the valve and turn it vigorously for a few minutes, and you will remove
all roughness.

Constant use may sometimes make a burr on the valve which will cause it
to stick. Put it through the above course and it will be as good as
new. If this little process was generally known, a great deal of
trouble and annoyance could be avoided.

It will not be necessary to describe other styles of pumps. If you know
how to run the cross head pump, you can run any of the others. Some
engines have cross head pump only. Others have an independent pump.
Others have an injector, or inspirator, and some have both cross head
pump and injector. I think a farm engine should be supplied with both.

It is neither wise nor necessary to go into a detailed description of an
injector. The young reader will be likely to become convinced if an
injector works for five minutes, it will continue to work, if the
conditions remain the same. If the water in the tank does not become
heated, and no foreign substance is permitted to enter the injector,
there is nothing to prevent its working properly as long as the
conditions are within the range of a good injector. It is a fact that
with all injectors as the vertical distance the injector lifts is
increased, it requires a greater steam pressure to start the injector,
and the highest steam pressure at which the injector will work is
greatly decreased. If the feed water is heated, a greater steam
pressure is required to start the injector and it will not work with as
high steam pressure. The capacity of an injector is always decreased as
the lift is increased, or the feed water heated. To obtain the most
economical results the proper sized injector must be used. When the
exact quantity of water consumed per hour is known it can be easily