IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1881

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
ELECTRIC LAMPS." A communication from abroad by Camille Alphonse
Faure, of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 4th October 1881.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN ELECTRIC LAMPS." A communication from
abroad by Camille Alphonse Faure, of Paris, in the Republic of France.
This Invention relates to electric lamps in which light is obtained by incan-
descence, and has reference to the production of the carbon itself; also to holders
for carbons; also to the provision of means whereby the carbon may be removed
without the destruction of the body of the lamp; and further to improved incans
of exhausting the lamp and effecting its hermetic closure.
The form of incandescent lamp employed for the purposes of this Invention is
preferably in the shape of a small glass globe with a tubular stem or neck similar
to what is known as the Swan lamp. A metallic socket or collar is fixed at the
end of the stem by fusing the said stem on to the inside or outside of the socket,
or by previously electro plating the stem and turning the socket, which is then
soldered on to the electro plated deposit, or by pouring between the surface of the
socket and that of the stem a metal or material in a molten condition, which by
expanding in cooling will effectually close any space between the two and secure
an air tight joint. The carbon holder consists of a metal tube closed at one
extremity by a glass plug to which it is attached by the means herein before
described, and the tube is so shaped as to fit into the socket on the stem and
allow of the tube and socket being soldered or screwed together, or so arranged
that some material may be interposed between the two to make an air tight joint,
the object being to enable the carbon holder to be withdrawn by simply unscrewing,
unsoldering, or detaching the parts.

page_text: The two electrodes or conductors upon which is fixed the carbon filament or
other material capable of producing the incandescent light are arranged in the
following manner, viz.-One of the said electrodes is formed by a piece of wiro
soldered on to the tube or carbon holder, and the other is formed by means of a
small metallic tube passed through the glass plug hereinbefore referred to, so that
externally the carbon holder and socket form one conductor and this small tube
forms the other conductor; the carbon filament is secured inside at the ends of
the electrode by means of two spring clips of platinum or other suitable metal,
such clips being made by bending a piece of platinum wire, for example, into an
elongated loop, and then flattening such wire so as to give it strength and cooling
surface.
These clips are fixed on to the ends of the wire and small tube hereinbefore
described. The arrangement for effecting the final sealing is such that tho
ordinary glass sealing obtained by the fusion of the glass tube used to exhaust the
globe is dispensed with. This improved arrangement consists of a metallic cup
terminating the small metallic tube hereinbefore described, which cup is filled with
a fusible metal or material perforated with a fine hole through which exhaustion
takes place. After exhaustion the fusible metal is heated or partially fused,
whereby it is caused to run into and close up the said fine hole, and so finally seal
the lamp. The fusible metal in the cup is also utilized for making the connection
between the tube and the air pump by partially fusing the said metal round the
extremity of the tube connected with the pump.
It is obvious that the above said cup may be attached anywhere to the socket
instead of to the central tube.
The tube for exhausting the air may also be arranged at any other suitable part
of the socket in lieu of being passed through the stem, as herein before described.
In this case the extremity of the carbon is supported by a suitable conductor
passed through the glass plug.
The carbons are manufactured by drawing or cutting graphite or carbon into
small strips or pencils, which are then heated and bent into the form of loops or
any other required shape while hot. These conductors are capable of being used
to produce incandescent effects in electric lamps in the same manner as the carbon
filaments or other incandescent conductors ordinarily employed in such lamps, and
formed of vegetable materials bent into shape before being calcined.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
3rd April 1882.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN ELECTRIC LAMPS." A communication from
abroad by Camille Alphonse Faure, of Paris, in the Republic of France.
This Invention relates to electric lamps in which light is obtained by incan-
descence, and has reference to holders for carbons; also to the provision of means
whereby the carbon may be removed without the destruction of the body of the
lamp; also to improved means of exhausting the lamp and effecting its bermetic
closure; and also to the production of the carbon itself.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 is a sectional elevation of a lamp constructed according to the said
Invention.
The form of incandescent lamp employed for the purposes of this Invention is
preferably in tho shape of a small glass globe a with a tubular stem or neck a³, it
being similar to what is used in the lamp known as the "Swan lamp." A metallic
socket or collar bis fixed at the end of the stem a² by fusing the said stem on to
the inside of the said socket, but preferably by previously electro-plating the stem
so as to cover it with a metallic coating 62 and then turning the socket b, which
may then be soldered on to the electro-plated deposit 6 or be fixed thereto by
pouring between the surface of the socket and that of the stem, or metal, or
material, as at 6, in a molten condition, which by expanding in cooling will
effectually close any space between the two and secure an air-tight joint; or the
socket itself may be formed on the glass stem a² by the process of electro-deposition.
The carbon holder consists of a metal tube c closed by a plug d of glass, porcelain,
or other non-conductor, to which it is or may be attached air tightly by the means
herein before described. The said tube c is so splayed out or shaped into a trough c²
at the other end as to contain a metal c³, which fuses or melts at a comparatively
low temperature for receiving the outer edge of the socket b so as to make an
air-tight joint, the object being to enable the carbon holder and the carbon held
thereby to be withdrawn by simply fusing the metal c³ so as to unsolder the parts.
The two electrodes or conductors f, g, upon which is fixed the carbon filament /
or other material capable of producing the incandescent light are arranged in the
following manner:-The one electrode is formed by a piece of wire g soldered or
brazed on to the tube or carbon holder and the other electrode is formed by
means of a small metallic tube i passed through the plug d and through a plate 2ª
to which the wire f is attached by brazing or soldering the said plug d, forming an
insulator between the electrodes. The carbon holder c and socket b form ono
conductor, and the small tube i forins the other conductor for completing the
circuit through the carbon filament, which is secured inside at the ends of the
electrode by means of two spring clips of platinum, steel, or other suitable metal,
the said clips being made by bending a piece of steel or of platinum wire, for
example, into an elongated loop, and then flattening such wire so as to give it
strength and cooling surface.
Figures 2 and 3 are views of one of the clips, the said views being taken at right
angles the one to the other. These clips are fixed on to the ends of the wires f..

page_text: by brazing, rivetting, or by other means capable of withstanding the heat, and the
carbon ends being passed between the tongues of the clips the said clips hold the
carbon firmly in position, whilst the said carbon may readily be withdrawn when
desired for renewal. The arrangement for effecting the final sealing is such that
the ordinary glass sealing obtained by the fusion of the glass tube used to exhaust
the globe is dispensed with. This improved arrangement consists of a metallic
cup terminating the small metallic tube i, which cup is filled with a metal it
which fuses or melts at a comparatively low temperature, and which before the
globe is exhausted is perforated with a fine hole through which exhaustion takes
place. This hole is shewn at in Figure 4, which represents (drawn to an
enlarged scale) the cup is and part of the tube i of a lamp in position upon the
tube m of the air pump, the lamp itself being omitted from this Figure. The
metal being heated so as to become soft is simply pressed upon the said tube m
to attach the lamp thereto by the embedding of the end of the said tube in the said
metal. After exhaustion the fusible metal is heated or partially fused, and the
lamp being slightly pressed up upon the tube m to prevent the access of air to the
lamp, the pressure of the external air causes the said metal to run into and
close up the said fine hole , and so seal the lamp and secure the vacuum.
It is obvious that the above said cup may be attached anywhere to the socket
instead of to the central tube. The tube for exhausting the air may also be
arranged at any other suitable part of the socket in lieu of being passed through
the stem, as herein before described. In this case of course the wire is continued
through or supported by a suitable conductor passed through the plug d.
It will also be readily understood that the socket may be formed on or affixed
to the inside of the neck a², or that the said neck with its metallic socket formed
on or affixed thereto may be imbedded directly into the metal c³. By using at 63,
c³, and i³, a metal which expands on cooling, a very tight joint can be formed. In
any case the metal c³ and it is of such a nature (for example, tin or alloys thereof),
that the application of a hot tool or iron to the trough cor cup ³ will fuse the
said metal.
The carbons for electric lamps are manufactured according to this Invention by
drawing or cutting graphite or carbon into small strips or pencils, which are then
beated and bent into the form of loops or any other required shape while hot.
These carbons are capable of being used to produce incandescent effects in electric
lamps in the same manner as are the carbon filaments or other incandescent
conductors ordinarily employed in such lamps, and formed of vegetable materials
bent into shape before being carbonized.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. The electric lamp, constructed substantially as hereinbefore described and
illustrated in Figure 1 of the accompanying Drawings.
Second. Preparing the globe of electric lamps for metallic connection with its
socket or with the carbon holder by depositing by electro-plating or deposition a
metal upon the neck or stem of the said globe, as horeinbefore described.
Third. Effecting the junction of the globe with the carbon holder of electric
lamps by means of a metal fusible at a comparatively low temperature, substan-
tially as hereinbefore described with reference to the trough c² and metal c³, and
for the purpose of forming a tight joint and rendering the carbon holder readily
removeable.
Fourth. Effecting the attachment for exhausting and the sealing of electric
lamps to secure the vacuum therein by means of a metal fusible at a comparatively
low temperature, substantially as hereinbefore described with regard to the cup is
and metal 4.

page_text: Fifth. The clips & for connecting the carbons of electric lamps with the circuit
wires, as hereinbefore described and illustrated in Figures 2 and 3 of the accoin-
panying Drawings.
Sixth. Manufacturing carbons for electric lamps by drawing or forming graphite
or carbon into strips or pencils, and then heating them and bending them into
shape whilst hot.
In witness whercof, I, the said John Henry Johnson, have to this my
Specification hereunto set my hand and seal, this First day of April, One
thousand eight hundred and eighty two.