Delaware state journal. [volume] (Wilmington, Del.) 1870-1883, 1880-09-23
THE EIECTRIo LfGHT.
An Account of Its Present Condition
and Prospects by the Menio Part
Inventor,

An Account OF Its Present Condition
and Prospects by the Menio Part
Inventor.
Mr.. Thomas A. Edison contributes an
article to the October number of the North
American RepidD, in which he states that
he has succeeded in making the electric
light entirely practicable for illuminating
purposes. He shows the advantage of
electricity over gas, and explains how his
system IL to be introduced. He comments
upon the unfavorable opinions that have
been passed upon his work, and says that
similar Judgments were pronounced upon
telegrapy, steam navigation, and other
great discoveries
Mr.. Edison begins his article with few
words to those who have expressed their
impatience ut the delays in the perfectirg
of the electric light. The delays which
have occurred to defer its general intro
duction are chargeable, he says, not to any
defects since discovered in the Original
theory of the system ia its practical
workings, but to the enormous mass Of
details which have 10 be mastered before
the system caa go into operation on u
large scale and on commercial basis as a
rival of the existing system or lighting by
gas. Important improvements have been
brought about by these delays in the
direction of economy and simpltication at
almost every point in the system, as we'll
as in the details of manufacturing the
apparatus.
The lamp, the inventor tells us, has
been completely transformed. To quote
mis- words -
The perfected lamp consists of an oval bulb
of glass about five inches in hight, pointed at
one end, and with short stem three-quarters
OF All inch in diameter at the other. Two
wires Of platinum enter the bulb through this
stem, supporting the loop or U-shaped thread
of carbon, which is about two inches in hight.
The stem il Theoretically sealed after the
introduction of the carbon loop. At its
pointed end the bulb terminates in an open
tube through which the air in the bulb il
exhausted by means of u mercury pump till
not over one-millionth part remains. The
tube IL then closed. The outer extremities OF
the two platinum wires are connected with
the wires of an electric circuit, and at the
base OF the lamp is q screw by which the
circuit il made or broken at pleasure. When
the circuit is made the resistance offered Ia
the passage of the electric current by the
carbon causes the loop to acquire a high
temperature and to become incandescent, but
as this takes place i'll u vacuum, the carbon il
not consumed. The ''life' of a carbon lool
through which n current IL passed continu-
orsly varies from $50 to 900 hours. With an
intermitted current the loop has an equa
duration of life, and as the average time al
artificial light is used is five hours per day il
follows that one lamp will last about six
months. Each lamp costs about so cents, and
when one fails another may be easily substi-
tnted for it..
Another important modification of the
system, introduced since the latest author
lied accounts of the light WAS published
is the substitution of dynamo-machine
for magnetic o-machines in the stations from
which the electricity is to be supplied tc
the several districts of a city-a change in
the direction Of simplicity and economy
To the question which is 30 often asked
when will public demonstration of tht
working of thissy stem be made, the in
ventor implies:
Such demonstration will in all probabilit,
be made at Mcnlo Park within two month
from this date. The time which has elapseI
since the preliminary demonstration of las
January has been by no means season of in
| action for the promoters of this enterprise
There il vast gulf between the most success
ful laboratory experiment possible and tn
actualization of the results of that experimen
i'll commercial sense. A prodidigious amour
of work was neccssitated by the establishment
of factories for producing the lamps, th,
generators and the other essential parts o
the system in large quantities. so as to b
able to supply the first demand.
Mr.. Edison goes into the particular
concerning his lamp, giving a statement o
its advantages over gas in the matter o
simplicity in the management an
economy. He repeats what has alread
been made public concerning the plans TO
lighting cities. Estimates are being mad
of the exact cost of 'plant" in differen
cities; contracts are being negotiated fo
the manufacture on large scale o
engines, dynamos, lamps, wire and all til
other supplies needed for the practical in
PRODUCTION of the system throughout tn
country.