onsume the incandescent carbon. He also found that
a large current could be divided into smaller ones by splitting up the
conductor into minor filaments. Triumph in household illumination was
thus achieved, and when, in October, 1878, the results of Edison's
experimenting were announced to the world, gas fell from twelve to
twenty per cent. The alarm was premature, however, since the new
illumination did not, after all, prove so satisfactory as to displace
the old. It largely did so for streets, factories, and halls, but to no
very great extent for residences.

[Illustration: Drawing of lamp.]
Edison's Platinum Lamp on Carbon Support, 1879.

[Illustration: Drawing of lamp.]
Edison's Paper Carbon Lamp.

[Illustration: Drawing of lamp.]
Edison's First Incandescent Platinum Lamp.

[1883-1884]

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