CHAPTER VI.

THE ELECTRIC MOTOR. BARLOW’S SPUR WHEEL--DAL NEGRO’S ELECTRIC PENDULUM--PROF. HENRY’S ELECTRIC MOTOR--JACOBI’S ELECTRIC BOAT--DAVENPORT’S MOTOR--THE NEFF MOTOR--DR. PAGE’S ELECTRIC LOCOMOTIVE--DR. SIEMENS’ FIRST ELECTRIC RAILWAY AT BERLIN, 1879--FIRST ELECTRIC RAILWAY IN UNITED STATES, BETWEEN BALTIMORE AND HAMPDEN, 1885--THIRD RAIL SYSTEM--STATISTICS ELECTRIC RAILWAYS AND GENERAL ELECTRIC CO.--DISTRIBUTION ELECTRIC CURRENT IN PRINCIPAL CITIES. Although the electric motor of to-day depends for practical value entirely upon the dynamo which supplies it with electric power, nevertheless the motor considerably antedated the dynamo. The genesis of the electric motor began in 1821 with Faraday’s observation of the phenomenon of the conversion of an electric current into mechanical motion. In his experiment a copper wire was supported in a vertical position so as to dip into a cup of mercury, while a small bar magnet was anchored at one end by a thread to the bottom of the cup and floated in the mercury in upright position. The mass of mercury being connected to one pole of a battery, and the vertical wire to the other, it was found that when the circuit was completed by clipping the wire into the mercury, the floating bar magnet would revolve around the wire as a center. [Illustration: FIG. 26.--BARLOW’S WHEEL.] In 1826 Barlow, of Woolwich, made his electrical spur wheel, Fig. 26, and in 1830 the Abbe Dal Negro, in Padua, is said to have constructed a sort of vibrating electrical pendulum, both of which devices were crude forms of magnetic engines. Dal Negro’s machine, see Fig. 27, consisted of a magnet A, movable about an axis situated about one-third of its length, and the upper extremity of which was capable of oscillating between the two branches of an electro-magnet E. A current being sent into the electro-magnet, passed through an eight-cupped mercurial commutator C, which the oscillating magnet controlled by means of a rod _t_ and a fork F. When the magnet had been attracted toward one of the poles of the electro-magnet this very motion of attraction acting upon the commutator changed the direction of the current, and the magnet was repelled toward the other branch of the electro-magnet, and so on. [Illustration: FIG. 27.--DAL NEGRO’S ELECTRIC MOTOR.] In 1828 Prof. Joseph Henry produced his energetic electro-magnets sustaining weights of some thousands of pounds, and gave prophetic suggestion of the possibilities of electricity as a motive power. In 1831 he devised the electric motor shown in Fig. 28, which is described in Prof. Henry’s own words as follows: “A B is the horizontal magnet, about seven inches long, and movable on an axis at the center; its two extremities when placed in a horizontal line are about one inch from the north poles of the upright magnets C and D. G and F are two large tumblers containing diluted acid, in each of which is immersed a plate of zinc surrounded with copper; _l m s t_ are four brass thimbles soldered to the zinc and copper of the batteries and filled with mercury. “The galvanic magnet A B is wound with three strands of copper bell wire, each about twenty-five feet long; the similar ends of these are twisted together so as to form two stiff wires _q r_, which project beyond the extremity B, and dip into the thimbles _s t_. [Illustration: FIG. 28.--PROF. HENRY’S ELECTRIC MOTOR.] “To the wires _q r_ two other wires are soldered so as to project in an opposite direction, and dip into the thimbles _l m_. The wires of the galvanic magnet have thus, as it were, four projecting ends; and by inspecting the figure it will be seen that the extremity _p_, which dips into the cup _m_, attached to the copper of the battery in G, corresponds to the extremity _r_ which dips into the cup _t_, connecting, with the zinc in battery F. When the batteries are in action, if the end B is depressed until _q r_ dips into the cups _s t_, A B instantly becomes a powerful magnet, having its north pole at B; this, of course, is repelled by the north pole D, while at the same time it is attracted by C; the position is consequently changed, and _o p_ comes in contact with the mercury in _l m_; as soon as the communication is formed, the poles are reversed, and the position again changed. If the tumblers be filled with strong diluted acid, the motion is at first very rapid and powerful, but it soon almost entirely ceases. By partially filling the tumblers with weak acid, and occasionally adding a small quantity of fresh acid, a uniform motion, at the rate of seventy-five vibrations in a minute, has been kept up for more than an hour; with a large battery and very weak acid the motion might be continued for an indefinite length of time.” Following Prof. Henry came Sturgeon’s rotary motor of 1832, Jacobi’s rotary motor of 1834, Fig. 29, which had electro-magnets both in the field and armature; Davenport’s motor of 1834, Zabriskie’s motor of 1837, in which a vibrating magnet converted reciprocating into rotary motion; Davenport’s motor of 1837 (U. S. Pat. No. 132, Feb. 25, 1837), Fig. 30; Page’s rotary motor of 1838, Walkley’s motor of 1838 (U. S. Pat. No. 809, June 27, 1838); Stimson’s motor of 1838 (U. S. Pat. No. 910, Sept. 12, 1838); Page’s motor of 1839, Cook’s of 1840 (U. S. Pat. No. 1,735, Aug. 25, 1840); Elias’ motor of 1842, invented in Holland; Lillie’s motor of 1850 (U S. Pat. No. 7,287, April 16, 1850); the Neff motor of 1851 (U. S. Pat. No. 7,889, Jan. 7, 1851), of which illustration is given in Fig. 31, and Page’s motor of 1854 (U. S. Pat. No. 10,480, Jan. 31, 1854). In 1835 Davenport constructed a small circular railway at Springfield, Mass. [Illustration: FIG. 29.--JACOBI’S ROTARY ELECTRIC MOTOR.] In 1839 Prof. Jacobi, with the aid of Emperor Nicholas, applied his electric motor to a boat 28 feet long, carrying fourteen passengers, and propelled the same at a speed of three miles an hour. About the same time Robert Davidson, a Scotchman, experimented with an electric railway car sixteen feet long, weighing six tons, and attaining a speed of four miles an hour. In 1840 Davenport, by means of his electric motor, printed a news sheet called the _Electro Magnet and Mechanics’ Intelligencer_. In 1851 an electric locomotive made by Dr. Page in accordance with his subsequent patent of 1854, drew a train of cars from Washington to Bladensburg at a rate of nineteen miles an hour. [Illustration: FIG. 30.--DAVENPORT MOTOR.] [Illustration: FIG. 31.--NEFF MOTOR.] [Illustration: FIG. 32.--WESTINGHOUSE ELECTRIC MOTOR.] All these motors were operated by voltaic batteries, and on account of the cost of the latter but little practical use of the electric motor was made until the dynamo was invented. In 1873 an accidental discovery led to the rapid practical development of the electric motor. It is said that at the industrial exhibition at Vienna in that year, a number of Gramme dynamos were being placed in position, and a workman in making the electrical connections for one of these machines, inadvertently connected it to another dynamo in active operation, and was surprised to find that the dynamo he was connecting began to revolve in the opposite direction. This was the clue that led to the important recognition of the structural identity of the dynamo and the modern type of electric motor. The dynamo and the electric motor then grew into development together, and the same inventors who brought the dynamo to its present high efficiency, produced electric motors of corresponding principles and value. In the illustration, Fig. 32, is shown a modern electric motor. It is a Westinghouse two-phase machine, of 300 horse power, of the self starting induction type, designed to operate at a speed of 500 revolutions per minute when supplied with two-phase currents of 3,000 alternations per minute and 2,000 volts pressure. [Illustration: FIG. 33.--SIEMENS’ FIRST ELECTRIC RAILWAY.] The most important application of the electric motor is for street car operation. The first electric railway was that of Dr. Werner Siemens, at Berlin, in 1879, an illustration of which is given in Fig. 33. The first electric railway in America was installed at Baltimore in 1885, and ran to Hampden, a distance of two miles. [Illustration: FIG. 34.--OVERHEAD TROLLEY CAR.] [Illustration: FIG. 35.--UNDERGROUND ELECTRIC TROLLEY SYSTEM.] The familiar overhead trolley cars, and the far superior conduit trolley system, represent perhaps the largest use made of electric motors. The motors are arranged under the cars in varying forms adapted to the structure of the car. In the overhead trolley, shown in Fig. 34, the current is taken from the overhead wire by a flexible trolley pole, and in the conduit system a trolley known as a plow extends from the bottom of the car through a narrow slot in the top of the conduit and makes a traveling contact with the conductor rails within the conduit, which carry the electric current. Fig. 35 is an end view of a street car of the latter type, with the conduit and conductor rails in cross section. The current goes from one rail to one bearing surface of the plow, thence to the motor on the car and back to the other bearing surface of the plow and the other conductor rail in the conduit. [Illustration: FIG. 36.--THIRD RAIL SYSTEM ON THE N. Y., N. H. & H. RAILROAD--FRONT END OF MOTOR CAR.] A third system, which has supplanted to some extent the use of steam on short line railways, is the so-called third rail system, of which an example is seen in Fig. 36. A third conductor rail is placed between the usual track rails, and from this conductor the current is taken by a sliding shoe on the car, and carried to the motor and thence through the car wheels to the track rails. To reduce danger from the live rail, the third rail in some systems is made in sections, and, by an automatic switching process as the car moves along, only the sections of the rail beneath the car are brought into circuit, all other portions being cut out. The use of electric motors has greatly extended, cheapened, and expedited the street car service. All the principal thoroughfares of cities and even towns are now so equipped, and radiating suburban lines extend for miles from the city, affording for five cents a pleasant and cheap excursion for the poor to the green fields and fresh air of the country. [Illustration: FIG. 37.--ELECTRIC RAILWAY MOTOR, CLOSED.] [Illustration: FIG. 38.--ELECTRIC RAILWAY MOTOR, OPENED.] Figs. 37 and 38 show an electric motor used on street cars, as made by the General Electric Company. Externally it presents the appearance of some curious, uncouth, cast iron box, which, to the uninitiated, piques the curiosity, and when opened adds no explanation of its real character. In it, however, the electrician finds a most interesting combination of metal and magnetism. [Illustration: FIG. 39.--ELECTRIC LOCOMOTIVE OF B. & O. TUNNEL IN BALTIMORE.] In Fig. 39 is shown one of the most powerful electric locomotives ever constructed. It was built in 1895 by the General Electric Company for the Baltimore & Ohio Railroad, to draw trains through the long tunnel from the Camden Street Station in Baltimore, for the purpose of avoiding smoke and gas in the tunnel, which is 7,339 feet long. The locomotive weighs ninety-six tons, or twenty-five tons above the average steam locomotive. It was designed to draw 100 trains daily each way, moving passenger trains of a maximum weight of 500 tons at thirty-five miles an hour, and freight trains of 1,200 tons at fifteen miles an hour. It has two trucks, and eight drive wheels of sixty-two inches diameter. There are four motors, two to each truck, each rated at 360 horse power. Other important applications of the electric motor are, the propelling of automobile carriages, small boats, and fish torpedoes, operating steering gear for ships, passenger elevators, rock drills in mines, running printing presses, fans, sewing machines, graphophones, and in all applications where space is limited and cleanliness a desideratum. According to Mulhall there were in 1890 in the United States and Canada about 645 miles of street railway operated by electricity. This about concluded the first decade of the life of the electric railway. Some idea of the rapid increase in this field may be had by the statement of the same authority that there were in 1890, at the end of this first decade, forty-five additional electric railroads in course of construction, aggregating 512 miles of way, which nearly doubled the previous existing mileage. In 1898 it was estimated that there were in the United States 14,000 miles of electric railroads, with a nominal capital of $1,000,000,000, and employing 170,000 men. In the same year a single electrical contract was entered into between the Third Avenue Railroad and the Union Railway Company of New York, acting as one, and the Westinghouse Electrical and Manufacturing Company, amounting to $5,000,000. This was for the electrical equipment of their respective railway lines, and is the largest electrical contract ever made. The change in equipment from other motive power to the electric is rapidly going on in all directions, and the rapid succession of trains will doubtless cause it, for passenger traffic on short lines, to eventually supersede steam. The eighth annual report of the General Electric Company shows for the year 1899 orders received for railway and other electrical equipment amounting to $26,323,626; goods shipped, $22,379,463.75; profit on same, $3,805,860.18. The growth of its business from 1893 to 1899 shows the following per cent. of increase: In 1893, 36 per cent. above 1892; in 1894, 126 per cent. above 1893; in 1895, 10 per cent. above 1894; in 1896, 60 per cent. above 1895; in 1897, 60 per cent. above 1896; in 1898, 21 per cent. above 1897; in 1899, 51 per cent. above 1898. The capitalization in electrical appliances in the United States in 1898 is estimated at $1,900,000,000, most of which is devoted to industries in which the electric motor is used. The export of electrical apparatus from this country amounts to more than three million dollars annually, and it is said that there are eight times as many electric railways in the United States as in all the rest of the world combined. The use of electrical current in twelve principal cities in the United States was distributed in 1898 as follows: Lamps, arcs, and motors in sixteen candle power equivalents. Boston 616,000 New York 1,718,000 Chicago 1,278,000 Brooklyn 322,000 Baltimore 224,000 Philadelphia 488,000 St. Louis 303,000 San Francisco 231,000 Buffalo 125,000 Rochester 184,000 Cincinnati 201,000 New Orleans 81,000 Boston makes the largest use of electrical current in proportion to its population of any city in the world. Rochester is next. Both of these cities employ in electrical units of 16 c. p. equivalents, more than one electric lamp for every man, woman and child in their respective populations. The dynamo and the electric motor have together wrought this great development. The dynamo takes mechanical power and converts it into electrical energy, and the electric motor takes the electrical energy and converts it back into mechanical power. Standing behind them both, however, is the steam engine, and these three afford a beautiful illustration of the law of correlation of forces. The force starts with the combustion of coal under the boiler of the steam engine. When carbon unites chemically with oxygen, it is an exothermic reaction that gives off heat as correlated energy. The influence of heat on the molecules of water in the boiler causes them, by repellent action, to assume the qualities of an elastic gas, and this expanding as steam drives the piston of the steam engine. The steam engine overcomes by force the resistance existing between the dynamo’s field magnets and armature coil, and sets up in the latter the correlated force of an electric current, and the electric current, traveling to its remote destination by suitable conductors, enters the coils of the electric motor in reverse relation to that of the dynamo, and in producing the reverse effect between the armature and field magnets, electrical energy is converted back into mechanical power. It is not possible to obtain in the electric motor the full equivalent of the dynamo’s current, nor in the dynamo the full equivalent of the steam engine’s power, nor in the steam engine the full equivalent of the chemical energy in the combustion of coal. Loss by radiation, by conduction, by friction, and by electrical resistance precludes this, but while there is loss in a utilitarian sense there is no real loss, for force like matter, is indestructible, and the proof of this universal law by Joule, in 1843, constitutes one of the highest triumphs of philosophy and one of the most important discoveries of the Nineteenth Century.