particularly to the single tube injector. The double tube injector
under the same conditions as above should work from I4 pounds to 250,
and from I5 to 2I0, but as this injector is not generally used on farm
engines you will most likely not meet with it very often.

The injector should not be placed too near the boiler, as the heat from
it will make it difficult to start the injector each time after it has
been standing idle.

If the injector is so hot that it will not lift the cold water, there is
no way of cooling it except by applying the water on the outside. This
is most effectively done by covering the injector with a cloth and
pouring water over the cloth. If, after the injector has become cool,
it still refuses to work, you may be sure that there is some obstruction
in it that must be removed. This can be done by taking off the cap, or
plug-nut, and running a fine wire through the cone valve or cylinder
valve. The automatic injector requires only the manipulation of the
steam valve to start it. There are other makes that require, first: that
the injector be given steam and then the water. To start an injector
requires some little tact, (and you will discover that tact is the
handiest tools you can have to make you a good engineer). To start an
injector of the Pemberthy type; first give it sufficient steam to lift
the water, allowing the water to escape at overflow for a moment or long
enough to cool the injector, then with a quick turn shut off and open up
the supply which requires merely a twist of the wrist.

If the injector fails to take hold at once don't get ruffled but repeat
the above move a few times and you will soon start it, and if you have
tact, (it is only another word for natural ability) you will need no
further instructions to start your injector. But remember that no
injector can work coal cinders or chaf and that all joints must be air
tight. Don't forget this.

It is now time to give some attention to the heater. While the heater
is no part of the pump, it is connected with it and does its work
between the two horizontal check valves. Its purpose is to heat the
water before it passes into the boiler. The water on its way from the
pump to the boiler is forced through a coil of pipes around which the
exhaust steam passes on its way from the cylinder to the exhaust nozzle
in the smokestack.

The heaters are made in several different designs, but it is not
necessary to describe al