Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1880-01-16
EdisOn's Electric Light.
HIS NEW VACUUM LAMP, AND HOW IT IS MADE.
tFrom New York Lettor,l

HIS NEW VACUUM LAMP, AND HOW IT IS MADE
tFrom New York Jettorl
found the great inventor in his library
over an office where the accounts are kept
As he has a hundred men in his employ, strict
system is necessary. Edison is a tall, thick
set, pale man, with sunken eyes, and the gem
eral air of a man accustomed TO pass night af-
ter night in experiments, as he sometimes
does His assistant, Mr.. Bachelor, showed
me over the premises, Edison having already
explained everything to some thirty different
visitors and having no voice left. First,
was taken into furnace room in which the
now celebrated carbonized horseshoes are
made. Little bits of the best bristol board
are heated for 20 minutes in an iron matrix,
coming out as carbonized black threads,
something in the shape of horseshoes, about
an inch across Edison experimental With
2O0O kinds of cards before getting the best.
II is found that this carbonized card stands
the heat of the electric current better than
platinum. The next step in the manufacture
of the lamp is to fasten two platinum wires to
tho horseshoe, one to each end. The wiros
are an inch or so long, and 14-1000 Of an inch
in diameter. Then the horseshoe, with the
two bits Of wire hanging from it, is inserted
in a glass bulb about the size of an egg, and
open at the top. Tho bottom of this bulb is
heated over a spirit lamp, aud when at melt
ing point, the two wires are allowed to pene-
trate the glass, the horseshoe remaining in
side and with the wire projecting through the
bottom Of the glass and firmly welded into it.
The glass blower who is q man brought over
from Germany on purpose, then draws the
open top of the bulb together in the shape of
a tube, and the lamp is taken TO Geisler
vacuum pump, where by an improvement of
Edison's the air is exhausted until only one
millionth remains. As soon as the right
vacuum is obtained the lamp is sealed up,
finished.
II now an electric current is passed into the
lamp by means of the platinum wires, the
carbon horseshoe instantly becomes incandes-
cent, giving forth a clear, soft, steady light,
without the slightest flicker Edison uses for
generating the current modification of the
gramme magneto-electric machine From
one Of these machines, which occupies about
a floor space of two square feet, he can get
current enough to light 80 lamps of the inten-
sity Of one four-foot gas burner each. 1t re-
quires about six horse power TO run one gen
Grating machine. As steam power in large
quantities in New York city costs about one
cent an hour per horse power, it will be seen
that the light will cost about one.eighth
of a cent an hour or for an evening of four
hours each lamp will cost half q cent. Edison is
COnuOent tlhL no matter now low Iue gus
companies put their gas he can sell a better
light, cheaper. When l was in the buildings
there were 30 of these lamps burning, all Civ
ing a pure, pleasant light. Many Of them
had been burning night and day for 81 days.
No one is more surprised at their success than
Edison himself. As yet however, the test
has been too short to assert that a complete
success has been made If the lamps burn
six months then it will be time to sell gas
stock. The same current which is used for
the lamps can also be utilized for running a
sewing machine or pumping water. l saw a
sewing machine go beautifully by just switch
ing off the current used to light one burner
into little electric motor. 1t is objected
that the carbon horseshoes will not last more
than a month or two. Only time can decide
these points. Edison himself is the first to
say that six months time is necessary. The
lamps will cost about twenty-five cents to
make, and the whole cost OF making the
change from gas to electricity will not be
more than ten dollars for an ordinary dwell
ing house.