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VII. ELECTRIC LOCOMOTION.
ОглавлениеThe dawn of the nineteenth century saw, as vehicles of locomotion, the saddled hackney, the clumsy wagon, the ostentatious stage-coach, the primitive dearborn, the lumbering carriage, the poetic “one-hoss shay.” The universal energy was the horse. A new energy came with the application of steam, and with it new vehicular locomotion,—easier, swifter, stronger, for the most part cheaper, rendering possible what was hitherto impossible as to time and distance.
This signal triumph of the century may not have been eclipsed by the introduction of subsequent locomotive changes, but it was to be supplemented by what, at the beginning, would have passed for the idle dream of a visionary. The horse-car came, had its brief day, and went out with all its inconveniences, cruelties, and horrors before, in part, the traction-car, and, in part, the rapidly revolutionizing energy of electricity.
ELECTRIC LOCOMOTIVE.
The first conception of a railway to be operated by electricity dates from about 1835, when Thomas Davenport, of Brandon, Vt., contrived and moved a small car by means of a current from voltaic cells placed within it. In 1851, Professor Page, of the Smithsonian Institution, ran a car propelled by electricity upon the steam railway between Washington and Baltimore, but though he obtained a high rate of speed, the cost of supplying the current by means of batteries—the only means then known—prohibited the commercial use of his method.
With the invention of the dynamo as an economic and powerful generator of electricity, and also the invention of the motor as a means of turning electrical energy to mechanical account, the way was open, both in the United States and Europe, for more active investigation of the question of electric-car propulsion. Between 1872 and 1887, different inventors, at home and abroad, placed in operation several experimental electric railways. Few of them proved practical, though each furnished a fund of valuable experience. An underground electric street railway was operated in Denver as early as 1885; but the one upon the trolley plan, which proved sufficiently successful to warrant its being called the first operated in the United States, was built in Richmond, Va., in 1888. It gave such impetus to electric railway construction that, in five years’ time, enormous capital was embarked, and the new means of propulsion was generally accepted as convenient, safe, and profitable.
The essential features of the electric railway are: (1.) The track of two rails, similar to the steam railway, (2.) The cars, lightly yet strongly built. (3.) The power-house, containing the dynamos which generate the electricity. (4.) The feed-wire, usually of stout copper, running the length of the tracks of the system, and supported on poles or laid in conduits. (5.) The trolley-wire over the centre of the track, supported by insulated cross-wires passing from poles on opposite sides of the tracks, and connected at proper intervals with the feed-wire. (6.) The trolley-pole of metal jointed to the top of the car, and fitted with a spring which presses the wheel on the end of the pole up against the trolley-wire with a force of about fifteen pounds, and which also serves to conduct the electricity down through the car to the motor. (7.) The motor, which is suspended from the car truck, and passes its power to the car axle by means of a spur gearing. The power requisite for an ordinary trolley-car is about fifteen horse-power. The speed of trolley-cars is regulated in cities to from five to seven miles per hour, but they may be run, under favorable conditions, at a speed equal to, or in excess of, that of the steam-car.
As a means of city transit, and of rapid, convenient, and economic intercourse between suburban localities and rural towns and villages, the electric traction system ranks as one of the greatest wonders of the century. The speed with which it found favor, the enormous capital it provoked to activity, the stimulus it gave to further study and invention, the surprising number of passengers carried, go to make one of the most interesting chapters in electric annals. The end of the century sees thousands of these electric roads in existence; a comparatively new industry involving over $100,000,000; a passenger traffic running into the billions of people; a prospect that the trolley will succeed the steam-car for all utilizable purposes within the gradually extending influence of cities and towns upon their rural surroundings.
In speaking of the passing of the horse-car and its substitution by the trolley, a distinguished writer has well said: “Humanity in an electric-car differs widely from that in the horse-car, propelled at the expense of animal life. It is more cheerful, more confident, more awake to the energy at command, more imbued with the subtlety and majesty of the propelling force. The motor confirms the ethical fact that each introduction of a higher material force into the daily uses of humanity lifts it to a broader, brighter plane, gives its capabilities freer and more wholesome play, and opens fresh vistas for all possibilities. We applaud Franklin for seizing the lightning in the heavens, dragging it down to earth, and subjugating it to man. Let this pass as part of the poetry of physics. But when ethics comes to poetize, let it be said that electricity as an applied force lifts man up toward heaven, quickens all his appreciations of divine energy, draws him irresistibly toward the centre and source of nature’s forces. There is no dragging down and subjugation of a physical force. There is only a going out, or up, of genius to meet and to grasp it. Its universal application means the raising of mankind to its plane. If electricity be the principle of life, as some suppose, what wonder that we all feel better in an electric-car than any other? The motor becomes a sublime motive. God himself is tugging at the wheels, and we are riding with the Infinite.”
ELECTRIC RAILWAY. THIRD RAIL SYSTEM.
Enthusiasts say the trolley is only the beginning of electric locomotion, and that there is already in rapid evolution an electric system which will supersede steam even for trunk-line purposes. In vision, it presumes a speed of one hundred and twenty-five miles an hour instead of forty; greater safety, cleanliness, and comfort; and what is most momentous and startling, an economy in construction and operation which will warrant the sacrifice of the billions of dollars now invested in steam-railway properties. The proposition is not to sacrifice the steam-railway track, but to add to it a third rail, which is to carry the electric current. Then, by means of feed-conduits alongside of the track, and specially constructed electric locomotives and cars, the system is supposed to reach the practical perfection claimed for it. Experiments with such an electrical system, made upon branch lines of some of our trunk-line railways, as the Pennsylvania, New York Central, and New Haven & Hartford, give much encouragement to the hypothesis that it may become the next great step in the evolution of electrical science.
Another means of electric propulsion was provided by the investigations of Planté, which resulted in his invention of the “accumulator” or “storage battery,” in 1859. His battery consists of plates of lead immersed in dilute sulphuric acid. By the passage of an electric current through the acid, it is electrolytically decomposed. By continuing the current for a time, first in one direction and then in another, the lead plates become changed, the one at the point where the current leaves the cell taking on a deposit of spongy lead, and the one at the point where the current enters the cell taking on a coating of oxide of lead. When in this condition, the battery is said to be stored, and is capable of sending out an electric current in any circuit with which it may be connected. After exhausting itself, it can be re-stored or re-charged in the same way as at first. Faure greatly improved on Planté’s storage battery in 1880, by spreading the oxide of lead over the plates, thus greatly reducing the time in forming the plates. Subsequently, further improvements were made, till batteries came into existence capable of supplying a current of many hundred amperes for several hours. One of the first practical uses to which the storage battery was put was in the propulsion of street-cars; but its weight proved a drawback. It was found better adapted for the running of boats on rivers, and, in the business of water-freightage for short distances, has in many instances become a rival of steam. It found one of its most interesting applications in helping to solve the problem of the automobile, or “horseless carriage,” either for pleasure purposes or for street traffic. In this problem it has, at the end of the century, an active rival in compressed air; but as the “horseless carriage” is rapidly coming into demand, means may soon be found to utilize the strong and persistent energy of the storage battery, without the drawback found in its great weight.