es locomotive builders
very little--that is, compensating the difference between the speeds of
the two driving-wheels when turning corners. Just as the inside man of a
military company takes short steps when turning and the outside man
takes long ones, so the inside wheel of a vehicle turns slowly while the
outside wheel revolves quickly when rounding a corner. As most
automobiles are propelled by power applied to the rear axle, to which
the wheels are fixed, it is manifest that unless some device were made
to correct the fault one wheel would have to slide while the other
revolved. This difficulty has been overcome by cutting the axle in two
and placing between the ends a series of gears which permit the two
wheels to revolve at different speeds and also apply the power to both
alike. This device is called a compensating gear, and is worked out in
various ways by the different builders.

The locomotive builder accomplishes the same thing by making his wheels
larger on the outside, so that in turning the wide curves of the
railroad the whole machine slides to the inside, bringing to bear the
large diameter of the outer wheel and the small diameter of the inner,
the wheels being fixed to a solid axle.

The steam machine can always be distinguished by the thin stream of
white vapour that escapes from the rear or underneath while it is in
motion and also, as a rule, when it is at rest.

The motor of a steam vehicle always stops when the machine is not
moving, which is another distinguishing feature, as the gasoline motors
run continually, or at least unless the car is left standing for a long
time.

As the owners of different makes of bicycles formerly wrangled over the
merits of their respective machines, so now motor-car owners discuss the
value of the different powers--steam, gasoline, and electricity.

Though steam was the propelling force of the earliest automobiles, and
the power best understood, it was the perfection of the gasoline motor
that revived the interest in self-propelled vehicles and set the
inventors to work.

A gasoline motor is somewhat like a gun--the explosion of the gas in the
motor-cylinder pushes the piston (which may be likened to the
projectile), and the power thus generated turns a crank and drives the
wheels.

The gasoline motor is the lightest power-generator that has yet been
discovered, and it is this characteristic that makes it particularly
valuable to propel automobiles. Santos-