The history of the first locomotives in America. From original ...

TREVITHICK'S ENGINE. 39
that the steam-racks and force-pumps, as also the bel-
lows used in generating combustion, were worked off
the same crank-axle.
This was the first successful high-pressure engine
constructed on the principle of moving a piston, by the
elasticity" of steam, against the . pressure of the atmosphere,
and without a vacuum. Such an engine had
been described by Leopold, though in his apparatus the
pressure acted only on one side of the piston, while in
Trevithick's and Vivian's engine the piston was not
only raised but likewise depressed by the steam. This
was original with them, and of great merit.
This kind of carriage on common roads was toler-
ably successful. It was exhibited at the city of London,
and attracted great crowds to witness its performance
and it drew behind it a carriage filled with passengers.
But it soon became obvious that the roads in England
were too rough and uneven for the successful use of
such machines, and it was soon after abandoned by
Trevithick as a practical failure.
Trevithick next turned his attention to the inven-
tion of a steam-carriage or locomotive, to run upon the
tram-roads then in general use in England ; and in
1804, he commenced, his machine ; in the same year
it was completed and tried upon the Merthyr-Tydvil
EaUway, in South Wales. On this .
occasion
it suc-
ceeded in drawing after it several wagons containing
ten tons of bar-iron, at the rate of five miles an hour.
The boiler of this machine was cylindrical in form, flat
at the ends, and constructed of cast-iron. The furnace
and flues were inside the boiler, in which a single cylin-
der of eight inches in diameter and four feet six inch
stroke was immersed upright. Although this locomo-
tive, when tried upon the railroad as above stated, suc-
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