ross 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
determined from the capacities given in the price lists which sized
injector must be selected.

An injector must always be selected having a maximum capacity in excess
of the water consumed. If the exact amount of water consumed per hour
is not known, and cannot be easily determined, the proper size can be
approximately determined from the nominal H. P. of the boiler. The
usual custom has been to allow 7 I/2 gallons of water per hour, which is
a safe rule for the ordinary type of boiler.

WHAT A GOOD INJECTOR OUGHT TO DO.

With cold feed water, a good injector with a two foot lift ought to
start with 25 pounds pressure and work up to I50 pounds. With 8 foot
lift, ought to start at 30 pounds and work up to I30. With feed water
heated to I00 degrees Fahrenheit it should start with the same lift,
that is, will say 2 foot, at 26 and work Up to I20, and at 8, from 33 up
to I00. You will see by this that conditions, consisting of variation of
temperature in the feed water and different lifts, change the efficiency
of your injector very materially, and the water can soon get beyond the
ability of your injector to work at all. The above refers more