as the energy is converted into the form of light through the
incandescence of the filament. Such a conversion is called "work"
as distinguished from "drop," although a fall of initial electrical
pressure is involved in each case.

The percentage of "drop" varies according to the quantity of copper
used in conductors, both as to cross-section and length. The smaller the
cross-sectional area, the greater the percentage of drop. The practical
effect of this drop would be a loss of illumination in the lamps as we
go farther away from the source of energy. This may be illustrated by
a simple diagram in which G is a generator, or source of energy,
furnishing current at a potential or electrical pressure of 110 volts;
1 and 2 are main conductors, from which 110-volt lamps, L, are taken in
derived circuits. It will be understood that the circuits represented in
Fig. 1 are theoretically supposed to extend over a large area. The main
conductors are sufficiently large in cross-section to offer but little
resistance in those parts which are comparatively near the generator,
but as the current traverses their extended length there is a gradual
increase of resistance to overcome, and consequently the drop increases,
as shown by the figures. The result of the drop in such a case would
be that while the two lamps, or groups, nearest the generator would be
burning at their proper degree of illumination, those beyond would give
lower and lower candle-power, successively, until the last lamp, or
group, would be giving only about two-thirds the light of the first two.
In other words, a very slight drop in voltage means a disproportionately
great loss in illumination. Hence, by using a primitive system of
distribution, such as that shown by Fig. 1, the initial voltage would
have to be so high, in order to obtain the proper candle-power at
the end of the circuit, that the lamps nearest the generator would be
dangerously overheated. It might be suggested as a solution of this
problem that lamps of different voltages could be used. But, as we are
considering systems of extended distribution employing vast numbers of
lamps (as in New York City, where millions are in use), it will be seen
that such a method would lead to inextricable confusion, and therefore
be absolutely out of the question. Inasmuch as the percentage of
drop decreases in proportion to the increased cross-section of the
conductors, the only feasible plan would seem to be to in