The Washington critic., 1888-05-15
Arc Lighting and its Diff
culties.
WHAT HAS BEEN ACCOMPLISHED,
Reports from New York, Brooklyn,
Philadelphia, Washington, Chi
cago and Other Cities.


N electric wires. This topic is one of alb
sorbing interest at the present time. Mu-
nicipal and legislative authority seek to
compel the burying OF all the wires with
out discrimination, and to cast upon the
parties interested the burden of finding
practical means to accomplish the end.
Mr.. Leggltt said;
Electric arc light wires may he EN-
ployed successfully, trained in the air on
poles, and an underground system is
practicable which can reproduce the same
conditions. Let us examine these Condi-
tions. All substances are conductors, as
copper, iron, lead rubber, glass, dry air.
Some substances are such poor conduC-
tors that, in comparison with those that
are better, we call them non-conductors,
and the greatest available non-Conductor
is dry air We use these poor or non
conductors, such as rubber, glass,
paraiiine, wood and dry air as insulators,
and we find dry air to be our most per-
feet insulator. Dry air Is n better insul la
Tor than rubber; if, therefore, in dry air
two rubber covered wires cross in close
proximity to each other the induction is
greater between them than would be the
case If both wires were bare. But air
is usually laden with moisture,
and water, charged as il is with the min
eTal salts and acids of the atmosphere, is
good conductor. We therefore coat our
line wires with an insulating material to
shield them from direct contact with
moist surfaces or other good conductors,
and so reduce in amount the current
which is always escaping by connection
TO the ground and which varies in direct
proportion TO the conducting property of
the intermediate medium.
Where insulated wires are trained on
poles, we have, at the rate of 30 poles to
the mile, thirty points at which small
amount of current may and always does
seep OIL to the ground.
Now let us put an insulated cable in
conduit i'll the ground. The conditions
are all changed in the most aggravating
manner
Instead of comparatively dry air,
the air is clanmy and heavily laden
with moisture, instead of a mass
of surrounding AIR as on the poles
but an. inch more or less in thickness.
Instead of resting at 30 points in mile
on glass supports, connected TO dry nom
conducting wooden poles to make the
passage to the ground as much obstructed
as possible, the line touches the condui
at, say, two or three points in the space of
every foot, or at, say, ten thousand points
in mile, and the conduit, itself it much
better conductor than glass or dry wood
is all that separates it from the earth.
The bearings at which the current may
leak away have been multiplied from
thirty contacts to ten thousand contacts
per mile while the conductivity of the
medium at each point has been greatly
enhanced. A regular arched subway
nearly TO a successful plan, but only a
State or city could stand the
necessary outlay. A subway of
this character, ! feet wide and
$ feet high, for Chestnut street alone
in Philadelphia was estimated would cost
the, city 81, 100000. After completion
such a. subway would have to be supplied
with forced ventilation to keep it dry. If
then the insulated wires could be sup
ported so rs to touch at but thirty points
TO the mile, the conditions of exterior
wire training on poles would be fairly APP
proximated.
Operations looking to the underground
ing of arc light wires have been prose-
cuted on large scale at New York,
Brooklyn, Chicago, Philadelphia and
Washington.
notwithstanding al reports to the con-
trary, find that ut New York, although
the Subway Commission has expended
vast sums of money and has succeeded in
burying certain telephone and telegraph
wires, no arc light line has, up TO this
time, been buried in New York city, and
this is fully corroboratcd by the report of
the Board of Electrical Control of Janu-
AIRY q, 1898.
At Brooklyn, n. Y, the Board of Com
missioners of Electrical Surveys instituted
thorough investigation Of this subject in
1886, and in its report of December 80,
1856, says:
with regard to electric light conduct
Ors this board has found no device which
would, with certainty, in its opinion, en-
able the wires carrying arc light currents
TO be safely and successfully operated in
the same conduit with telephone and tel
egraph conductors without disturbance
or injury to the latter.
But the board desires to say, emphat-
ically, that those fluent critics who talk
of putting electric light conductors un-
derground, making no distinction be.
tween arc lights and incandescent lights,
or between the arc lights of different sys-
tens, are Ignorant Of the alphabet of the
Tie president of the board visited all
the principal cities in Great Britain and
Europe. He found no arc-light wires
underground, and although a few years
since such wires were trained in the Paris
sewers, they have been removed, and no
arc-light wires are now allowed therein.
The Brooklyn Commission made
another report December 10, 1887, and on
this topic says. GAS was fully explained
in the last report. the subject of under
ground conduits for arc currents is the
one which presents the most numerous
and novel difficulties,
"Since IL has been impossible for Brook
lyn to take the lead in the experimental
solution of these, the only remaining
course was to watch carefully the progress
of experiments in other cities. This has
been done, both by correspondence and
by personal visits of members of the
board. The principal cities in which eX-
periments OF this kind have been in
progress are New York, Chicago Phila.
delphia, Baltimore and Washington. In
one or another of these, several systems
which We're regarded with favor a year
ago have since developed defects or even
come to entire failure.
'lt cannot he said that amy system
has yet been completely proven to
be permanently satisfactory. There
are one on two, however, which
promise well, and this board
awaits with attentive interest their fur
tber trial, regrctting only its inability
through the cause already specified, t'
cooperate in the experimental inycstiga
ton of the different and delicate ques
tiOns involved.
There arenO arc light wires under
ground up To this time in Brooklyn.
AT Washington In 1854 cables were laid
in = street from Ninth To fifteenth,
In few months It was necessary t.
dig up few of the same. Later ther'
was much more trouble and il was nj
taken up and relaid
About one yearafter the first laying i
was wholly abandoned because they coult
not make it, work.
In 1855 they laid cables on Pennsylva
mia avenue, from Ninth 10 First street
and imported an expert from Antwerp t.
Jay them. Twelve cables were laid il
folid cement and no expense spared t,
insure SuQpQSS