CHAPTER IV.
The Atlantic Cable.

Among the applications of the telegraph which deserve special mention for magnitude and importance is the Atlantic Cable. For boldness of conception, tireless persistence in execution, and value of results, this engineering feat, though nearly a half century old, still challenges the admiration of the world, and marks the beginning of one of the great epochs of the Nineteenth Century. It was not so brilliant in substantive invention, as it added but little to the telegraph as already known, beyond the means for insulating the wires within a gutta percha cable, but it was one of the greatest of all engineering works. It was chiefly the result of the energy and public spirit of Mr. Cyrus W. Field, an eminent American citizen. Three times was its laying attempted before success crowned the work. The first expedition sailed August 7, 1857, and consisted of a fleet of eight vessels, four American and four English, starting from Valentia on the Irish coast. On August 11 the cable parted, and 344 miles of the cable were lost in water two miles deep. In 1858 a renewal of the effort to lay the cable was made. Improvements were added in the paying out machinery, and a different manner of coiling the enormous load of cable on the vessels was resorted to, and provisions also were made to protect the propeller from contact with the cable. On June 10 the telegraphic fleet steamed out of Plymouth harbor. It consisted of the U. S. frigate “Niagara,” with the paddle-wheel steamer “Valorous” as a tender, and the British frigate “Agamemnon,” with the paddle-wheel steamer “Gorgon” as a tender. After three days at sea, terrible gales were encountered and much damage resulted. The vessels were to proceed to midocean, and the portions of the cable carried by the “Niagara” and “Agamemnon” were to be spliced, and the two vessels were then to sail in opposite directions to their respective coasts. The first splice was made on the 26th of June. After paying out two and a half miles each, the cable parted. Again meeting and splicing, forty miles each were paid out, and the cable again parted. On the 28th another splicing was effected, and 150 miles each were paid out, and again the cable parted, and the expedition had to be abandoned. After much financial embarrassment and adverse criticism, the courageous and public-spirited directors who had control of the enterprise dispatched another expedition, which sailed July 17, 1858. The two vessels, “Niagara” and “Agamemnon,” with their tenders, proceeded to midocean, and following the same method of connecting the ends of their respective cable sections, they sailed in opposite directions. On August 5, 1858, Mr. Cyrus Field announced by telegram from Trinity Bay, on the coast of Newfoundland, that Trinity Bay in America, and Valentia in Ireland, 2,134 miles apart, had been connected, and the great Atlantic cable was an established fact.

On August 16, 1858, the first message came over from Queen Victoria to President Buchanan of the United States, as follows:

“To the President of the United States, Washington:

“The Queen desires to congratulate the President upon the successful completion of this great international work, in which the Queen has taken the deepest interest.

“The Queen is convinced that the President will join with her in fervently hoping that the Electric Cable which now connects Great Britain with the United States will prove an additional link between the nations whose friendship is founded upon their common interest and reciprocal esteem.

“The Queen has much pleasure in thus communicating with the President, and renewing to him her wishes for the prosperity of the United States.”

to which the President replied as follows:

“Washington City, Aug. 16, 1858.

“To Her Majesty Victoria, Queen of Great Britain:

“The President cordially reciprocates the congratulations of Her Majesty, the Queen, on the success of the great international enterprise accomplished by the science, skill, and indomitable energy of the two countries. It is a triumph more glorious, because far more useful to mankind, than was ever won by conqueror on the field of battle.

“May the Atlantic Telegraph, under the blessing of Heaven, prove to be a bond of perpetual peace and friendship between the kindred nations, and an instrument destined by Divine Providence to diffuse religion, civilization, liberty and law throughout the world. In this view will not all nations of Christendom spontaneously unite in the declaration that it shall be forever neutral, and that its communications shall be held sacred in passing to their places of destination, even in the midst of hostilities?

(Signed)

“James Buchanan.”

Great rejoicing on both sides of the ocean followed, and the public print was filled with accounts of the enterprise. The following selection from the Atlantic Monthly of October, 1858, is an apostrophe in lofty sentiments of verse, which to-day stirs the Twentieth Century heart as a joyous prophecy fulfilled:

After a few months of working, the cable became inoperative, but its success was a demonstrated fact, and in 1866 a new cable was laid by the aid of that monster steamer “The Great Eastern,” since which time the cable has become one of the great factors of modern civilization.

Probably the most important of the inventions relating to submarine telegraphs is the siphon recorder, invented by Sir William Thompson, now Lord Kelvin (U. S. Pat. No. 156,897, Nov. 17, 1874). It is called a siphon recorder because the record is made by a little glass siphon down which a flow of ink is maintained like a fountain pen. This siphon is vibrated by the electric impulses to produce on the paper strip a zigzag line, whose varying contour is made to represent letters. In the illustration, Fig. 15, m is an ink well, o a strip of paper, and n the ink siphon, one end of which is bent and dips down into the ink well, and the other end of which traces the record on the moving paper strip o. The siphon is sustained on a vertical axis l, and its lateral vibration is effected as follows: A light rectangular coil b b, of exceedingly fine insulated wire, is suspended between the poles N S of a powerful electro-magnet energized by a local battery. In the coil b b is a stationary soft iron core a, magnetized by the poles N S. The coil b b is suspended upon a vertical axis consisting of a fine wire f f, and the delicate electrical impulses over the submarine cable enter the coil b b through the axial wire f f as a conductor, and cause a greater or less oscillation of the coil b b between the poles N S of the electro-magnet. The coil b b is connected by a thread k to the siphon, and pulls the siphon in one direction, while the siphon is pulled in the opposite direction by a helical spring attached to an arm on the siphon axis l. The jagged lines seen in Fig. 16 spell the words ““siphon recorder”.”

To-day there lie in submerged silence, but pulsating with the life of the world, no less than 1,500 submarine telegraphs. Their aggregate length is 170,000 miles; their total estimated cost is $250,000,000, and the number of messages annually transmitted over them is 6,000,000. Thirteen cables work daily across the Atlantic, and an additional one is being laid from Germany. Messages now go across the Atlantic and are received on the siphon recorder at the rate of fifty words a minute, and at a cost of twenty-five cents a word. Our guns may thunder in the Philippines, and the news by cable, traveling faster than the earth on its axis, may reach the Western Hemisphere under the paradoxical condition of several hours earlier than it occurred. Cablegrams to Manila cost $2.38 a word, and the cable tolls for our War Department alone are costing at the rate of $325,000 a year. The logical outcome is a Pacific cable, a bill for which, connecting San Francisco and Honolulu, has already passed the United States Senate.

Messages from the Executive Mansion at Washington to the battlefield at Santiago were sent and responses received within twelve minutes, while a message dispatched from the House of Representatives in Washington to the House of Parliament in London, in the chess match of 1898, was transmitted and a reply received in thirteen and one-half seconds.

To-day the cable with the still small voice, more divine than human, speaks with one accent to all the nations of the earth. Differing though they may in tongue and skin, in thought and religion, in physical development and clime, the telegraph speaks to them all alike, and by all is understood. Truly it fulfils the prophecy so gracefully expressed in the verses quoted, and has become the common bond of union among the nations of the earth.

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CHAPTER V.
The Dynamo and Its Applications.

In the last thirty-five years of the Nineteenth Century there has grown up into the full stature of mechanical majority this stalwart son of electrical lineage. As the means for furnishing electrical power it stands to-day the great fountain head of electrical generation, and in its peculiar field ranks as of equal importance with the steam engine. Until about 1865 the voltaic battery, which generated electricity by chemical decomposition, was practically the only means for producing electricity for industrial and commercial purposes. It was through its agency that the telegraph, the electric light, and many other discoveries in electricity were made and rendered possible. Its cost and limited amount of current, however, restricted the limits of its practical application, and although its current could furnish beautiful laboratory experiments, its mechanical work was more in the nature of illustration than utilization. But with the advent of the dynamo electricity has taken a new and very much larger place in the commercial activities of the world. It runs and warms our cars, it furnishes our light, it plates our metals, it runs our elevators, it electrocutes our criminals; and a thousand other things it performs for us with secrecy and dispatch in its silent and forceful way. But what is a dynamo? To the average mind the most satisfactory answer would be—that it is simply a machine which converts mechanical power into electricity. Attach a dynamo to a steam engine, and the power of the steam engine will, through the dynamo, become transformed or converted into a powerful electric current. Any other source of mechanical power, such as a water wheel, gas engine, wind wheel, or even a horse or man, will serve to operate the dynamo; its primary and sole function being to take power and convert it into electricity.

The stepping stone to the dynamo in its development was the magneto-electrical machine. This is a machine founded upon the general principle observed by Faraday in 1831 and 1832, and also by Prof. Henry about the same time, that when a magnet is made to approach a helix of insulated wire it causes a current of electricity to flow in the helix as long as the magnet advances. If the magnet is passed through the helix, the current is reversed as soon as the magnet passes the middle point. The principle is the same if the magnet be made to approach and recede from the poles of an electro-magnet having a helix wound around a soft iron core. Likewise the same result occurs if the electro-magnet with its helix is made to approach and recede from a permanent magnet, the current in the helix flowing in one direction when it approaches the permanent magnet, and in the opposite direction when leaving the said magnet. The movement of the two elements in relation to each other requires some force to overcome the repellent and attractive actions, and this force is converted into electrical energy. This is the principle of the magneto-electric machine.

Saxton in the United States and Pixii in France were the first to produce organized devices of this class for generating electricity from magnetism. Pixii’s machine (1832) consisted of a permanent horse-shoe magnet which was caused to revolve in proximity to an armature upon which was wound a coil of insulated wire. On March 30, 1852, Sonnenberg and Rechten obtained a United States patent, No. 8,843, for an electrical machine for killing whales, and on August 19, 1856, Shepard obtained U. S. Pat. No. 15,596 for the machine which came to be known as the “Alliance” machine. Both of these machines had permanent field magnets, and were early types of magneto-electric machines. The efficiency of these magneto-electric machines was necessarily limited to the strength of the inducing field magnets, which, being permanent magnets, were a positive and fixed factor. It was an easy step to substitute electro-magnets for permanent magnets, as the field or inducing magnets, and also to excite the (electro) field magnet by voltaic batteries, but the important step which resulted in the machine which is called the “dynamo” (from the Greek “Δυναμις”—power) was yet to come.

This step consisted in taking the current induced in the revolving helix or armature (by the field magnets) and sending it back through the coils of the field magnets which produced it, thereby increasing the energy of the field magnet coils, and they in turn with an increased efficiency and reciprocal action induce still stronger currents in the armature coils, and so a building up process, or principle of mutual and reciprocal excitation, is carried on until the maximum efficiency is reached. This principle was the discovery of Soren Hjorth, of Copenhagen, and is fully described in his British patent, No. 806 of 1855, for “An Improved Magneto-Electric Battery.” As the prototype of the dynamo, it is worthy of illustration. In the illustration, Figs. 18 and 19, a is a revolving wheel bearing the armature coils, C permanent magnets, d electro-magnets (field magnets), and g the commutator. Quoting from his specifications, he says: ““The permanent magnets acting on the armatures brought in succession between their poles, induce a current in the coils of the armatures, which current, after having been caused by the commutator to flow in one direction, passes round the electro-magnets (field magnets), charging the same and acting on the armatures. By the mutual action between the electro-magnets and the armatures an accelerating force is obtained, which in result produces electricity greater in quantity and intensity than has heretofore been obtained by similar means.””

Although the principle of the dynamo was clearly embodied in the Hjorth patent, its value was not appreciated until some time later. Eleven years later Wilde (U. S. Pat. No. 59,738, Nov. 13, 1866), employed a small machine with permanent magnets to excite the coil-wound field magnets of a larger machine. But Siemens (British Pat. No. 261 of 1867), taking up the principle employed by Hjorth, dispensed with his superfluous permanent magnets, having found that the residual magnetism, which always remained in iron which has once been magnetized, was sufficient as a basis to start the building up process. Farmer, Wheatstone and Varley also recognized this fact about the same time. Siemens’ patent also was the first embodiment of what is known as the bobbin armature. Gramme and D’Ivernois (British Pat. 1,668 of 1870, and U. S. Pat. No. 120,057, of Oct. 17, 1871), were the first to bring out the continuously wound ring armature.

Active development now began in various types and by various inventors, including Weston, Brush, Edison, Thomson and Houston, Westinghouse, and others, who have brought the dynamo to its present high efficiency.

The revolving coils of the dynamo are called the armature, and the fixed electro-magnets are called the field magnets, and these latter may be two or more in number. When two are used they are arranged on opposite sides of the armature, and form what is known as the bipolar machine. A larger number constitutes the multipolar machine. The field magnets in the multipolar machine usually are arranged in radial position around the entire circumference of the revolving armature, and are held in a fixed circular frame. To give a clear idea of the principles of the dynamo, the bipolar machine is best suited for illustration, and is here given in Figs. 20 and 21, in which Fig. 20 represents the dynamo complete, and Fig. 21 a detail of the end of the armature and commutator. This armature consists of coils or bobbins of insulated wire, each section having its terminals connected with separate insulated plates on the hub, which plates are known as the commutator. When any section of the armature approaches the pole of a field magnet, the current induced in that section of the armature coils by the field magnet, is taken off from a corresponding plate of the commutator by flat springs, seen in Fig. 20, and known as brushes. The field magnets A and B, Fig. 20, are shown with only a few turns of wire about them for clearer illustrations of the connections, which are made as follows: The wire a is extended in coils around the field magnet B, and thence around field magnet A, and thence to the upper brush on the commutator, thence through the wire coils or bobbins of the rotary armature C, and thence by the lower brush to the wire b. The terminals of the wires a and b extend to the point of utilization of the current, whether this be electric lights, motors, or other applications. In this illustration, the circuit, it will be seen, passes through both the coils of the field magnets and the coils of the armature, involving the principle of mutual excitation.

There are two principal kinds of dynamos—those producing the alternating currents, and those producing the continuous current. In the first the current alternates in direction, or is composed of an infinite number of impulses of opposite polarity: one polarity when a section of the armature coil is approaching a north field magnet pole or receding from a south pole, and the other polarity when receding from a north field magnet pole and approaching a south pole. In the continuous current machine, the commutator and brushes are so arranged as to take up all the impulses of the same polarity and conduct them away by one brush, and gathering all the impulses of the opposite polarity and conducting them away by another brush. Thus the current of each brush, in the continuous current machine, is always of the same polarity, and the polarity of one being always positive, and that of the other negative, the current flows continuously in the same direction. A third species of dynamo is the pulsatory, in which the current flow is invariable in direction, but proceeds in waves.

A change in the character of the current generated by the dynamo is made by what is known as the “transformer,” in which the principle of the induction coil is made available. In this way, for instance, the high potential currents generated by the powerful water wheels at Niagara Falls are taken twenty miles to Buffalo, and are there transformed into other currents of lower potential, suited to incandescent lighting and other various uses. A similar scheme is in process of fulfillment in the establishment of a water power electric plant near Conowingo, Maryland, on the Susquehanna River, to furnish electrical power to Baltimore, Wilmington and Philadelphia.

An important development in electrical generation and transmission is to be found in what is known as the polyphase, multiphase, or rotating current, pioneer patents for which were granted to Tesla May 1, 1888, Nos. 381,968, 381,969, 382,279, 382,280, 382,281 and 382,282.

Realizing the possibilities of the dynamo, the Legislature of New York in 1888 passed a law, which went into effect in 1889, in that State, substituting death by electricity for the hangman’s noose. The criminal is strapped in the chair, seen in Fig. 22, one terminal of the wire from the dynamo is strapped upon his forehead, and the other to anklets on his legs, and like a flash of lightning the deadly energy of the dynamo performs its work.

Not the least of the applications of the dynamo is its use in electro-metallurgy for plating metals, and also for promoting chemical reactions. The electric furnace, stimulated into higher heat by the dynamo than can be otherwise obtained, has brought about many valuable discoveries, and made great advances in various arts. The metal aluminum, and the hard abrasive or polishing and grinding material known as “carborundum” are the products of the electric furnace, and so is the product known as “calcium carbide,” which, when immersed in water, gives off acetylene gas and is a product now universally used for that purpose, and rapidly increasing in commercial importance.

In Fig. 23 is seen the Acheson electric furnace for producing carborundum. The electric current traverses the furnace through a series of horizontal electrodes at each end, and highly heats a central core of carbon, which is disposed in a mass of silicious and carbonaceous material, and which latter is converted by the heat into silicide of carbon, or carborundum. In Fig. 24 is shown a continuous electric furnace constructed as a revolving wheel, under the Bradley patents. Rim sections 5 are placed on the wheel on one side and filled with a mixture of carbon and lime, through which the electric current is passed from the dynamo g. The heat of the current fuses the mass and converts it into calcium carbide, and as the wheel slowly revolves the rim sections 5 are removed from the opposite side, and the mass of calcium carbide, seen at x, is broken off. The electrolytic production of copper through the agency of the dynamo amounts to 150,000 tons annually, and the commercial reduction of aluminum by the electric furnace has grown from eighty-three pounds in 1883 to 5,200,000 pounds in 1898, and its cost has been reduced to about 33 cents per pound.

The storage battery, holding in reserve its stored up electric energy, also owes its practical value entirely to the dynamo which charges it, and thus makes available a portable source of supply.

To contemplate the dynamo with its clumsy, enormous spools, it suggests to the imagination of the average observer the gigantic toy of some Brobdingnagian boy—but the dynamo is no toy. It is the most compact, business-like, and dangerous of all utilitarian devices. To touch its brushes may be instant death, for the dynamo is the prison house of the lightning, and resents intrusion. Hidden away from public gaze in some sequestered power house, and working night and day like some tireless, dumb, and mighty genii, it sends its magnetic thrills of force silently through the many miles of wire extending like radii from some great nerve center through the conduits in our streets, and stretching from pole to pole like giant cobwebs through the air. Responding to its force, thousands of little incandescent threads leap into radiant brightness and shed their mellow and genial light in our offices, our stores, hotels, and homes. Brilliant arc lamps, rivaling the sun in power, make night into day, and produce along our streets coruscations, silhouettes, and dancing shadows in spectacular and unceasing pageants. From the towering lighthouses of our coasts its beams are thrown seaward, and a beacon for the mariner shines beyond all other lights. The great search light of our ships is in itself but a hollow mockery until the dynamo whispers in its ear the word ““light!”” and then its beam, reaching for miles along the horizon, discovers a stealthy enemy, or signals the safe return to port. The mighty force of the dynamo entering the electric motors on the street cars turns the wheels and transports its load with scarcely a passenger inside realizing how it is all done. The same energy turns the electric fan, and with kindly service soothes the weary sufferer, and at another place remorselessly takes the life of the condemned criminal. The dynamo is one of the great factors of modern civilization, and its potential name, like that of “dynamite,” rightly defines its character.

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CHAPTER VI.
The Electric Motor.

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.

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.

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.”

““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.

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.

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.

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.

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.

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.

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.

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.

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