feeder system was that
relating to the equal distribution of current on a large scale over
extended areas, in order that a constant and uniform electrical pressure
could be maintained in every part of the distribution area without
prohibitory expenditure for copper for mains and conductors.

This problem had a twofold aspect, although each side was inseparably
bound up in the other. On the one hand it was obviously necessary in a
lighting system that each lamp should be of standard candle-power, and
capable of interchangeable use on any part of the system, giving the
same degree of illumination at every point, whether near to or remote
from the source of electrical energy. On the other hand, this must be
accomplished by means of a system of conductors so devised and arranged
that while they would insure the equal pressure thus demanded, their
mass and consequent cost would not exceed the bounds of practical and
commercially economical investment.

The great importance of this invention can be better understood and
appreciated by a brief glance at the state of the art in 1878-79,
when Edison was conducting the final series of investigations which
culminated in his invention of the incandescent lamp and SYSTEM of
lighting. At this time, and for some years previously, the scientific
world had been working on the "subdivision of the electric light," as
it was then termed. Some leading authorities pronounced it absolutely
impossible of achievement on any extended scale, while a very few
others, of more optimistic mind, could see no gleam of light through the
darkness, but confidently hoped for future developments by such workers
as Edison.

The earlier investigators, including those up to the period above named,
thought of the problem as involving the subdivision of a FIXED UNIT
of current, which, being sufficient to cause illumination by one large
lamp, might be divided into a number of small units whose aggregate
light would equal the candle-power of this large lamp. It was found,
however, in their experiments that the contrary effect was produced,
for with every additional lamp introduced in the circuit the total
candle-power decreased instead of increasing. If they were placed in
series the light varied inversely as the SQUARE of the number of lamps
in circuit; while if they were inserted in multiple arc, the light
diminished as the CUBE of the number in circuit. [29] The idea of
maintaining a constant potential and o