f the switchboard.

Now snap on the field switch. Instantly the needle will begin to move
forward, though slowly; and it will stop. Turn the rheostat handle
gradually; as you advance it, the voltmeter needle will advance.
Finally you will come to a point where the needle will indicate 110
volts.

If you have designed your transmission line for a drop of 5 volts at
half-load, advance the rheostat handle still further, until the
needle points to 115 volts. Let the machine run this way for some
time. When assured all is right, throw on the main switch, and turn on
the light at the switchboard. Then go to the house and gradually turn
on lights. Come back and inspect the dynamo as the load increases. It
should not run hot, nor even very warm, up to full load. Its brushes
should not spark, though a little sparking will do no harm.

Your plant is now ready to deliver current up to the capacity of its
fuses. See that it does not lack good lubricating oil, and do not let
its commutator get dirty. The commutator should assume a glossy
chocolate brown color. If it becomes dirty, or the brushes spark
badly, hold a piece of fine sandpaper against it. Never use emery
paper! If, after years of service, it becomes roughened by wear, have
it turned down in a lathe. Occasionally, every few weeks, say, take
the brushes out and clean them with a cloth. They will wear out in the
course of time and can be replaced for a few cents each. The bearings
may need replacing after several years' continuous use.

Otherwise your electric plant will take care of itself. Keep it up to
speed, and keep it clean and well oiled. Never shut it down unless you
have to. In practice, dynamos run week after week, year after year,
without stopping. This one, so long as you keep it running true to
form, will deliver light, heat and power to you for nothing, which
your city cousin pays for at the rate of 10 cents a kilowatt-hour.

PART III

GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES

CHAPTER X

GASOLINE ENGINE PLANTS

The standard voltage set--Two-cycle and four-cycle gasoline
engines--Horsepower, and fuel consumption--Efficiency of small
engines and generators--Cost of operating a one-kilowatt plant.

Electricity is of so much value in farm operations, as well as in the
farm house, that the farmer who is not fortunate enough to possess
water-power of his own, or to live in a community where a cooperative
hydro