her by an Armington & Sims engine, and both machines were on
a solid foundation. At the station at Milan, Italy, the first 'Jumbos'
operated in multiple arc were driven by Porter-Allen engines, and
dash-pots were applied to the governors. These machines were also upon a
solid foundation, and no trouble was experienced.

"At the Pearl Street station, however, the machines were supported upon
long iron floor-beams, and at the high speed of 350 revolutions per
minute, considerable vertical vibration was given to the engines. And
the writer is inclined to the opinion that this vibration, acting in the
same direction as the action of gravitation, which was one of the two
controlling forces in the operation of the Porter-Allen governor, was
the primary cause of the 'hunting.' In the Armington & Sims engine the
controlling forces in the operation of the governor were the centrifugal
force of revolving weights, and the opposing force of compressed
springs, and neither the action of gravitation nor the vertical
vibrations of the engine could have any sensible effect upon the
governor."]

The Pearl Street station, as this first large plant was called, made
rapid and continuous growth in its output of electric current. It
started, as we have said, on September 4, 1882, supplying about four
hundred lights to a comparatively small number of customers. Among those
first supplied was the banking firm of Drexel, Morgan & Company, corner
of Broad and Wall streets, at the outermost limits of the system. Before
the end of December of the same year the light had so grown in favor
that it was being supplied to over two hundred and forty customers whose
buildings were wired for over five thousand lamps. By this time three
more "Jumbos" had been added to the plant. The output from this time
forward increased steadily up to the spring of 1884, when the demands of
the station necessitated the installation of two additional "Jumbos"
in the adjoining building, which, with the venous improvements that had
been made in the mean time, gave the station a capacity of over eleven
thousand lamps actually in service at any one time.

During the first three months of operating the Pearl Street station
light was supplied to customers without charge. Edison had perfect
confidence in his meters, and also in the ultimate judgment of the
public as to the superiority of the incandescent electric light as
against other illuminants. He realized, however, that i