IMPROVEMENTS IN THE PRODUCTION OF ELECTRIC LIGHT AND IN APPARATUS THEREFOR
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Edward Griffith Brewer at the
Office of the Commissioners of Patents, with his Petition, on the
5th August 1875.-A communication from abroad by Stephan
Alexandrovitch Kosloff, of St. Petersburg, in the Empire of
Russia.
I, EDWARD GRIFFITH BREWER, of Chancery Lane, London, do hereby
declare the nature of the said Invention of "IMPROVEMENTS IN THE
PRODUCTION OF ELECTRIC LIGHT AND IN APPARATUS THEREFOR," (a communication
to me from abroad by Stephan Alexandrovitch Kosloff, of St. Petersburg,
in the Empire of Russia), to be as follows:-
These improvements consist essentially in the subdivision of the
electric light, which is produced by means of an electric current heating
to a white heat sticks of carbon placed in the circuit, and being
hermetically enclosed in a globe filled with nitrogen gas, all as herein-
after set forth.
First. The linequal expansion by heat of different substances employed
in electric light apparatus has not been hitherto sufficiently considered
by other inventors, they therefore placed their carbons on metal

page_text: conductors, which served as supports, and fixed them firmly thereto
either by pincers or by being screwed to the same, or by other means.
This way of joining together two different substances subject to different
temperatures produced the breakage of the carbon, the latter not
expanding in the same ratio as the metal, or because the expansion of
the metal being greater than that of the carbon the metal in heating
detached itself gradually from the carbon and produced electric sparks.
In my system the carbon is placed between two insulating supports,
either of china clay, crystal, calcined magnesia, or other insulating
substances, the carbon fitting in and being allowed to move a little in
the hollow of the said supports.
Second. Every metal which is outwardly attached, screwed or fixed in
any other way to the carbon, detaches itself in heating and produces
electric sparks and consequently the melting of the metal. In my
system I introduce the metal wires into the carbon, which gives me a
better contact when the carbon is heated by the current and does not
produce electric sparks. In order not to put the metal into direct
contact with the white hot carbon thicker end pieces of carbon with
holes crosswise (that is to say through the length and the thickness)
serve as communicators of the electric current, and these thicker pieces
of carbon not being such bad conductors as the thinner sticks of carbon,
(which are destined to give the light, and which fit into the thicker
picces of carbon heat to a lesser degree the metal introduced into
them.
Third. The connection of the principal conductors with the metallic
wires, which are introduced into the thick end pieces of the carbon, I
effect by means of hinges or fastenings of fine twisted metallic wire,
leaving a little space to move about in case of dilation resting thereon
with their own weight. I thus obtain a sufficient contact without
producing electric sparks. My connections cannot increase the loss of
electric current, because the heat produced by an electric current passing
through two pieces of metal not firmly attached to each other, but
closely touching each other, is much smaller than the heat caused to
my connections by the contact with a white hot body in a high
temperature.
Fourth. In order to avoid the inconvenience of the preparation of
nitrogen gas and its introduction into the lamp after the air has been
withdrawn from it, according to my Invention I produce the gas by

page_text: rarifying the air in the globe in which the apparatus is placed by means
of the carbon itself which is heated by the electric current, and which
at the same time is to give the light. By dilating the air which could
not occupy the same space in the globe it is caused to escape out of the
globe through a valve or valves and then cannot re-enter the globe.
The small quantity of oxygen remaining in the rarified air in the globe
is transformed into oxide of carbon. In order to have as little air as
possible in my lamps I fill the superfluous space in the globe with
massive picces, or pieces in the shape of tubes closed at one end, of
china clay, calcined magnesia, crystal, or any other insulating substance,
with a hollow through their whole length for their metallic conductors,
or even of carbon with insulators instead of employing metallic
conductors. I also make use of these massive pieces as supports for the
carbon bearers of the sticks of carbon which are destined to give the
light. If I make the said filling pieces as insulated pieces of carbon,
carbon connections may be employed for connecting with the thin
carbon sticks. The globe and the said massive pieces must be of
sufficient length, according to the strength of the light which it is
intended to produce, in order that the valve or valves may not be
exposed to too great a heat, and in order that by employing a hydraulic
joint or closing of any liquid which being exposed to a certain heat
does not produce vapours which would consume the carbon; I altogether
avoid mercury as being dangerous to the health. The said massive
pieces may also be of metal, but in that case I introduce insulators in
order that the currents may meet in the sticks of carbon. When I
have not at my disposal a stronger electric source to enable me to light
thicker sticks of carbon then I place several thin sticks of carbon into
the same lamp, and I light them successively the one after the other,
and in order to cause the electric current to pass automatically from
one carbon to another I employ the following system:-I introduce the
metallic wires which traverse the thick pieces of carbon not at the same
height, but gradually a little lower than in the preceding piece of
carbon. In case of breakage of one of the lighted carbons the thick
piece of carbon being fastened on one side only will incline through its
weight towards the wire extending in the shape of a ring from the
second carbon, and having a wire in the form of a hook or a plate, place
itself into the ring of the second carbon, the current being interrupted
in the first carbon is communicated to the second carbon, and from the
second to the third and so forth.

page_text: In lamps with several carbons the insulators between which the
thick pieces of carbon repose are of a round shape with a small opening
to allow guards to be placed into them, which prevent the thicker pieces
of carbon from descending lower than they ought. After having put
the carbon into its place the opening is shut up by means of a bolt or
hook.
In lamps with several carbons one pole is in communication with one
end of all the carbons, whilst the other pole is put into communication
with all the carbons which are to be lighted, first, that is to say, with
the carbons where the aforesaid metallic wire is highest.
If I do not want to make use of the automatic mechanism in the
lamps with several carbons I employ a commutator, where one pole is
in communication with the one end of all the carbons, whilst the other
pole may be put into connection with each series of carbons in the
different lamps having separate conductors. The system of placing the
lamps into the circuit may be effected in two ways, namely, either by
placing one series of lamps united by a metallic wire in such a way
that the current traverses all the carbons, the conductor of one pole
being in communication with the first lamp, and the conductor of the
other pole in communication with the last lamp, or by subdividing the
current, that is to say, the current of one pole is subdivided from one
point, and conducts the current by separate conductors to each lamp.
The current of the other pole subdivided in the same way meets the
current of the first pole in each lamp.