other senses, seeing, hearing, tasting or smelling. After this division of life had been established the world was ready for the other and more important form of life--the fishes, the birds, cats, dogs, horses, cows, with others that we call domestic animals, and also the lions, tigers, elephants and others which constitute the division of wild animals. This kind of life was given some or all of the five senses, but not all classes of animal life possess all these senses. Some of the lower forms of animal life, like the oysters, clams, in the fish family, cannot see, hear, smell or taste. They can only feel; others are able to do more of these things, and many have all of the five senses. When Did Man Begin to Live? Man was not created until all the other living things on earth had been started, and he was given additional powers so that he might become the ruler of all the other living things, principally because he was given a brain with power to think, reason and originate. Why Must Life Be Reproduced? Life must be reproduced because living things die. They have power to live only for a certain length of time. The other life in the world is used to provide food for man, and if there were no way of reproducing life it would not be long before man had eaten all the vegetables and the animals too, and would himself then starve to death. To avoid such a calamity God put into each living thing, both vegetables and animals, a power to cause other things of the same kind as itself to grow. This is called the power of reproduction. With this power each kind of living thing can bring other specimens of the same kind into the world and each kind of living thing can do this without aid from any other kind of life. The trees, the flowers, and other kinds of vegetable life would reproduce themselves without the aid of man, as would also the fishes and other kinds of animal life. Man, however, just to have things conveniently at hand, uses his power over other life to cause his vegetables to grow near where he lives, and keep the animals which he wishes to use as food in some place where he doesn’t have to hunt for them every time he wishes meat for his table. This, however, he does only with the animals which he has domesticated or tamed. When he wants meat from the animals which are still wild he must hunt for them as he used to do. Each kind of life has the power, however, to reproduce only its own kind. If you plant a peach stone you will sooner or later have a peach tree which will bear peaches, and these peaches from the young tree will look and taste just like the peach whose pit or stone you planted. There may be other kinds of fruit trees all about, and also trees which do not bear fruit. All of the trees secure the food upon which they live and grow from the same soil. Even the grass under your peach tree eats the same things as your peach tree, but it remains always true that things in the vegetable kingdom will grow only to be like the thing from which it came. Have Plants Fathers and Mothers? The little trees grow up to be exactly like their fathers and mothers (for they have fathers and mothers), which is something all living things must have. These are not the same kind of fathers, or mothers either, that a boy or girl has, exactly, but they are parents just the same. So far as the trees, flowers and plants are concerned we call the parents father and mother natures, which is a term used merely to keep you from confusing vegetable life fathers and mothers with the regular kind. In the vegetable kingdom you cannot always see these father and mother natures, which enable them to reproduce their kind of life, but everything in the vegetable and also in the animal kingdom has them. How Do Plants Reproduce Life? In the spring we put seeds into the ground and later on plants grow up where the seeds were planted, and later the flowers come. The seeds contain the baby plants, which come to life, and after bursting the covering of the seed, unfold and grow up into plants if placed in the ground, where they can obtain the proper amount of warmth and moisture to give them a start. Why Do Plants Have Seeds? To get at this subject in the best manner we must study first how plants produce seeds and what happens. The power in a plant to make another plant like it grow comes from the flower. Ordinarily we think of the flowers as beautiful to look at and delightful to smell, but the flowers do not grow for the mere purpose of being beautiful, but are for a more useful purpose--to develop a seed which, when planted, will produce another plant. The machinery for producing a perfect seed is in the flower or blossom. Every flower has a definite plan of construction. The leaves and colors vary, but the plan for a perfect flower is always there. The petals which are generally colored are called the _crown_. When you pluck off the petals you see a number of green leaves at the bottom where the petals were attached. These form what is called the _calyx_, and help to hold the petals in place. Inside the flower are little stems which grow to the petals. These are called _stamens_. Every one of these little stems is hollow, and if you split one open you will discover a _fine powder_. This powder is called _pollen_, and is the “father” nature of the plant. In the calyx, the part we had left after we plucked off the petals, is the “mother” nature of the plant. The main part of the mother nature is the stem of the flower called the _ovary_, and this is where the seeds grow. These seeds in the ovary, however, will not become perfect seeds unless some of the pollen from the “father” nature of the plant touches them and fertilizes them. At the proper age of the flower some of this pollen powder passes into the ovary and fertilizes the seeds and makes them good seeds. This is only one kind of flower, however. In this kind the father and mother natures are in the same flower. In other kinds of plants the father and mother natures are found on different parts of the same plant. Why Does an Ear of Corn Have Silk? The corn plant is one of this kind. You know what it looks like--a tall plant, generally six or seven feet high. The ears of corn grow out of the side of the corn stalk. The ear is covered with husks and out of the end of the ear hangs a bunch of brown silk threads which we term corn silk. Up at the top of the plant you will see the tassel, but you may not have known that this is the flower of the corn plant. The tassel or flower in this case contains the “father nature” of the corn plant, and the ear of corn contains the “mother nature.” The husks on the outside of the ear of corn protect the grains of corn on the ear inside and keep them tender. The ear of corn is really the ovary of the corn plant, because that is where the seeds grow. You will guess, of course, that the grains of corn on the ear are but seeds of the plant. Were you to examine one of these ears of corn on the plant when it had just started to form you would find no kernels on the cob, but only little marks which indicated where the grains of corn are expected to grow, but if you want to know, then, how many grains of corn were expected to grow on the ear, you could easily tell by counting the little silk threads which you see on the cob and which stick out over the end. There will be a thread of silk for each grain of corn that is expected to grow. Every grain of corn must receive some of the pollen powder from the tassel or father nature at the top of the corn plant or it will not develop into a nice large, juicy kernel. How Does the Pollen Touch the Grain of Corn? Before the kernels of corn grow the tassel is in bloom. The wind blows and shakes the pollen powder off of the tassel and the powder falls on the ends of the silk which stick out of the little ear of corn to be. Each thread of silk then carries a little of the powder down to the spot on the ear where it is attached and thus the grain of corn receives the fertilizing necessary to develop it into a ripe seed. If you leave the ear of corn alone the kernel will eventually become yellow and hard and can then be planted and will produce other corn plants. Man, however, finds the ear of corn a delightful food, if taken at a time when the seeds are fully grown but not yet ripened into perfect seeds. At this stage the grains of corn would not grow up again if planted, because they have not yet become perfect seeds. Do Father and Mother Plants Always Live Together? We come now to the kinds of plants on which the “father” and “mother” natures are on different plants of the same kind. At times they will grow side by side, at other times they will be in the same field, but very often they grow at quite a distance from each other. In some instances the nearest father tree will be even miles away from the mother tree of the same kind. But in any event the pollen from the father nature must reach the mother nature of the plant or tree before a perfect seed can be produced. In cases of this kind the father nature will be on one tree or plant and the ovary or mother nature on another. The wind helps out nature in some of these cases by blowing the pollen of the father plant to the ovary of the mother plant. In many other instances the bees and insects help. Why Do Flowers Have Smells? Where the bees do this it is because the bee has been visiting the flowers in his search for honey. They do not fly from flower to flower for the purpose of uniting the mother and father natures of plants, but they help the flowers incidentally while getting the honey for which they are searching. In gathering his honey the busy bee will go all over the father flower and get his legs all covered with pollen powder. Sooner or later he comes to a mother flower of the same kind of plant or tree from which he has father pollen on his legs, and, still bent on gathering honey, he incidentally rubs the pollen powder on to the ovary of the mother flower and the fertilization takes place. The wonderful thing about this is that the father pollen of one kind of a plant will not fertilize the mother nature of another kind of plant. To illustrate this, if a bee carrying pollen on his legs from a walnut blossom visits the mother blossom of a hickory tree the pollen of the walnut would not affect the hickory blossom, but would still have the proper effect on the first walnut mother blossom he visited. This is how life in general is reproduced among the plants and trees. Life in the vegetable kingdom has no sense of feeling or any of the other senses, but this kind of life is still true to its own nature and is a wise thing in the plan of creation, because, since all seed will produce only plants like those from which the seed came, man can control the growth of the vegetables and fruits he needs as food. He knows when he plants corn that he will get corn in return, because perfect seed never makes a mistake. It would mix things up terribly for man if this were not so, because man might then plant one thing and find another thing growing. It would be a sad thing to plant wheat and find thistles growing. In order that seeds may grow they must be planted under conditions that suit the kind of vegetable life in the seed. Man has to study and learn what these conditions are. If a seed is planted too deeply the sun may not have a chance to warm the ground to that depth, and if it is planted too near the surface it may become too warm and be killed by the sun. When planted under the proper conditions the seed soon begins to grow. It grows upward toward the sun to get light and air, and it sends roots down into the ground to get food and moisture. The life in the vegetable kingdom is soon able to take care of itself. How Are Fishes Born? The next step in the study of the reproduction of life brings us to the animal kingdom. The first thing we discover in this section is that in the animal kingdom father and mother natures are almost always separated. In plants and trees these parent natures are sometimes in the same flower, often separated, but on the same plant, and in other instances on different plants miles apart. What we must remember, then, is that in the case of plants it is given more or less to the chance of wind or other circumstances to bring the parent natures together. In the animal kingdom there are a few cases where the mother and father natures are found in the same living object, as in the oyster and clam families, one of the lowest forms of animal life. These have but one of the five senses--that of feeling. This class of animals--the cold-blooded animals--includes the fishes, and in most members of this class the father and mother natures are separated and in different bodies. Step by step from now on we enter higher forms of animal life, and through each step we find a greater difference between the father and mother natures, and in the animal kingdom we speak of the father and mother natures as “_male_ and _female_.” In the animal kingdom, too, what we have previously called the seed is known as the _egg_. Seeds and eggs are the same so far as their usefulness is concerned, but we say eggs in the animal kingdom to distinguish from seeds in the vegetable kingdom. Fish have eggs, then, and it is from the eggs that little fish are born into the world and grow to be of eatable size. You recognize the eggs of the fish in the “roe,” which is eaten as food. Not all fish eggs are used as food, however. In the fish world the eggs are developed in the body of the female fish. Each little round speck in a “shad roe” is one egg, and there are many thousands in a single “roe.” Each egg will produce a little fish, under favorable conditions. These eggs develop in the body of the female fish in winter. In the spring, which is the time in which most living things are born, and, therefore, the time for hatching out fish eggs, all of the fish swim from the deep water where they live in winter to the places where the water is shallow and warm, and in these shallow waters the female fish expels the eggs from her body where the sun can get at them and hatch them by warming them. After the female fish has thus laid the eggs, the male fish swims over the eggs as they lay in the water, and expels from his body over them a fluid which is white in appearance and which fertilizes the fish eggs. If any of this fluid fails to reach some of the eggs it is not possible for the sun to bring them to life. When the eggs are laid and fertilized the mother and father fishes swim away and they never see their children or recognize them as such, even if they meet them later in life. The parent fish do not act like other fathers and mothers, and they do not need to, because as soon as a baby fish is born he is able to find his own food and needs no help from father or mother to teach him how to find it or enable him to grow into a real fish. Of course, many of the tiny fish are eaten by other fish and not all the eggs which the mother fishes lay hatch into live fish, because, if they did, the waters would be so crowded with fish that there would not be any room for the water. A single female fish will lay millions of eggs in a year, and if each egg developed into a fish there would be far too many. This order of animals, which includes turtles, frogs, etc., is the cold-blooded class of animal life. They have only part of the five senses. They all can feel and some of the fishes can see and hear, but a great many of them, particularly those kinds which live on the bottom of the ocean, cannot either see or hear, and some members of the fish family cannot even swim. The thing to remember about fishes in connection with the reproduction of life is that the mother fish must select a place which is favorable to deposit the eggs, but after that her responsibility ceases. The father merely fertilizes the eggs, and then his responsibility ceases. The little fish look out for themselves as soon as they are born and never know what it is to have a father or mother to look after them. When we study the next higher form of animal life we find that the young ones have to be looked after, and that this becomes more necessary as we ascend the scale of animal life until we reach man, the most intelligent of all animals and yet the most helpless of all at birth. How Birds Are Taught to Fly. The next step brings us to the birds. Before they can look after themselves the little birds must learn how to search for food and the kinds of food good for them. They have to learn the habits of their kind of life. The higher you go in the study of animal life the greater seem to be the dangers which surround the young animals and the longer it takes to teach them how to look after themselves and what to do for themselves. The bird family includes not only the robins, larks, sparrows and pigeons, but also the ducks, geese, and chickens, etc. We are all more or less familiar with birds’ eggs, and if not we know what a hen’s egg looks like. The eggs of the bird family are laid in nests, which is the first sign of home building in the animal kingdom. The birds are the first of the large class of warm-blooded animals. The egg here represents again the reproductive power. The eggs, too, form in the body of the female bird, but are laid in a nest which the parent birds build together. Now this is the first step away from the fish family. The fish looks for a suitable place to lay the eggs and then goes off and leaves them. The birds, however, have to make a nest in which to deposit the eggs. The fish, as you remember, depended upon the warm sun shining on the shallow water to hatch out the eggs, thus depending on an outside force to supply the necessary warmth. In the bird family the mother bird must cover the eggs with her own body and keep them warm until they hatch out. Then, too, the father and mother birds feed the young until they are strong enough to fly and find food for themselves, and so the mother and father birds look after their babies until they are old enough to look after themselves. When this time arrives the old birds cease to bother about the young ones altogether. The fishes never act like parents after the baby fishes are born, because the little fish are able to look after themselves right away. The parent birds are a good deal like fathers and mothers for a time, but only so long as it takes them to teach their little bird children to look out for themselves. Then they forget the children completely. It requires but a few days and no parental care to hatch out a family of baby fishes and no attention at all after birth. It requires several weeks and much patience for the parent birds to hatch out their eggs, and it involves care and attention for several weeks to teach baby birds to take care of themselves. This being a father or mother in the animal kingdom becomes a greater responsibility in every step as we get closer to man, and when we reach man we find him to be the most helpless offspring of all at birth, and that it takes more time, care and attention to bring up a human child to maturity than any other animal. What Makes the Hollow Place at One End of a Boiled Egg? This hollow place on the end of the boiled egg (sometimes it shows on the side) is the air which is put inside of the egg when it is formed so that the little chicken will have air to breathe from the time it comes to life within the egg until it becomes strong enough to break the shell and go out into the world. There is also food in the egg for him. When you boil the egg this pocket of air within the shell, which would have been used up by the chick if the egg had been set to hatch instead of being cooked for breakfast, begins to fight for its space and pushes the boiling egg back and forms the hollow place. The purpose of the air in the egg is a good thing to remember when we come to study the higher forms of animal life from the standpoint of how they reproduce themselves. The mammals are the next higher form of animals. The babies of this class of animals must be fed for several weeks or months before they are ready to come into the world. A little chicken is ready to come out of the egg almost as soon as it comes to life, and, therefore, needs only a little air and food before it is strong enough to peck its way out, but the babies of mammals begin to live months before they are ready to come into the world, and they need a great deal of air and food during this time. This class includes the dogs, horses, cows, cats and all other animals in the Zoo and in the woods. The name mammals means the same as “mamma,” and indicates an animal which must be fed from the body of a female mammal even after it is born. In this class the eggs are retained within the body of the female animal instead of being laid in a nest or some other place, as in animals of lower classes, after being fertilized by the male animal, so that the baby animal may secure its food and air from within the mother’s body after the life within the egg is begun. The mother’s body supplies the necessary warmth to develop the life of the little animal in the egg, just as the birds supplied this with their bodies. In the bird class it only takes a few hours to give the little bird sufficient strength to peek his way out, but in the mammal class it is a long time before the baby animal is strong enough to come out into the world, and even after it is born the babies of mammals require a great deal of care and attention before they are able to look out for themselves. During this period the animal secures all of its food from the breast of the mother animal. Another reason why the eggs of mammals are retained within the bodies of the females is the need for protecting the young animals from enemies. In the animal kingdom each kind of animal preys upon another kind. They attack and devour each other and are constantly in danger. If, then, mammals laid eggs in nests and sat upon them to hatch them out, the mother animals sitting on the nests would be continually in danger of attack from their enemies. They would either have to flee and subject the nest and its contents to the danger of destruction or else stay and fight, and perhaps be destroyed. But by carrying her egg within her body the mother mammal is able to move about from place to place and protect her baby. Is Man an Animal? Men, women and children belong to the “mammal” class of animals. The offspring of the human family is the most helpless of all animals at birth. The young of most kinds of mammals can stand on their legs shortly after being born, but the human baby requires months before it can stand up. A baby horse can also walk within a few hours, but human children do not begin to walk until they are more than a year old. Why Cannot Babies Walk as Soon as Born? The human baby has a great many more things to learn than a horse baby before it is safe for him to go about alone. It takes time for the brain to develop, and if a baby could walk before the brain had even partially developed it would only get into trouble. This, then, is what we have learned about the reproduction of life and the reasons for its being different in different classes of life. First, we had the division of organic life into the vegetable and animal kingdoms. Life in the vegetable kingdom has none of the five senses, for plants cannot see, hear, feel, smell or taste. They cannot move from place to place, but remain where they grow until destroyed or removed. On the other hand, all animal life has at least one of the five senses--feeling. The oysters and clams belong to this class. Starting with this level of life in the animal kingdom we find that as we go on up through the different classes we find each class able to do things which make it superior to the class below it, until we reach the human mammal, who can do most of all. And, further, that since each class as we go up in the scale of life has greater ability to do things than the class beneath it, so in each case the task of the parents in preparing their offspring for their kind of life becomes greater, and the period during which the offspring is learning becomes longer and longer until we reach the human family, in which we find that parents have the greatest responsibility, and the children are the most helpless of all animals, but that in the final result man has a right, on account of his superior qualities, to be the ruler of the other creatures of the world. What Are Ball Bearings? Some years ago a gentleman in trying to find some way to reduce the friction, which is constantly developed to a certain extent, even when the axle is oiled, discovered that if between the axle and the inside of the hub a circle of steel balls were arranged, so that the hub of the wheel did not touch the axle at all, but rested on the little balls which in their turn touched the axle, that a great deal of the friction was eliminated. This proved to be a wonderful invention, and when this combination is arranged and oiled, there is hardly any friction. Why a Gasoline Engine Goes [Illustration: FIG. 1.] As you know, gasoline is a very inflammable fluid, and will explode if placed too close to fire. This explosive quality is the basic principle of the gasoline engine. By admitting a small quantity of gasoline vapor into an enclosed cylinder, and exploding it by means of an electric spark, repeating this operation continuously, the engine is given a regular rotary motion. Look at Fig. 1. Starting from the gasoline tank, the fluid is fed into the ‘carburetor’, which is a sort of atomizer. Here the gasoline is mixed with air, and broken up into a very fine spray, in which condition it will explode readily. The engine will not start of itself. Its fly-wheel must first be turned by hand, or by some other outside force, until the first explosion takes place. After this its action is automatic. As shown in Fig. 1, the fly-wheel is being turned, and is drawing the piston down the cylinder, which in turn sucks gasoline vapor, (shown by little arrows) through the ‘intake valve’. This ‘intake valve’, and the ‘exhaust valve’ on the opposite side of the cylinder, are opened and closed at the proper time through the action of the gears shown in the illustration. Passing to Fig. 2, the fly-wheel in turning has drawn the piston to its lowest point, and is now shown forcing it up the cylinder. This compresses the gasoline vapor in the cylinder to a density at which its explosion produces the greatest amount of power. The intake and exhaust valves are both closed. ~WHAT CAUSES THE EXPLOSION IN A GAS ENGINE~ Fig. 3 shows the explosion. The cylinder has been filled with compressed gas, and the piston has again started on its downward travel. The spark plug, set in the top of the cylinder, makes a spark every time an electrical current passes through it. A switch on the engine permits the current to pass to the spark plug only when the engine is at this position in its action. (Fig. 3.) The consequent explosion drives the piston downward with great force, turning the fly-wheel, which by its weight continues the rotary motion after the downward impulse of the piston has been expended. Fig. 4 shows the fly-wheel, still turning, forcing the piston up and thus expelling the burned gases from the cylinder through the exhaust valve, held open for this purpose. From this position the engine goes again to that of Fig. 1, and through 2, 3, and 4, continuously, exploding every second revolution, and giving a regular rotary motion to the fly-wheel. [Illustration: FIG. 2.] [Illustration: FIG. 3.] [Illustration: FIG. 4.] The illustrations show a one-cylinder motor, but these engines can be built with two or more cylinders, arranged to explode at different times, thus giving very smooth action to the fly-wheel and main shaft. Aeroplanes, almost all automobiles, various pumps and other machinery are driven by gasoline engines. The rotary motion can readily be transmitted by chains or gears to the propellor of an aeroplane or motor boat, or the wheels of an automobile. It is only in the past few years that the gasoline engine has reached its present high state of perfection. [Illustration: THE BEGINNING OF AN AUTOMOBILE CRANKCASE SHOWING BEARINGS. The heart of the automobile is the engine. It is built around the crankcase, which is its foundation or base.] [Illustration: CRANKCASE WITH CRANKSHAFT AND FLY-WHEEL ADDED. The crankshaft serves the same purpose in an automobile as the pedals do on a bicycle. The fly-wheel on the end helps it to keep turning at an even speed.] [Illustration: Gasoline vapor is exploded in the cylinders. This pushes the piston down, and as the piston is connected to the crankshaft it starts the crankshaft turning. The piston and the rod that connect it to the crankshaft are just like the feet and limbs of any one riding a bicycle. Cylinders showing piston in place and connected to crankshaft.] [Illustration: The gears or “cog-wheels” are for running the fan, the pump and other parts.] [Illustration: THE HEART OF THE AUTOMOBILE Cylinder added to crankcase. The cylinders are next bolted down to the crankcase, the pistons and crankshaft having been connected, as shown in Fig. 3. A cover is placed over the gears to keep them clean.] [Illustration: An oil pan or reservoir is attached to the bottom of the crankcase to hold oil for the engine.] [Illustration: The carburetor furnishes the gasoline vapor for the cylinders. It is connected to the engine by a crooked pipe called the intake manifold. After the gasoline has been exploded a valve opens and allows the burned gases to escape through another pipe, called the exhaust manifold.] [Illustration: Oil is poured in the spout which is at the left of the carburetor. It runs down into the reservoir and is pumped up through the engine a little at a time. Oil pump and filler added to motor.] [Illustration: THE POWER PLANT OF AN AUTOMOBILE The electric generator makes electricity to be used for starting the engine and lighting the car.] [Illustration: The magneto gives an electric spark, which explodes the gasoline in the cylinders. The water pump keeps water flowing around the cylinders to prevent them from getting too hot. This water comes back to the pump through the radiator at the front of the car. Wind blows through the radiator and cools off the water. The tire pump on up-to-date cars is run by the engine. It does not pump except when the gears, which are shown in the picture, are pulled together.] [Illustration: An electric motor starts the engine by turning the fly-wheel. This makes it unnecessary to get out and crank the car by hand.] [Illustration: SECOND STAGE OF CONSTRUCTION The transmission is added. The transmission makes it possible to reverse the car. It also enables the driver to go into high-speed gear when on level roads and low-speed gear for starting and for pulling hills.] [Illustration: Double-drop pressed steel frame. The frame on which the car is built.] [Illustration: Addition of semi-elliptic and three-fourths-elliptic springs to frame. Large springs are placed at the front and rear of the frame. They make the car ride smoothly.] [Illustration: Adding the front axle.] [Illustration: READY FOR THE WHEELS Showing addition of full-floating rear axle.] [Illustration: Completed engine and transmission is next fastened to the frame and connected to the rear axle by the drive shaft.] [Illustration: Showing addition of gasoline tank and gas lead to carburetor.] [Illustration: Showing how steering gear is connected.] [Illustration: WHAT THE COMPLETED CHASSIS LOOKS LIKE Wheels are next added to chassis.] [Illustration: Completed chassis with radiator added. The water which keeps the engine from getting too hot is pumped around the cylinders and then through the radiator. The wind blows through the little openings in the radiator, and cools off the water. Then the water is pumped around the cylinders again.] [Illustration: The steps and fenders are next attached.] [Illustration: THE MARVELLOUS GROWTH OF TWENTY YEARS The finished car.] [Illustration: GASOLINE AUTOMOBILE. The first American-built automobile, now in Smithsonian Institute, Washington, D. C., where this photograph was taken. The rude carriage that was a curiosity twenty years ago and less--the vehicle that vied with the two-headed calf and the wild man of Borneo at the county fairs--was the beginning of the greatest transportation aid since the birth of civilization. Because of it our standards of living have become higher. It has broadened the horizon of all of us. Built by Elwood Haynes, in Kokomo, Indiana, 1893-1894. Equipped with one-horse-power engine. Successful trial trip made at speed of six or seven miles an hour, July 4, 1894. Gift of Elwood Haynes, 1910. 262,135.] [Illustration: When an automobile passed you twenty years ago.] [Illustration: HOW AUTOMOBILES HAVE IMPROVED LEFT SIDE VIEW RIGHT SIDE VIEW A new exhibit in the Smithsonian Institute, officially known as “Exhibit Number 56,860,” is attracting a great deal of attention from visitors to the National Museum. It consists of a complete Haynes six-cylinder unit power plant, and has been given a position at the side of the original Haynes “horseless carriage,” where the striking contrast shows the remarkable improvement that has been made in motor design and construction during the past twenty-two years. The most important features of the power plant are shown clearly and comprehensively by having sections cut away from the various parts, so that the visitors to the Institute are enabled to see the mechanical construction, and the relation of the component devices. On the right side of the engine, the intake and exhaust manifolds are shown in their natural position. A full vertical section of the Stromberg carburetor gives a good idea of how the gasoline is mixed with the air and supplied to the cylinders. The Leece-Neville generator has its casing cut away to give a view of the windings and cores. Numerous windows have been cut into the crankcase to disclose the crankshaft construction and the oil reservoir. The transmission gears are also shown in this manner. Most of the electrical equipment is shown clearly on the left side of the motor. Here an interesting feature is the full vertical section of the American Simms high-tension dual magneto. A half section has been removed from the rear cylinder, and the piston as well, to give a glimpse of the interior construction. A large portion of the Leece-Neville starting motor casing has been cut away. The cover-plate on the switch controlling the starting motor has been replaced with a glass cover to display the method of completing the circuit from the battery to the motor. A skeleton selector switch is mounted at the rear of the transmission case, instead of its usual position on the steering wheel. The electric gear-shifting mechanism is made visible by using a glass plate for the top cover-plate on the transmission.] Why Does the Heart Beat When the Brain Is Asleep? Under ordinary conditions the heart beats are controlled by certain nerve cells which are located within the heart itself, and these cause the heart to beat even while the brain is asleep. This explains why the heart beats when the brain is asleep, and the fact that the brain when asleep does not exercise its functions, shows how necessary this arrangement and the control of ordinary heart beats is. If this were not so, we should not be able to live while asleep. It is just like the management of a great business in this sense. The general manager of a great business has control of the entire works, but there are occasions when he must be thinking of only one thing in connection with the business, and so he must have his organization so complete, that the parts which he cannot be thinking about at the time will do their work just the same. So he surrounds himself with competent assistants, who look after certain departments while he is busy or away or asleep, and if anything goes wrong while he is away, he calls on special forces to set things right. Now, the brain is the general manager of the whole body and has these nerve cells in the heart as a sort of assistant manager to look after the heart beats in ordinary conditions, and to keep the heart going while he is asleep. But, by reason of his office as general manager, the brain has a special way of sending orders to the heart through special nerves which run from the brain down each side of the neck to the heart. There are two pairs of these special nerves. One pair, if set in motion, will make the heart beat faster, and the other pair will make the heart beat more slowly. Why Do Our Hearts Beat Faster When We Are Running? When you start running, the brain knows at once that your legs and other parts of the body will need more blood to keep them going, and so the brain sends down orders through his special nerves which make the heart beat faster, to get busy, and they do. Then when you stop running, your heart is beating faster than necessary--there is really an oversupply of blood being pumped through your system for the time being, and that makes you uncomfortable, until the brain sends word through the other set of nerves to the heart to slow down the heart beat. It is better to stop running gradually, to give the heart a chance to get back to its normal beat gradually also. Why Do I Get Out of Breath When Running? This is also caused by your brain in its efforts to keep up your supply of good blood. We breathe to take air into the lungs, where the blood which has once been through the arteries and comes back on its return trip to the heart, is exposed to the air in the lungs, before going back into the heart. The air which we take into our lungs purifies the once used blood and makes it into good blood again. When you run the heart pumps blood into your arteries faster to enable you to run. Thus also, the arteries send much more blood back to the heart through the veins, and this must be purified by the lungs before going back into the heart. To attend to purifying this extra amount of spoiled blood the lungs need more air, and thus you are made to breathe in more air for the purpose. Unless you are in good training--your wind in good condition as we say--it is almost impossible for you to supply the lungs with enough air for the purpose, but whether you can do it or not, the lungs call upon you for more air, and cause you to try to get it, and that is what makes you get out of breath. Why Does My Heart Beat Faster When I Am Scared? The natural tendency of a scared creature is to run or fly. The effect of being scared has the same effect on the brain that your starting to run has. The brain is always as quick as you are, and knowing that when you are scared your actual or natural inclination is to run, it is merely getting you in shape so that you can move or run fast. Why Does Cold Make Our Hands Blue? Your hands appear blue when cold because the veins which are near the surface are filled with impure blood which is purplish in color. Your hands become cold because there is not sufficient circulation of warm red blood going on to keep them warm. The blood in circulating through your body sends warm red blood through the arteries, and this is returned to the heart through the lungs by way of the veins. The veins carry only used-up blood or what is left of the good red blood when the arteries are through with it. Its color is a purplish blue. When your hands are blue it means that circulation of good red blood has practically stopped--the red blood is not flowing from the heart through the arteries in sufficient quantity and there is no color in the arteries, as the blood from the arteries has practically all gone into the veins. The veins are full to purplish blue blood, and this makes the hands look blue, because there are a great many veins in the hands close to the surface. Why Do I Get Red in the Face? Now, when you rub your cold blue hands together, you start the circulation going again, and that brings the red blood into the arteries, giving you the healthy red color again. When you run hard to get red in the face because you are causing an unusual amount of red blood to flow through your whole body by your violent exercise. Some people with an extraordinary amount of circulation are red in the face all the time. This is because of the presence of a great deal of blood in the arteries, or because the walls of their arteries are so much thinner than others that the red blood shows through more easily. Is Yawning Infectious? Yawning is infectious to the extent that other habits are. The desire to yawn which comes to us when we see some one else does so comes under the heading of suggestion. The power of suggestion is greater than many of us realize. We are great imitators of each other. When one of us is downhearted, we are apt to become happy and glad simply by being with other people who are happy and glad. If enough people one at a time tell a perfectly well man that he looks sick, he will actually feel ill, provided he does not suspect a game is being played on him. So a good actor carries his audience with him. He can make them laugh or cry almost at will, and if he yawns, his audience will begin yawning. Often, however, there is no acting connected with the yawning of the first person. Then the yawn is caused because the person is not sending enough good air into the lungs for purifying the blood, and the yawn is only nature’s way of making us take an exceptionally deep breath of air in at one time. This lack of sufficient good air in the lungs may not be due to the poor breathing, but to the amount of bad air in the room. In such cases it is quite likely that other people in the room yawn when one of them starts it because they all begin to feel the need of more good air at about the same time. What Makes Me Want to Stretch? The necessity or desire to stretch comes to us because certain parts of the body are not receiving the proper amount of blood circulation and it is these parts that we stretch at such times. If you have ever been to a ball game, you know, of course, that it has become customary for the crowd, no matter how large, to stretch its legs and arms during the last half of the seventh inning. In fact, that has come to be a fixture at ball games and is universally known as the “stretch inning.” Now, it is not so much the result of a desire to encourage the home team as the natural following out of nature’s laws that originally started this practice. The end of the seventh inning at a ball game generally means that the crowd has been sitting quite still for the greater part of an hour and a half, just long enough for the circulation to become poor in parts of the body, and the custom of stretching at a ball game thus comes from the necessity of getting a little more speed into the action of the heart to increase the blood supply. In other words, the stretching constitutes a mild form of exercise. You will notice the ball players themselves do not stretch themselves in the last half of the seventh inning. They are getting enough exercise without that. It is natural, however, for us to stretch as we wake up from sleep after having lain quietly in one position for one or more hours. It is nature’s way of causing the heart to work faster. What Happens When I Stretch? What happens is simply this. When you stretch your arms and legs, you squeeze the arteries and veins which are a part of your arms and legs, much as happens when you pull on a piece of rubber tubing. The tubing becomes flat instead of perfectly round, and it is not so easy to send water through a flat tube as through a round one. Just so with the heart. It is the heart’s business to send blood through the arteries at all times, and when you make them flat the heart’s job becomes just a little harder, and it goes to work beating just a little faster to overcome this extra difficulty. By that time you are through stretching and the heart is busy pumping blood a little faster than ordinarily, and that is what makes you feel so good after you have stretched. Why Can We Think of Only One Thing at a Time? If you are asking the question intelligently, you must know that to think means to concentrate, and in that sense we can only think of one thing at a time, because it takes all of that part of the brain which is used for thinking for just one thing. To give close attention to any one subject means to turn the entire brain force practically in one direction. To let other things pass through the mind at the same time may appear not to interfere with the one thought, but they do, and our conclusions suffer accordingly. You can be doing something with one part of your body, while engaged in thinking of one thing, but only such things as are more or less mechanical as the result of habit, such as walking, or moving the arms--things which the parts have done so often that actual attention by the brain is not absolutely essential. Take for instance, the fact that a man in deep thought on one subject will sometimes walk up and down the room or along the sidewalk. He can do this walking and still think concentratedly, but if he stubs his toe on the leg of a chair or on a rough place in the walk, his thought is broken, because the brain immediately takes itself out of the thought and pays its attention to the toe that was stubbed. Why Do I Turn White When Scared? Simply because, when you are scared or frightened, the blood almost leaves your face entirely. Under normal conditions, the red blood which is flowing through the arteries of your face, gives the face a reddish tinge, and your face becomes white when you are frightened, because then the blood leaves the face. It is quite singular, but when you are really frightened, whatever the cause may be, the human system receives such a shock that the heart just about stops beating all together. When your heart stops beating of course the flow of the blood from the heart stops and then there is no supply of fresh red blood coming through the arteries under the skin of your face. Therefore you look white--the color your face would be if no blood ever flowed through your arteries and veins. Some people have faces so white they look as though they were scared all the time. This is not because they have no blood flowing through the veins and arteries in their faces, but because their supply of blood is less than other peoples, and sometimes because the walls of their arteries and veins are much thicker than the average that the color of the blood does not show through. There are also many people who have so much blood in their systems all the time, and the walls of whose arteries are so thin, that they look at all times as though they might be blushing. What Makes Me Blush? Anything that will make your heart send an extra supply of blood into the arteries and veins which supply your face with blood, will make you blush. Embarrassment will do this. So will anger generally, although sometimes people get so angry that the blood is driven out of their faces. In this case they are so angry that their heart has stopped beating, practically. What Occurs When We Think? When we think the mind is acting on sensations; it is receiving, in conjunction with memories of sensations it has previously received. Sensations as they reach the mind arouse the mind to activity and, as soon as the sensation is received, the mind begins to compare the new sensation with sensations received at previous times, and by putting things together reaches a conclusion. When you are thinking you are really trying to call upon memory to help you. You know the thought of one thing calls up another, and this leads to something else. This association of ideas is the faculty which enables us to think consecutively and accurately. It is the business of the mind to receive the sensations that enter it and arrange them in their proper places. That memory of past sensations is the important part of thinking, is proven by the fact that when we have forgotten a thing we are unable to think what it was. Can Animals Think? For this reason if animals have memory they should be able to think. It is now believed that many animals have to a certain extent the power to remember. A dog will recognize his master even though he has not seen him for years. We might think he does this by his highly developed power of smell, but if his master has come from a direction opposite to that from which the dog first sees him, he could not have tracked him by his smell. A dog will recognize his master from quite a distance, so he must have to a certain extent the ability to remember or the power of association of ideas, which amounts to the same thing. Again, a horse that once belonged to the fire department, even though now hitched to a milk wagon, will have the impulse to run to the fire when he hears the fire gong. And an old war horse will prick up his ears as he used to when he hears the bugle call. Why Do I Sneeze? You sneeze sometimes when you look up at the sun or at a bright light. There does not seem to be any real good explanation of why looking at a bright light should make you sneeze. It is due to the connection there is between the nerves of the eyes and the nose. You generally blink if you look at a bright light suddenly, and the blinking process stirs the nerves inside of the nose to make you sneeze. You know, of course, that the start of the sneeze is inside of your nose. The nose is, besides being the organ of smell, the channel through which we take air into the lungs, when we breathe properly. The nose is lined with membranes, back of which are a net of very small nerves which are extremely sensitive. The membranes are placed there to catch and hold the impure particles of matter which come into the nose when we take in a breath of air, and sneezing is only one effective way of cleaning out the nose. It is brought on only when some particularly difficult job of nose-cleaning has to be done. Pepper up the nose will make you sneeze quickly, because pepper produces a very great irritation inside the nose, and the nose goes to work at once to get rid of it in the quickest possible manner as soon as the pepper comes in. Other things have the same effect. Sometimes a cold in the head causes you to sneeze. The sneeze in that event is merely nature’s effort to clean out the nose when other efforts have failed. There are many suggestions for stopping a sneeze before it takes place, after you feel it coming on, such as putting the finger on each side of the nose, and many others. But a half sneeze does not remove the cause of the sneeze, so it is much better to sneeze it out, and many people enjoy the after effects of sneezing so much that they take snuff into the nose to produce it. What Happens When I Swallow? The muscles of your throat act in the form of a ring when food passes into your throat. The food does not drop directly into your stomach. In other words, the action is not quite the same as when you drop a stone out of the window. When you do the latter, the stone hits the sidewalk or whatever is below at the time, with a smash. It would hardly do to have our food drop into the stomach, so the muscles of the throat are arranged to contract in rings which push or squeeze the food downward, and the food is passed from one ring of muscles to the other. It is just like pushing a ball down into the foot of a stocking that is apparently too small for it to drop down. You put the ball in the top of the stocking and then by making a ring of your fingers around the stocking you can push the ball down. When you swallow, you start the muscles of your throat to making these rings. The upper ring squeezes the food on to the ring below it and so on down to the stomach. What Makes the Lump Come In My Throat When I Cry? The “lump” which comes up into your throat when you cry is caused by a sort of paralysis of the rings of muscles in your throat. The muscles of your throat can make these rings or waves upward also, but it is more difficult upward than downward--probably because of lack of practice, as we say. When you have put something into your stomach that makes you sick and causes you to vomit, the throat muscles take the matter from your stomach and bring it back to the mouth in the same way, except, of course, that this action begins at the bottom. Sometimes when you cry, or lose control of yourself in some other way (you know, of course, that in crying you always lose control of yourself, don’t you) practically the same effect is produced as when you have something in your stomach that should come out. Crying, or the thing that happens sometimes when we cry, makes the throat muscles act just as if we were vomiting, and as the action is an unnatural one, when the ring or wave reaches the top of the throat, we feel the lump or ball as we call it. We feel the lump because the throat has been made to go through the motion of eliminating something in an unnatural way, just as your arm will hurt if you pretend to have a ball or a stone in it, and in throwing the imaginary ball or stone, you put the same force into your movements as you would if you had an actual ball or stone in your hand and were seeing how far you could throw it. Why Do We Stop Growing? We eventually stop growing because certain of the cells of the body lose their ability of increasing in size and producing other cells. It is one of the marvels of the construction of the human body that this is so and one of the wisest provisions also. At first the cells of the body crave lots of food and increase in size, divide and then the parts go on growing until they become of a certain size, when they again divide and each part goes on growing, etc., and thus we grow. A growing boy needs more fond than a mature man, because he needs some of it to grow with, while the man only has to keep what growth he has going, i. e., alive. We say this limit of growth is a wise provision of nature because if there were no limit to the size we might become, we would not know how large to build houses, barns, etc., or else we would have to build them so large to start with that we would be lost in them for a long time. We would constantly be forced to change these things and there would be no basis to reckon from. Dogs might be as big as elephants and then they would be of no use to us, or of what use would a dog as big as an elephant be to a boy of five years. You see it would not do at all to have this rule changed. Why Do We Grow Aged? We age directly in accordance with the lives we lead. You can bend a wire back and forth a number of times at the same point without breaking it, but eventually it will break. Just so with the human body. You can use each part of it for its own purposes a number of times, but eventually the break will come. Or, you can fail to make a part of it perform its regular functions, and it will die--the break will come. The human body is the most wonderful machine in the world, but even it will eventually wear out. Every time you move your arm, leg or some other part of your body, you destroy some tissues. The body replenishes and builds up those tissues again for a certain time. When you bend a joint in your body, the body oils the joint naturally, but as you grow older, or rather, as you use the different parts of your body more and more, it brings nearer always the time, when the body cannot, of its own accord, build up again the tissues you have destroyed. That is why some people become very old at forty and others are still comparatively young at seventy. It requires a great deal of care and attention and the elimination of all abuse of the body to keep us young when we are old. The use of drink, lack of sufficient sleep and other abuses prevent the body from restoring the tissues which have been destroyed. Worry and sorrow age us very rapidly, because these things affect the nerves. If the nerves are not quiet we cannot get any rest and without rest we grow old very rapidly. What Causes Wrinkles? Wrinkles come to us in several ways. An easy way to cause wrinkles is to scowl and frown and get into the habit of doing this. When you scowl or frown you pucker up the skin on your forehead into wrinkles and if you continue the habit the skin on your forehead makes the wrinkles permanent. You have given your skin the wrinkle habit. This acts just the same way as your arm would, if you tied it up in a sling and held it close to your side for a very long time--a number of weeks. When you took the sling off you would find your arm useless--a dead arm. It had developed the habit of doing nothing. In old people, however, wrinkles come more naturally. There it is the case of the skin not receiving the proper nourishment and attention to keep the circulation of the blood right. When people become old they are apt to lose the fat which has accumulated under their skins. If they had taken just the right amount of exercise all of their lives and kept their circulation perfect in all parts of the body, there would have been no fat there. But when the fat accumulates, it makes the skin grow larger, and then when the fat disappears and people get thin again, the skin is too large and makes the wrinkles. Does Thunder Sour Milk? Milk will sour in any kind of warm and moist temperature and, because just before and during a thunderstorm the air is generally quite warm and moist, it is only natural that it should turn sour. It is wrong, however, to say or think that thunder makes milk sour. Thunder is only a noise and noise cannot do anything but make itself heard. The fact that it is generally warm and moist, however, when it thunders, coupled with the fact that these conditions of the air sour milk very rapidly, have led people to connect the two in their minds and caused them to fall into the error of believing that the thunder is responsible for the change in the milk. What Makes the Rings in the Water When I Throw a Stone Into It? Every movement has a beginning. When a movement on the earth is once started it keeps on going until something stops it. If nothing stops it it will go on forever. When you shout you start air waves going in every direction, which keeps on going until stopped by something which has the power to break up their waves. When you throw a stone into the ocean you start a series of ripples or waves which spread out in every direction and if you dropped your stone into the exact middle of the ocean--half way from each side--in a perfectly calm sea undisturbed by other forces, your ring of ripples would go on getting larger until it landed on the beach or shore on each side of the ocean at the exactly the same time and there the beach or shore would stop it. The original ring of ripples is caused by the fact that when you drop a stone into the water it disturbs the water where it goes in and the water moves away from the stone to the sides, and as the stone goes down, over and up above it, and the whole body of the water is disturbed in such a way that makes the ripple appear on the surface and spread out in every direction. As the stone goes down into the water further and further the disturbance is repeated and ring after ring appears on the surface. Of course there are many disturbances in the water at all times. Many things may happen to break up your little ring of ripples before they touch the sides of the ocean--a ship--a fish--the wind--or one of many other things, and because this is true you would have difficulty in sending the waves made by your little pebble across the ocean, but you can take a dishpan from the kitchen and after filling it with water drop pebbles into it as nearly the middle as possible, and you will see the ripples or waves your pebble makes spread out from the point where the pebble entered the water in all directions. Why Are There Many Languages? Different languages developed in different parts of the world because there was no inter-communication between people in different communities, and each was really developing a language for itself. In doing so they developed their language without knowing that other communities were working out the same problems for themselves. So they first developed their own sign and gesture language and later on their word or sound language and kept on using it. While they may thus have developed the use of some of the same signs and sounds or combination of sounds to express one thing perfectly understandable to themselves, these sounds or combinations of sounds might mean something entirely different to another community, where that particular sound or combination of sounds may have been hit upon to mean something entirely different. Of course, not all languages were developed in this way. There are, you know, a great many languages used in the world. Some of them are offshoots of others, where part of a community moved to another part of the world, taking their language with them, but developing it further along new lines, and using new combinations of sounds for new words. Then also, there are many words which mean the same thing in different languages and are spoken with practically the same sounds. This is due to the movement of people from one nation to another and bringing their own words with them, so to speak. In many instances a stranger would come to another nation, and use his own word for expressing a certain thing and that would eventually be taken up and used as a better word, and the old word dropped. It is strange that this should be true, but this accounts for the fact that many words are the same in sound and meaning in numerous languages. What Makes a Match Light When We Strike It? The match lights when we rub it along a rough substance, because the rubbing produces sufficient heat on the end of the match to set fire to the head, as we call it, which is made of chemicals that light more easily than the stick of wood, which is the rest of the match. The fire thus started is hot enough and burns long enough to set fire to the wooden part of the match. To explain this more fully, let me say this. Rub your finger quickly along your coat sleeve or along the seat of your trousers, long a favorite place for men to strike matches, pretending that your finger is a match. You find the end of your finger becomes warm, don’t you? Not warm enough to set your finger on fire, of course, but if you had the same combination of chemicals on the end of your finger that there is on the match, you would set the chemicals afire and this would burn your finger, just as it sets fire to the wooden part of the match. It took a great many years to discover the combination of chemicals of which the head of the match is made. Before that discovery was made it was far from easy to light the light in the evening as it is now. It must have been a serious thing to let the fire go out in the furnace in those days. What Makes the Kettle Whistle? The kettle whistles only when the water boils and the steam or gas which is the form the water turns into when boiling is trying to escape through the spout of the kettle. You see, when the water starts boiling, the inside of the kettle is at once filled with steam and more is coming out of the water all the time. This steam must get out some way, so it rushes for the spout of the kettle, and because so much of it is trying to get out of a comparatively small opening at once there is quite a pressure and this results in making the whistle out of the spout of the kettle. It is just the same process as when you whistle yourself. To whistle you fill your mouth with air and force it out through your lips, which you have closed excepting for a small opening, by the pressure you can bring to bear with the roof and sides of your mouth, and if you have learned to make your lips into the proper shape and apply the pressure steadily you can sound a very long note and make different notes by making the opening in your lips large or small. The kettle spout has only one size of opening so the sound is practically the same at all times though louder at sometimes than at others. This is caused by the varying pressure at which the steam in the kettle is being forced out. What Makes the Water From a Fountain Shoot Into the Air? The water from the fountain shoots into the air because water anywhere will run down if given a chance. To produce a fountain you must have a source of water supply for the fountain which is higher than the openings of the fountain out of which the water shoots. The water comes out of the holes in the fountain for the same reason that it comes out of the faucet in the kitchen or bath room. In the latter case the water comes from the waterworks reservoir in which the level of the water is much higher than the opening in the faucet in your home. Being higher the water in the reservoir is trying to get away through the pipes all the time and all the pipes leading from the reservoir are full of this water trying to get away. Just as soon as you turn the valve in the faucet the water comes out and runs down into the bowl. If you were to turn the opening of the faucet up instead of down as it is, the water would shoot up instead of down. Not very much, it is true, but it would act much like the water from the fountain. The reason it does not shoot up high in the air like a fountain is because the opening in the faucet is the same size as the opening in the little pipe which leads the water from the street into the house. If you would turn the opening of the faucet up and attach to it a pipe which made the opening much smaller (the size of the opening in the fountains), you would see the water shoot into the air just as it does from the fountain. When you reduce the size of the opening you increase the pressure of the water coming from the pipes in proportion to the reduction you have made in the size of the opening. Water from the fountain will not, however, shoot as high as the level of the water in the reservoir because, as soon as it leaves the pipes, it encounters the pressure of the air outside the pipes and the law of gravitation which pulls all things toward the center of the earth. It is not natural for water to shoot into the air as it does in a fountain. The only way water can go naturally is down, and it only goes up a little way from a fountain because of the pressure of the water in the pipes behind the openings in the pipes in the fountain. What Keeps a Balloon Up? A balloon stays up in the air, because of the air in it, together with the weight of the balloon, is less than an equal bulk of the air in which it floats. In former days of ballooning the balloons were filled with hot air and were then found to rise and stay up until the air inside of the balloon became of the same temperature as that in which it floated. When this stage was reached, the balloon itself would fall because the material of which it was made was denser than air. Today balloonists fill their balloons with gas which is lighter than air, even when as cool as the air in which they rise and are thus able to stay up a long time. You, of course, have seen many of the red, white and blue paper balloons which are sent up on the Fourth of July. You will remember that father, or whoever it is that is sending them up, lights the oil-soaked knot of cloth that is attached to the balloon immediately below the opening at the bottom. He first lights this and then holds the balloon for a time with his hands. Soon, however, you will remember that the balloon starts upward with father still holding it. This is because the air inside the balloon is becoming heated. You will notice also that at first he has to hold out the sides of the top of the balloon with his hands or has some one help him do this, but that even so the balloon does not stand out round and full as it should. When the balloon starts to rise, however, you will notice that it is round and full. This is because the air in the balloon has become heated and is expanding. Soon the balloon is tugging to get away and father lets go and it rises and sails away with the wind. As long as the fire below it burns, and if the wind does not upset it so as to make the paper part catch fire, the balloon will stay up; but, when the fire burns out, the balloon will come down. The balloon merely rises because the air inside, and held there by the covering of the balloon, is warmer air and lighter than the air on the outside. Why Did People of Long Ago Live Longer Than We Do Now? When reading of people who lived long years ago and especially when reading about the length of their lives, we are told that in the old days people lived longer than they do now. Some of the early historical records speak of single individuals who lived hundreds of years. There is great doubt as to whether these statements are founded on fact. In thinking about this we must first take into consideration that these records of long ages were recorded at a time when man had no accurate ideas of the actual passage of long periods of time such as a year. They did not have our calendar as a basis for figuring at all. Learned men now tell us that the actual age of men who lived at the time these records of great ages were recorded probably lived shorter lives than we do now, and that what they record as a period of one year was probably a much shorter period than one year. It is true beyond the question of a doubt that the people of today live longer on the average than people who lived ten, twenty or more years ago. In other words, the average period of life has increased steadily. This is due to the fact that we have taken great care of our bodies; have improved the conditions in which we live, and made them more sanitary; have learned to fight and check and eradicate diseases, which only a few years ago we could not prevent people dying of when they once contracted them, and we know from the records which we keep that actually people live longer on the average today than only a few years ago, and it is safe to say that they live longer now on the average than at any time in the world’s history. Is There a Reason for Everything? The world is so constructed that there must be a reason or cause for everything. There are so many forces in the world that man has not yet been able to locate the original cause of every one of them. Concerning other things, he sees the effects without having any knowledge of the forces which are their cause. Other things he has never even bothered to inquire about, but simply takes them for granted. But every force, which means, of course, everything in the world, must have had a beginning and therefore something or a combination of things must have caused it to begin, and the thing or things that caused it to be is the reason for its being. Every little while someone makes a discovery of some new force, and then we suddenly realize that this force has been in existence all the time although not known to man, and we discover through this the reason for many other things being as they are. The other thing or side of the question is also true. We cannot have a cause without an effect. You cannot do anything without causing something to happen and producing an effect on one or more other objects either animate or inanimate. You cannot move your hand without creating some disturbance in the air. When you make a noise, low or loud, you produce sound waves. When you burn a stick of wood, you create smoke, ashes and gases of various kinds. You change the whole nature of what was the piece of wood, and yet no particle of what made the stick of wood is ever destroyed or lost, but appears in some other thing in the air or on or in the earth. What Makes an Echo? An echo is caused when the waves of air which you create when you shout are thrown back again when they are stopped by something they encounter and are turned back without changing their shape. Any kind of a sound wave will make an echo in this way. You see, you can have no sound of any kind without sound waves. You could not make a sound if there were no air. Now, when you shout, you start a series of sound waves that go out from you in every direction and they spread away from you in circles just like the rings of ripples that are caused when you drop a stone into a pool of water. You can prove this to yourself easily by having one, two, three or more of your friends stand around you in a large circle. You can place them as far away from you as your shout can be heard if you wish. When you shout, each of your friends will hear the shout at the same time, provided, of course, they are at equal distances from you. Sometimes these sound waves as they go away from you in circles strike objects that turn the waves back unbroken just as they came to them. The waves will bounce back just like a rubber ball from a wall against which it has been thrown and this is the echo. However, some things that the sound waves strike break up these waves entirely and others partially. No doubt you have sometimes noticed when you shout you hear a distinct echo and that at other times, standing in the same place, you cannot hear any echo, although you shout in the same way. This is explained by the fact that at times conditions of the air are such that no echo is produced while at other times a perfect echo results. What is a Whispering Gallery? The possibilities of an echo have to be taken into account by the architects and builders of all public buildings, such as theaters, halls and churches, where anyone is to speak or entertain others. Unless they are very careful the walls and ceilings may be so arranged that when any one sings or speaks in the room, there is such an echo that it interferes with the music or speaking. It sometimes happens also that through some peculiarity in which the walls and ceiling of a building are constructed there will be certain places in the room where an echo can be heard, even a whisper, and which cannot be heard in other parts of the room at all. This is likely to occur in rooms where there is a dome-shaped ceiling. There will be certain spots in the room hundreds of feet apart, where if you stand on one spot and another person is on another definite spot clear across the room, the tiniest whisper can be heard, while the people in between cannot hear at all. This is called a whispering gallery. Of course, loud talking would produce the same effect. A whispering gallery is a gallery with an echo which can be heard from certain positions. There are a number of famous whispering galleries of the world. In the room beneath the great dome of our Capitol at Washington is an almost perfect whispering gallery. There are quite a number of points at which you can stand and hear the whispers across the room which is more than a hundred feet. These whispering galleries come accidentally, of course. It would be difficult to deliberately construct a building in such a way as to produce a whispering gallery. Why Do We Get a Bump Instead of a Dent When We Knock Our Heads? When you knock your head against a sharp corner, or if some one hits you on the head with anything with a sharp edge, you do receive a dent in your head, but it does not last. In other words, the head has one of the qualities of a rubber ball. You can press your finger against the sides of the rubber ball and push it in, but when you take your finger off the ball resumes its shape. Just so with your head--it resumes its shape after a blow. After doing this, however, a bump or lump is formed. I will endeavor to tell you how the bump is formed or rather what causes it to form. You cannot knock your head against anything that is harder than your head without causing some injury to the parts which received the bump. Now, what happens then is just what happens to any other part of your body when it is injured whether as a result of a bump, a cut or a bee or mosquito sting. As soon as the injury occurs the brain starts the “repair crew” to work. The result is that first a great supply of blood is rushed to the injured part with the result that the blood vessels are filled up and extended with blood. Certain parts of the blood cells find their way through the walls of the blood vessels at the part of the injury and other fluids from the body are piled up there, so to speak, to form a congestion. This “piling up or congestion” distends the skin and raises the bump. On the head where the layer of muscular structure is thinner and where there is less space between the bones of the skull and the outside skin, the bump will be larger and more noticeable, because a good deal of blood and other fluids are piled up in a comparatively small space, and so the skin gets pushed out further to accommodate this great congestion, whereas in other parts of the body the bump may be quite as large but not so noticeable. [Illustration: HOW MEN GO DOWN TO THE BOTTOM OF THE SEA PUTTING ON THE SUIT. Socks, trousers and shirt in one, and a copper breastplate.] [Illustration: PUTTING ON THE IRON-SOLED SHOES. They are purposely made heavy, to help the diver sink.] The Deep Sea Diver What Does the Bottom of the Sea Look Like? It looks very much like the land on which we live. There are mountains and valleys, rocks and crags, trees and grass, just the same as we see on land, except, of course, that there are no human beings to be seen. Instead of birds flitting about the tree-tops, fish swim about them, and where the squirrel and rabbit bound through the woods on land, the great king crab and sea turtle drag their unwieldy forms on the ocean’s bottom. Some of the scenes at the bottom of the sea are like fairyland, and in tropical waters are often as beautiful and spectacular as those we see in theatrical pantomimes. Delicately tinted sea-shells, great trees of snow-white coral, sea foliage of every tint and shape, and deep dark caverns, in which lurk the devil-fish and other odd looking fish. The Diver’s Outfit. The armor of to-day consists of a rubber and canvas suit, socks, trousers and shirt in one, a copper breastplate or collar, a copper helmet, iron-soled shoes, and a belt of leaden weights to sink the diver. [Illustration: ADJUSTING THE TELEPHONE. This enables the diver to talk at all times to those above him.] [Illustration: PUTTING ON THE HELMET. It is made of tinned copper, with three glass-covered openings, to enable the diver to look out.] [Illustration: TELEPHONING FROM THE BOTTOM OF THE OCEAN TESTING THE TELEPHONE. Every precaution is taken to see that everything is in order before the diver goes down.] [Illustration: THE FINAL TEST. The least error in the adjustment may mean death to the diver.] The helmet is made of tinned copper, with three circular glasses, one in front and one on either side, with guards to protect them. The front eye-piece is made to unscrew and enable the diver to receive or give instructions without removing the helmet. One or more outlet valves are placed at the back or side of the helmet to allow the vitiated air to escape. These valves only open outwards by working against a spiral spring, so that no water can enter. The inlet valve is at the back of the helmet, and the air on entry is directed by three channels running along the top of the helmet to points above the eye-pieces, enabling the diver to always inhale fresh air. The helmet is secured to the breastplate below by a segmental screw-bayonet joint, securing attachment by one-eighth of a turn. The junction between the water-proof dress and the breastplate is made watertight by means of studs, brass plates and wing-nuts. A life or signal-line and also a modern telephone enables the diver to communicate at all times with those above him. The cost of a complete diving outfit ranges from $750.00 to $1,000.00. The weight of the armor and attachments worn by the diver is 256 pounds, divided as follows: Helmet and breastplate, 58 pounds; belt of lead weights, 122 pounds; rubber suit, 19 pounds; iron-soled shoes, 27 pounds each. The air which sustains the diver’s life below the surface is pumped from above by a powerful pump, which must be kept constantly at work while the diver is down. A stoppage of the pump a single instant while the diver is in deep water would result almost in his instant death from the pressure of the water outside. The greatest depth reached by any diver was 204 feet, at which depth there was a pressure of 88¹⁄₂ pounds per square inch on his body. The area exposed of the average diver in armor is 720 inches, which would have made the diver at that depth sustain a pressure of 66,960 pounds, or over 33 tons. The water pressure on a diver is as follows: 20 feet 8¹⁄₂ lbs. 30 feet 12³⁄₄ lbs. 40 feet 17¹⁄₄ lbs. 50 feet 21³⁄₄ lbs. 60 feet 26¹⁄₄ lbs. 70 feet 30¹⁄₂ lbs. 80 feet 34³⁄₄ lbs. 90 feet 39 lbs. 100 feet 43¹⁄₂ lbs. 120 feet 52¹⁄₄ lbs. 130 feet 56¹⁄₂ lbs. 140 feet 60³⁄₄ lbs. 150 feet 65¹⁄₄ lbs. 160 feet 69³⁄₄ lbs. 170 feet 74 lbs. 180 feet 78 lbs. 190 feet 82¹⁄₄ lbs. 204 feet 88¹⁄₂ lbs. The dangers of diving are manifold, and so risky is the calling that there are comparatively few divers in the United States. The cheapest of them command $10.00 a day for four or five hours’ work, and many of them get $50.00 and $60.00 for the same term of labor under water. The greatest danger that besets the diver is the risk he runs every time he dives of rupturing a blood-vessel by the excessively compressed air he is compelled to breathe. He is also subject to attacks from sharks, sword-fish, devil-fish, and other voracious monsters of the ocean’s depths. To defend himself against them, he carries a double-edged knife as sharp as a razor. It is the diver’s sole weapon of defense. Just how far back the art of submarine diving dates is a matter of conjecture, but until the invention of the present armor and helmet, in 1839, work and exploration under water was, at best, imperfect, and could only be pursued in a very limited degree. Feats of Divers. ~THE GREATEST DIVING FEAT~ Millions of dollars’ worth of property has been recovered from the ocean’s depth by divers. One of the greatest achievements in this line was by the famous English diver, Lambert, who recovered vast treasure from the “Alfonso XII,” a Spanish mail steamer belonging to the Lopez Line, which sank off Point Gando, Grand Canary, in 26¹⁄₂ fathoms of water. The salvage party was dispatched by the underwriters in May, 1885, the vessel having £100,000 in specie on board. For nearly six months the operations were persevered in before the divers could reach the treasure-room beneath the three decks. Two divers lost their lives in the vain attempt, the pressure of water being fatal. The diver recovered £90,000 from the wreck, and got £4,500 for doing it. One of the most difficult operations ever performed by a diver was the recovering of the treasure sunk in the steamship “Malabar,” off Galle. On this occasion the large iron plates, half an inch thick, had to be cut away from the mail-room, and then the diver had to work through nine feet of sand. The whole of the specie on board this vessel--upward of $1,500,000--was saved, as much as $80,000 having been gotten out in one day. It is an interesting fact that from time to time expeditions have been fitted out, and companies formed, with the sole intention of searching for buried treasure beneath the sea. Again and again have expeditions left New York or San Francisco in the certainty of recovering tons of bullion sunk off the Brazilian coast, or lying undisturbed in the mud of the Rio de la Plata. [Illustration: The last look just before going down.] [Illustration: Coming up after a successful trip.] At the end of 1885, the large steamer Imbus, belonging to the P. & O. Co., sank off Trincomalee, having on board a very valuable East-India cargo, together with a large amount of specie. This was another case of a fortune found in the sea, for a very large amount of treasure was recovered. Another wreck from which a large sum of gold coin and bullion was recovered by divers, was that of the French ship “L’Orient.” She is stated to have had on board specie to the value of no less than $3,000,000, besides other treasure. A parallel case to “L’Orient” is that of the “Lutine,” a warship of thirty-two guns, wrecked off the coast of Holland. This vessel sailed from the Yarmouth Roads with an immense quantity of treasure for the Texel. In the course of the day it came on to blow a heavy gale; the vessel was lost and went to pieces. Salvage operations by divers, during eighteen months, resulted in the recovery of £400,000 in specie. Humorous scenes do not play much of a part on the ocean’s bottom, and the sublime and awe-inspiring are far more in evidence there than the ludicrous, yet even beneath the waves there are laughable scenes at times. A diver had been engaged to inspect a sunken vessel off the coast of Cuba. Arriving on the scene he discovered a number of native sponge-divers, who descend to considerable depths, diving down from their canoes to the sunken vessel trying to pick up something of value. They paid little attention to the arrival of the wrecking outfit, and did not notice the diver descend, until suddenly what seemed to them to be a horrible human-shaped monster, with an immense head of glistening copper and three big, round, glassy eyes, came walking around the vessel’s bow and made a big salaam to them. That was enough. They shot surfaceward like sky-rockets, climbed frantically into their canoes and hurriedly rowed away. What Happens When Anything Explodes? By explosives are meant substances that can be made to give off a large quantity of gas in an exceedingly short time, and the shorter the time required for the production of the gas the greater will be the violence of the explosion. Many substances that ordinarily have no explosive qualities may be made to act as explosives under certain circumstances. Water, for example, has caused very destructive boiler explosions when a quantity of it has been allowed to enter an empty boiler that had become red hot. Particles of dust in the air have occasioned explosions in saw mills, where the air always contains large quantities of dust. A flame introduced into air that is heavily laden with dust may cause a sudden burning of the particles near it, and from these the fire may be conveyed so rapidly to the others that the heat will cause the air to expand suddenly, and this, together with the formation of gases from the burning, will cause an explosion. It must not be thought, however, that fine sawdust or water would ordinarily be classed as explosives. The term is generally applied only to those substances that may be very easily caused to explode. The oldest, and most widely known, explosive that we possess is gunpowder, the invention of which is generally credited to the Chinese. It is a mixture of potassium nitrate, or saltpeter, with powdered charcoal and sulphur. The proportions in which these substances are mixed vary in different kinds of powder, but they usually do not differ much from the following: Sulphur 10 per cent. Charcoal 16 per cent. Saltpeter 74 per cent. The explosive quality of gunpowder is due to the fact that it will burn with great rapidity without contact with the air, and that in burning it liberates large volumes of gas. When a spark is introduced into it, the carbon, charcoal, and sulphur combine with a portion of the oxygen contained in the saltpeter to form carbonic acid gas and sulphurous acid gas, and at the same time the nitrogen contained in the saltpeter is set free in the gaseous form. This action takes place very suddenly, and the volume of gas set free is so much greater than that of the powder that an explosion follows. In the manufacture of gunpowder all that is absolutely necessary is to mix the three ingredients thoroughly and in the proper proportions. But to fit the powder for use in firing small arms and cannon it is made into grains of various sizes, the small sizes being used for the small arms with short barrels, and the large sizes for cannon. The reason for this is that if the powder is made in very small grains it all burns at once, and the explosion takes place so suddenly that an exceedingly strong gun is required to withstand the explosion, while if larger grains are employed the burning is slower and continues until the projectile has traveled to the muzzle of the gun. In this way the projectile is fired from the gun with as much force as if the explosion had taken place at once, but there is less strain on the gun. What Causes the Smoke When a Gun Goes Off? Powder of this latter kind always produces a considerable quantity of smoke when it is fired, because there is a quantity of fine particles formed from the breaking up of the saltpeter and from some of the charcoal which is not completely burned. This smoke forms a cloud that takes some time to clear away, which is a very objectionable feature. In order to get rid of it, efforts were made to produce a substance that would explode without leaving any solid residue, and that could be used in guns. These efforts were finally successful, and there are now several brands of smokeless powder in use. What is Smokeless Powder Made Of? The most satisfactory forms of smokeless powder are all made from guncotton or nitrocellulose. This substance, which is made by treating cotton with a mixture of nitric and sulphuric acids, is a chemical compound, not a mixture like gunpowder; and when it is exploded it is all converted into gases, of which the chief ones are carbonic acid gas, nitrogen, and water-vapor. To cause the explosion of guncotton it is not necessary to burn it, but a mere shock or jar will cause it to decompose with explosive violence. Of course, such a violent explosive as this could not be used either in small arms or in cannon, but guncotton can be converted into less explosive forms which are suitable for use in guns, and the majority, of smokeless powders are made in this way. The methods used in producing the smokeless powders are kept secret by the various countries that use them. What is Nitroglycerine? Another very powerful explosive, which is closely related to guncotton, is nitroglycerine. This compound is made by treating glycerine with the same sort of acid mixture that is used in making guncotton. It explodes in the same way that guncotton does and yields the same products. It is an oily liquid of yellow color, and on account of its liquid form it is difficult to handle and use. The difficulty in handling nitroglycerine led to the plan of mixing it with a quantity of very fine sand called infusorial earth. When mixed with this a solid mass called dynamite is formed, which is easier to handle and more difficult to explode, but which has almost as much explosive force as nitroglycerine. A more powerful explosive than either nitroglycerine or guncotton is obtained by mixing them together. When this is done the guncotton swells up by absorbing the nitroglycerine and becomes a brownish, jelly-like substance that is known as blasting gelatin. This is generally considered the most powerful explosive obtainable. What Makes Nitroglycerine and Guncotton Explode So Readily? Let us now consider for the moment what it is that makes guncotton, nitroglycerine, and blasting gelatin explode so readily. The explanation is found in the presence in them of nitrogen. As you remember from what you learned about air, nitrogen is an extremely inactive element. It has no strong tendency to combine with other elements, and when it does enter into combination with them the compounds formed are almost always easily decomposed. In the compounds that have just been described a shock causes a loosening of the bonds that hold the nitrogen, and the whole compound goes to pieces just as an arch falls when the keystone is removed. What Is Silver? Since the earliest time recorded in history, silver has been the most used of the precious metals, both in the arts and as a medium of exchange. Even in the prehistoric times silver mines were worked and the metal was employed in the ornamental and useful arts. It was not so early used as money, and when it began to be adopted for this purpose, it was made into bars or rings and sold by weight. The first regular coinage of either gold or silver was in Phrygia, or Lydia, in Asia Minor. Silver was used in the arts by the Athenians, the Phœnicians, the Vikings, the Aztecs, the Peruvians, and in fact by all the civilized and semi-civilized nations of antiquity. It is found in almost every part of the globe, usually in combination with other metals. The mines in South America, Mexico, and the United States are especially rich. Silver is sometimes found in huge nuggets. A mass weighing 800 pounds was found in Peru, and it is claimed that one of 2,700 pounds was extracted in Mexico. The ratio of the value of silver and gold has varied greatly. At the Christian era it was 9 to 1; 500 A.D. it was 18 to 1; but in 1100 A.D. it was only 8 to 1. In 1893 it was as high as 2,577 to 1. The subject has entered largely into American politics as a disturbing element, and in 1896 the Democratic party, in its national convention, declared for the free coinage of the metals at 16 to 1. The Republican party adhered to the gold standard and declared against the free coinage of silver. Each party reaffirmed in 1900 this plank in its platform. In both years the Democrats were defeated. What Is Worry? Worry is a feeling of fear, but is never of the present. It is always about something that may happen or that has happened. It is generally in the future, sometimes in the past, but never in the present. An animal that knows neither future nor past cannot worry. Babies, living only as they do in the present, cannot worry. All creatures, excepting human beings, live only in the present and therefore they do not worry, for such creatures cannot remember what happened in the past or guess what is going to happen. A human being after arriving at a certain age is given such powers that his mind can go back to the past and cast itself forward into the future as he thinks it will be, because he has imagination. As a matter of fact we live less in the present than in the past or future. Why Do We Worry? We worry because we are able through a power called self-consciousness to place ourselves through our minds for the time being. Either--back somewhere in the past without carrying our physical bodies with us; for if we could take our bodies with us, we would be in the present again, and then worry is impossible; or, we use our imagination and project the future entirely apart from our bodies, for we cannot project our bodies into the future, and if we could we would again be in the present. We worry over going to have an operation performed which may or not be dangerous, but quite necessary. We may still think we worry when the operation begins, but as soon as that occurs the time becomes the present, and though we may fear, we cannot worry in the present. [Illustration: _Back View of Shield_ _Longitudinal Section through Shield & Tunnel_ _Diagram showing method of tunnel construction by shield and compressed air._ _Scale; ¹⁄₈ inch · 1 foot_ _Jacobs & Davies Inc. 30 Church St. N.Y._ _Oct. 15. 1910._ FIGURE 1.] The Story in a Tunnel How a Tunnel Is Dug Under Water. Fig. 1. On the left is a cross section showing, in diagram, the back view of a shield. The heavy black circle is the “tail” or “skin.” The small circles within the tail are the hydraulic rams which at a pressure of 5,000 pounds to the square inch force the shield forward. The square compartments within the shield are the openings through which the men pass to dig away the ground. In the middle of the shield is shown the swinging “erector” which picks up the iron lining plates and puts them in position. The view on the right is a longitudinal section of the tunnel showing the shield and the bulkhead wall across the tunnel with the air locks built into it. The front of the shield ahead of the doors is made with a sharp edge called the “cutting edge” and this makes it easier for the shield to advance in case all the ground in front has not been removed. This view shows how the tail overlaps the last portion of the iron lining. Some distance behind the shield comes the concrete bulkhead wall with the air locks contained in it. There are two shown in the view. The upper one is the emergency air lock, always kept ready so that in case of an accident the men have a means of escape even though the lower part of the tunnel is filled with rushing water or mud. The lower air lock is for the passage of men and materials during ordinary working. This view also shows that all the tunnel ahead of the bulkhead wall is under compressed air while the finished tunnel behind the bulkhead wall is under the ordinary or normal air pressure. When the tunnel is finished the air locks and bulkhead walls are removed. [Illustration: FRONT VIEW OF A DRIVING SHIELD This shows the front of one of the shields used on the Pennsylvania Railroad tunnels crossing the North River at New York. The cutting edge is clearly seen and the various compartments, each with its door, which divide up the front of the shield. These shields weighed about 200 tons each.] HOW TUNNELS ARE BUILT. These notes describe very generally the way in which tunnels are built through mud and gravel under parts of the sea or large rivers in such a way that the men who build them are protected and as safe as the carpenter who is building a house. The way these tunnels are built is called the “shield” way because the machine used is called a shield. It is given this name because it shields the tunnel builders from the water and the mud which are ready at every moment to overwhelm them and kill them. The shield was invented in 1818 by a great Engineer, Marc Isambard Brunel, who was a Frenchman living in England. The idea of the shield came to him as he saw how the sea worm which attacks the wooden piles of docks along the shore bores the holes it makes in the wood. The head of this worm is very hard and can bite its way through the hardest woods. As it goes through the wood its body makes a hard shelly coating which lines the holes which its head has made and prevents the hole from getting filled up. This is the general idea of a tunnel built by a shield. The first shield was used by Mr. Brunel to make a tunnel across the Thames River at London, England. This is still the biggest tunnel ever built by a shield, although not the longest, and is still used by railroad trains. This tunnel was begun in 1825 and was finished in 1843, and provides a history of almost unexampled and not-to-be-excelled courage in attacking difficulties and skill in defeating them. Since the days of Brunel many great improvements have been made in the shield and in the way of working it but the same idea is still there. [Illustration: HOW THE SHIELD IS PUSHED FORWARD This shows the rear end or tail end of one of the smaller shields, used on the Hudson and Manhattan Railroad tunnels under the North or Hudson River at New York. It shows the skin, the hydraulic jacks within the skin and the piping and valves for working them. It also shows the doors leading to the front or “face.” The erector is not shown, but the circular hole in the middle shows where it would be attached.] [Illustration: This shows one side of an air lock bulkhead wall with the air lock in place. The boiler-like appearance of the lock is clearly visible, as well as the door and the pressure gauge to tell the air pressure inside the lock.] [Illustration: This is a rear view of one of the Pennsylvania Tunnel shields, taken after a length of tunnel had been completed. All the details of construction are shown, but in this case the erector is clearly seen also. The valves which control the erector and the rams which push the shield forward are seen near the top of the shield. The rods across the tunnel are turn-buckles used to keep the iron lining from getting out of shape in the soft mud. These are removed later. The floor and tracks in the bottom are temporary and are used for bringing materials to and from the shield.] After the days of Brunel’s shield another great help was given to tunnel builders by the invention of the use of compressed air to hold back the water which saturates the ground in which the tunnel is being built. ~WHO INVENTED THE COMPRESSED AIR METHOD~ The first real invention of compressed air for this purpose was made by Admiral Sir Thomas Cochrane who, in 1830, took out a patent for the use of compressed air to expel the water from the ground in shafts and tunnels and, by this means, to convert the ground from a condition of quicksand to one of firmness. This patent covers all the essential features of compressed air working. As suggested above, the thing which compressed air does in a tunnel is to push the water out from all the spaces which it fills in the ground, so that the men who are digging away the ground for the tunnel are working in firm dry ground instead of a mixture of earth and water which will run into and fill the hole they dig as soon as it is dug. Whenever a tunnel is being built below a body of water through ground which is porous, or in other words through any ground except solid rock or dense clay, the water fills every crevice and space in the ground and is exerting a pressure of about half a pound per square inch above the ordinary pressure of the air, (which is 15 pounds to the square inch) for every foot of depth below the surface of the water; so that supposing the tunnel is 40 feet below the water the water has a pressure of nearly 20 pounds per square inch on every square inch of the surface of the tunnel. This pressure causes the water to flow violently into any hole or opening that is made in the ground, and, unless the water is prevented from moving by some means or other, the opening made would be very quickly filled with water and also with ground as the rush of water will carry the sand, gravel or mud with it. By Cochrane’s invention the whole tunnel is filled with air under a pressure equal to the pressure of the water. This compressed air therefore balances the pressure of the water and holds it back from moving, and if the pressure of the air is made slightly greater than that of the water the water is driven back from the tunnels for a short distance so that when the tunnel is being dug the ground instead of being wet is quite dry. This explains the principles of the shield and compressed air way of making a tunnel. The following describes very shortly how these principles are put to actual use. Most tunnels which are built by shield and compressed air under rivers or arms of the sea are lined with cast iron plates to protect the railway or roadway which is in the tunnel. The tunnel is a circular tube, or shell, and the plates have flanges on all sides which are bolted together. This shell is put into place, plate by plate, by means of the shield which not only protects the workmen and the work under construction, but which helps to build the iron shell. In fact it corresponds to the sea worm which bores through the wood and lines the hole with a shell. In the case of the tunnel the shell is made of iron. The shield itself consists of a steel tube or cylinder slightly bigger in diameter than the tube or tunnel it is intended to build. The front edge of this shield is made up of a ring of sharp edged castings which form what is called the “cutting edge.” Just behind the cutting edge is a bulkhead or wall of steel, in which are openings which may be opened or closed at will. Behind this bulkhead are placed a number of hydraulic jacks or presses arranged around the shield and within it, so that by thrusting against the last erected ring of iron lining the whole shield is pushed forward. The rear end of the shield is a continuation of the cylinder which forms the front end, and this part, called the “tail,” always overlaps the last few feet of the built up iron shell. [Illustration: This is a photograph of a model of the Pennsylvania Tunnels to New York City, made for the Jamestown Tercentenary Exposition of 1907. It is given because it illustrates, as no photograph of actual work could do, the relationship between the shield, the tunnel itself and the air lock. This view shows the rear part of the shield on the extreme left, with the erector picking up an iron plate. It shows a man bringing a car with two of the iron plates up to the shield. Behind this man comes the bulkhead wall with the emergency air lock in the top and the ordinary air lock for passing in and out at the bottom. It also shows the upper platform to the emergency lock along which the men can get to the emergency lock in case of an accident.] [Illustration: This is another view of the same model, but showing the front view of the shield. The doors on the air locks are clearly shown.] [Illustration: This is a photograph taken in one of the Pennsylvania tunnels under the Hudson River. It shows the soft mud, through which the tunnel is being built, flowing in a thick stream through one of the doors of the shield. The mud under the Hudson, where these tunnels are, is so soft that often the shield was pushed through the mud with all the doors shut, so that no mud came into the tunnel and no digging had to be done, but the shield pushed its way bodily through the mud, the rings of iron lining being built up behind as usual. Generally, however, a certain amount of mud was brought in and had to be removed. This photograph shows how it looked.] ~HOW THE SHIELD CUTS THROUGH THE GROUND~ The diagram, Fig. 1, shows more clearly what is meant. From an inspection of Figure 1 it is clear that, when the openings in the shield bulkhead are closed, the tunnel is protected from an inrush of either water or earth; the openings in the bulkhead may be so regulated that control is maintained over the material passed through. After a ring of iron lining has been erected within the tail of the shield, the shield doors are opened and men go through them and dig out enough earth for the shield to go ahead. The rams are then thrust out thus pushing the shield ahead. Another ring of iron is built up within the tail for which purpose an hydraulic swinging arm, called the “erector,” is mounted on the shield face. This erector picks up the plates and puts them into position, one by one, while the men bolt them together. Excavation is then carried on again and the whole round of work repeated, gaining every time the jacks are rammed or thrust out a length equal to the length of one ring of iron lining. In carrying out this work in ground charged with water the shield is assisted by introducing compressed air as described before. To use the compressed air thick bulkhead walls of masonry are built across the tunnel behind the shield and into the space between the shield and the bulkhead wall air is pumped, compressed to the same pressure as that of the water in the ground, or in other words the pressure of the air in pounds per square inch is about half the number of feet the tunnel is below the water surface. This dries the ground and simplifies enormously the difficulty of working in it. The diagram, (Fig. 1) shows a bulkhead wall across the tunnel. In order to pass from the ordinary air outside the bulkhead into the compressed air inside it, all the men and the materials have to pass through the “air locks” which are built into the wall. They are called air locks because they are like the locks on a canal which raise the water from a lower to a higher level or lower it from a higher to a lower level as the case may be. The difference is that an air lock enables one to pass from air at a low pressure to one of a higher, or vice versa. An air lock is made like a large boiler with a door at each end. If we wish to enter the compressed air we enter the lock from the outside. The door at the end has been tightly closed to prevent the compressed air from rushing out. We close the door behind us and are now tightly shut in the boiler-like lock. We now open a valve and compressed air begins to flow quickly into the air lock and the air gets hotter and hotter, due to the compression of the air. Very likely an intense pain begins to make itself felt in the ears but by swallowing hard and blowing the nose it may be relieved. It is caused by the air pressure being greater on the outside of the ear drum than on the inside. If the delicate ear passages are choked, because of a cold or some such reason, it is unsafe to go further or the ear drum may burst. When the pressure in the air lock has reached that in the working chamber, the door leading to the shield may be opened and we can pass to the working space and note the work going on. There is no especial bodily sensation to be felt except a slight exhilaration and it is curious to find that one cannot whistle. On leaving the compressed air we enter the air lock by the door we left; a valve is turned and the air begins to escape and the pressure in the air lock begins to go down. As it does so the air becomes colder and colder and the whole lock is filled with a wet fog due to the chilling by expansion of the air. The air has to be allowed to escape very slowly, as bubbles of air and gas otherwise form in the blood vessels and tissues of the body giving rise to the very painful complaint known to tunnel builders as “the bends,” and in very serious cases to paralysis and even death. The higher the air pressure the more slowly must one come out into the ordinary air. [Illustration: MAKING THE JOINTS WATER TIGHT This shows the erector building up the iron lining in one of the Pennsylvania tunnels at New York. It shows clearly how the iron plates are bolted together to make the rings of iron lining.] [Illustration: The last, or closing, plate of each iron ring is called the “key,” and is much shorter than the others. This photograph shows the shield erector on one of the Pennsylvania tunnels picking up and putting into place a key plate. This picture gives an idea of the mud and dirt and wet in which the men who work in tunnels have to do their work.] [Illustration: Wherever possible, every space and crevice outside the iron lining is filled with cement forced, in a liquid state, through the iron lining by compressed air. This photograph shows the operation of “grouting,” as it is called. The man at the left is in control of the grouting. He has the hose, through which the grout is forced, screwed to a pipe which passes through a hole made for the purpose in the iron lining plates and called a “grout hole.” The two men in the middle of the picture are attending to the “grouting machine” by which the work is done. Water and cement are fed into the small boiler-like tank, the tank closed and compressed air admitted thus blowing the liquid cement through the hose and behind the iron lining. When no more grout can be forced behind the iron lining all the space has been filled. The man on the right is the engineers’ inspector taking note of how much grouting is done, and seeing that the work is properly carried out.] [Illustration: This shows the process by which the iron lining is made perfectly water-tight, so that, when the compressed air is taken off, no water at all can get into the tunnel. Two operations are shown here. One is called “grommetting the bolts,” the other is called “caulking the joints.” The two men on the left, hanging on to the wrench, are tightening up the bolts as tight as they can after having put on, underneath the washers at the head and nut of each bolt, a ring of spun yarn dipped in red lead and oil or tar or some such water-proof material. A few of these “grommets” may be seen at the feet of the third man from the left. The other four men are caulking the joints between the iron plates by driving into the joints a mixture of sal ammoniac and iron borings. This sets as hard as iron and if properly done makes a perfectly water-tight joint.] [Illustration: THE REMARKABLE ACCURACY OF ENGINEERING Usually when crossing, with a tunnel, a wide river or estuary the tunnel is started from each shore and the shields are pushed through the ground until they meet somewhere about the middle of the river. This shows two of the Pennsylvania tunnel shields which have met far below the Hudson River. The white arrow shows where each shield ends. The platform of one shield on which the man stands corresponds exactly with the platform of the other shield. As may be imagined, it takes very careful and skillful engineering and surveying work, both before the work is begun and while it is being carried out, to enable tunnel shields to meet like this. This part of the art of tunnelling would take an article to itself.] When the shield has been pushed across the entire length of the water way which has to be tunnelled, and the whole of the iron tube or shell is in place, a thick lining of concrete is placed inside the iron shell to protect it and make the tunnel stronger. As an added safeguard wherever the tunnel is in rock, gravel, strong clay or other ground which is not so soft that it does not close tightly in on the outside of the tube, liquid cement is forced by compressed air through holes made in the iron plates for this purpose. This liquid cement enters every pore or crevice in the surrounding ground and when it has set hard it still further protects the iron with a coating of cement. Pieces have been cut out of the iron lining of a tunnel built under the river Thames at London, England, in 1869, which showed that the iron at all places was as good as the day it was first put in forty years before, and iron put in the lining of the Hudson River Tunnel about 1878 when removed after thirty years was in perfect condition. [Illustration: SHIELD AT END OF JOURNEY Sometimes, however, shields are not driven to meet one another, but end their journey at some shaft or in some other tunnel previously built, after having gone through thousands of feet of all kinds of ground, from the hardest rock, which had to be blasted out foot by foot before the shield could advance, through hard pan, gravel, boulders, piles, rip-rap, made ground and mud so soft that it flows like melted butter. Naturally, after an experience like this a shield does not look as spick and span as when it started in life. This photograph shows one of the shields of the Hudson and Manhattan Railroad in New York just reaching the end of its journey, battered and bent but still in the ring.] [Illustration: This shows a piece of curved tunnel near Morton Street, on the Hudson and Manhattan Railroad, and is given because of the clear showing it gives of the iron lining. The track and floor are only the temporary roads for use during construction.] [Illustration: Sometimes it is necessary to make borings of the ground below the tunnels. In some of these bore holes vast quantities of water are found at a much higher pressure than the tunnel compressed air. This picture shows a spouting bore hole in one of the Pennsylvania tunnels during construction.] [Illustration: The last thing to do before laying the track is to put the concrete inside the iron lining. This picture shows this work going on and the wooden forms or ribs for holding up the concrete while it is setting.] [Illustration: THE LAND END OF A GREAT TUNNEL UNDER THE HUDSON This view is given to show how complicated an underground structure may have to be made to take care of the requirements of traffic. This view shows the three great reinforced concrete caissons sunk through the earth at Jersey City in order to contain the switches and crossings required to form the New Jersey connections of the uptown and downtown tunnels of the Hudson and Manhattan Railroad. These caissons were sunk under air pressure by excavating below them just as though they were tunnels turned up on end. In sinking these caissons the material passed through was water-logged made ground, and the hulls of two sunken canal boats were encountered and had to be cut into pieces small enough to be taken out through the locks. The usual passenger rushing at high speed in the trains between Jersey City and Newark and New York has little idea of the very complicated structure necessary to allow of his doing so. The information in this article was supplied by Jacobs & Davies, Inc., Consulting Engineers, 30 Church Street, New York, the Engineers for the Pennsylvania Railroad, Hudson River Tunnels, the Hudson and Manhattan Railroad, and many other tunnels in various parts of the world. The illustrations were kindly supplied by the Pennsylvania Railroad and the Hudson and Manhattan Railroad.] ~DANGERS OF TUNNEL BUILDING~ This account of tunnelling by shield and compressed air is very short and gives no more than a bare statement of the principles and chief methods of such work. Nothing has been said of the engineering difficulties involved in the design of such work, nor of the delicate surveying work necessary if one should hope to start two shields a mile or two apart and have them meet as shown in Fig. 13 like two great glass tumblers placed rim to rim after having travelled through thousands of feet of every kind of ground. Nothing has been said of the men who work on this most arduous form of subterranean navigation, how they cheerfully face the dark and the water ever threatening above them and the unseen but not less deadly ally, and yet foe, the compressed air, with its dreaded result, the bends, or the men on the surface who keep the air compressors running without pause or stop day in and day out until the work is done so that their comrades below may work in safety. Nothing has been said of the curious accidents that are liable to occur as when the air pressure in the tunnel gets too high, overbalances the water pressure and blows a hole through the river-bed and forms a geyser in the river above. It gives no account of the special difficulties which arise when special conditions are found; for example, when the lower part of the tunnel is in rock and the upper part is in soft material. In fact it is nothing more than a bare outline but it hoped that some, who may not be clear in their minds as to how tunnels are built, may learn some of the first principles of this most romantic kind of work from this bald narrative. Why Do My Teeth Chatter? Your teeth chatter because when you are cold in a way that makes your teeth chatter the little muscles which close the jaw act in a series of quick little contractions which pull the jaw up, and then let it fall by its own weight. This is repeated many times and, as the action is quick, the chattering occurs. It is a peculiar thing that this occurs in spite of the will or brain, when, as a matter of fact, these muscles which operate the jaws are especially under the control of the brain. The chattering is really a spasm caused by the cold, and all spasms act independent of the will. Cold seems to act on the jaw muscles a good deal like some poisons which cause spasms. Where Did All the Water in the Oceans Come From? No, it did not come from the rivers which empty themselves into the oceans, because the oceans were there before the rivers existed. Part of it comes from the rivers now, but only a little in comparison to all the water there is in the ocean. I will try to tell you simply how all the water got into the ocean. There was a time when there was no water on the earth at all. That was when the earth was red hot, just as it is to-day on the inside, and at that time all the water we have to-day was up in the air in the form of gases. Strange as it may seem to you, if you take two gases, one called hydrogen and the other oxygen, and mix them the right way, they will turn into water, and if you had the right kind of chemical apparatus you could take water and turn it into these gases again. When, then, the earth was still all red hot, all of our water was up in the air in the form of these two gases. Then, later on, when the amount of heat on the earth was just right to make these gases mix together, the water came down out of the air in great quantities, and there was so much of it that it completely covered the whole earth and no land was visible. Later on, for various reasons, mountains were thrown up on the earth’s surface by great earthquakes, and every time a mountain or a high place was formed there had to be a hole or low place some place else, and the water ran into these low places and stayed there, and that uncovered more of the land, because there wasn’t enough water to fill all the holes and cover the land too, and that is what makes our continents and islands and all of the land we see. There is now about three times as much earth covered with water as there is land. Of course, the sun is always picking up water through what is called evaporation, which means that it is taken into the air in the form of gases. Later it comes down again in the form of rain and falls into the oceans or on the land, where it sinks in, finally finding a stream or river, and sooner or later gets back into the ocean again. Why Don’t the Water in the Ocean Sink In? This is due to the fact that there is a kind of substance at the bottom of the ocean which the water cannot penetrate, in spite of the tremendous pressure which the great body of deep water exerts. In all places where the bottom of the ocean has a covering which water can sink into it does so, but there are such a few places where this is possible, by comparison, that the amount that gets out that way is not noticeable. This water, if it can keep on going, will eventually reach the inside of the earth, where it is red hot, and is turned into steam. Where Does the Water in the Ocean Go at Low Tide? To get to the answer of this you must know something about the tides. The tide is caused by the pull of the moon on the waters in the ocean. The moon revolves about the earth once each day and has the ability to draw up the waters in the ocean toward it, as we have seen in our study of the tides. Now, when it is high tide in one place it is low tide in another. The moon does not make more water, but only pulls it toward it from side to side. When it is low tide where we are the water has simply moved as a body toward the place where it is high tide. The tides act a good deal like a see-saw, except that they move from side to side instead of up and down. When one end of the see-saw goes up the other end goes down, and when the “down” end comes up the other end goes down. So the answer to your question really is that at low tide the water which made it high tide a few hours before has gone to some place where it is at that moment high tide. Why Does the Ocean Look Blue at Times and at Other Times Green? Sometimes when we look at the ocean from the pavilion or while on the sand of our favorite bathing beach the water in the ocean looks very beautifully blue, and on other days will look dark green from the same point. Why is it? If you will stop to think that at night when there is no moon or other light the water in the ocean looks black, I think you will soon be on the right track to answer the question yourself. When the sky is blue--the kind of blue we like to see in the sky when we are at the beach--the water in the ocean is blue, because the sea reflects the color of the sky, and when the sky is overcast and gray the color reflected by the sea will be gray also. But, say you, sometimes the water in the ocean is dark green, and yet the sky is never green. Quite true, and I will try to tell you what produces the green color. This happens sometimes where the water is shallow, either near the shore or out further where there is a sandbar or other shallow place. Sometimes at such points the sunlight strikes the water at such an angle that the rays go clear to the bottom and are reflected from that point--the bottom--to our eyes. In such a case the light will be changed through a combination of the color of the bottom at that point and the color of the sky itself at the time to make the color green as it is reflected to our eyes from the bottom. Why Does Water Run? Water runs because it has not enough of anything in it to make it stick together. In school language we call this sticking-together-thing “cohesion.” The principle of cohesion makes all the difference there is, so to speak, between solids, liquids and gases. A brick, a stone, a stick of wood, or a piece of iron and all other solid substances have a certain amount of this property of cohesion, and the particles stick together, enabling us to build buildings and other things which become permanent structures. These solid substances are either naturally cohesive or else man, as in the case of the brick, has brought together certain things with little or no cohesion and made them stick together permanently. In the case of the brick, he takes a quantity of clay, which is cohesive only to a certain degree, bakes it in an oven and it becomes hard enough--more cohesive--so that he can pile one on top of the other and make a building. Then he puts sand, mixed with other things--lime and water--between the bricks to hold the bricks together, and makes a structure that will last. Two bricks have no natural cohesion for each other and, therefore, they can only be held together by something that has cohesion within itself and also for the bricks. The lime, sand and water make mortar which is cohesive when properly mixed, while in themselves neither lime nor sand have much cohesive property, and water has none at all. Liquids have little or no cohesion. Water has none, or very little. Syrup has a good deal more, but will run over the edge of a piece of bread and butter if you are not careful. Gases have no cohesive properties at all and, therefore, fly all over the place, through any opening they can find, either at the top of the room or under the crack of the door. They are always trying to get to some place else and will keep moving as long as not confined. Gases can move in any direction. Liquids, however, while they are inclined to be constantly on the move, can only go in one direction--down hill, and they go down fast or slow if there is a chance, in proportion to the amount of stick-together properties they have. Liquids can never go up of their own accord, excepting in the process of evaporation, and then only when changed into gases. A lake of water will dry up completely by evaporation unless fed by streams of water constantly flowing in, because evaporation is constantly taking place wherever water is exposed to the air. What Makes the Water Boil? What we call boiling in the water we see when water is put over a hot fire long enough to make it boil, is the changing of the water from what we generally regard it--a liquid--into gases. Water consists of two gases--hydrogen and oxygen--in fact, two parts of hydrogen gas and one part of oxygen gas when mixed will always make pure water. Now, then, if liquid water is heated to a certain point or temperature it turns into the two gases, oxygen and hydrogen, and comes to the top of the water, which still remains in liquid form, in the form of a bubble and explodes into the air--not a very loud explosion, but still an explosion. The process of turning liquid water into gases is a gradual one, and that is why the water does not all turn into one large bubble at once and explode away. If you keep the fire going long enough, all the water in the vessel will explode away into the air, a few bubbles at a time. If you hold a cold plate over the vessel as the bubble explodes you can catch some of these gases in the form of bubbles on the under side of the plate, which are again liquid water. When the water becomes hot enough it turns into bubbles and as bubbles rise that is what makes the boiling you see. When the same gases then come together again in a certain proportion under proper temperature they turn into liquid water. At What Point of Heat Does Water Boil? The boiling point of water is the temperature at which it begins to pass into the form of gases. This varies in different altitudes. At the sea level the boiling point is at 212° Fahrenheit. On the top of mountains, for instance, water would boil at a much lower temperature. It would be possible to go high enough in a balloon so that the water would fly from the pan in the form of gas without making the water hot. Also, a mile below the level of the sea it would take many more degrees of heat to make the water boil. It is said that high up in a balloon you could not boil an egg hard in a pan of boiling water if you kept it in the boiling water for an hour or more, whereas we know that an egg will be hard-boiled if we keep it in boiling water down where we live for more than five minutes. The degree of heat at which water passes away into the form of gases is regulated by the pressure of the air on the water and other things about us. At the average level in the United States where people live the pressure of the air on everything is fifteen pounds to the square inch, and at this pressure water boils only after it reaches a temperature of 212° Fahrenheit. As we go up the mountains the pressure becomes less and less as we go up. At the top of Mount Blanc, which is 15,781 feet high, water boils at 185° Fahrenheit. If we took a balloon from the top of the mountain we would come to a height where there was no air pressure at all. What Do We Mean by Fahrenheit? The name Fahrenheit is used to distinguish the kind of scale most commonly used on thermometers in Great Britain and the United States. Gabriel Daniel Fahrenheit, a native of Dantzic, made the first thermometer on which this scale was used, and it is named after him. In this scale for thermometers the space between the freezing point and the boiling point is divided into 180 degrees--the point for freezing being marked 32 degrees and the boiling point 212 degrees. Why Can’t We Swim as Easily in Fresh Water as in Salt Water? Our bodies are heavier than fresh water, i. e., a bulk of fresh water equal to the size of our body would weigh less than our body, so that the first tendency is to sink to the bottom if we find ourselves in fresh water. If man had not learned to swim that is what he would always do, sink to the bottom; but having learned how to keep from sinking, he is able to swim in fresh water. However, we find that an amount of salt water equal to the bulk of a man in size is heavier than an equal amount of fresh water, although such a bulk of ordinary salt sea water will still weigh less than the man. A man will sink in salt water also if he has not learned to swim or float, but he can keep up with less effort in salt water, and also swim in it more easily. In a nutshell, then, the answer to this question is that salt water is heavier than fresh water. You can make salt water so full of salt that it becomes heavier than a man. Great Salt Lake in Utah is so salty that one cannot sink in it for this reason. You could drown yourself in it, of course, by keeping your head under water, but whether in shallow water or deep water you would not sink in Great Salt Lake. Why Do We Say Some Water Is Hard and Other Water Soft? What we call hard water contains certain salts which soft water does not contain. This salt in hard water is lime or some other salts which the water has picked up out of the ground as it passed through either coming up or going down. On the other hand, we can guess after having been told this much that if we can find any water that has not passed through the ground, and, therefore, not had a chance to pick up any salts, we will have soft water. From that point it is easy to guess, then, that rain water must be soft water, and so it is. The water in the cisterns, which is rain water, is soft water, and the kind we get out of the wells is hard water. We do not like to wash either our faces or our clothes in hard water, especially when it is necessary to use soap, because when we use soap with hard water the soap undergoes chemical change which prevents its dissolving in the water. Therefore, you cannot easily do a good job of washing in hard water. On the other hand it is easy to dissolve the soap in pure rain water or soft water and that is the kind we, therefore, prefer for washing. How Does Water Put a Fire Out? This is at first a puzzling question, because back in your mind is the thought that since hydrogen and oxygen are necessary to make a fire burn, it seems strange that water, which is composed of oxygen and hydrogen, will also put it out. A burning fire throws off heat, but if too much of the heat is taken from the fire suddenly the temperature of the fire is sent down so far below the point at which the oxygen of the air will combine with it that the fire cannot burn. We speak commonly as though water thrown on a fire drowns it. That is practically what happens. Scientifically what happens is that the water thrown upon the fire absorbs so much of the heat to itself that the temperature of the fire is reduced below the point where oxygen will combine with the carbon in the burning material and the fire goes out. To answer the unasked part of your question at the same time I will say that hydrogen and oxygen when combined as water will put the fire out rather than make it burn, more because when these gases take the form of water they are already once burned, and you know that anything, substance or gas, which has already been burned cannot be burned again. It required great heat to make oxygen and hydrogen combine and form water, and it also takes great heat to separate them again. So they are really burned once before they become water. Where Does the Rain Go? Eventually almost all of the rain that falls runs into the rivers and lakes and later finds its way into the ocean, where it is again taken up into the air by the sun’s rays. But many other things happen to parts of the rain which do not find their way into the ocean. In the paved street, of course, where the water cannot sink in, it flows into the gutter and thence into the sewer and on down to the river or wherever it is that the sewers are emptied. You see, it depends very much on what the earth’s surface is covered with at the place where the rain falls. When it strikes where there is vegetation a great deal of it stays in the soil at a depth of comparatively few feet. If it is soil where trees and other plants grow a great deal of it is sucked up from the ground by this vegetation and given back into the air through the leaves and flowers. Some of the rain keeps sinking on down into the earth until it strikes some substance like rock or clay, through which it cannot sink, and then it follows along this until it finds something it can get through and collects in a pool and forms an underground lake, and may cause a spring to flow. Then there are also worms and other forms of animal life in the earth which use up some of the water. But it all gets back into the air eventually to come down some time again in the form of rain. Why Does Rain Make the Air Fresh? The main answer to this question must be that the rain in coming down through the air drives the dust and other impurities which are in the air before it, and so cleans the air and makes it absolutely clean. In addition to this it is now stated that since very often rain is produced by electrical changes in the air, and that these electrical changes produce a gas called ozone, which has a delightfully fresh smell, it is this ozone that makes us say the air has become fresh. The air above our cities is almost constantly filled with smoke, containing various poisonous gases, and these are driven away by the falling rain. Then, too, there is always a greater or less accumulation of dirt, garbage and other things in the cities which give off offensive smells constantly, but which we do not notice always because we become used to them. When the rain comes down it washes the streets and destroys these smells, and that makes the air fresh and delightful to take into the lungs. In the country the air is more nearly pure all the time, because the things which spoil the air in the city are not present. Is a Train Harder to Stop Than to Start? The answer is yes. It is harder to stop a train than to start it, or rather it takes more power. The speed of a train depends upon the motive power. When a train is stopped and you wish to start it, you must apply enough motive power to start it going. There must be enough power to move the weight of the train and overcome the friction of the wheels on the track. It is, of course, easier to move a thing that weighs less than a heavier one. If you throw a ball ten feet into the air, it will perhaps not sting your hand when you catch it on its return; but, if you throw it one hundred feet into the air, it will sting your hands when you catch it. Besides, it will come down faster the last ten feet of the way than the ball which you threw only ten feet into the air. This is because when movement is applied to anything you add power to it. The ball which comes down from one hundred feet in the air acquires more power in falling and it takes more power to stop it. A train in motion has not only the power of the weight of the train behind it, but also the additional weight which the movement of the train has given it. Therefore, it takes more power to stop it than to start it. To stop a train you must apply the same amount of power as is in the moving train because the power to stop any moving thing must always be at least as great as the power which is moving it. What Makes the Knots In Boards? We find knots in the boards which we notice in a lumber pile or in any other place where boards happen to be, because the smaller limbs which grow away from the larger limbs of trees grow from the inside as well as the outside of the tree. When you see a knot in a board it means that before the tree was cut down and the log sawed up into boards, a limb was growing out from the inside of the tree at the spot where the knot occurs. You will also find that the wood in the knot is harder generally than the rest of the board. This is because more strength is required at the base of a limb and in the part of the limb which grew inside the tree than in other parts, for the limb must be strong enough to support not only the limb itself, but also the smaller limbs which grow out of it. How Many Stars Are There? Man may never know how many stars there are. The best we can do is to figure on the number that can be seen with the largest telescopes which have been invented, for, of course, you know there must be many millions of them which to us are invisible. We have counted the stars so far as we can see them; or, rather, so far as we can photograph them. Astronomers have found that a photographic plate exposed to the stars will show more of them than can be seen by the naked eye. This is because the materials on a photographic plate are more sensitive to the light of the stars than the human eye. By this method man has been able in a way to count the stars he can see. It adds up to more than a hundred million of them. Astronomers found this out by taking photographs of the heavens at night, devoting one picture to each section, until the entire heavens had been covered, and then counting them. [Illustration: WHERE PAINT COMES FROM MAKING LEAD BUCKLES--THE FIRST STEP IN PAINT MAKING.] The Story in a Can of Paint Paint such as is most frequently used is the material used for painting buildings, such as houses, barns, stores, and many others which we need not mention here. This paint is used on these buildings mostly for two very important reasons--one being to beautify the buildings, the other being to protect them from the ravages of the weather, much in the same way that your clothes protect you from the weather. Paint such as we mention here may be regarded as the most simple and useful form. You have no doubt frequently seen the painter-man spreading paint on some building, or perchance, you have seen your father doing it, and have noticed that paint is a fluid substance looking something like cream, which is applied to the surface to be painted with a suitable brush and is brushed out smoothly. After the first coat is dry, other coats are put on in the same way until enough paint has been put on to thoroughly hide the unevenness of the lumber and making it of a uniform color. This paint is made by simply mixing together dry powder, which is usually called pigment, with a thin, yellowish liquid which is called linseed oil. In the earlier days, the painter-man mixed this paint himself whenever he desired to use it. In these more modern times, he usually buys this paint already prepared. Perhaps a little history of the preparation of the package of a can of paint which he buys may be interesting to you. Let us imagine that the can of paint is white. In this case, the pigment which is used is a white powder and is made of either metallic lead or metallic zinc. The preparation of this fine white powder is very interesting and requires considerable time to perfect. Let us consider the pigment known as white lead first. This is produced by causing metallic lead, which is of a bluish-gray color and very heavy, to change from its original form by a process which is known as “corrosion.” This corrosion is brought about by first taking the metallic lead, which at this stage exists in large pieces known as “pigs.” These pigs of lead are melted in a furnace and then molded into small, thin shapes which are buckles. [Illustration: HOW WHITE LEAD IS MADE FILLING THE STACK WITH LEAD BUCKLES.] [Illustration: LEAD BEING TAKEN OUT OF THE STACKS. The next step is to take an earthenware vessel, which resembles an ordinary stone crock, and first pour into it a small quantity of acetic acid, which is about the same as table vinegar. Then the crock or pot is filled up with the lead buckles. Where this white lead is made in a large way many thousands of these pots are placed in a building, the sides of which are walled up tight, the spaces between the crocks being filled in with tan bark. After the floor has been covered with a layer of these crocks, the layer is covered with boards, in order to provide a foundation for setting in the next layer of crocks and tan bark. The layer of boards also serves as a floor to keep the tan bark from falling into the open crocks on the tier below. This procedure is followed with tier after tier until the building is completely filled. Corrosion of the metallic lead in the pots now begins, because the tan bark generates some heat, becoming finally quite warm. This heat causes the acetic acid or vinegar to throw off vapor or steam, which attacks the metallic lead, causing it to decompose or corrode. This process goes on for many weeks (sometimes as much as fifteen or sixteen weeks), until those buckles of metallic lead have become a mass of white powder and nearly all trace of the original metallic lead has disappeared.] [Illustration: A LEAD BUCKLE AFTER CORROSION.] [Illustration: A LEAD BUCKLE BEFORE CORROSION.] [Illustration: HOW OXIDE OF ZINC IS OBTAINED WASHING THE LEAD. SCREENS COVERED WITH CLOTH REMOVE ALL FOREIGN MATTER. After these many weeks have passed, the pots containing the white powder of carbonate of lead, as it is called, is taken out of the building where corrosion took place, and the white deposit is put through an elaborate system of refining, which is called “washing,” and, in fact, is really washed in water, and is then dried in very large copper pans. After being dried it is in the form of large white cakes, resembling pieces of chalk. These cakes are then passed through a mill, which grinds them to very fine powder, which is packed in barrels ready to be shipped and used by the paint-maker.] [Illustration: FURNACE WHERE THE SULPHUR IS ROASTED OUT OF THE ORE. Now that we have followed through the process of making the white-lead powder, or pigment, let us take a little time to study the preparation of the other white powder, known to the paint trade as “oxide of zinc.” This is prepared in a manner quite different from that of the white lead. First the ore which is mined from the earth containing the metallic zinc is carefully selected by expert workmen and placed in a special kind of furnace, being mixed with hard coal, such as we use in our heating stoves.] [Illustration: A ZINC SMELTER--THE MEN KEEP THEIR MOUTHS COVERED SO AS NOT TO INHALE THE VAPOR, WHICH IS POISONOUS The burning of the coal causes an intensely high temperature, sometimes being several thousand degrees. This causes the zinc ore to be consumed as it were or to pass into a form of vapor. This vapor is carried through huge pipes which are several feet in diameter and extend for a long distance. While these vapors are passing through these pipes it becomes cooled. After becoming cooled it takes on the form of very fine white powder, coming from the pipes in much the same way that snow falls from the sky in the winter. This is collected and placed in barrels, after which it is ready for the paint-maker without further preparation.] ~WHERE LINSEED OIL COMES FROM~ Since we have followed the preparation of the two important white pigments used in making our can of paint, it is now important that we devote a little thought to the liquid which is to be used. This is called “Linseed Oil.” Linseed oil is of a golden yellow color, resembling the appearance of thin syrup which we sometimes have on the table. This oil is taken from the seed of the flax plant. It might better be called “Flaxseed Oil,” yet it is not commonly known by that name, but is nearly always referred to as “Linseed Oil.” Flax is grown in many parts of the world, the most important places being the United States of America, Dominion of Canada, Ireland, India and the Argentine Republic. In the United States, the seed is sown early in spring, much the same as is done with other crops, and ripens and is harvested early in the fall of the year. The harvesting and separation of the seed from the plant or straw is done very much in the same way that other crops, such as wheat and oats, are harvested. The seed is then taken to market and is ready for the extraction of the oil, which is done by men who are known as “oil crushers.” [Illustration: PRESSING OIL OUT OF FLAXSEED.] [Illustration: REMOVING OIL CAKE FROM PRESS.] The oil is extracted from the seed by a very simple process. Usually the seeds are heated by steaming them, after which they pass through a mill, being ground to a coarse mass, which is then placed in very powerful machines called “Hydraulic Oil Presses,” which squeeze the oil from the seed, leaving the remainder in the form of large cakes which are then ground to a mealy-like powder which is used as food for cattle and is very much prized. The oil which has been extracted by this process is put into large tanks where it is clarified and is then ready for the paint-maker. This oil is often referred to as “Vegetable Oil” and it has one very peculiar and very important characteristic which makes it useful and necessary for use in paint. This property is that of drying or becoming solid, losing all tendency to stickiness after it has been spread out thinly and exposed to the air for a short time. [Illustration: WHERE LEAD IS GROUND IN OIL.] [Illustration: WHERE PAINTS ARE MIXED.] Now that we have given attention to the preparation of the most important things used in the making of our can of paint, let us look a little to the manner in which they are put together, and the result. The oil is necessary in making paint in order to make it fluid, so that the paint may be brushed on to the wood or other surface, and also so that the pigment or powdered material which has been put into the paint will have something to hold it to the surface. The oil or other liquid which may be used is usually called “Binder” by the paint man because it binds the pigment in the paint and to the surface on which it has been spread or applied. In a large paint factory, the two white pigments, lead and zinc, are mixed with linseed oil in large machines known as “Mixers” into a smooth paste which is then run through other machines called “Mills,” where the paste is ground very fine into large tubes where the paint is finished by mixing in enough more oil to make it of the proper thickness or consistency for brushing. In this state it can be used, but would not be entirely satisfactory because it would dry very slowly. For that reason, the paint-maker adds in a small amount of what is known as “Drier,” which causes the paint to dry much more rapidly after it is spread out on any surface. The paint-maker may also add in a small amount of thin liquid called “Turpentine,” which also aids in the drying and the working of the paint. Turpentine is a very thin liquid which looks like water, and it is derived from the sap of one species of pine which grows abundantly in the southern portion of the United States. The sap is taken from the tree by tapping the tree or making an incision called a box, at certain seasons. After the sap is collected it is put through a heating process called “distilling,” which separates the water-white liquid, called turpentine, leaving a large mass of heavy material which is commonly known as “Rosin.” This turpentine is very useful to the paint-maker and the painter. It is also used for many other purposes. ~WHAT MAKES THE DIFFERENT COLORS OF PAINT~ The paint which we have described is the most simple kind and is white. There are many other kinds of paint used, being of many different colors. All of these different kinds require different treatment and preparation and would require many large books to explain even in a brief way. The white paint which we have described may be colored or tinted to many different hues by adding suitable color pigments. These color pigments are of many kinds and are derived from many different sources. The vegetable kingdom is represented as well as the mineral and animal kingdoms. The linseed oil which we have already mentioned, is derived from the vegetable kingdom. This also applies to some few of the pigments. A very important instance which we might mention is a beautiful rich brown called “Vandyke Brown.” This is made from decayed vegetation which is found in swampy districts. There are many pigments derived from the mineral kingdom. White lead and zinc oxide have already been described as useful. Among colored pigments coming from this kingdom, we might mention yellow ochre, sienna, umber, cobalt blue, and many others. The animal kingdom supplies quite a number, one of which is a beautiful red known as “Carmine.” This is taken from a small insect or fly which is found in certain tropical climates. The production of carmine is very expensive and the product is highly prized. Another important development of the animal world is what is called “Bone Black.” This is made by taking ordinary animal bones, putting them into a suitable furnace and burning them, which really produces bone charcoal, which is refined by powdering and washing, and finally produces a beautiful black, such as used for painting fine coaches and carriages. Why Does a Dog Turn Round and Round Before He Lies Down? Away back in the history of the animal kingdom, when the ancestors of our domestic dog were wild, they slept in the woods or open. When they were ready to lie down, they first had to trample the grass about them flat to make a place to lie down. This became a habit and one of the instincts of the animal which has been transmitted to the dogs of today who keep it up. It is an inherited habit quite useless to the dogs of to-day. How Is Light Produced? You already learned that a substance called ether is found in all substances, filling the spaces between the molecules. When the molecules are made to vibrate, the ether naturally also vibrates. As soon as the vibrations become sufficiently rapid, they produce the sensation of light. These vibrations also produce heat. In heated bodies the molecules are always found to be in vibration, and a body may become so hot that it gives off light. We notice this when iron becomes red hot. Heat and light are found together in bodies in many instances. In fact, most of the light we have comes from bodies which are hot. The sun is so hot, that it is surrounded by the gases of many substances that exist as solids on earth. We have some bodies which produce light which is not accompanied by much heat. The glow-worm, or firefly, seems to make light with little or no heat; but we do not yet know how this is done. Almost all sources of artificial light require that heat be produced before light obtained. Only such vibrations of the ether which are sufficiently rapid produce enough light to enable us to see. For this reason, a piece of red hot iron, which is made luminous by heat and whose particles vibrate less rapidly produce little light. What Makes Rays of Light? Whenever the ether is made to vibrate rapidly enough at any point, the vibrations go in straight lines from the source of light in all directions. A single line of vibrating particles in the ether, is known as a ray. A number of rays, that issue from one point, are said to form a pencil. A pencil of light may be produced by holding near a candle a screen, with a hole in it. Sometimes rays of light are brought together in a point, as may be done by means of a burning glass, and one of these bundles of rays is known as a convergent pencil. A bundle of rays that lie parallel to each other forms a beam. The rays that come to us from the sun are practically parallel and are called sunbeams. Why Does a Nail Get Hot When I Hammer It? When we are in the sunshine, or standing before a fire, we feel hot; when we take snow or ice in our hands, they feel cold. The thing which produces these sensations is called heat. When we feel heat, it is because heat is absorbed by our bodies, and when we feel cold, it is being thrown off by them. To answer this question, we must see how heat may be produced. If we draw a cord rapidly through our fingers, they feel hot, and if we rub a coin briskly with a cloth or our hands, it becomes warm; if we take a nail and hammer it on a hard substance, it becomes too warm for us to hold. In these instances heat is produced by retarding or checking the motion of a body. When we draw a cord through our fingers, it moves less easily; we retard its motion by gripping it and this is what makes the heat we feel. When we strike the nail with a hammer, the motion of the hammer is checked by the nail, and the faster we pound with the hammer, the hotter the nail becomes. From these experiments we learn that whenever the motion of a substance is checked, or retarded, heat is generated, and the substance made hot. In explaining this method of producing heat, it was at one time thought that all bodies contained a substance which produced the heat and that, when rubbed or hammered, this substance was thrown off. About the end of the 18th century, however, it was shown by Benjamin Thompson (Count Rumford), that substances when rubbed give off heat. From this we learned that heat is not a substance, because the quantity of any substance, present in a body, cannot be limitless. If it were a substance which produced the heat, the supply would sooner or later be exhausted, and rubbing could no longer produce heat. Heat produced by rubbing, or by striking substances together, is caused as follows: If two substances are struck upon each other, the whole of those substances are checked, but the molecules of the substances are made to vibrate very rapidly, and these vibrations produce the heat we feel. How Do We Obtain Heat? We get most of our heat from the sun. If the heat from the sun did not reach us, no living thing would exist on the earth. No plants or animals could live; the oceans and rivers would be solid ice. Another important source of heat, is chemical action. Chemical action is what causes fire. Even when it does not cause fire, it produces a great deal of heat. When we breathe to keep our bodies warm, it is a chemical action that occurs. Fire is the most important form of chemical action, as a source of heat. Why Does a Glow-Worm Glow? A glow-worm is a kind of beetle which may be found in the yards and hedges in the summer time. The name applies only to the female of the species which is wingless and whose body resembles that of a caterpillar somewhat and emits a shining green light from the end of the abdomen. The male of this species has wings but does not show any light as does the female and resembles an ordinary beetle. The male flies about in the evenings looking for the female and she makes her light glow in order that the male may find her. Glow-worms are found mostly in England. There are, however, some members of the same species of beetle common to the United States. We speak of them as fireflies or lightning bugs. The female of these also is the only one carrying a light, although unlike the glow-worm she has wings and can fly. Why Do They Call It Pin Money? This expression originally came from the allowance which a husband gave his wife to purchase pins. At one time pins were dreadfully expensive so that only wealthy people could afford them and they were saved so carefully that in those days you could not have looked along the pavement and found a pin which you happened to be in need of as you can and often do today. By a curious law the manufacturers of pins were only allowed to sell them on January 1st and 2nd each year and so when those days came around the women whose husbands could afford it, secured pin money from them and went out and got their pins. Pins have become so very cheap in these days that we are rather careless with them, but the expression has continued to live although today when used, it means any allowance of money which a husband gives a wife for her personal expenses. Pins were known and used as long ago as 1347 A. D. They were introduced into England in 1540. In 1824 an American named Might invented a machine for making pins which enabled them to be manufactured cheaply. About 1,500 tons of iron and brass are made into pins every year in the United States. Why Do People Shake Hands With the Right Hand? In the days of very long ago when all men were prepared to fight at any and all times because one could not know whether another approaching was a friend or an enemy, all men went armed. This was before the day of guns when the sword was the great weapon of defense. Upon occasion when one man approached another, each had to decide whether the other came on a peaceful mission or not. People in those days were mostly right handed as they are now and when fighting carried their swords in their right hands. If, then, a man wished to speak with a stranger or, as might easily be necessary, to one who may even be known to be unfriendly, he put out his right hand upon approaching to show that he had no deadly or dangerous weapon in it. The other man could see this and knew from the extended open hand that no harm was intended and that the approach was peaceful. If, then, he was willing to meet the other, he also extended his right arm with the hand open to show him who was approaching that his fighting hand was empty also; and when they met each would grasp the hand of the other so that neither one could change his mind and assume a fighting attitude without the other having an equal warning. How Did the Custom of Clinking Glasses When Drinking Originate? In the days of the Roman gladiators, before a duel with swords, it became the custom of each of the participants to drink a glass of wine before fighting. Just before the fighting commenced two glasses of wine were brought and the gladiators drank. These two glasses of wine were provided by the friends of either one or the other of the gladiators. To guard against treachery, through some over zealous friend of the fighters furnishing poisoned wine was necessary. So before drinking and to show there was no treachery, the gladiators came close together and poured wine from one glass into the other back and forth until the wine in the glasses was thoroughly mixed. If the wine in one glass then had been poisoned, the poisoned wine would thus be in both glasses, and if there had been any treachery, both gladiators would be poisoned if they drank. The wine was poured from one glass to the other to show that there was no treachery. This custom continued in use for a long time until the idea of drinking before a fight was abandoned. The custom, however, of showing friendliness in this way while drinking continued for a long time. Later it became a mere custom, however, to show a friendly spirit toward the one who was drinking with you, and when the danger of poisoned wine was past, the actual act of pouring the wine from one glass to another was changed to merely touching the glasses together. Thus today we have the friendly custom of touching glasses together long after the necessity of guarding against treachery while drinking has passed. Why Cannot Fishes Live In the Air? It is a curious thing isn’t it that if a boy falls into the water, he will drown if he cannot swim or someone does not help him out, and that if a fish falls out of the water onto the land, he will drown also, even though he knows how to swim, better than anything else he does. A boy cannot secure the air which he needs to live on if he is under the water, because there is not enough air for him there and a fish cannot secure enough air for him to live on when he is on land where the air is plentiful, because, the boy takes his air from the air itself and the fish gets his air out of the water. To live by breathing the air we find on or above the land, it is necessary to have lungs and fishes do not have lungs. In the case of the boy under the water he would have to have gills to enable him to make use of the air which is in the water to live by and he has no gills. A fish can only live a little while out of the water, but even so he can live longer out of the water than a boy can under the water. Lest you read sometime of the flying fish and think they must be able to live out of the water, I will tell you before you ask the question that the flying fish never stays out of the water for more than a few seconds at a time. His flying leaps amount to little more than long leaps from wave to wave. He swims along very fast in the water, coming right up to the surface and out into the air and the speed at which he has been swimming regulates the distance he will go when he shoots into the air, as he has no means of propelling himself through the air, but only into it. He has, however, wing-like fins, which he spreads out when in the air and which enables him to glide through the air and thus remain in the air longer. What Makes a Fish Move in Swimming? This is a puzzling question, I am sure. Of course, you at once cause several other questions as soon as you ask this one such as the following: Does the water in front of him move out of the way and then close in behind him? If so, where does it go in the meantime? Does the fish move the water forward or up or down or what does he do? The answer is, of course, in the movements of the fish’s tail. The fish in swimming is surrounded with water, top, bottom and all sides of him. The pressure of the water on the fish is the same at all points so that any motion made by him would have a tendency to make him move. As a matter of fact the tail in moving from side to side creates a current in the water from the head to the tail, or rather would produce an actual current if the fish remained perfectly still. Instead of making an actual current of water, the body of the fish is moved forward. As to whether the water ahead of him opens up first and then the water behind him is a more difficult question to answer. To the appearance it would seem as if the water moved at both ends and sides at once, but according to scientific theory, the water at the head of the fish is displaced first. Why Are Birds’ Eggs of Different Colors? This is a wise provision of nature to help the mother birds hide her eggs away from the eyes of her enemies. In the animal kingdom every kind of life is the natural prey of some other kind of animal. A bird will have enemies which try to catch her as food. A bird cannot fight back, so must fly away when danger threatens, in order to save her life. This means that she must leave the eggs in the nest for the time being. At certain times she must also leave her nest and search for food for herself. In order that the eggs so left alone may have a better chance of not being discovered, nature has arranged matters so that the eggs take the color very much of the surroundings in which they are laid. Eggs of some birds are spotted or look like pebbles, because the mother bird lays them in the sand. Some of them are green, almost the color of the materials from which the bird builds the nest, and so the colors have a real, and to the birds, a valuable purpose. Why Does a Hen Cackle After Laying an Egg? The hen cackles because she is glad. She is glad because she has just accomplished something, which she was put on earth to do. If you study the life on the earth carefully with this in mind, you will discover that all kinds of life give expression in some form of gladness, when they have performed the things they are on earth for. It’s the hen’s way of expressing herself and letting the chicken world know. The dog wags his tail when he is pleased; boys and girls jump up and down when they are pleased, whether they have been doing anything commendable or not. No doubt also the actual laying of the egg causes some discomfort to the hen and the corresponding feeling of gladness would come naturally after the discomfort disappeared. Why Will Water Run Off a Duck’s Back? The reason that water runs of a duck’s back, is that the feathers of ducks are oily and, as water and oil will not mix, the water runs off instead of soaking in. The feathers on a duck are so thick on the body of the duck, top and bottom, that even if it were not for the oil which is on the feathers the water would have some difficulty in soaking through the feathers. But the main reason why the feathers on a duck’s back cause water striking them to run off is that the duck has an oil gland which is constantly producing grease or oil and which the duck uses in giving his feathers a thin coating of oil to make them slick with oil and when any water strikes the duck it runs off. Other birds which live in the water a great deal have this oil gland for the same reason. THE STORY IN A STEEL RAIL [Illustration: A Blast Furnace. Molten iron is brought from the blast furnaces to the open-hearth furnaces, and dumped into a receptacle called a mixer, the capacity of which ranges from 400 tons to 1000 tons, depending upon the number of furnaces to be served.] [Illustration: One-thousand-ton Mixer.] Pictures in this story by courtesy of Bethlehem Steel Co. [Illustration: INSIDE OF OPEN HEARTH FURNACE Charging Side of an Open-hearth Furnace. An open-hearth furnace consists of a long, shallow hearth, suitably enclosed in fire-brick, and bound together with steel binding. The furnace is heated by burning gas and air, which have previously been preheated, so that a temperature is obtained in the furnace ranging from 2900 to 3050 degrees Fahrenheit.] [Illustration: Pouring Side of an Open-Hearth Furnace. The open-hearth process consists of the purification of iron by oxidizing out the impurities and burning out the carbon of the iron until a tough and ductile steel is produced, which can be made of any desired composition by the addition of the necessary quantities of alloys just previous to tapping and pouring. The impurities in the iron are oxidized by the slag lying on top of the metal, and the burning out of the carbon, which is a very slow operation, is hastened by the addition of iron ore, the oxygen of which combines with the carbon of the iron and passes off is a gas going up the stack. When an open-hearth furnace is ready for a charge, a variable amount of scrap, say 30 per cent of the total weight of material used for the heat, is charged into the furnace. With this scrap is charged sufficient lime or limestone to make the slag, as well as some iron ore to assist in reducing the carbon of the iron. In about two or three hours the required amount of molten iron is brought from the mixer in ladles, and poured into the furnace on top of the scrap, lime and ore.] [Illustration: MOLTEN STEEL BEING POURED LIKE WATER Molten Steel Being Poured Into Ladle. When the scrap has all been melted, a test is taken to determine the amount of carbon remaining in the bath. Iron ore is added from time to time until the carbon in the bath has been reduced to the desired point, and the metal is sufficiently hot to pour. At this point “recarburizers” (consisting of Ferro-Manganese, Ferro-Silicon, and pig-iron, or coal) are added to get the required composition. The tap hole at the back of the furnace is opened, and the steel is allowed to run out into a ladle, the slag coming last and forming a blanket over the steel in the ladle.] [Illustration: Crane Carrying Ingot and Soaking Pit Furnaces. The ladle is picked up by an electric crane and carried over cast-iron moulds, which are set on cars, the steel being poured into the moulds, resulting in steel ingots. A sufficient amount of time is allowed for the steel to become chilled or set, when the cars are pushed under an electric stripper, where the moulds are removed from the ingots. After the ingots leave the stripper they are taken to the scales and weighed, and after weighing are put into the soaking pits. The pits get their name from the part they play in the heating of the steel for rolling. When the steel ingot is stripped the outside of the ingot is cool enough to hold the inside, which is still in a liquid state, and the steel is put into the soaking pits to allow the inside to settle into a solid mass, after which the ingot is reheated for rolling. The length of time in the soaking pits depends upon the size of the ingot, as the larger the ingot, the greater length of time is required to set. When the steel is ready for rolling it is taken from the pits by overhead electric cranes, and placed into a dump buggy at the end of a roller line, which leads to the blooming mill. The dump buggy derives its name from the fact that when the ingot is placed into same in an upright position, the buggy, in order to place the ingot into a horizontal position on the roller line, dumps over, in the same way as if one were to rock too far forward in a rocking-chair, the dump buggy operating on the same principle.] [Illustration: GETTING READY TO MAKE A RAIL Blooming Mill and Engine. The ingot travels down the movable-roller line to the blooming-mill rolls, which roll it down from a piece 19 inches by 23 inches to what is known as an 8 inch by 8 inch bloom, which is the size usually used in the manufacture of rails. The blooming mill derives its name from the fact that after an ingot is rolled in same it is no longer called an ingot, but a bloom. After leaving the blooming mill the bloom travels along another roller line to the shears, where it is cut into two or three pieces, the number of pieces depending on the size of the rail which is to be rolled. The blooms are then lifted over the roller line at the shears by a transfer crane, and placed on a traveling roller line which connects with the rear of the reheating furnace. This furnace is about 35 feet long, and is so constructed that when the bloom is pushed in at the rear of the furnace, another bloom drops from the front or discharge end of the furnace.] [Illustration: THE INGOT BECOMES A RAIL The Ingot Becomes a Rail. The bloom dropping out, being sufficiently hot to roll into rails, travels along another roller line to the roughing or first set of rolls. Here the bloom is given five passes in the rolls, and is then transferred to the strand or second set of rolls, where it receives five additional passes; after this operation it is transferred to the finishing or third set of rolls, in which it is given one pass. The bloom has now been converted into a rail, and the rail travels on another roller line to the hot saw, where it is cut into 33-foot lengths, this being the standard length in this country for all rails. The rails when hot are cut by the hot saw to lengths of about 33 feet 6¹⁄₂ inches, the allowance of inches being made for shrinkage in cooling. It is difficult to believe that steel shrinks to this extent, but this is a fact, and while the rails are cooling on the hotbeds they have the appearance of being animated, as they move first one way and then the other. After the rails are on the hotbed a sufficient length of time to cool, they are taken from the hotbed and placed on a traveling roller line, which takes them to an endless chain conveyor. The statement that rails are put on hotbeds for cooling seems paradoxical, but the hotbeds are so called because the rails are placed on them while hot, and are left there until they have cooled. The endless-chain conveyor places the rails on another bed, from which they are picked up by an electric crane and distributed to the straightening presses, where all burrs (which have been caused by the hot-sawing operation) are removed before the rails are straightened. After straightening they are transferred to drill presses, where they have holes drilled into them for the accommodation of the splice bar, after which they are placed on the loading docks.] [Illustration: After being carefully examined by the railroad company’s inspectors they are picked up from the loading docks by electric magnets attached to a crane, and are placed in cars ready for shipment.] Who Made the First Felt Hat? The felt hat is as old as Homer. The Greeks made them in skull-caps, conical, truncated, narrow- or broad-brimmed. The Phrygian bonnet was an elevated cap without a brim, the apex turned over in front. It is known as the “cap of liberty.” An ancient figure of Liberty in the times of Antonius Livius, A.D. 115, holds the cap in the right hand. The Persians wore soft caps; plumed hats were the headdress of the Syrian corps of Xerxes; the broad-brim was worn by the Macedonian kings. Castor means a beaver. The Armenian captive wore a plug hat. The merchants of the fourteenth century wore a Flanders beaver. Charles VII, in 1469, wore a felt hat lined with red, and plumed. The English men and women in 1510 wore close woolen or knitted caps; two centuries ago hats were worn in the house. Pepys, in his diary, wrote: “September, 1664, got a severe cold because I took off my hat at dinner”; and again, in January, 1665, he got another cold by sitting too long with his head bare, to allow his wife’s maid to comb his hair and wash his ears; and Lord Clarendon, in his essay, speaking of the decay of respect due the aged, says “that in his younger days he never kept his hat on before those older than himself, except at dinner.” In the thirteenth century Pope Innocent IV allowed the cardinals the use of the scarlet cloth hat. The hats now in use are the cloth hat, leather hat, paper hat, silk hat, opera hat, spring-brim hat, and straw hat. What Is the Hottest Spot on Earth? The hottest regions on earth is said to be along the Persian Gulf, where little or no rain falls. At Bahrein the arid shore has no fresh water, yet a comparatively numerous population contrive to live there, thanks to the copious springs which break forth from the bottom of the sea. The fresh water is got by diving. The diver, sitting in his boat, winds a great goat-skin bag around his left arm, the hand grasping its mouth; then he takes in his right hand a heavy stone, to which is attached a strong line, and thus equipped he plunges in, and quickly reaches the bottom. Instantly opening the bag over the strong jet of fresh water, he springs up the ascending current, at the same time closing the bag, and is helped aboard. The stone is then hauled up, and the diver, after taking breath, plunges in again. The source of the copious submarine springs is thought to be in the green hills of Osman, some 500 or 600 miles distant. Where Do We Get Ivory? Ivory is a hard substance, not unlike bone, of which the teeth of most mammals chiefly consist, the dentine or tooth-substance which in transverse sections shows lines of different color running in circular arcs. It is used extensively for industrial purposes and is derived from the elephant, walrus, hippopotamus, narwhal, and some other animals. The ivory of the tusks of the African elephant is held in the highest estimation by manufacturers; the tusks vary in size, ranging from a few ounces in weight to 170 pounds. Holtzapffel states that he saw fossil tusks on the banks of rivers of Northern Siberia which weighed 186 pounds each. Ivory is simply tooth-substance of exceptional hardness, toughness, and elasticity, due to the firmness and regularity of the dentinal tubules which radiate from the axial pulp-cavity to the periphery of the tooth. How Did Trial by Jury Originate? ~WHY JURIES HAVE TWELVE MEN~ A jury consists of a certain number of men selected according to law and sworn to inquire into and determine facts concerning a cause or an accusation submitted to them, and to declare the truth according to the evidence. The custom of trying accused persons before a jury, as practised in this country and England, is the natural outgrowth of rudimentary forms of trial in vogue among our Anglo-Saxon ancestors. The present system of trial by jury is the result of a gradual growth under the English Common Law. There is no special reason why twelve is the usual number chosen for a complete jury except the necessity for limiting the number. In a grand jury the number according to law must not be less than twelve nor more than twenty-three, and twelve votes are necessary to find an indictment. The ancient Romans also had a form of trial before a presiding judge and a body of judices. The right of trial by jury is guaranteed by the United States Constitution in all criminal cases, and in civil cases where the amount in dispute exceeds $20. A petit or trial jury consists of twelve men, selected by lot from among the citizens residing within the jurisdiction of the court. Their duty is to determine questions of fact in accordance with the weight of testimony presented and report their finding to the presiding judge. An impartial jury is assured by drawing by lot and then giving the accused, in a criminal case, the right to dismiss a certain number without reason and certain others for good cause. Each of the jurymen must meet certain legal requirements as to capacity in general and fitness for the particular case upon which he is to sit, and must take an oath to decide without prejudice and according to the testimony. A coroner’s jury or jury of inquest is usually composed of from six to fifteen persons, summoned to inquire into the cause of sudden or unexplained deaths. Can Animals Foretell the Weather? Certain movements on the part of the animal creation before a change of weather appear to indicate a reasoning faculty. Such seems to be the case with the common garden spider, which, on the approach of rainy or windy weather, will be found to shorten and strengthen the guys of his web, lengthening the same when the storm is over. There is a popular superstition that it is unlucky for an angler to meet a single magpie, but two of the birds together are a good omen. The reason is that the birds foretell the coming of cold or stormy weather, and at such times, instead of searching for food for their young in pairs, one will always remain on the nest. Sea-gulls predict storms by assembling on the land, as they know that the rain will bring earthworms and larvæ to the surface. This, however, is merely a search for food, and is due to the same instinct which teaches the swallow to fly high in fine weather, and skim along the ground when foul is coming. They simply follow the flies and gnats, which remain in the warm strata of the air. The different tribes of wading birds always migrate before rain, likewise to hunt for food. Many birds foretell rain by warning cries and uneasy actions, and swine will carry hay and straw to hiding-places, oxen will lick themselves the wrong way of the hair, sheep will bleat and skip about, hogs turned out in the woods will come grunting and squealing, colts will rub their backs against the ground, crows will gather in crowds, crickets will sing more loudly, flies come into the house, frogs croak and change color to a dingier hue, dogs eat grass, and rooks soar like hawks. It is probable that many of these actions are due to actual uneasiness, similar to that which all who are troubled with corns or rheumatism experience before a storm, and are caused both by the variation in barometric pressure and the changes in the electrical condition of the atmosphere. Nearest Approach Ever Made to Perpetual Motion in Mechanics. An inventor has patented a double electric battery which seems to come exceedingly near to perpetual motion. Instead of using the zinc battery, he professes to have hit upon a solution which makes a battery seven times as powerful as the zinc battery, with absolutely no waste of material. The power of the battery grows gradually less in a few hours of use, but returns to its original unit when allowed to rest a few hours. He has two batteries so arranged that the power is shifted from one to the other every three hours. A little machine has been running for some years in the patent office at New York. Certain parts of the mechanism are constructed of different expansive capacities, and the machine is worked by the expansion and contraction of these under the usual variations of temperature. In the Bodleian Library at Oxford there is an apparatus which has chimed two little bells continuously for forty years, by the energy of an apparently inexhaustible “dry-pile” of very low electrical energy. A church clock in Brussels is wound up by atmospheric expansion induced by the heat of the sun. As long as the sun shines this clock will go till its works wear out. Mr. D. L. Goff, a wealthy American, has in his hall an old-fashioned clock, which, so long as the house is occupied, never runs down. Whenever the front door is opened or closed, the winding arrangements of the clock, which are connected with the door by a rod with gearing attachments, are given a turn, so that the persons leaving and entering the house keep the clock constantly wound up. Do Plants Breathe? Plants, like animals, breathe the air; plants breathe through their leaves and stems just as animals do by means of their respiratory organs. When a young plant is analyzed it is found to consist chiefly of water, which is all removed from the soil; there is about 75 per cent or more of this fluid present, and the rest is solid material. Of this latter by far the most abundant constituent is carbon, almost every atom of which is removed from the atmosphere by the vital action of minute bodies contained in the green leaves. The carbon is taken into the plant as carbonic acid gas. Plants also absorb oxygen, hydrogen, and nitrogen from the atmosphere in different quantities through their leaves, and also by means of their roots. These new products stored are in turn used in building up the different organs of the plant. Plants give off used-up moisture through their leaves, just as animals perspire through the pores of their skins. Calculations have been made as to the amount of water thus perspired by plants. The sunflower, only 3¹⁄₂ ft. high, with 5,616 square inches of surface exposed to the air, gives off as much moisture as a man. What Depth of Snow Is Equivalent to an Inch of Rain? Newly fallen snow having a depth of about 11¹⁄₃ inches is equivalent to one inch of rain. A cubic foot of newly fallen snow weighs 5¹⁄₂ pounds and a cubic foot of fresh or rain water weighs 62¹⁄₂ pounds or 1,000 ounces. An inch of rain means a gallon of water spread over every two square feet, or about a hundred tons to every acre. The density of snow naturally varies a good deal according to the speed with which it falls. Temperature, also, has much to do with its bulk. In cold, crisp weather, when the thermometer registers several degrees of frost, snow comes down light and dry; but in moist, cold weather, when the temperature is only just below thirty-two degrees, the snow falls in large, partially thawed flakes, and occupies much less space where it falls than that which reaches the earth during the prevalence of a greater degree of cold. How Are the Stars Counted? Stars are counted by means of the telescope and photography. The Astronomer-Royal for Ireland, Sir Robert S. Ball, in one of his lectures mentioned a photograph which had been obtained by Mr. Isaac Roberts representing a small part of the constellation of the Swan. The picture is about as large as the page of a copy-book, and it is so crowded with stars that it would puzzle most people to count them; but they have been counted by a patient person, and the number is about 16,000. Many of these stars are too faint ever to be seen in the greatest of telescopes yet erected. Attempts are now being made to obtain a number of similar photographs which shall cover the whole extent of the heavens. The task is indeed an immense one. Assuming the plates used to be the same size as that above mentioned, it would require at least 10,000 of them to represent the entire sky. The counting of stars by the telescope was first reduced to a system by the Herschels, who introduced “star-gauges,” which were simply a calculation by averages. A telescope of 18 in. aperture, 20 ft. focus, and a magnifying power of 180, giving a field of view 15 in. in diameter, was used for the purpose. The process consisted in directing this instrument to a part of the sky and counting the stars in the field. This, repeated hundreds of times, gave a fair idea of the average number of stars in a circle of 15 in. diameter in all parts of the sky. From this as a basis it is possible to reckon the number of stars in any known area. How Is the Volume of Sound Measured? Sound arises from vibrations giving a wave-like motion to the surrounding atmosphere, the wave gradually enlarging as it leaves the source of disturbance, while at the same time the motion of the air particles becomes less and less. The simplest method of determining the number of vibrations of a sound is by means of Savart’s apparatus. This consists of two wheels--a toothed or cog-wheel and a driving-wheel. They are so adjusted that the cog-wheel is made to revolve with great rapidity, its teeth hitting upon a card fixed near it. The number of revolutions is indicated by a counter attached to the axis of the cog-wheel. Suppose that sound is traveling in the air at the rate of 1,000 ft. per second, and that Savart’s wheel is giving a sound produced by 200 taps on the card per second, it follows that in 1,000 ft. there will be 200 waves or vibrations, and if there be 200 waves in 1,000 ft. each wave or vibration must be 5 ft. in length. The velocity of sound through air varies with the temperature of the latter, but is usually reckoned at 1,130 ft. per second. At What Rate Does Thought Travel? Thought travels 111 feet per second, or about a mile and a quarter per minute. Elaborate experiments have been made by Professors Heimholtz, Hersch, and Donders, to ascertain the facts on this question, the result of which was that they found the process of thought varied in rapidity in different individuals, children and old persons thinking more slowly than people of middle age, and ignorant people more slowly than the educated. It takes about two-fifths of a second to call to mind the country in which a well-known town is situated, or the language in which a familiar author wrote. We can think of the name of the next month in half the time we need to think of the name of the last month. It takes on the average one-third of a second to add numbers containing one digit and half a second to multiply them. Those used to reckoning can add two to three in less time than others; those familiar with literature can remember more quickly than others that Shakespeare wrote “Hamlet.” It takes longer to mention a month when a season has been given than to say to what season a month belongs. The time taken up in choosing a motion, the “will time,” can be measured as well as the time taken up in perceiving. If it is not known which of two colored lights is to be presented, and you offer to lift your right hand if it be red and your left if it be blue, about one-thirteenth of a second is necessary to initiate the correct motion. What Is the Largest Tree In the World? In San Francisco, encircled by a circus tent of ample dimensions, is a section of the largest tree in the world--exceeding the diameter of the famous tree of Calaveras by five feet. This monster of the vegetable kingdom was discovered in 1874, on Tule River, Tulare County, about seventy-five miles from Visalia. At some remote period its top had been broken off by the elements, or some unknown forces, yet when it was discovered it had an elevation of 240 feet. The trunk of the tree was 111 feet in circumference, with a diameter of 35 feet 4 inches. The section on exhibition is hollowed out, leaving about a foot of bark and several inches of the wood. The interior is 100 feet in circumference and 30 feet in diameter, and it has a seating capacity of about 200. It was cut off from the tree about twelve feet above the base, and required the labor of four men for nine days to chop it down. In the center of the tree, and extending through its whole length, was a rotten core about two feet in diameter, partially filled with a soggy, decayed vegetation that had fallen into it from the top. In the center of this cavity was found the trunk of a little tree of the same species, having perfect bark on it, and showing regular growth. It was of uniform diameter, an inch and a half all the way; and when the tree fell and split open, this curious stem was traced for nearly 100 feet. The rings in this monarch of the forest show its age to have been 4,840 years. Where Did the Term Yankees Originate? This is a word said to be a corruption of Yengees, the Indian pronunciation of English, or of the French “Anglais,” when referring to the English Colonists. It was first applied to the New Englanders by the British soldiers as a term of reproach, later by the English to Americans generally, and still later to the people of the North by the Southerners. How Far Does the Air Extend? It is, perhaps, generally known that enveloping the earth is a layer of air fifty or more miles in thickness. Just how thick this layer is we do not know, but we do know that it extends many miles from the earth. You may assure yourselves of this in a very simple manner by watching the shooting stars that may be seen on any clear night. These are nothing but masses of rocks that give off light only when they have been made red-hot by friction with the air in their rapid flight. The fact that we often see these stars while they are still many miles from the earth proves to us that the air through which they are passing extends to that height. What Makes Us Feel Hungry? Hunger is a peculiar craving which we are accustomed to say comes from the stomach. It is the business of the stomach to change such food as we take into it in such a way that the rest of the organs of the body which we have for the purpose can make blood out of it. When you feel the sensation of hunger, it means that the blood-producing system is calling on the stomach to furnish more blood-making material. The stomach prepares the food for blood production by mixing with it certain juices which the stomach is able to supply. As soon as the stomach is then called upon to supply more blood-making material, it goes to work on what is in the stomach and begins mixing things. If, however, there is nothing in the stomach, the craving which we call hunger is produced. It is, therefore, then not altogether the stomach which makes us hungry, but the parts of our body which actually turn the food into blood after the stomach has prepared it. To prove this it is only necessary to say that the sensation of hunger will stop if food which is easily absorbed and, therefore, does not need the preparation which the stomach generally gives, is introduced into the system through other parts of the body, as, for instance, by injecting it into the large intestine, which is a part of the body, the food passes through after it leaves the stomach ordinarily. What Makes Us Thirsty? Thirst is a sensation of dryness and heat which is generally communicated to us through the tongue and throat. The sensation of thirst can be artificially produced by passing a current of air over the membranes which cover the tongue and throat, but thirst is naturally due to a shortage of water in the body. The human body requires a great deal of water to keep it in condition, and when the supply becomes low a warning is given to us by making the membranes of the tongue and throat dry. In connection with thirst, however, as in the case of hunger, where the warning is given by the stomach, thirst will be appeased by the