the instant it reaches them. By the time the steam
has reached the opposite end of the boiler coils, it is no longer steam,
but a hot, dry gas at a terrific pressure. From the boiler coils the
steam passes into the steam-chest of the engine, and thence into the
cylinder, where it expands, delivering its energy to the piston.

It will be seen that the water-pump _E_ is geared to the engine. Owing
to this, it is necessary to start the water circulating through the
boiler coils by the hand pump _F_. This hand pump forces water through
the boiler coils just as the power pump does. After the hand pump is
started the engine is turned over a few times until it starts. The
valve _H_ is then closed, which cuts the starting pump _F_ entirely out
of the system, because when the engine starts it also drives the water
pump _E_, and therefore the action becomes entirely automatic.

The relief-cock _L_ is placed in the system to be used if the engine
stalls. By opening the relief-cock the pressure in the complete system
is immediately relieved. At all other times the relief-cock is closed.

A second pump, _I_, is also included in the system. This, like the
water-pump, is geared to the engine and driven by it. It is the duty of
this pump to convey oil from the lubricating tank _M_ into the steam
feed-pipe just before it enters the steam-chest. In this way the live
superheated steam carries a certain amount of lubricating oil with it in
the cylinder.

Owing to the high temperature of the superheated steam, it is impossible
to use brass cylinders on the steam-engines employed with flash steam
systems. Steel seems to be the only cheap metal that is capable of
withstanding the attack of flash steam. Brass is out of the question,
since its surface will pit badly after it is in use a short time.

The boiler of a flash steam plant is covered with sheet iron so as to
prevent drafts of air from deflecting the flame from the center of the
boiler coils. The cover is provided with ventilators, so that the burner
will not be smothered. If enough oxygen does not enter the interior of
the boiler coils, poor combustion will result, and the gasolene flame
will not develop its maximum heat. Upon referring again to the diagram,
it will be seen that the exhaust steam pipe from the engine discharges
into the stack of the boiler covering. This discharge greatly
facilitates the circulation of air through the boiler coils.

After a flash steam plant has