A considerable amount of progress had previously been made by various workers in attempting to reduce the volume of light in each lamp and increase the number of lights for a given power expended. Forms of incandescent arc lamps, or semi-incandescent lamps, were tried on a considerable scale abroad, but none have survived. So, also, many attempts to produce a lamp giving light by pure incandescence of solid conductors proved for the most part abortive. Edison himself worked for nearly two years on a lamp based upon the old idea of incandescent platinum strips or wires, but without success. The announcement of this lamp caused a heavy drop in gas shares, long before the problem was really solved by a masterly stroke in his carbon filament lamp. Curiously, the nearest approach to the carbon filament lamp had been made in 1845, by Starr, an American, who described in a British patent specification a lamp in which electric current passed through a thin strip of carbon kept it heated while surrounded by a glass bulb in which a vacuum was maintained. Starr had exhibited his lamps to Faraday, in England, and was preparing to construct dynamos to furnish electric current for them in place of batteries, but sudden death put an end to his labors. The specification describing his lamp is perhaps the earliest description of an incandescent lamp of any promise, and the subsequently recorded ideas of inventors up to the work of Edison seem now to be almost in the nature of retrograde movements. None of them were successful commercially. Starr, who was only twenty-five years of age, is reported to have died of overwork and worry in his efforts to perfect his invention. His ideas were evidently far in advance of his time.
The Edison lamp differed from those which preceded it in the extremely small section of the carbon strip rendered hot by the current, and in the perfection of the vacuum in which it was mounted. The filament was first made of carbonized paper, and afterwards of bamboo carbon. The modern incandescent lamp has for years past been provided with a filament made by a chemical process. The carbon formed is exceedingly homogeneous and of uniform electric resistance. Edison first exhibited his lamp in his laboratory at Menlo Park, New Jersey, in December, 1879; but before it could be properly utilized an enormous amount of work had to be done. His task was not merely the improvement of an art already existing; it was the creation of a new art. Special dynamo machines had to be invented and constructed for working the lamps; switches were needed for connecting and disconnecting lamps and groups of lamps; meters for measuring the consumption of electric energy were wanted; safety fuses and cut-offs had to be provided; electroliers or fixtures to support the lamp were required; and, lastly, a complete system of underground mains with appurtenances was a requisite for city plants.
Even the steam-engines for driving the dynamos had to be remodelled and improved for electric work, and ten years of electric lighting development did more towards the refinement and perfection of steam-engines than fifty years preceding. Steadiness of lights meant the preservation of steady speed in the driving machinery. The Pearl Street station in New York City was the first installation for the supply of current for incandescent lighting in a city district. The constant pressure dynamos were gradually improved and enlarged. The details of all parts of the system were made more perfect, and in the hands of Edison and others the incandescent lamps, originally of high cost, were much cheapened and the quality of the production was greatly improved. Lamps originally cost one dollar each. The best lamps that are made can be had at present for about one-fifth that price. Millions of incandescent lamps are annually manufactured. Great lighting stations furnish the current for the working of these lamps, some stations containing machinery aggregating many thousands of horse-power capacity. Not only do these stations furnish electric energy for the working of arc lamps and incandescent lamps, but, in addition, for innumerable motors ranging in size from the small desk fan of one-tenth horse-power up to those of hundreds of horse-power. The larger sizes replace steam or hydraulic power for elevators, and many are used in shops and factories for driving machinery such as printing-presses, machinery tools, and the like.
In spite of the fact that it was well known that a good dynamo when reversed could be made a source of power, few electric motors were in use until a considerable time after the establishment of the first lighting stations. Even in 1884, at the Philadelphia Electrical Exhibition, only a few electric motors were shown. Not until 1886 or thereafter did the “motor load” of an electric station begin to be a factor in its business success. The motors supplied are an advantageous adjunct, inasmuch as they provide a day load, increasing the output of the station at a time when the lighting load is small and when the machinery in consequence would, without them, have remained idle. The growth of the application of electric motors in the closing years of the century has been phenomenal, even leaving out of consideration their use in electric railways.
Twenty years ago an electric motor was a curiosity; fifty years ago crude examples run by batteries were only to be occasionally found in cabinets of scientific apparatus. Machinery Hall, at the Centennial Exhibition of 1876, typified the mill of the past, never again to be reproduced, with its huge engine and lines of heavy shafting and belts conveying power to the different tools or machines in operation. The modern mill or factory has its engines and dynamos located wherever convenient, its electric lines and numerous motors connected thereto, and each of them either driving comparatively short lines of shafting or attached to drive single pieces of machinery. The wilderness of belts and pulleys which used to characterize a factory is gradually being cleared away, and electric distribution of power substituted. Moreover, the lighting of the modern mill or factory is done from the same electric plant which distributes power.
The electric motor has already partly revolutionized the distribution of power for stationary machinery, but as applied to railways in place of animal power the revolution is complete. The period which has elapsed since the first introduction of electric railways is barely a dozen years. It is true that a few tentative experiments in electric traction were made some time in advance of 1888, notably by Siemens, in Berlin, in 1879 and 1880, by Stephen D. Field, by T. A. Edison, at Menlo Park, by J. C. Henry, by Charles A. Van Depoele, and others. If we look farther back we find efforts such as that of Farmer, in 1847, to propel railway cars by electric motors driven by currents from batteries carried on the cars. These efforts were, of course, doomed to failure, for economical reasons. Electric energy from primary batteries was too costly, and if it had been cheaper, the types of electric motor used yielded so small a return of power for the electric energy spent in driving them that commercial success was out of the question. These early efforts were, however, instructive, and may now be regarded as highly suggestive of later work. Traction by the use of storage batteries carried on an electric car has been tried repeatedly, but appears not to be able to compete with systems of direct supply from electric lines. The plan survives, however, in the electric automobile, many of which have been put into service within a year or two. The electric automobile is not well fitted for country touring; it is best adapted to cities, where facilities for charging and caring for the batteries can be had. Moreover, the electric carriage is of all automobile carriages the most easily controlled, most ready; it emits no smell or hot gases and is nearly noiseless.
About 1850, Hall, a well-known instrument maker of Boston, catalogued a small toy electric locomotive dragging a car upon rails which were insulated and connected with a stationary battery of two Grove cells. This arrangement was sold as a piece of scientific apparatus, and appears to be the first example of an electrically driven vehicle connected by rolling contacts to an immovable energy source. Other early experimenters, such as Siemens, Field, and Daft, subsequently to Hall, used in actual railway work the supply by insulated tracks. This was supplanted later by overhead insulated wires or by the insulated third rail. Siemens & Halske, of Berlin, used a special form of overhead supply in 1881, and during the electrical exhibition in Paris in that year, a street tramway line was run by them. Later, Edison experimented with a third-rail-supply line at Menlo Park; and at Portrush, in Ireland, an actual railway was put in operation by Siemens & Halske, using the third-rail system. This was about 1883. The power of the Portrush railway was that of a water-wheel driving the generating dynamo.
The modern overhead trolley, or under-running trolley, as it is called, seems to have been first invented by Van Depoele, and used by him in practical electric railway work about 1886 and thereafter. The universality of this invention for overhead supply marks the device as a really important advance in the art of electric traction. Van Depoele was also a pioneer in the use of an underground conduit, which he employed successfully in Toronto in 1884. The names of Edward M. Bentley and Walter H. Knight stand out prominently in connection with the first use of an underground conduit, tried under their plans in August, 1884, at Cleveland, on the tracks of the horse-railway company.
We have barely outlined the history of the electric-motor railway up to the beginning of a period of wonderful development, resulting in the almost complete replacement by electric traction of horse traction or tramway lines, all within an interval of scarcely more than ten years.
The year 1888 may be said to mark the beginning of this work, and in that year the Sprague Company, with Frank J. Sprague at its head, put into operation the electric line at Richmond, Virginia, using the under-running trolley. Mr. Sprague had been associated with Edison in early traction work, and was well known in connection with electric-motor work in general. The Richmond line was the first large undertaking. It had about thirteen miles of track, numerous curves, and grades of from three to ten per cent. The enterprise was one of great hardihood, and but for ample financial backing and determination to spare no effort or expenditure conducive to success, must certainly have failed. The motors were too small for the work, and there had not been found any proper substitute for the metal commutator brushes on the motors—a source of endless trouble and of an enormous expense for repairs. Nevertheless, the Richmond installation, kept in operation as it was in spite of all difficulties, served as an object-lesson, and had the effect of convincing Mr. Henry M. Whitney and the directors of the West End Street Railway, of Boston, of the feasibility of equipping the entire railway system of Boston electrically. Meanwhile the merging of the Van Depoele and Bentley-Knight interests into the Thomson-Houston Electric Light Company brought a new factor into the field, the Sprague interests being likewise merged with the Edison General Electric Company.