points which would glow steadily and adjust themselves while burning. European scientists were also experimenting on a current passed through a closed tube in an atmosphere of high rarefaction in order to obtain a light; but no material suitable for such combustion could readily be found. As late as 1872, when Tyndall was delivering his scientific lectures throughout the United States, he was obliged to carry with him a battery of a hundred cells to supply a current for his experiments. No effort had been made as yet to supply a current outside a laboratory; but from several inventors there came almost simultaneously machines which revolved an armature, consisting of coils of wire wrapped about an iron core, between the poles of one or more electro-magnets. These were known as "magneto-electric" machines, or as "dynamo-electric" machines, a name soon shortened to "dynamo." A current generated on such a machine could be carried to a distance on a wire and utilized in any desired manner.

1

These successful attempts to convey a current along a wire were not reached without long and tedious experimentation. It was one hundred and twenty years after Franklin demonstrated that lightning was a discharge of electricity, and seventy years after Volta announced that electricity could be produced by chemical action," before electrical energy

1 Iles, Flame, Electricity, and Camera, 107, 108.

2 Bigelow, Franklin's Works, I., 276-281; Iles, Flame, Electricity, and Camera, 100.

was turned to commercial use in the magnetic telegraph. Just before Morse perfected that invention, Faraday and Henry1 suggested that currents of electricity could be produced by a revolving magnet, yet thirty years elapsed before the armature was invented which made modern applications possible.

2

After many improvements by various inventors, C. F. Brush, of Cleveland, produced an arc light suitable for streets and parks; and in 1879 the first electric lighting station under this system was installed at San Francisco. Experimenters working on the bulb or vacuum light were using for the filament to be illuminated cotton thread, cartridgepaper, and platinum wire. In 1879, Thomas Edison, an American inventor, after searching the vegetable kingdom of the world, adopted a filament of bamboo supported on platinum wires, and gave out the first practical incandescent light. By arranging the lights in a multiple series and by dividing the current and conveying it along different lines, the power supplied to the several lamps was properly regulated and the lighting of large areas from the same plant made possible. In 1882 the first Edison electric lighting plant for incandescent lighting was opened in New York City, the current being carried

1 Tyndall, Faraday as a Discoverer, passim; Smithsonian Institution, Board of Regents, Proceedings, 1887.

2 U. S. Eleventh Census (1890), Manufactures, Part III., 239. Iles, Flame, Electricity, and Camera, 124; Harper's Weekly, XXV., 456; Edison, "The Success of the Electric Light," in North Am. Rev., CXXXI., 295.

from a common station by wire instead of having a storage battery in each house, as was contemplated by a rival system.1 So rapidly had the American methods improved that two of the four lights shown at the Electrical Exhibition in Paris in 1881 came from the United States. In 1880 there were over seventy establishments in the United States engaged in manufacturing electrical supplies to the value of two and a half million dollars. When Garfield was inaugurated, in 1881, the city of Washington was illuminated by electricity. At the Philadelphia Exhibition of 1884, twelve engines, combining 1800 horse-power, furnished the current for hundreds of electric lights, aggregating 1,500,000 candle-power. Of these 5600 were incandescent lamps, some with colored bulbs, arranged in effective manner about the buildings and grounds. A monster arc light, said to be of one hundred thousand candle-power, shone from a tower; and numerous lights of a similar kind made the grounds as light as the interior of a building."

It was not enough that electricity should be made to convey people and illuminate cities; it must perform other tasks. Among the curiosities shown at the Centennial Exposition was a "lover's telegraph," which consisted of a string connecting two boxes or bits of tubing with a flexible diaphragm closing one end of each, the ends of the string being 1 U. S. Twelfth Census (1900), X., 157. 'Appleton's Annual Cyclop., 1884, pp. 304–310.

attached to these diaphragms. The vibrations made by the voice of a person speaking in one box were conveyed to the string by the diaphragm, and could be heard by the person at the other box.1 Attempts were next made to send the vibrations through a wire by the aid of the electric current, and success soon followed. In 1877 the newspapers told exciting stories of a concert in New York, the music of which was carried to a distance by means of a wire and distinctly heard through the use of the "telephone," the invention of Elisha Gray. Another instrument, serving the same purpose, the invention of Professor Bell of Boston, conveyed distinctly the sound of voices over a wire stretched between Boston and Salem. Conversation was carried on by the participants concerning the weather and the railway strike. The Salem people were amazed to hear that it was raining in Boston. At the request of the inventor, who was in Salem, his letters were opened in his Boston office and their contents heard in Salem, "with as much clearness," said an astonished reporter, 'as though Mr. Watson had been a private secretary at his elbow." 3 There seemed no limit to the commercial uses to which this invention could be put when once the wires were strung between cities. Many predicted that it would soon replace the telegraph.

2

1 Iles, Flame, Electricity, and Camera, 239.

? Prescott, Bell's Electric Telephone (1884), passim; Frank Leslie's Weekly, XLIV., 124 (March 24, 1875).

Independent, March 28, 1877.

VOL. XXIII.-4

The demand for rapid transportation in the cities produced another invention of unlimited potentiality, although injured by too much popularity which made it a temporary "fad." At the Centennial Exposition was displayed an imported "bicycle," an adaptation of the velocipede which had been in limited use for the past fifty years. Two years later an American company was organized to manufacture the modern machine. In 1884 no les than six thousand bicycles were manufactured by half a dozen companies, and it was estimated that at least thirty thousand were in use. Bicycle "meets" were held in various cities,1 and bicycle clubs made long tours through the country, adding to the comity of the people. The machine consisted practically of one large wheel over which the rider was mounted, balanced by a small wheel at the rear. The danger of this precarious position led to the invention in 1884 of a "safety" machine, with two moderate wheels of equal size. Being adapted to both sexes, it speedily replaced the former style of build. In 1886 the public realized the possibilities of the bicycle and the craze was begun. In 1890 it was necessary to create a special department of the patent office to consider the numerous applications for patents connected with the bicycle. The use of the machine, although eventually superseded by the automobile, led to a renewed interest in sports and in the study of nature, aided in scattering the crowded people of the

1 Harper's Weekly, XXV., 400.