Book 9, of accidental risings of water.

924. THE ORDER OF THE BOOK. Place at the beginning what a river can effect. 925. A book of driving back armies by the force of a flood made by releasing waters. A book showing how the waters safely bring down timber cut in the mountains. A book of boats driven against the impetus of rivers. A book of raising large bridges higher. Simply by the swelling of the waters. A book of guarding against the impetus of rivers so that towns may not be damaged by them. 926. A book of the ordering of rivers so as to preserve their banks. A book of the mountains, which would stand forth and become land, if our hemisphere were to be uncovered by the water. A book of the earth carried down by the waters to fill up the great abyss of the seas. A book of the ways in which a tempest may of itself clear out filled up sea-ports. A book of the shores of rivers and of their permanency. A book of how to deal with rivers, so that they may keep their bottom scoured by their own flow near the cities they pass. A book of how to make or to repair the foundations for bridges over the rivers. A book of the repairs which ought to be made in walls and banks of rivers where the water strikes them. A book of the formation of hills of sand or gravel at great depths in water. 927. Water gives the first impetus to its motion. A book of the levelling of waters by various means, A book of diverting rivers from places where they do mischief. A book of guiding rivers which occupy too much ground. A book of parting rivers into several branches and making them fordable. A book of the waters which with various currents pass through seas. A book of deepening the beds of rivers by means of currents of water. A book of controlling rivers so that the little beginnings of mischief, caused by them, may not increase. A book of the various movements of waters passing through channels of different forms. A book of preventing small rivers from diverting the larger one into which their waters run. A book of the lowest level which can be found in the current of the surface of rivers. A book of the origin of rivers which flow from the high tops of mountains. A book of the various motions of waters in their rivers. 928. [1] Of inequality in the concavity of a ship. [Footnote 1: The first line of this passage was added subsequently, evidently as a correction of the following line.] [1] A book of the inequality in the curve of the sides of ships. [1] A book of the inequality in the position of the tiller. [1] A book of the inequality in the keel of ships. [2] A book of various forms of apertures by which water flows out. [3] A book of water contained in vessels with air, and of its movements. [4] A book of the motion of water through a syphon. [Footnote 7: _cicognole_, see No. 966, 11, 17.] [5] A book of the meetings and union of waters coming from different directions. [6] A book of the various forms of the banks through which rivers pass. [7] A book of the various forms of shoals formed under the sluices of rivers. [8] A book of the windings and meanderings of the currents of rivers. [9] A book of the various places whence the waters of rivers are derived. [10] A book of the configuration of the shores of rivers and of their permanency. [11] A book of the perpendicular fall of water on various objects. [12] Abook of the course of water when it is impeded in various places. [12] A book of the various forms of the obstacles which impede the course of waters. [13] A book of the concavity and globosity formed round various objects at the bottom. [14] Abook of conducting navigable canals above or beneath the rivers which intersect them. [15] A book of the soils which absorb water in canals and of repairing them. [16] Abook of creating currents for rivers, which quit their beds, [and] for rivers choked with soil. General introduction. 929. THE BEGINNING OF THE TREATISE ON WATER. By the ancients man has been called the world in miniature; and certainly this name is well bestowed, because, inasmuch as man is composed of earth, water, air and fire, his body resembles that of the earth; and as man has in him bones the supports and framework of his flesh, the world has its rocks the supports of the earth; as man has in him a pool of blood in which the lungs rise and fall in breathing, so the body of the earth has its ocean tide which likewise rises and falls every six hours, as if the world breathed; as in that pool of blood veins have their origin, which ramify all over the human body, so likewise the ocean sea fills the body of the earth with infinite springs of water. The body of the earth lacks sinews and this is, because the sinews are made expressely for movements and, the world being perpetually stable, no movement takes place, and no movement taking place, muscles are not necessary. --But in all other points they are much alike. I. OF THE NATURE OF WATER. The arrangement of Book I. 930. THE ORDER OF THE FIRST BOOK ON WATER. Define first what is meant by height and depth; also how the elements are situated one inside another. Then, what is meant by solid weight and by liquid weight; but first what weight and lightness are in themselves. Then describe why water moves, and why its motion ceases; then why it becomes slower or more rapid; besides this, how it always falls, being in contact with the air but lower than the air. And how water rises in the air by means of the heat of the sun, and then falls again in rain; again, why water springs forth from the tops of mountains; and if the water of any spring higher than the ocean can pour forth water higher than the surface of that ocean. And how all the water that returns to the ocean is higher than the sphere of waters. And how the waters of the equatorial seas are higher than the waters of the North, and higher beneath the body of the sun than in any part of the equatorial circle; for experiment shows that under the heat of a burning brand the water near the brand boils, and the water surrounding this ebullition always sinks with a circular eddy. And how the waters of the North are lower than the other seas, and more so as they become colder, until they are converted into ice. Definitions (931. 932). 931. OF WHAT IS WATER. Among the four elements water is the second both in weight and in instability. 932. THE BEGINNING OF THE BOOK ON WATER. Sea is the name given to that water which is wide and deep, in which the waters have not much motion. [Footnote: Only the beginning of this passage is here given, the remainder consists of definitions which have no direct bearing on the subject.] Of the surface of the water in relation to the globe (933-936). 933. The centres of the sphere of water are two, one universal and common to all water, the other particular. The universal one is that which is common to all waters not in motion, which exist in great quantities. As canals, ditches, ponds, fountains, wells, dead rivers, lakes, stagnant pools and seas, which, although they are at various levels, have each in itself the limits of their superficies equally distant from the centre of the earth, such as lakes placed at the tops of high mountains; as the lake near Pietra Pana and the lake of the Sybil near Norcia; and all the lakes that give rise to great rivers, as the Ticino from Lago Maggiore, the Adda from the lake of Como, the Mincio from the lake of Garda, the Rhine from the lakes of Constance and of Chur, and from the lake of Lucerne, like the Tigris which passes through Asia Minor carrying with it the waters of three lakes, one above the other at different heights of which the highest is Munace, the middle one Pallas, and the lowest Triton; the Nile again flows from three very high lakes in Ethiopia. [Footnote 5: _Pietra Pana_, a mountain near Florence. If for Norcia, we may read Norchia, the remains of the Etruscan city near Viterbo, there can be no doubt that by '_Lago della Sibilla_'--a name not known elsewhere, so far as I can learn--Leonardo meant _Lago di Vico_ (Lacus Ciminus, Aen. 7).] 934. OF THE CENTRE OF THE OCEAN. The centre of the sphere of waters is the true centre of the globe of our world, which is composed of water and earth, having the shape of a sphere. But, if you want to find the centre of the element of the earth, this is placed at a point equidistant from the surface of the ocean, and not equidistant from the surface of the earth; for it is evident that this globe of earth has nowhere any perfect rotundity, excepting in places where the sea is, or marshes or other still waters. And every part of the earth that rises above the water is farther from the centre. 935. OF THE SEA WHICH CHANGES THE WEIGHT OF THE EARTH. The shells, oysters, and other similar animals, which originate in sea-mud, bear witness to the changes of the earth round the centre of our elements. This is proved thus: Great rivers always run turbid, being coloured by the earth, which is stirred by the friction of their waters at the bottom and on their shores; and this wearing disturbs the face of the strata made by the layers of shells, which lie on the surface of the marine mud, and which were produced there when the salt waters covered them; and these strata were covered over again from time to time, with mud of various thickness, or carried down to the sea by the rivers and floods of more or less extent; and thus these layers of mud became raised to such a height, that they came up from the bottom to the air. At the present time these bottoms are so high that they form hills or high mountains, and the rivers, which wear away the sides of these mountains, uncover the strata of these shells, and thus the softened side of the earth continually rises and the antipodes sink closer to the centre of the earth, and the ancient bottoms of the seas have become mountain ridges. 936. Let the earth make whatever changes it may in its weight, the surface of the sphere of waters can never vary in its equal distance from the centre of the world. Of the proportion of the mass of water to that of the earth (937. 938). 937. WHETHER THE EARTH IS LESS THAN THE WATER. Some assert that it is true that the earth, which is not covered by water is much less than that covered by water. But considering the size of 7000 miles in diameter which is that of this earth, we may conclude the water to be of small depth. 938. OF THE EARTH. The great elevations of the peaks of the mountains above the sphere of the water may have resulted from this that: a very large portion of the earth which was filled with water that is to say the vast cavern inside the earth may have fallen in a vast part of its vault towards the centre of the earth, being pierced by means of the course of the springs which continually wear away the place where they pass. Sinking in of countries like the Dead Sea in Syria, that is Sodom and Gomorrah. It is of necessity that there should be more water than land, and the visible portion of the sea does not show this; so that there must be a great deal of water inside the earth, besides that which rises into the lower air and which flows through rivers and springs. [Footnote: The small sketch below on the left, is placed in the original close to the text referring to the Dead Sea.] The theory of Plato. 939. THE FIGURES OF THE ELEMENTS. Of the figures of the elements; and first as against those who deny the opinions of Plato, and who say that if the elements include one another in the forms attributed to them by Plato they would cause a vacuum one within the other. I say it is not true, and I here prove it, but first I desire to propound some conclusions. It is not necessary that the elements which include each other should be of corresponding magnitude in all the parts, of that which includes and of that which is included. We see that the sphere of the waters varies conspicuously in mass from the surface to the bottom, and that, far from investing the earth when that was in the form of a cube that is of 8 angles as Plato will have it, that it invests the earth which has innumerable angles of rock covered by the water and various prominences and concavities, and yet no vacuum is generated between the earth and water; again, the air invests the sphere of waters together with the mountains and valleys, which rise above that sphere, and no vacuum remains between the earth and the air, so that any one who says a vacuum is generated, speaks foolishly. But to Plato I would reply that the surface of the figures which according to him the elements would have, could not exist. That the flow of rivers proves the slope of the land. 940. PROVES HOW THE EARTH IS NOT GLOBULAR AND NOT BEING GLOBULAR CANNOT HAVE A COMMON CENTRE. We see the Nile come from Southern regions and traverse various provinces, running towards the North for a distance of 3000 miles and flow into the Mediterranean by the shores of Egypt; and if we will give to this a fall of ten braccia a mile, as is usually allowed to the course of rivers in general, we shall find that the Nile must have its mouth ten miles lower than its source. Again, we see the Rhine, the Rhone and the Danube starting from the German parts, almost the centre of Europe, and having a course one to the East, the other to the North, and the last to Southern seas. And if you consider all this you will see that the plains of Europe in their aggregate are much higher than the high peaks of the maritime mountains; think then how much their tops must be above the sea shores. Theory of the elevation of water within the mountains. 941. OF THE HEAT THAT IS IN THE WORLD. Where there is life there is heat, and where vital heat is, there is movement of vapour. This is proved, inasmuch as we see that the element of fire by its heat always draws to itself damp vapours and thick mists as opaque clouds, which it raises from seas as well as lakes and rivers and damp valleys; and these being drawn by degrees as far as the cold region, the first portion stops, because heat and moisture cannot exist with cold and dryness; and where the first portion stops the rest settle, and thus one portion after another being added, thick and dark clouds are formed. They are often wafted about and borne by the winds from one region to another, where by their density they become so heavy that they fall in thick rain; and if the heat of the sun is added to the power of the element of fire, the clouds are drawn up higher still and find a greater degree of cold, in which they form ice and fall in storms of hail. Now the same heat which holds up so great a weight of water as is seen to rain from the clouds, draws them from below upwards, from the foot of the mountains, and leads and holds them within the summits of the mountains, and these, finding some fissure, issue continuously and cause rivers. The relative height of the surface of the sea to that of the land (942-945). 942. OF THE SEA, WHICH TO MANY FOOLS APPEARS TO BE HIGHER THAN THE EARTH WHICH FORMS ITS SHORE. _b d_ is a plain through which a river flows to the sea; this plain ends at the sea, and since in fact the dry land that is uncovered is not perfectly level--for, if it were, the river would have no motion--as the river does move, this place is a slope rather than a plain; hence this plain _d b_ so ends where the sphere of water begins that if it were extended in a continuous line to _b a_ it would go down beneath the sea, whence it follows that the sea _a c b_ looks higher than the dry land. Obviously no portions of dry land left uncovered by water can ever be lower than the surface of the watery sphere. 943. OF CERTAIN PERSONS WHO SAY THE WATERS WERE HIGHER THAN THE DRY LAND. Certainly I wonder not a little at the common opinion which is contrary to truth, but held by the universal consent of the judgment of men. And this is that all are agreed that the surface of the sea is higher than the highest peaks of the mountains; and they allege many vain and childish reasons, against which I will allege only one simple and short reason; We see plainly that if we could remove the shores of the sea, it would invest the whole earth and make it a perfect sphere. Now, consider how much earth would be carried away to enable the waves of the sea to cover the world; therefore that which would be carried away must be higher than the sea-shore. 944. THE OPINION OF SOME PERSONS WHO SAY THAT THE WATER OF SOME SEAS IS HIGHER THAN THE HIGHEST SUMMITS OF MOUNTAINS; AND NEVERTHELESS THE WATER WAS FORCED UP TO THESE SUMMITS. Water would not move from place to place if it were not that it seeks the lowest level and by a natural consequence it never can return to a height like that of the place where it first on issuing from the mountain came to light. And that portion of the sea which, in your vain imagining, you say was so high that it flowed over the summits of the high mountains, for so many centuries would be swallowed up and poured out again through the issue from these mountains. You can well imagine that all the time that Tigris and Euphrates 945. have flowed from the summits of the mountains of Armenia, it must be believed that all the water of the ocean has passed very many times through these mouths. And do you not believe that the Nile must have sent more water into the sea than at present exists of all the element of water? Undoubtedly, yes. And if all this water had fallen away from this body of the earth, this terrestrial machine would long since have been without water. Whence we may conclude that the water goes from the rivers to the sea, and from the sea to the rivers, thus constantly circulating and returning, and that all the sea and the rivers have passed through the mouth of the Nile an infinite number of times [Footnote: _Moti Armeni, Ermini_ in the original, in M. RAVAISSON'S transcript _"monti ernini [le loro ruine?]"_. He renders this _"Le Tigre et l'Euphrate se sont deverses par les sommets des montagnes [avec leurs eaux destructives?] on pent cro're" &c. Leonardo always writes _Ermini, Erminia_, for _Armeni, Armenia_ (Arabic: _Irminiah_). M. RAVAISSON also deviates from the original in his translation of the following passage: "_Or tu ne crois pas que le Nil ait mis plus d'eau dans la mer qu'il n'y en a a present dans tout l'element de l'eau. Il est certain que si cette eau etait tombee_" &c.] II. ON THE OCEAN. Refutation of Pliny's theory as to the saltness of the sea (946. 947). 946. WHY WATER IS SALT. Pliny says in his second book, chapter 103, that the water of the sea is salt because the heat of the sun dries up the moisture and drinks it up; and this gives to the wide stretching sea the savour of salt. But this cannot be admitted, because if the saltness of the sea were caused by the heat of the sun, there can be no doubt that lakes, pools and marshes would be so much the more salt, as their waters have less motion and are of less depth; but experience shows us, on the contrary, that these lakes have their waters quite free from salt. Again it is stated by Pliny in the same chapter that this saltness might originate, because all the sweet and subtle portions which the heat attracts easily being taken away, the more bitter and coarser part will remain, and thus the water on the surface is fresher than at the bottom [Footnote 22: Compare No. 948.]; but this is contradicted by the same reason given above, which is, that the same thing would happen in marshes and other waters, which are dried up by the heat. Again, it has been said that the saltness of the sea is the sweat of the earth; to this it may be answered that all the springs of water which penetrate through the earth, would then be salt. But the conclusion is, that the saltness of the sea must proceed from the many springs of water which, as they penetrate into the earth, find mines of salt and these they dissolve in part, and carry with them to the ocean and the other seas, whence the clouds, the begetters of rivers, never carry it up. And the sea would be salter in our times than ever it was at any time; and if the adversary were to say that in infinite time the sea would dry up or congeal into salt, to this I answer that this salt is restored to the earth by the setting free of that part of the earth which rises out of the sea with the salt it has acquired, and the rivers return it to the earth under the sea. [Footnote: See PLINY, Hist. Nat. II, CIII [C]. _Itaque Solis ardore siccatur liquor: et hoc esse masculum sidus accepimus, torrens cuncta sorbensque._ (cp. CIV.) _Sic mari late patenti saporem incoqui salis, aut quia exhausto inde dulci tenuique, quod facillime trahat vis ignea, omne asperius crassiusque linquatur: ideo summa aequorum aqua dulciorem profundam; hanc esse veriorem causam, quam quod mare terrae sudor sit aeternus: aut quia plurimum ex arido misceatur illi vapore: aut quia terrae natura sicut medicatas aquas inficiat_ ... (cp. CV): _altissimum mare XV. stadiorum Fabianus tradit. Alii n Ponto coadverso Coraxorum gentis (vocant B Ponti) trecentis fere a continenti stadiis immensam altitudinem maris tradunt, vadis nunquam repertis._ (cp. CVI [CIII]) _Mirabilius id faciunt aquae dulces, juxta mare, ut fistulis emicantes. Nam nec aquarum natura a miraculis cessat. Dulces mari invehuntur, leviores haud dubie. Ideo et marinae, quarum natura gravior, magis invecta sustinent. Quaedam vero et dulces inter se supermeant alias._] 947. For the third and last reason we will say that salt is in all created things; and this we learn from water passed over the ashes and cinders of burnt things; and the urine of every animal, and the superfluities issuing from their bodies, and the earth into which all things are converted by corruption. But,--to put it better,--given that the world is everlasting, it must be admitted that its population will also be eternal; hence the human species has eternally been and would be consumers of salt; and if all the mass of the earth were to be turned into salt, it would not suffice for all human food [Footnote 27: That is, on the supposition that salt, once consumed, disappears for ever.]; whence we are forced to admit, either that the species of salt must be everlasting like the world, or that it dies and is born again like the men who devour it. But as experience teaches us that it does not die, as is evident by fire, which does not consume it, and by water which becomes salt in proportion to the quantity dissolved in it,--and when it is evaporated the salt always remains in the original quantity--it must pass through the bodies of men either in the urine or the sweat or other excretions where it is found again; and as much salt is thus got rid of as is carried every year into towns; therefore salt is dug in places where there is urine.-- Sea hogs and sea winds are salt. We will say that the rains which penetrate the earth are what is under the foundations of cities with their inhabitants, and are what restore through the internal passages of the earth the saltness taken from the sea; and that the change in the place of the sea, which has been over all the mountains, caused it to be left there in the mines found in those mountains, &c. The characteristics of sea water (948. 949). 948. The waters of the salt sea are fresh at the greatest depths. 949. THAT THE OCEAN DOES NOT PENETRATE UNDER THE EARTH. The ocean does not penetrate under the earth, and this we learn from the many and various springs of fresh water which, in many parts of the ocean make their way up from the bottom to the surface. The same thing is farther proved by wells dug beyond the distance of a mile from the said ocean, which fill with fresh water; and this happens because the fresh water is lighter than salt water and consequently more penetrating. Which weighs most, water when frozen or when not frozen? FRESH WATER PENETRATES MORE AGAINST SALT WATER THAN SALT WATER AGAINST FRESH WATER. That fresh water penetrates more against salt water, than salt water against fresh is proved by a thin cloth dry and old, hanging with the two opposite ends equally low in the two different waters, the surfaces of which are at an equal level; and it will then be seen how much higher the fresh water will rise in this piece of linen than the salt; by so much is the fresh lighter than the salt. On the formation of Gulfs (950. 951). 950. All inland seas and the gulfs of those seas, are made by rivers which flow into the sea. 951. HERE THE REASON IS GIVEN OF THE EFFECTS PRODUCED BY THE WATERS IN THE ABOVE MENTIONED PLACE. All the lakes and all the gulfs of the sea and all inland seas are due to rivers which distribute their waters into them, and from impediments in their downfall into the Mediterranean --which divides Africa from Europe and Europe from Asia by means of the Nile and the Don which pour their waters into it. It is asked what impediment is great enough to stop the course of the waters which do not reach the ocean. On the encroachments of the sea on the land and vice versa (952-954). 952. OF WAVES. A wave of the sea always breaks in front of its base, and that portion of the crest will then be lowest which before was highest. [Footnote: The page of FRANCESCO DI GIORGIO'S _Trattato_, on which Leonardo has written this remark, contains some notes on the construction of dams, harbours &c.] 953. That the shores of the sea constantly acquire more soil towards the middle of the sea; that the rocks and promontories of the sea are constantly being ruined and worn away; that the Mediterranean seas will in time discover their bottom to the air, and all that will be left will be the channel of the greatest river that enters it; and this will run to the ocean and pour its waters into that with those of all the rivers that are its tributaries. 954. How the river Po, in a short time might dry up the Adriatic sea in the same way as it has dried up a large part of Lombardy. The ebb and flow of the tide (955-960). 955. Where there is a larger quantity of water, there is a greater flow and ebb, but the contrary in narrow waters. Look whether the sea is at its greatest flow when the moon is half way over our hemisphere [on the meridian]. 956. Whether the flow and ebb are caused by the moon or the sun, or are the breathing of this terrestrial machine. That the flow and ebb are different in different countries and seas. [Footnote: 1. Allusion may here be made to the mythological explanation of the ebb and flow given in the Edda. Utgardloki says to Thor (Gylfaginning 48): "When thou wert drinking out of the horn, and it seemed to thee that it was slow in emptying a wonder befell, which I should not have believed possible: the other end of the horn lay in the sea, which thou sawest not; but when thou shalt go to the sea, thou shalt see how much thou hast drunk out of it. And that men now call the ebb tide." Several passages in various manuscripts treat of the ebb and flow. In collecting them I have been guided by the rule only to transcribe those which named some particular spot.] 957.