er Brown starts his engine to do his farm chores
every day, his by-product of electricity is stored automatically.

Such installations are not expensive. A storage battery capable of
lighting 8 tungsten lamps, of 16 candlepower each, continuously for 8
hours (or fewer lamps for a longer time); a switchboard containing all
the required regulating instruments; and a dynamo of suitable size,
can be had for from $250 to $300. All that is necessary to put such a
plant in operation, is to belt the dynamo to the gasoline engine so
that it will run at proper speed; and to connect the wires from dynamo
to switchboard, and thence to the house service. The dynamo required
for the above plant delivers 10 amperes at 45 volts pressure, or 10 x
45 = 450 watts. A gasoline, gas, or oil engine, or a windmill of
1-1/2 horsepower furnishes all the power needed. If the farmer uses
his engine daily, or every other day, for other purposes, the cost of
power will be practically negligible. With this system electric lights
are available at any time day or night; and when the gasoline engine
is in service daily for routine farm chores, the battery will never
run low.

This system is especially desirable where one uses a windmill for
power. The speed of the windmill is constantly fluctuating, so much so
in fact that it could not be used for electric light without a storage
battery. But when equipped with a regulator on the switchboard which
permits the current to flow only when the battery needs it, and then
only when the speed of the windmill is correct, the problem of turning
wind power into electric light is solved.

* * * * *

If the farmer does not desire to go to the additional expense of
automatic regulation, there are cheaper plants, requiring attention
for charging. These plants are identical with those described above,
except they have no regulators. With these plants, when the battery
runs low (as is indicated by dimming of the lights) it is necessary to
start the engine, bring it up to speed, adjust the dynamo voltage to
the proper pressure, and throw a switch to charge the battery. For
such plants it is customary to run the engine to charge the battery
twice a week. It is necessary to run the engine from 8 to 10 hours to
fully charge the discharged battery. When the battery approaches full
charge, the fact is evidenced by so-called "gassing" or giving off of
bubbles. Another way to determine if the