ss than astonishing. In the future the
motor car will revolutionize our modes of life to an extent comparable
to the changes effected by the advent of the steam-engine. Even since
1896, when the "man-with-the-flag" law was abolished in the British
Isles, the motor has reduced distances, opened up country districts, and
generally quickened the pulses of the community in a manner which makes
it hazardous to prophesy how the next generation will live.

_Note._--The author is much indebted to Mr. Wilfrid J. Lineham, M. Inst.
C.E., for several of the illustrations which appear in the above
chapter.

[8] Steam-driven cars are not considered in this chapter, as their
principle is much the same as that of the ordinary locomotive.

[9] On some cars natural circulation is used, the hot water flowing from
the top of the cylinder to the tank, from which it returns, after being
cooled, to the bottom of the cylinder.

[10] For explanation of the induction coil, see p. 122

Chapter V.

ELECTRICAL APPARATUS.

What is electricity?--Forms of electricity--Magnetism--The
permanent magnet--Lines of force--Electro-magnets--The electric
bell--The induction coil--The condenser--Transformation of
current--Uses of the induction coil.

WHAT IS ELECTRICITY?

Of the ultimate nature of electricity, as of that of heat and light, we
are at present ignorant. But it has been clearly established that all
three phenomena are but manifestations of the energy pervading the
universe. By means of suitable apparatus one form can be converted into
another form. The heat of fuel burnt in a boiler furnace develops
mechanical energy in the engine which the boiler feeds with steam. The
engine revolves a dynamo, and the electric current thereby generated can
be passed through wires to produce mechanical motion, heat, or light. We
must remain content, therefore, with assuming that electricity is energy
or motion transmitted through the ether from molecule to molecule, or
from atom to atom, of matter. Scientific investigation has taught us how
to produce it at will, how to harness it to our uses, and how to measure
it; but not _what_ it is. That question may, perhaps, remain unanswered
till the end of human history. A great difficulty attending the
explanation of electrical action is this--that, except in one or two
cases, no comparison can be established between it and the operation of
gases and fluids. When dealing with the s