Evening star. [volume] (Washington, D.C.) 1854-1972, 1879-12-27
EDIsoN's HORSESHOE LIGHT.

| EDISON'S HORSESHOE LIGHT.
A Charred Paper Burner Glowing
! for One Hundred HOurs-Prepar-
ing <a Publicly Demonstrate that
He Can 40 what He Claims-HoW
the Air Is DraS-.n From the Lamps.
New York SUM-
There's no unearthly graveyard glare about
mat" said Mr.. Edison, In hts laboratory in
notice, there are sr no sharp Shadows" you VIII
On table before him was one OF his new
horse.Sho electric lamps-one OF a dozen that
laboratory. This room, Mr.. EdisonS Office his
shop. his house, and five other houses are now
lighted nightly with the new lamps; but this is
his preparations are made For this he viii fix
10 date, but he hopes to be ready on Monday
night next. The new lamp resembles a mlnia-
small pear shaped globe. The loop OF fire has
1a1ne orange ttnge, and a soft light, not very
different from gas-light in color, but purer and
without flicker. The reason that the ordinary
electric light produces black and sharply defined
shadows IS that 1t proceeds from very small
point Although it may appear to be as large
darntEg needle held between 1t and the eye
will place the eye completely In shadow. The
new light proceeding from loop over an inch
high and three-quarters OF an zach wide, shoots
rays across the edge OF every object from Its
different parts at varying angles. This causes
the sha mad ' TO SHADE GRADUALLY a on into light
OF the horseshoe, it appears to be over an
eighth OF an inch In width. but pair OF blue
glasses rob 1t OF its fringe: and it then shrinks
TO its true dimensions, about a Jhirty-second
OF an inch. 1t then shows Like loop OF white
hot iron.
Suppose, Mr.. Edison, tip that lamp with
my cane" said visitor, won't that loop OF
charred bristol board hreak:"
I'm show you," replied the inventor.
He then went to workbench, on which
stood small box OF the CARBON horseShoes
They had been prepared for lamps but had
proved TO be faulty and were condemned Lay
ing one Of them on a table, he placed finger on
one of the ends OF the Shoe and lifted the other
up and laid 1t nearly over on the table in the
opposite direction from its fellow. 1t twisted at
the top where the curvature was the greatest.
and finally broke there, just before the movable
end touched the table.
"This is paper" said Mr. Edison. at isn't
merely the remains Of bristol board. You may
make paper out Of various substances, and this
is charcoal paper. 1t has all the texture of the
paper left in. All have done to 1t is to drive
on an the other substances that were in 1t by
heating II In an oven. The texture remains as
it was The interlaced fabric Is left, AID it re-
tains its strength"
Then Mr.. Edison took one Of the lamps and
Jared 1t in his hands without breaking the
horseshoe, which could be seen vibrating inside
the globe
one Of the lamps hanging from the ceiling had
heen in use fer five days. It had been burned In
al about one hundred hours. and the horseshoe
seemed as perfect as ever. BY Mr. EdiSon'S d.
rection all the other lamps were turned off, and
lowed to run through the single lamp remain
ing. 1t ran uIA from about eighteen candle
rover to such pitch of luminosity that one
could read advertisements in the sun at the dis
lance Of IS feet. The rim of the horseshoe wild
ened until one could not see through 1t, and the
Whole resembled In shape an elongated silver
dollar. The laboratory Is 100 feet long and
about 30 feet wide, but all parts of IL were illu
minated.
Mr.. Edison expected that the lamp would be
destroyed In one of three ways: either the small
platinum wires connected with the horseshoe
would be melted, or the glass would crack near
where the platinum wires pierced it; or the
yafnly waiting until his visitors were tired for
the destruction of the lamp, Mr.. Edison had the
other lamps relighted.
Across long table in the laboratory ran two
wires three inches apart. If both were touched
at the same time a faint electrical effect was
produced on the nerves of the hand. Mr.. Edl
son took several lamps and laid them along be-
tween these wires. Each lamp had two wires
| extending from the bottom. When these wires
were, we're attached to the Two parallel wires each
! were several lamps near them, fed from the
same wires, but their luminosity was not SuS-
ceptibly diminished. Mr.. Edison hopes, IN prac-
tice to feed eight lamps with each horse power
he uses,
planned, "iS that the resistance offered by that
little piece Of charred paper, about two inches
in length, If Strengthened out Is as great as the
resistance of ten miles of telegraph wire.
tRa 1as sea Saa Of 9 ss
through ten miles of telegraph wIre the result
would be the same as If an equal current were
little horseshoe It IS this resistance That con- con.
| v"rts the electricity into heat, and causes the
charcoal to glow so brilliantly. All I do IS to
make make the e. horseshoe part OF the circuit by
ammonia. naphthaline, or other noxious gases
and vaPors, are given off, and only one-flf-
ssea1h - Of the heat produced by gaset is
Mr. Edison laid his hand on the globe of one
OF his burning lamps and invited bis visitors to
co the same. The heat was not unbearable,
although the glass touched was not an inch
from the glowing charcoal
Mr.. Edison said that so much OF the air had
teen IT moved from the globe by the method he
,mrlo1 ed to produce vacuum that its pressure
was only one-mtllionth OF that Of ordinary air.
] % exhaust lamp of air it is connected with
system Of glass tubes. One Of these tubes is
it. driving The air out at the top. The air is not
allowed to remain at the top, and when the
mercury fails by its own weight vacuum is
formed above It. This however S, is not perfect
long, upright tube A connection is formed be-
tween them, so that what air there Is In either
may circulate through both. The second tube
has small caliber, except where it is enlarged
little to serve Us an a1rchamber, Or, as 1t might
be termed, a partial vacuum chamber II
stream of mercury Is made to run down the tube
through the chamber, break into drops In the
chamber, and then run down the remaining part
OF the tube in broken column, between each two
pOlt1OnS OF the broken column Will be carried
downward small portion of air so long as any
is left in the chamber. By this process Sprengel
was able to produce a nearly perfect vacuum in
about twenty-four hours. While Mr.. Edison
was making use OF Sprengel tube, however, he
by accident allowed the mercury to pour
through the tube In an uninterrupted stream.
TO his surprise he found that although 1t was
not in accordance with SprengepS theory, the
air was exhausted faster than before. In some
way, which he does not attempt to explain with
certainty, the air was carried out by the con-
tinuouS stream of mercury more rapidly than
by means OF the vacant spaces In the interrupt
cd stream This discovery enabled him % pro-
duce such vacuum as he desired in one hour.
The other important processes In the making
II lamp require only Sk1iiful glass blowing
and nice manipulation in preparing the carbon
horse-shoes. 1t can, therefore, be made very
cheaply. Only small amount of platinum
wire is used. Platinum is the only conductor OF
electricity Mr.. Edison has found that he can
pass through glass, and then seal up the OPEN
Ing around 1t with an alright joint. This is
because in the first place, the platinum will ad-
here to glass in fused state; and, In the second
place, because it has very nearly the same
amount Of expansibility under like degrees of
heat.
Mr. Edison intends to measure the amount of
electricity each family uses In this way: He
Will draw Off from the wire entering the house
certain quantity Of the electricity, say one five
hundredth, and let it run through a solution of
Sulphate of copper. The more electricity that
runs through this chemical. the greater the