Ignition is effected electrically by a series of sparks playing between
two platinum points in the slide valve, and this permits of regulating
the instant of ignition through the edges of the orifices. The angular
velocity is regulated by a Watt's governor, which secures an isochronism
of the motion independently of the charge.

The setting in motion of so powerful an engine is effected very easily
by means of an arrangement that permits of introducing into the
cylinder, while the piston is in the center of the stroke, a mixture of
air and gas whose pressure is sufficient at the arrival to expel the
inert products. After this the ignition takes place, and the explosion
is sufficient to set the motor in motion.

The trials made by Mr. Witz with the motor represented in Fig. 3 gave
the following results, deduced from an experiment of 68 hours. The
figures relate to one effective horse power, measured with the brake
upon the shaft of the motor.

Consumption of anthracite. 516 grammes.
" " coke. 96 "
Consumption of water for the injection
of steam. 0.487 liters.
Consumption of water for cooling
the cylinder. 50.0 "
Consumption of oil for lubricating
the cylinder. 3.74 grammes.
Consumption of grease. 0.45 "
Consumption of gas reduced to
0° C. and to 760 mm. 2,370 liters.