Edison’s First Incandescent Platinum Lamp.
The most stupendous engineering work yet accomplished by man, the great bridge spanning East River between Brooklyn and New York, was completed in May, 1883, excavations for its foundations having begun so early as 1870. This wonder of the world was designed by John A. Roebling, and after his death in 1869 finished by his son, W. A. Roebling. It cost about $16,000,000, two-thirds coming from the city of Brooklyn, one-third from New York. A gigantic stone tower, 277 feet high, was built on each side of the river. Through arched apertures in these toward the top ran the roadway, its ends being 119 feet above the water. The centre of the bridge was supported by four steel wire cables, 16 inches in diameter, which passed from solid masonry structures nearly 1,000 feet away from the water’s edge on either shore, up over the two towers, dipping, at the centre of the river, to nearly the level of the roadway. On account of their great weight they had to be braided, strand by strand, in their permanent position. Suspenders from these cables grappled the body of the bridge at frequent intervals. The main span was I,595-1/2 feet long, the entire work about 6,000 feet. There were five passageways—two on the outside for carriages, the next two for cable cars, the middle one for foot passengers. The bridge curved upward from each tower, being at the middle 135 feet above the water in summer, and three feet higher in winter, owing to contraction by the cold. All but the very largest ships sailed under without shortening their masts.
In connection with the great bridge, as likewise in a way possessing an importance for the whole nation, we may mention the ingenious deepening of Hell-gate Channel, East River, by tunnelling beneath the water and using dynamite; and also the introduction of elevated railways in New York City and Brooklyn. This project had been mooted by 1868. Exactly ten years later two sections of railway were open for travel in New York. The first elevated road in Brooklyn began operation in 1885. These new avenues of travel at once became immensely popular. In 1884, no fewer than 250 engines and 800 cars were in use by the New York lines, carrying over 300,000 passengers daily, or about 103,000,000 for the year. Nearly at the same time with the introduction of these roads in New York, new methods of traction for surface street railways, by electricity and by cable, were introduced in various cities of the country, bidding fair soon to do away with horses for this service.
The Brooklyn Bridge, looking up the East River.
The Manhattan Elevated Railway, New York.
One of the most interesting and valuable inventions of this or any century was that of the telephone, devised by Alexander Graham Bell, and first put to business use in 1877. For ten years Mr. Bell had been experimenting upon the possibility of conveying sound by means of the electric wire. In 1876 he had so far succeeded as to exhibit a pair of his instruments in successful operation at the Philadelphia Centennial Exhibition. In April of the next year the Cambridge Water Board, the Pennsylvania Railroad, and many other corporations ordered the instrument for practical service. From this time the business grew with incredible rapidity. The American Bell Telephone Company was incorporated, and in January, 1886, had in use 330,000 telephones. There were this year in various cities of the United States 752 telephone exchanges. The total length of telephone wires operated by this company was 114,371 miles. In addition to the system which centred in the Bell Company there were several competing telephone establishments in continual litigation with the Bell. The total mileage of telephone wires in the United States in 1887 was estimated at 130,000 miles. There were the same year 170,000 miles of telegraph wire, besides private lines. In 1893, the aggregate length of telegraph lines in the United States open to the public exceeded 210,000 miles. There were, besides, government and private lines to a length vast but not ascertainable. In addition to all this, the Bell Telephone Company, which conducted the main telephone business of the country, owned, the same year, 307,748 miles of wire, which the lines of other companies increased to 440,750 miles.
