is in all cases the result of work done on electricity, either by the
oxidation of zinc, or in some other way. This is a broad principle, but
it is strictly consistent in every respect with the truth. Electricity,
then, is, as we have said, totally different from coal; and it can never
become a substitute for it alone. Water power, air power, or what we
may, for want of a better phrase, call chemical power, combined with
electricity, can be used as a substitute for coal; but electricity
cannot of itself be employed to do work. It is true, however, that
electricity, on which work has already been done, may be found in
nature. Atmospheric electricity, for example, may perhaps yet be
utilized. It is by no means inconceivable that the electricity contained
in a thunder cloud might be employed to charge a Faure battery; but up
to the present no one has contemplated the obtaining of power from the
clouds, and whether it is or is not practicable to utilize a great
natural force in this way does not affect our statement. The use of
electricity must be confined to its power of transmitting or storing up
energy, and this truth being recognized, it becomes easy to estimate the
future prospects of electricity at something like their proper value.

It has been proved to a certain extent that electricity can be used to
transmit power to a distance, and that it can be used to store it up.
Thus far the man of pure science. The engineer now comes on the stage
and asks--Can practical difficulties be got over? Can it be made to pay?
In trying to answer these questions we cannot do better than deal with
one or two definite proposals which have been recently made. That with
which we shall first concern ourselves is that trains should be worked
by Faure batteries instead of by steam. It is suggested that each
carriage of a train should be provided with a dynamo motor, and that
batteries enough should be carried by each to drive the wheels, and so
propel the train. Let us see how such a scheme would comply with working