imperfectly arranged.

In 1801 Franzose Lebon described a machine to be driven by means of
coal-gas. Two pumps were used to compress air and gas, and the mixture
was fired, as recommended by the inventor, by an electric spark, and
drove a piston in a double-working cylinder.

The atmospheric engine of Samuel Brown, 1823, had a piston working in a
cylinder into which gas was introduced, and the latter, being ignited,
expanded the air in cylinder whilst burning like a flame. The fly-wheel
carried the piston up to the top of its stroke, then water was used to
cool the burnt gases, which also escaped through valves, the latter
closing when the piston had reached the top of its stroke. A partial
vacuum was formed, and the atmospheric pressure did work on the piston
on its down stroke. A number of cylinders were required in this engine,
three being shown in the specification all connected to the same
crank-shaft. According to the _Mechanic's Magazine_, such an engine with
a complete gas generating plant was fitted to a boat which ran as an
experiment upon the Thames.

A two-cylinder engine working on to a beam was built in Paris, but no
useful results were obtained.

Wright's engine of 1833 used a mixture of combustible gas and air, which
operated like steam in a steam engine. This engine had a water-jacket,
centrifugal governor, and flame ignition. In 1838 Barnett applied the
principle of compression to a single-acting engine. He also employed a
gas and air pump, which were placed respectively on either side of the
engine cylinder, communication being established between the receiver
into which the pumps delivered and the working cylinder as the charge
was fired. The double-acting engines which Barnett devised later were
not so successful.

From this time to about 1860 very few practical developments are
recorded. A number of French and English patents were taken out,
referring to hydrogen motors, but are not of much practical value.

Lenoir's patent, dating from 24th January 1860, refers to a form of
engine which received considerable commercial support, and consequently
became very popular. A manufacturer, named Marinoni, built several of
these engines, which were set to work in Paris in a short time. Then,
due to sudden demand, the Lenoir Company was formed to undertake the
manufacture of these engines. It was claimed that a 4-horse-power engine
could be run at a cost of 3.4 shillings per day, or just one half the