Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1880-01-15

if it does last more than twenty minutes, the
idea is stolen from some one else. There are
lamps that have been burning, night and day,
with about FIVE minutes stoppage-owing to
an accident to the generating machine-tor
twenty.one days. As the average use of a
gas.burner even in winter is not more than six
hours day, this represents service of about
three months ordinary usage We have in.
vited our detractors and critics to come and
see what we have done, but they will not
come, contenting themselves with letters to
the newspapers demonstrating the impossi.
blity Of our success"
During the whole of the reporters visit, it
was impressed upon him that neither Mr..
Edison nor his assistants asserted the COM
plete success of their lamp. 1t was as yet an
experiment, point which the public is in:
clined to overlook If the lamps burned
steadily for six months, then it would be time
to exult. For all that Edison knows, the
lamps may fail tomorrow. No one has been
more surprised at their endurance than he
himself asaas
THE CARBoNIZED HORsE-sHoEs.
First, the reporter was taken to the furnace
room where the cardboard horse-shoes are car
bombed. For months Edison has been work.
ing on platinum as fit substance for the in
candescent thread. He discovered, by acci
dent, about six weeks ago, that carbonized
cardboard would do as we'll, and since then
has directed all his energies to finding the
best cardboard for this use and the best way
of preparing it. Two thousand samples of
card were tried, and fine bristol board was
found most satisfactory. A die cuts out lit
tie horseshoes about an inch and half in
diameter, or about twice the size of the jew
elled pins of that shape. Three of these are
placed, with tissue paper between each, in a
matrix or box of iron, and the box is heated
to white heat in charcoal furnace. In
about twenty minutes the iron plates show
signs of melting and then are withdrawn. A
dozen of the carbonized shoes lay on the ia
BILE. In baking they had been reduced about
one.third, and were nothing but black threads,
rather frail, but stout enough to allow of
careful handling with pincers. From the fur.
mace the horseshoes 60 into the next room,
where they are attached to platinum wires
about an inch long, intended to carry the cur.
rent. Each wire terminates at the horseshoe
in little clamp in which the ends of the
horseshoe are caught. ~
THE GLASS LAMP.
Then they are ready for the glass-blower,
man brought over from the works in Ger.
many where the Geisler tubes are made, and
specially adroit at dealinAwith vacuum tubes.
It is necessary that the carbon shall be en-.
closed in glass vessel from which the air
is completely exhausted Otherwise, when
the current is sent through, there would be a
flash, and the carbon would fall to pieces.
The glass blower takes glass bulb, open at
the top, and heats the bottom over spirit
lamp. When it is about to melt, he plunges
the two platinum wires, attached to the car.
bon, through the melting glass; The horse
shoe remains inside the bulb with its two
wires projecting through the bottom: These
wires are fourteen-thousandths of an inch in
diameter. 1t has been objected by critics
that the difference in the co.ef6ciency of ex-
pansion and contraction between platinum
and glass, would open loophole at the thin
point of entrance of the wire and allow the
air-pressing on the outside with pressure of
fourteen pounds to the square inch, to get
in and destroy the vacuum. Edison says, on
the other hand, that Geisler tubes, construct.
ed very much in the same way, have been
known to maintain vacuum for twenty years,
and that the difference in expansion between
platinum and glass is exceedingly small. At
any rate, so far the lamps have maintained a
better vacuum than is obtained in a Geisler
tube, with perfect success. The glass. blower
now draws the open top of the bulb into
narrow tube, and the lamp is taken to have
the air exhausted. This is accomplished in
half an hour by Edison's ingenious modi6ca.
tion of the ordinary Geisler pump. By the
usual methods, it would require day to ex-
haust the air from each Of these lamps. BY
the present process, only one-millionth of the
air remains at the end of twenty minutes.
The air is of course exhausted by the tube
left open at the top of the bulb. When the
mercury test shows that all the air is exhaust
ed, spirit lamp is held under this tube, and
as soon as the glass becomes soft, the atmos-
pheric pressure on the outside closes the tube,
and the lamp is finished. About thirty lamps
a day are now made at Menlo Park. At
wholesale, the cost for each lamp will not
exceed twenty-five cents, and may be less.
If now an electric current is passed through
the platinum wires leading into the lamp,
the horseshoe becomes instantly incandescent
and sends out white light very similar to
that thrown out by iron at white heat. The
platinum is the only metal which would not
melt in so great a heat.
THE GENERATING MACHINE AND METER.
The generating machine which Edison uses
at Menlo Park, are notifications OF the
Gramme magnetic. electro machine. He has
several of his own design and is busy con-
structipg more. Each machine takes up about
two square feet of floor room only, and is ca
pable of furnishing electricity for fifty lamps.
It requires about six horse power to run each
machine. Edison's plan for practical work
ing in New York City is to have one central
station for every eight or ten city blocks. A
powerful engine will run as many of these
generating machines as are required: de
estimates that one good-sized cellar will con-
tain the whole "plant" for furnishing the light
to several blocks of hundred houses each.
The lamps will be placed on circuits of fifty
lamps each. The meter for measuring the
electricity used by each consumer consists
of a bath of fcopper salts, into which will run
a wire carrying say one:fftieth of the current
passing into the house. According to the in.
tensity and duration of the current, the depos'
it of copper in the bath will be greater or less.
and will determine exactly the amount of
elootr;oitv used No method has vet been