d to deal with steam. For
instance, the gasoline motor cannot be started as easily as a
steam-engine. It is necessary to make the driving-shaft revolve a few
times by hand in order to start the cylinders working in their proper
order. Therefore, the motor of a gasoline machine goes all the time,
even when the vehicle is at rest. Friction clutches are used by which
the driving-shaft and the axles can be connected or disconnected at the
will of the driver, so that the vehicle can stand while the motor is
running; friction clutches are used also to throw in gears of
different sizes to increase or decrease the speed of the vehicle, as
well as to drive backward.

[Illustration: AN AUTOMOBILE BUCKBOARD]

The early gasoline automobiles sounded, when moving, like an artillery
company coming full tilt down a badly paved street. The exhausted gas
coughed resoundingly, the gears groaned and shrieked loudly when
improperly lubricated, and the whole machine rattled like a runaway
tin-peddler. Ingenious mufflers have subdued the sputtering exhaust, the
gears are made to run in oil or are so carefully cut as to mesh
perfectly, rubber tires deaden the pounding of the wheels, and carefully
designed frames take up the jar.

Steam and gasoline vehicles can be used to travel long distances from
the cities, for water can be had and gasoline bought almost anywhere;
but electric automobiles, driven by the third of the three powers used
for self-propelled vehicles, must keep within easy reach of the charging
stations.

Just as the perfection of the gasoline motor spurred on the inventors to
adapt the steam-engine for use in automobiles, so the inventors of the
storage battery, which is the heart of an electric carriage, were
stirred up to make electric propulsion practical.

The storage battery of an electric vehicle is practically a tank that
holds electricity; the electrical energy of the dynamo is transformed
into chemical energy in the batteries, which in turn is changed into
electrical energy again and used to run the motors.

Electric automobiles are the most simple of all the self-propelled
vehicles. The current stored in the batteries is simply turned off and
on the motors, or the pressure reduced by means of resistance which
obstructs the flow, and therefore the power, of the current. To reverse,
it is only necessary to change the direction of the current's flow; and
in order to stop, the connection between motor and battery is