in the smokestack.

The heaters are made in several different designs, but it is not
necessary to describe all of them, as they require little attention and
they all answer the same purpose. The most of them are made by the use
of a hollow bedplate with steam fitted heads or plates. The water pipe
passes through the plate at the end of the heater into the hollow
chamber, and a coil of pipes is formed, and the pipe then passes back
through the head or plate to the hot water check valve and into the
boiler.

The steam enters the cylinder from the boiler, varying in degrees of
heat from 300 to 500. After acting on the piston head, it is exhausted
directly into the chamber or hollow bed-plate through which the pipes
pass. The water, when it enters the heater, is as cold as when it left
the tank, but the steam which surrounds the pipes has lost but little of
its heat, and by the time the water passes through the coil of pipes it
is heated to nearly boiling point and can be introduced into the boiler
with little tendency to reduce the steam. This use of the exhaust steam
is economical, as it saves fuel, and it would be injurious to pump cold
water directly into a hot boiler.

If your engine is fitted with both cross head pump and injector, you use
the injector for pumping water when the engine is not running. The
injector heats the water almost as hot as the heater. If your engine is
running and doing no work, use your injector and stop the pump, for,
while the engine is running light, the small amount of exhaust steam is
not sufficient to heat the water and the pressure will be reduced
rapidly. You will understand, therefore, that the injector is intended
principally for an emergency rather than for general use. It should