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.

[Illustration: Bridge and surrounding city.]
The Brooklyn Bridge, looking up the East River.

[Illustration: Tracks elevated about 30 feet on iron beams.]
The Manhattan Elevated Railway, New York.

[1877-1887]

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. The