IMPROVEMENTS IN INCANDESCENT ELECTRIC LAMPS
Year: 1883

page_text: LETTERS PATENT to George Frederick Redfern of the General Patent
"
Office N° 4 South Street, Finsbury in the county of Middlesex, Patent Agent
for an Invention of "IMPROVEMENTS IN INCANDESCENT ELECTRIC LAMPS
communicated to him from abroad by Alexander Bernstein of Boston in the
United States of America
PROVISIONAL SPECIFICATION left by the said George Frederick Redfern
at the Office of the Commissiouers of Patents on the 13th August 1883.
GEORGE FREDERICK REDFERN of the General Patent Office N° 4 South Street,
Finsbury in the county of Middlesex, Patent Agent "IMPROVEMENTS IN
INCANDESCENT ELECTRIC LAMPS [communicated to him from abroad by Alexander
Bernstein of Boston in the United States of America]
"
The present invention relates to the manufacture of hollow carbon cylinders,
which are with great advantage employed in electric incandescent lamps as well as
to the manner of uniting these carbons to the conducting wires.
Hollow carbon cylinders can as is well known be easily obtained by carbonizing
organic bodies, which are hollow in their natural state, as for instance, straw or
other similar plant stalks. Hollow carbon cylinders can also be obtained by pre-
cipitating upon a solid metal or carbon cylinder powdered carbon obtained by the
decomposition of hydrocarbons, and by subsequently withdrawing the said metal
cylinder by dissolving it in some acid or otherwise. But for different reasons
carbons which are well suited for use in incandescent lamps cannot be produced by
the methods herein before described.
In manufacturing carbons for incandescent electric lamps, according to those
improvements the material employed consists either of some suitable organic
texture or of some other organic substance pressed into the shape of sheets; for
this purpose paper is preferably used and amongst textile fabrics those of silk are
preferred as yielding an excellent carbon. When paper is used, it can be cut into
strips or sheets; these paper strips are rolled into hollow cylinders or tubes, by
employing for this purpose a core or mandril which is afterwards withdrawn, or
they can be rolled up into the desired form without making use of a mandril. The
Pace B11

page_text: tubes or hollow cylinders thus obtained are then provided with means to keep them
in the desired shape and they are then carbonized.
As a general rule the said fabric or other organic substance having the form of
sheets is cut into strips; one side of these strips is pasted over with some suitable
carbonaceous cement, such as gum or paste, after which the said strips are rolled
up upon a core or mandril of a suitablo size so as to form two or three layers. As
soon as the gum or other cement employed has somewhat dried, the hollow cylinders
thus prepared will have become sufficiently hardened to allow of the mandril being
withdrawn. The cylinders are then placed in iron boxes filled with powdered
plumbago or charcoal, and carbonized in a stove in the usual manner. During this
operation the silk fabric contracts and hollow cylinders of a great and homogeneous
density are thus produced.
The hollow carbon cylinders thus prepared are then fit for being placed in
incandescent lamps in the following manner :-
In the bottom part of the glass globe of the lamp are scaled the conducting
wires, and the carbon cylinder is held by its ends in a vertical position by large
carbon sockets, serving as carriers for the carbons and establishing their connection
with the conducting wires which pass respectively to the said carbon sockets.
Should it be desirable, in order to avoid the necessity of conveying one of the
conducting wires to the upper part of the glass globe, the hollow carbon cylinder
may be curved in the form of a loop.
In order to manufacture such curved hollow carbons the application of plain
textile fabrics is less suitable. For this purpose kuit or braided tubes-made of silk
or of some other organic fibres containing a large amount of carbon are proferably
employed. Portions of these tubes of appropriate length. are put upon mandrils
and pasted over with a suitable carbonaceous cement, such as gum or paste. As
soon as this cement has somewhat dried, the tubes are withdrawn from the said
mandrils and placed in moulds of a convenient form, where they are left to
completely harden and set to the desired form of loop. The carbonization of these
tubes is performed in the usual manner.
It has already been mentioned that the connection of the carbon cylinders with
the conducting wires is effected by means of largo carbon sockets. These sockets
are provided with bored holes intended to receive the ends of both the carbon
cylinders and the conducting wires. The holes for receiving the carbon cylinders
have a somewhat larger diameter, corresponding with the diameter of the cylinders,
whilst the opposite holes are smaller and correspond with the diameter of the
conducting wires. The said two holes of each carbon socket are united by a
countersunk hollow tapering to the smaller hole and adapted to fit the head of tho
conducting wiro which is formed of a conical shape. In putting together the
several parts of this lamp, the conducting wires, proviously covered with a coment
composed of a mixture of charcoal-powder and guin, are introduced into the corre
sponding holes of the said carbon sockets and the ends of the hollow tubular
carbons also covered with the samo coment are introduced into the larger holes of
the sockets and the cement is left to dry and to completely harden

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Frederick Redfern in the Patent Office on the
31st January 1884.
GEORGE FREDERICK REDFERN of the General Patent Office 4 South Street
Finsbury in the County of Middlesex Patent Agent "IMPROVEMENTS IN
INCANDESCENT ELECTRIC LAMPS (a communication to me from abroad by
Alexander Bernstein of Boston in the United States of America)
"
The present invention relates to the manufacture of hollow carbon cylinders
which are with great advantage employed in electric incandescent lamps, as well as
to the manner of uniting these carbons to the conducting wires
Hollow Carbon cylinders can as is well known be easily obtained by carbonizing
organic bodies, which are hollow in their natural state, as for instance straw or
other similar plant stalks; hollow carbon cylinders may also be obtained by
precipitating upon a solid inetal or carbon cylinder powdered carbon obtained by
the decomposition of hydro-carbons, and by subsequently withdrawing the said
metal cylinder by dissolving it in some acid or otherwise, but for different reasons
all carbons which are well suited for use in incandescent lamps cannot be produced
by the methods herein before described.
In manufacturing carbons for incandescent electric lamps according to these
improvements the material employed consists either of some suitable organic
texture or of some other organic substance pressed into the shape of sheets; for
this purpose paper is preferably used and amongst textile fabrics those of silk aro
preferred as yielding an excellent carbon. When paper is used it can be cut into
strips or sheets; these paper strips are rolled into hollow cylinders or tubes, by
employing for this purpose a core or mandril, which is afterwards withdrawn, or
they can be rolled up into the desired tubular shape without making use of a
mandril. The tubes or hollow cylinders thus obtained are then provided with
suitable means to keep them in the desired shape and they are then carbonized.
As a General rule the said fabric or other organic substance having the form of
sheets is cut into strips; one side of these strips is pasted over with some suitable
carbonaceous cement such as gum or paste, after which the said strips are rolled up
upon a core or mandril of a suitable size so as to form two or three superposed
layers. As soon as the gum or other coment employed has somewhat dried, the
hollow cylinders thus prepared will have become sufficiently hardened to allow of
the mandril being withdrawn, The cylinders are then placed in iron boxes filled
with powdered plumbago or charcoal and carbonized in a stove in the usual
manner During this operation the silk fabric contracts and hollow cylinders of a
great and homogeneous density are thus produced
The hollow carbon cylinders thus prepared are then fit for being placed in
incandescent lamps in either of the manners following and represented in figures 1
and 2 of the annexed drawing which figures shew in vertical section two forms of
incandescent electric lamps. In all the figures of the drawing similar letters
represent similar or corresponding parts
In figure 1, A, represents the glass globe of the lamp, in the tapering bottom
part of which are sealed the conducting wires B, and C; F, is the carbon cylinder
held by its ends in a vertical position by large carbon sockets D, and E, serving as
carriers for the carbon and establishing its connection with the conducting wires
and B, which pass respectively to the said carbon sockets D and E.
Should it be desirable in order to avoid the necessity of conveying the conducting
wire C, to the upper part of the glass globo the hollow carbon cylinder may be
curved in the form of a loop, as shewn in figure 2.

page_text: In order to manufacture such curved hollow carbons the application of plain
textile fabrics is less suitable. For this purpose knit or braided tubes made of silk
or of some other organic fibres containing a large amount of carbon are preferably
employed. Portions of these tubes of appropriate length are put upon mandrils
and pasted over with a suitable carbonaceous cement such as gum or paste. As
soon as this cement has somewhat dried, the tubes are withdrawn from the said
mandrils and placed in moulds of a convenient form, where they are left to
completely harden and set to the desired form of curve. The carbonization of
these tubes is performed in the usual manner
It has already been mentioned that the connection of the carbon cylinder with
the conducting wires is effected by means of the large carbon sockets D, and E,
These sockets, one of which is represented in vertical section at figure 3 are
provided with bored holes intended to receive the ends of both the carbon cylinder
and the conducting wires The holes for receiving the ends of the carbon cylinder
have a somewhat larger diameter corresponding with the diameter of this
cylinder, whilst the opposite holes are smaller and correspond with the diameter
of the conducting wires. The said two holes of each carbon socket are united by
a counter sink tapering from the larger to the smaller hole and adapted to fit the
head of the conducting wire which is formed of a conical shape as shown in
figuro 4. In putting together the several parts of this lamp, the conducting wires
previously covered with a cement composed of a mixture of charcoal powder, and
gum, are introduced into the corresponding holes of the said carbon sockets and
both ends of the hollow tubular carbon also covered with the same cement are
introduced into the larger holes of the sockets and the cement is left to dry and to
completely harden.
The fitting of the lamp upon the lamp holder may be effected in any suitable
manner. The method which I prefer however is illustrated in figure 5 of the
drawing and is as follows The lower tapering portion of the lamp is fitted in a
socket G of suitable conducting metal and filled with insulating material; the
conducting wire C, coming from the carbon socket D, is brought in contact with
this metallic socket G, whilst the other wire B, coming from the other carbon
socket E, passes through a screw fitted in the centre of the socket G, and terminates
below the screw in a flat head H, The connection of the said metallic socket G,
and of the flat head H. with the two electric terminals of the lamp holder may be
effected in any suitable known manner
Having thus described the nature of the said invention and the manner of
carrying the same into effect what is claimed is :-
Firstly. The method or process herein described of manufacturing hollow carbons
for use in incandescent electric lamps by cutting suitable organic substances, such
as paper into sheets of suitable size, rolling the same into the desired cylindrical
form and then carbonizing the hollow cylinders thus produced substantially as
described
Secondly The herein described method or process of manufacturing hollow
carbons for use in incandescent electric lamps, consisting in rolling sheets of paper
into a cylindrical form by means of suitable cores or mandrils, and then with-
drawing the mandrils and carbonizing the hollow paper cylinders thus produced
substantially as described
Thirdly. The berein described method or process of manufacturing hollow
carbons for use in incandescent electric lamps consisting in cutting textile fabrics
or paper into sheets or strips of the desired shape and size covering one side of the
said sheets with suitable carbonaceous cement, rolling the said sheets into the
desired form, and finally carbonizing them whereby a hollow carbon of great
density and homogeneity is produced substantially as described
Fourthly. The herein described method or process of manufacturing hollow
tubular carbons for incandescent electric lamps consisting in putting knitted or
braided tubes made from organic fibres upon cores or mandrils, covering these
tubes with a suitable carbonaceous cement subsequently withdrawing them from

page_text: the mandrils as soon as they have somewhat dried and are in a semi-hardened
condition, placing the said tubes into suitably shaped moulds and finally carbonizing
them substantially as described
Fifthly. The manufacture and use of tubular carbons for incandescent electric
lamps the said carbons being made of carbonized paper or of carbonized textilo
fabric, substantially in the manner herein before described;
Sixthly. In an incandescent electric lamp, the combination of a hollow carbon
cylinder and conical headed conducting wires therefor with supporting sockets of
carbon placed at each end of the hollow cylindrical carbon and connecting the
same with the conducting wires the said carbon socket being bored out on one side
thereof to fit the ends of the said carbon cylinder and provided on the opposite
side with a smaller bored hole to receive the conducting wires, the two said holes
being united by a countersink tapering from the larger hole to the smaller hole
and adapted to fit the conical head of the conducting wiros substantially as and
for the purposes herein before described In witness whereof I the said Goorge
Frederick Redfern have hereto set my hand and seal this thirtieth day of January
in the year of our Lord one thousand eight hundred and eighty four.
G F REDFERN (LS) ·