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IN most towns and cities where electricity for light and
power is carried over long distances, it will be noticed that
small iron boxes are fastened to the poles at frequent
intervals, 'usually wherever there is a group of houses or
buildings supplied with the current. Many boys know that
the boxes contain “ transformers,” but do not quite under-
stand exactly what their purpose is, and how they are

When it is desired to convey electrical energy to a distance,-
for the purpose of producing either light or power, one of
the chief problems to be faced is, how to reduce to a mini-
mum any possible waste or loss of energy during its trans-
mission. Furthermore, since wires and cables of large size
are very costly, it is desirable that they be as small as
possible and yet still be able to carry the current Without
undue losses.

It has already been explained that wires ofler resistance
to an electrical current, and that some of the energy is lost
in passing through a wire because of this resistance. Small
Wires possess more resistance than large ones, and if small

wires are to be used, in order to save on the cost of the

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