d
and seventy-five patents in this branch of industry alone. These patents
may be roughly tabulated as follows:

Incandescent lamps and their manufacture....................149
Distributing systems and their control and regulation....... 77
Dynamo-electric machines and accessories....................106
Minor parts, such as sockets, switches, safety catches,
meters, underground conductors and parts, etc............... 43

Quite naturally most of these patents cover inventions that are in
the nature of improvements or based upon devices which he had already
created; but there are a number that relate to inventions absolutely
fundamental and original in their nature. Some of these have already
been alluded to; but among the others there is one which is worthy
of special mention in connection with the present consideration of a
complete system. This is patent No. 274,290, applied for November 27,
1882, and is known as the "Three-wire" patent. It is described more
fully in the Appendix.

The great importance of the "Feeder" and "Three-wire" inventions will be
apparent when it is realized that without them it is a question whether
electric light could be sold to compete with low-priced gas, on account
of the large investment in conductors that would be necessary. If a
large city area were to be lighted from a central station by means
of copper conductors running directly therefrom to all parts of the
district, it would be necessary to install large conductors, or suffer
such a drop of pressure at the ends most remote from the station as
to cause the lights there to burn with a noticeable diminution of
candle-power. The Feeder invention overcame this trouble, and made it
possible to use conductors ONLY ONE-EIGHTH THE SIZE that would otherwise
have been necessary to produce the same results.

A still further economy in cost of conductors was effected by the
"Three-wire" invention, by the use of which the already diminished
conductors could be still further reduced TO ONE-THIRD of this smaller
size, and at the same time allow of the successful operation of the
station with far better results than if it were operated exactly as at
first conceived. The Feeder and Three-wire systems are at this day used
in all parts of the world, not only in central-station work, but in the
installation and operation of isolated electric-light plants in
large buildings. No sensible or efficient station manager or electric
contractor