The Marietta journal. [volume] (Marietta, Ga.) 1866-1909, 1889-01-17

| curing large wires Tor low currents,
the distance to which the low cur
rents can be conveyed without un-
reasonable expense is very short.
A few years ago the above des-
cribed were the only two successful
systems, viz:
1. Arc lights, requiring small
wires, over which pressure currents
can be conveyed over large terrific
ry, making large distribution Of
lamps but a poor distribution of
light.
2. Direct current incandescent
system, suitable for use in few
adjacent blocks at best, but used
most successfully in single buildings
or manufacturing establishments.
The incandescent light is per-
fectly steady, for ordinary purposes
is made Is candle-power, and ex-
actly takes the place OF one good
gas jet. Since it's introduction it
has steadily grown in favor, and
now promises to occupy the first
place as method of obtaining
light.
The above described systems are
both "direct current" systems; that
is to say, the positive waves of cur
rent are collected together at one
pole of the machine and the mega
tive waves of the other pole. The
arc light is good street light, and
can be used within large areas
about the dynamo. The direct cur
rent incandescent is good domes-
tic light, but can be used within
very limited areas about the dyna-
mo.
Within few years the alternat-
ing current system has been de-
veloped. 1t is a system which an
alternating (alternate positive and
negative waves current is gener-
ated of high pressure. The high
pressure is required in order that
it may be conducted on small wires
over large areas. The current is al
ternating because an alternating
current may, by a special form of
induction coil or converter, be
converted from a current of high
pressure and small volume to one
OF low pressure and large volume.
Thus by this system we may convey
currents of high pressure over
small wires through the streets over
large areas. Then at each place
where it is desired to use incandes-
cent lights place converter and
reduce the current from say 1000
volts street pressure to so volts in
the house for use in the incandes-
cent lamps. While 1000 volts is
current dangerous to human life, it
is not so dangerous as the 1000 and
5000 volt arc current, and is never
brought in house, as the latter
must be, whenever an arc light is
used indoors.
There are special uses to which
each of the three systems are best
adapted. The arc light is most
suitable for street lighting, or for
large halls and interiors. The d.
rect current incandescenss system is
most suitable for single buildings,
such as factories, hotels, ETC.; usu-
ally where steam if kept up for
other purposes. The alternating
current incandescent system is best
adapted for the use of electric light
companies, where the aim is to fur
nish light over large areas for any
purpose. 1t can be used for street
lighting, and can be distributed bet
ter than arc light, though it has not
the dazzling brilliancy of that light.
1t is good domestic light, and in gen
eral covers larger field than either
or perhaps both OF the other two
systems.
The following estimates are made
as illustrations of what would be
the cost of'plant, cost of operation
and possible income for electric
light plant suitable for towns Of
four to six thousand inhabitants.
Estimate for an arc light plant OF
80 lamps of 1000 candle power
each.