and and
sold them for a trifle to get the money to meet the pay rolls of his
different shops. Later the inventor learned wisdom and associated with
himself keen business men to their common profit.

* Hendrick, "The Age of Big Business".

Edison set up his laboratories and factories at Menlo Park, New Jersey,
in 1876, and it was there that he invented the phonograph, for which he
received the first patent in 1878. It was there, too, that he began that
wonderful series of experiments which gave to the world the incandescent
lamp. He had noticed the growing importance of open arc lighting, but
was convinced that his mission was to produce an electric lamp for use
within doors. Forsaking for the moment his newborn phonograph, Edison
applied himself in earnest to the problem of the lamp. His first search
was for a durable filament which would burn in a vacuum. A series of
experiments with platinum wire and with various refractory metals led
to no satisfactory results. Many other substances were tried, even human
hair. Edison concluded that carbon of some sort was the solution rather
than a metal. Almost coincidently, Swan, an Englishman, who had also
been wrestling with this problem, came to the same conclusion. Finally,
one day in October, 1879, after fourteen months of hard work and the
expenditure of forty thousand dollars, a carbonized cotton thread sealed
in one of Edison's globes lasted forty hours. "If it will burn forty
hours now," said Edison, "I know I can make it burn a hundred." And
so he did. A better filament was needed. Edison found it in carbonized
strips of bamboo.

Edison developed his own type of dynamo, the largest ever made up to
that time, and, along with the Edison incandescent lamps, it was one of
the wonders of the Paris Electrical Exposition of 1881. The installation
in Europe and America of plants for service followed. Edison's first
great central station, supplying power for three thousand lamps, was
erected at Holborn Viaduct, London, in 1882, and in September of that
year the Pearl Street Station in New York City, the first central
station in America, was put into operation.

The incandescent lamp and the central power station, considered
together, may be regarded as one of the most fruitful conceptions in
the history of applied electricity. It comprised a complete generating,
distributing, and utilizing system, from the dynamo to the very lamp at
the fixture, ready for use. It even