IMPROVEMENTS IN AND RELATING TO ELECTRIC LIGHTING APPARATUS AND THE MANUFACTURE OF CARBONIZED MATERIAL TO FORM CONDUCTORS FOR THE SAME AND FOR OTHER PURPOSES
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN AND RELATING TO ELECTRIC LIGHTING APPARATUS AND
THE MANUFACTURE OF CARBONIZED MATERIAL TO FORM CONDUCTORS FOR
THE SAME AND FOR OTHER PURPOSES." A communication from abroad by
Hiram Stevens Maxim, of Brooklyn, New York, United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lako at the
Office of the Commissioners of Patents on the 21st April 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. “IMPROVEMENTS IN AND RELATING TO ELECTRIC
LIGHTING APPARATUS AND THE MANUFACTURE OF CARBONIZED MATERIAL TO
FORM CONDUCTORS FOR THE SAME AND FOR OTHER PURPOSES." [A communication
from abroad by Hiram Stevens Maxim, of Brooklyn, New York, United States of
America.]
The first part of my Invention relates to electric lamps producing light by a
voltaic are between two carbon electrodes, and especially to the class of such lamps
known as hanging lamps, in which the clockwork or other machinery for feeding
the carbons is located in a case above the focus, and I employ an improved method
of regulating such feeding mechanism, and an improved construction of the part
of the lamp carrying the lower carbon and the globe.
In lamps as heretofore made the regulator has not been sufficiently sensitive,
as it has required too great a change in the strength of the current to cause it to
nct, and this has been the cause of unsteadiness in the light. In order to obviato
this difficulty I have removed all friction from the regulating device by suspending
the working parts upon springs, which at the same time support the upper carbon
and its feeding mechanism free from contact with all other parts of the lamp, and
serve as frictionless conductors of the current to the carbon holder.
These electric lamps as heretofore constructed havo also been subject to another
difficulty. It is frequently necessary to remove the globe in order to perfectly
adjust the carbons when they are first put in, and in such lamps no means have
been hitherto provided for setting or removing the globe when the carbons are of

page_text: To obviate this
full length and adjusted without disturbing their adjustment.
difficulty I make the side rods which carry the globe-holder telescopic.
I also
I provide a case for containing the feeding mechanism and regulator.
provide an axial magnet or coil with an iron core of the saine which has a
brass extension. This extension carries a train of clock-work, and the magnet core
and its extension are suspended upon springs. A star wheel is mounted upon the
most rapidly moving shaft and carries one or more fans. A stationary detent is
affixed to the case; a controlling clamp or dash pot is connected with the magnet
core and its extension to prevent too rapid movement of the parts. A perpendicular
spiral spring is hung upon two adjusting scrows. One screw is attached to the case,
and the other screw to a projecting arm of the magnet core, and a spring tends to
support the core with its extension and connected mechanism; the tension of this
spring may be readily adjusted. A device forming a combined hook and lever is
pivotted to the case and fitted to hook over the said projecting arm, and thus hold
up the parts connected therewith. It is fitted with a lever handle for manipulation,
and has a spring bearing upon it so arranged that the lever has two positions of
rest, one when the hook is thrown forward, and one when it is thrown back. Set
screws are provided to limit the vertical movement of the magnet core and its
connected parts; flat horizontal springs are attached at one end to the case, and at
the other to projections affixed to the magnet core and its extensions. Side rods:
are attached to the said case with a joint of insulating material, and supporting the
globe holder. These rods are made hollow, and other rods rigidly attached to the
globe holder are inserted in them longitudinally.
Spring-catches are hinged to the globe holder, which hook over projections and
hold up the said globe holder.
The lower part of the upper carbon holder is made with a ball and socket joint
with part of the socket formed of a nut, so that the carbon may be readily adjusted.
The upper carbon holder is carried by a spindle passing longitudinally through the
magnet core and its extension. It has a rack on one side which engages with a
small pinion of the train of clock-work on the shaft having the slowest movement,
but otherwise is free to move longitudinally.
Another improvement relates to the class of electric lamps known as incandescent
lamps, in which light is produced by the incandescence of a continuous strip or
conductor forming a part of the electrical circuit.
It has been found necessary in practice to protect the conductor or incandescent
portion of such lamps from all access of oxygen, as all materials heretofore used
for such part of the lamp rapidly deteriorate at a high temperature with even a
very small amount of free oxygen present. Lamps of this class have been usually
constructed with a sealed glass globe enclosing the incandescent conductor, and
various means have been used for excluding or removing atmospheric oxygen from the
globe, such as displacing the air with an atmosphere of nitrogen and pumping out the
air with an air-pump. Such methods of removing oxygen from the globe have,
however, proved ineffectual for completely protecting the conductor of the lamp.
The presence of the nitrogen in the globe is objectionable, as the currents of
connection set up in it injure the conductor by "air washing" it and carry away
its heat, while it is extremely difficult, if not impossible, in practice to produce a
sufficiently perfect vacuum in such a globe by means of an air-pump alone to
prevent some small quantity of free oxygen from coming into contact with the
highly heated conductor.
Another difficulty in the use of such lamps has arisen from the liability of the
globe to leak at the places where the electrical connections pass through it, either
by reason of defective scaling or of fractures caused by unequal expansion and
contraction of the glass and the metallic connection. Such leaking is fatal to the
lamp however perfectly the air may have been removed from the globe when the
lainp was made.
Another difliculty has arisen from the liability of the incandescent conductor to
work loose from its supports. Such conductors are preferably made of carbon, and

page_text: the supports forming at the same time the electrical connections are usually made
of platinum with clamps securing the connections to the conductor. Carbon proper
for such conductors quite hard, and as is well known the surface of such materials
is not perfectly smooth. Where the carbon is prepared by carbonizing cardboard
or other fibrous material, the surface when examined under a microscope appears to
be made up of a succession of points corresponding with the ends of the fibres of
the material used. As the platinum is also quite hard, the contact between the
carbon and platinum where they are clamped together consists of a series of points
of carbon bearing upon the surface of the platinum, and pressure sufficiently to
press these points into the metal, so as to bring the two surfaces into perfect contact,
cannot be applied as it would crush the carbon.
When a sufficiently strong current is passed through the lamp to heat the carbon
conductor to incandescence, some of the points of carbon bearing upon the platinum
are liable to become so highly heated as to fuse a minute portion of the metal
immediately in contact with them, and in that case. a small voltaic arc is established
which soon destroys the connection.
It is the object of this part of my improvements to remedy these difficulties, and
also to provide a convenient and effective device for opening and closing the circuit
of the lamp.
I provide a globe made entirely of glass enclosing the incandescent part of the
lamp. An incandescent conductor of carbon is preferably arranged above its
supports. This conductor should be made of high or low resistance, according as a
large machine or a small machine is used, I prefer to construct it of carbon made by
the process hereinafter described.
Platinum supports are clamped to the lower end of the carbon conductor. They
serve as conductors of the current to the carbon, and pass through the globe where
tubes of glass constructed in one piece with the globe are sealed to the platinum
connections. These tubes are made to leave capillary spaces between the platinum
wires and the glass.
The lower ends of the carbon conductor are enlarged for the purpose of decreasing
its resistance; these enlarged ends are flattened. The upper ends of the supports
are also enlarged and flattened. 1 make the upper part of each support in a
separate piece like a washer with a hole or socket in its edge to receive the
supporting rod or wire which is secured in the hole, and I provide a washer of
platinum and washers of soft carbon; the latter I prefer to make of blotting paper
or other similar material, preferably carbonized by the process hereinafter described.
The parts are put together with one of the soft carbon washers upon each side of
and in contact with the flattened end of the conductor. The whole is held in place
by a platinum screw, and a nut screwed up tightly. The base of the lamp is
constructed of metal or other suitable material. Plaster of Paris is used to cement
the globe to the said base.
Shellac or copal is melted and poured into the base when inverted, to cover tho
A sub-
entire lower end of the globe and fill up the tubes about the connections.
base constructed of vulcanite or other insulating material with a metallic core is
screwed on to a nipple on the underside of the base, and has a socket for attaching
it to an ordinary gas fixture.
A ring of metal is inserted in the vulcanite part of the sub-base, and flush with
its upper
face directly under the end of a plug, so that when the base is screwed
down the said plug will form a contact with the ring.
A connection is continued outside of the sub-base by a wire which is joined
to the said ring, and another connection is continued through the gas fixture
and pipe.
The carbon conductor is mounted upon its supports, and the said supports are
sealed into the globe before the air is removed. The air is then exhausted as
perfectly as may conveniently be done by means of an air pump through an opening
in the bottom of the globe, and an atmosphere of hydrocarbon vapor or gas,
preferably vapor of gasoline, is then admitted to the globe. After this atmosphere

page_text: has become mixed with the residuum of air left in the globe it is in turn exhausted
ns perfectly as possible, thus leaving in the globe a highly attenuated or rarified
atmosphere of hydro-carbon vapor or gas mixed with an infinitesimal trace of air;
another atmosphere of hydro-carbon vapor or gas may then be admitted to the
globe and exhausted, and the operation may be repeated as many times ns
desirable.
After exhausting the gas or vapor as perfectly as possible the last time, the globe
is hermetically sealed. The base is then cemented to the globe, and melted shellac
and copal or other resinous gum free from oxygen is melted and poured into the
base when inverted, so as to fill the capillary spaces and cover the lower end of
the globe where the connections emerge from it. The base is then attached to its
sub-base, and the whole is mounted upon an ordinary gas fixture; the connecting
wires are properly joined and the lamp is ready for use.
Another part of these improvements relates to a process of manufacturing carbon
conductors for electric lamps producing light by the incandescence of a continuous
strip or conductor.
Various carbonaceous substances may be carbonized by this improved process,
such as wood, the inner bark of trees, cardboard, paper, and silk, cotton, or linen
fabrics. The material used is cut or bent into picces of a shape suitable for the
conductor of the lamp, but somewhat largor in each dimension to allow for shrinkage,
and is then charred in a retort while a current of hydro-carbon vapor or gas is
flowing through the retort and enveloping the material.
An apparatus suitable for making carbon conductors according to this process has
a carbonizer or retort for holding the material to be charred. It also has a car-
buretter containing volatile hydro-carbon oil, and is provided with a sheet of metal
in the carbonizer.
A sheet of tissue paper is placed upon the metal plate, and a layor of the material
is placed thereon enclosed between pieces of cardboard, and another sheet of tissue
paper is spread over the layer thus formed. Other sheets of metal and layers of
material are added until the carbonizer is full, and the whole is then covered with
sund.
The sheets of metal are arranged to leave a space for the escape of the gas, and
this space is covered with cotton batting.
The carbonizer thus filled is placed over a gas flame, or upon a stove, and hoated
to expel the aqueous vapor contained in the pores of the material, and the car-
buretted gas is admitted to the carbonizer and ignited where it escapes at the top.
After the material has been subjected to this heating for a considerable time the
carbonizer is placed in a mufhe furnace and raised to a whito heat, and kept there
until all the material is thoroughly charred, gas being supplied to the carbonizer and
circulating about the material therein.
I prefer to remove the carbonizer from the furnace soon after the material has
become thoroughly carbonized, and before any considerable amount of carbon from
the gas has been deposited upon them. The current of gas is kept passing through
the carbonizer until it is so far cooled that it will not ignite dry saw dust.
The essential feature of this process is the enveloping of the material in an 4
atmosphere or current of hydro-carbon gas or vapor during the carbonizing.
The process above described is especially applicable to the making of conductors
for electric lamps, but it may obviously be used for other purposes where a similar
quality of carbon is desired.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 21st
October 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO ELECTRIC-
LIGHTING APPARATUS AND THE MANUFACTURE OF CARBONIZED MATERIAL TO
FORM CONDUCTORS FOR THE SAME, AND FOR OTHER PURPOSES." A communication
from abroad by Hiram Stevens Maxim, of Brooklyn, New York, United States of
America.
The first part of my Invention relates to electric lamps producing light by a
voltaic are between two carbon electrodes, and especially to the class of such laips
known as hanging lamps, in which the clockwork or other machinery for feeding
the carbons is located in a case above the focus, and it consists in an improved
method of regulating such foeding mechanism, and in an improved construction of
the part of the lamp carrying the lower carbon and the globe.
In electric lamps as heretoforo made the regulator has not been sufficiently
sensitive, as it has required too great a change in the strength of the current to
cause it to act, and this has been the cause of unsteadiness in the light. In order
to obviate this difficulty I have removed all friction from the regulating device by
suspending the working parts upon springs, which at the same time support the
upper carbon and its feeding mechanism free from contact with all other parts of
the lamp, and serve as frictionless conductors of the current to the carbon-holder.
Lamps as heretofore constructed have also been subject to another difficulty. It is
frequently necessary to remove the globe in order to perfectly adjust the carbons
when they are first put in, and in such lamps no means have been hitherto provided
for setting or removing the globe when the carbons are of full length and adjusted
without disturbing their adjustment. To obviate this difficulty I make the side
rods which carry the globe-holder telescopic.
This part of my Invention is shown in Figures 1, 2, and 3 of the Drawings, in
which,―
Figure 1 is a front elevation of a lamp constructed in accordance with my
Invention.
Figure 2 is a side clevation, and Figure 3 is partly an elevation and partly a
central vertical section of the upper part of the saine showing the feeding mechanism
and regulator.
Figure 3 is drawn to an enlarged scale to show more clearly the construction of
the parts.
A is the case containing the feeding mechanism and regulator; B is an axial
magnet or coil, and C the iron core of the same; D is a brass extension of the
magnet core screwed into its upper end and extending some distance above it.
This extension D carries the train of clock-work E, which is of the usual form
used in such lamps, and the magnet-core and its extension are suspended upon the
springs T, T, and I. F is a star wheel mounted upon the most rapidly moving
shaft, and carrying one or more fans; G is a stationary detent affixed to the caso A;
H is a controlling clamp or dash-pot connected with the magnet core and its exten-
sion to prevent the too rapid movement of the parts. The perpendicular spiral
spring I is hung upon the two adjusting screws J and K. The nut of the screw K
has a fan-shaped projection bearing loosely against the side of the case to keep the
spring from turning.
The screw K is attached to the case A, and the screw J is attached to a projecting
arm S of the magnet-core, so that the spring I tends to support the core with its
extension and connected mechanism, and the tension of the spring may be readily

page_text: adjusted either from above or below. L is a combined hook and lever pivotted to
the case A, and fitted to hook over the projection S, and thus hold up the parts
connected therewith. The said hook is provided with a lever-handle for conve-
nience of manipulation, and has a spring R bearing upon it like the back spring of
a knife, and so arranged that the lever has two positions of rest, that is to say, one
when the hook is thrown forward and one when it is thrown back. N is the positive
binding post, and O is the negative binding post. The positive wire is carried from
the interior end of the post N to the coil of the magnet B, and passes thence to the
case A, from which it is conveyed to the upper carbon holder. A metallic spring is
attached to the core extension, and presses lightly upon the enclosed spindle to
ensure perfect electrical connection between the parts.
The binding post O is electrically connected with the lower carbon-holder by the
side rod d and the globe-holder X. P and Q are set-screws to limit the vertical
movement of the magnet-core and its connected parts. The flat horizontal springs
T, T¹, are attached at one end to the case A, and at the other to the projections
S, S¹, affixed to the magnet-core and its extensions. The side rods d, d, are
attached to the case A with a joint of insulating material, and support tho globe-
holder X. These rods are made hollow, and other rods rigidly attached to the
globe-holder are inserted in them longitudinally. This construction is shown in
Figure 1, where the rod d is represented partially in section. c is the interior rod,
and a is a head attached to it to bear against an interior shoulder at the lower end
of the tube d, and prevent an entire separation of the parts. U, U, are short
projections on the rods d, d, bevelled on their lower sides, and V, V, aro spring-
catches, which are hinged to the globe-holder, and which hook over the projections
U, U, and hold the said globe-holder up.
The lower rod may be made the outside one if desired, and I do not consider
the particular form or location of the fastening essential, although those shown are
effective and convenient. The lower part of the upper carbon-holder is made with
a ball and socket joint, with part of the socket formed of a nut M, so that the
carbon may be readily adjusted as regards direction, and secured firmly in position
by turning the nut. The upper carbon-holder is carried by a spindle W passing
longitudinally through the magnet-core and its extension. This spindle has a rack
on one side, which engages with a small pinion of the train of clock work on the
shaft having the slowest movement, but otherwise is freo to move longitudinally.
The operation of the said lamp is as follows, that is to say:-The magnet core C
and its extension D have a free vertical motion within the coil B, and are suspended
upon the horizontal flat springs T, T, and the spiral spring I, as above stated, and
as the magnet-core is located somewhat lower down than its coil it constantly
tends to riso when the coil is excited by a current of electricity. The spindle W
is supported by the train of clock work only, and its weight is so adjusted that it
will descend slowly when the gearing is free to move. The tension of the sup-
porting springs is so adjusted to the weight of the magnet-core and the parts which
it carries that the train of gearing shall hang just low enough to clear the detent G
when a current of ordinary strength is passing. The gearing then slowly turns,
and the spindlo W descends, bringing the carbons together to supply the con-
sumption at the focus.
If the points approach too closely to each other the current increases in strength,
the magnet-core is drawn in, the upper carbon is retracted, and the feeding
mechanism is arrested by the detent G. If, on the other hand, the points become
too widely separated the current is weakened, the magnet-coil loses its power, and
the core descends and advances the upper carbon; at the same time the gearing is
released from the detent, and the feeding process proceeds.
The apparatus may be adjusted with very great nicety by means of the adjusting
screws J and K and the spring I, and as the moving parts are freely suspended
and nicely balanced upon the supporting springs a very slight change in the current
passing through the coil is sufficient to bring the gearing into contact with the
detent or to release it.

page_text: Whenever it is desired to stop the light the hook L is sprung over the arm S,
and the feeding mechanism is by one operation retracted and locked.
Whenever it is necessary to renew the carbons the spindle W is pushed up (a
ratchet in the gearing allowing it to move upward freely), and the globe is removed.
When the new carbons are adjusted to position the globe-holder is depressed by
pressing down the catches V, V, and drawing out the telescopic side rods, the
globe is replaced over the lower carbon, and the globe-holder returned to its former
position without disturbing the adjustment of the carbons. It is evident that the
construction of the different parts may be considerably varied without essential
change in the apparatus. Instead of the magnet B with the movable core one or
more electro-magnets with fixed cores and movable armatures may be used, and
the spring I may be dispensed with by applying a tension-adjuster to one or both
of the other springs. Other forms of feeding devices than a rack and train of
gearing may be adapted to be stopped and started by a slight vertical movement
of their supports for the purpose of this Invention.
My next improvement relates to the class of electric lamps known as incandescent
lamps, in which light is produced by the incandescence of a continuous strip or
conductor forming a part of the electrical circuit.
It has been found necessary in practice to protect the conductor or incandescent
portion of such lamps from any access of oxygen, as all materials heretofore used
for this part of the lamp rapidly deteriorate ut a high temperature with even a
very small amount of free oxygen present. Lamps of this class have usually been
constructed with a sealed glass globe enclosing the incandescent conductor, and
various means have been used for excluding or removing atmospheric oxygen from
the globe, such as displacing the air with an atmosphere of nitrogen, and pumping
out the air with an air-pump. Such methods of removing oxygen from the globe
have, however, proved ineffectual for completely protecting the conductor of the
lamp. The presence of the nitrogen in the globe is objectionable, as the currents of
convection set up in it injure the conductor by "air washing" it and carry away its
heat, while it is extremely difficult, if not impossible, in practice to produce a
sufficiently perfect vacuum in such a globe by means of an air-pump alone to
prevent some small quantity of free oxygen from coming into contact with the
highly heated conductor.
Another difficulty in the use of such lamps has arisen from the liability of the
globe to leak at the places where the electrical connections pass through it by
reason either of defective sealing, or of fractures caused by unequal expansion and
contraction of the glass and the metallic connection. Such leaks are fatal to the
lamp however perfectly the air may have been removed from the globe when the
lamp was made.
Another difficulty has arisen from the liability of the incandescent conductor to
work loose from its supports. Such conductors are preferably made of carbon, and
the supports forming at the same time the electrical connections, are usually
made of platinum with clamps securing the connections to the conductor.
Carbon proper for such conductors is quite hard, and the surface of such
material is not perfectly smooth. Where the carbon is prepared by carbonizing
card board or other fibrous material the surface when examined under a microscope
appears to be made up of a succession of points, corresponding with the ends of the
fibres of the material used. As the platinum is also quite hard, the contact
between the carbon and platinum where they are clamped together, consists of a
series of points of carbon bearing upon the surface of the platinum and pressure
sufficient to press these points into the metal, so as to bring the two surfaces into
perfect contact cannot be applied as it would crush the carbon.
When a sufficiently strong current is passed through the lamp to heat the carbon
conductor to incandescence, some of the points of carbon bearing upon the platinum
are liable to become so highly heated as to fuse a minute portion of the metal
immediately in contact with them, and in this case a small voltaic arc is established
which soon destroys the connection.

page_text: It is one object of the present improvements to remedy these difficulties, and also
to provide a convenient and effective device for opening and closing the circuit of
the lamp.
This part of the Invention is shown in Figures 4to 9 of the Drawings;
Figure 4 is a vertical section of a lamp constructed in accordance with the said
Invention; Figure 5 is a side elevation, and Figure 6 is a horizontal section of the
base of the same; Figures 7, 8, and 9 are views of the conductor and its
connections on an enlarged scale to show the method of clamping the carbon to the
platinum.
A is a globe made entirely of glass enclosing the incandescent part of the lamp;
B2 is an incandescent conductor of carbon of any convenient form, but preferably
arranged entirely above its supports as shown. This conductor should be made of
high or low resistance according to whether a large machine of high electro-
motive force is used to operate many lamps, or a small machine is used to operate
few lamps. I prefer to construct the said conductor of carbon made by the
process hereinafter described, but any sufficiently dense and tough carbon may be
used.
C, C, are platinum supports clamped to the lower ends of the carbon conductor.
They serve also for conductors of the current to the carbon, and pass through the
globe at D2, D3, where tubes of glass constructed in one piece with the globe are
drawn up and sealed to the platinum connections. These tubes are made tapering
so as to leave capillary spaces 8, 8, between the platinum wires and the glass below
the points of sealing.
The construction of the clamps connecting the carbon to its supports is best
shown in Figures 7, 8, and 9. Figure 7 is a front view of the carbon and clamps ;
Figure 8 is a side view of one of the said clamps; and Figure 9 is a view of the
several parts detached from each other. The lower ends of the carbon conductor
are enlarged, as shown in Figure 7, for the purpose of decreasing its resistance, and
so preventing it from becoming as highly heated as the upper parts. These
enlarged ends are flattened for convenience of attachment and for the purpose of
providing large surfaces of contact with the adjacent parts. The upper ends of the
supports C, C³, are also enlarged and flattened.
For convenience of construction 1 make the upper part of each support in a
separate piece shaped like a washer with a hole or socket in its edge to receive the
supporting rod or wire which is secured in the hole by gold solder or in any other
suitable manner. This construction of the upper part of the support is best shown
at in Figure 9; is a washer of platinum; and m, m, are washers of soft
carbon.
The carbon washers 1 prefer to make of blotting paper or similar matorial
carbonized by the process hereinafter described, but such carbon inay be prepared
in other ways, and I do not wish to be limited to carbon prepared according to my
improved process. The parts are put together in the order shown in Figure S with
one of the soft carbon washers m upon each side of, and in contact with, the
flattened end of the conductor. The whole is held in place by the platinum
screw passing through all of the parts and the nut t, which is screwed up as
tightly as practicable without injury to the said parts. The soft carbon washers
yielding to the pressure fit into all the inequalities of the opposing surfaces and
form a durable packing between the conductor and the platinum supports, thus
insuring perfect electrical connection between the conductor, and the said supports;
E2 is the base of the lamp constructed of metal or any other suitable material;
Frepresents plaster of Paris for cementing the globe to the base; G³ represents
shellac or copal melted and poured into the base when inverted so as to cover the
entire lower end of the globe, and fill up the tubes 8, 8, about or around the
connections; H is a sub-base constructed of vulcanite or other insulating material
with a metallic core 12. The said sub-base screws on to a nipple on the underside
of the base, and has a socket J³ for attaching it to an ordinary gas-fixture.
The connection C is carried down and joined to the metallic base, but the

page_text: connection C terminates in a metallic plug K², carried slightly beyond the lower
surface of the base, but entirely insulated from it.
R is a ring of metal inserted in the vulcanite part of the sub-base and flush
with its upper face directly under the end of the plug K, so that when the baso is
screwed down the plug will form a contact with the ring.
The connection C is continued outside of the sub-base by the wire S², which is
joined to the ring R' while the connection C is continued through the gas-fixture
and pipe. The carbon conductor B is mounted upon the supports C2, C³, as above
stated, and the supports are sealed into the globe at D, D2, before the air is
removed. The air is then exhausted as perfectly as may conveniently be done by
means of a proper air-pump through an opening (not shewn in the Drawings) in
the bottom of the globe, and an atmosphere of hydro-carbon vapor or gas, preferably
vapor of gasoline, is then admitted to the globe. After this atmosphere has becoino
mixed with the residuum of air left in the globe it is in turn exhausted, thus
leaving in the globe a highly attenuated or rarefied atmosphere of hydrocarbon
vapor or gas mixed with an infinitesimal trace of air. Another atmosphere of
bydrocarbon vapor or gas may then be admitted to the globe and exhausted, and
the operation may be repeated as many times as desirable. I find that admitting
the hydrocarbon and exhausting it once or twice is usually sufficient, and after
exhausting the gas or vapor as perfectly as possible the last time the globe is
hermetically sealed. The base is then cemented to the globe and melted shellac
and copal or other resinous gun free from oxygen is melted and poured into the
base when inverted to fill the capillary spaces 8, 8, and cover the lower end of the
globe where the connections emerge from it.
The base is then attached to its sub-base, and the whole is mounted upon an
ordinary gas fixture. One connection from the generator of electricity is joined to
the gas pipe and the other to the wire S, and the lamp is ready for use.
The operation of this lamp is as follows:-The base is screwed down upon the
sub-base by turning the lamp, and the plug K2 is brought into contact with the
ring R2, thus completing the electrical circuit of the lamp, and a current of electricity
passes through the carbon B2, heating it to incandescence. Nearly if not quite all
of the carbon in the slight residuum of hydrocarbon vapor remaining in the globe
is precipitated upon the incandescent conductor at its hottest points, and an almost
absolute vacuum is established in the globe. If there should be any trace of oxygen
remaining in the globe it would unite with the carbon of the vapor or gas instead
of attacking the carbon of the conductor. As the hottest points of the conductor
are its weakest points, the slight deposit of carbon tends to correct any unevenness
of the conductor by building it up at its weak points. A much more perfect vacuum
can be produced in this manner than by the use of the air pump alone, and as only
a very small percentage of the residuum finally remaining in the globe is air,
atinospheric oxygen is very much more effectually removed from the globe than by
simply exhausting the air, as in the usual method.
If there is any imperfection in the sealing of the globe about the connections, or
if any slight cracks are made in the base of the globe by the unequal expansion
and contraction of the parts, all leakage of air into the globe is effectually prevented
by the gum or wax G; and even if heat enough is generated in the connections to
melt the gum, the part of the gum in the tubes 8, 8, will be prevented by capillary
attraction from dropping out, and the sealing of the connections will remain
perfect.
Another part of my improvements consists in a process of manufacturing carbon
conductors for electric lamps producing light by the incandescenco of a continuous
strip or conductor.
A variety of different carbonaceous substances may be carbonized by my improved
process, such as wood, the inner bark of trees, card-board, paper, and silk, cotton,
or linen fabrics. The material used is cut or bent into pieces of the shape desired
for the conductor of the lamp, but somewhat larger in each dimension to allow for

page_text: shrinkage, and is then charred in a suitable retort, while a current of hydro carbon
vapor or gas is flowing through the retort and enveloping the material.
I have shewn in the Drawings an apparatus suitable for making carbon conductors
according to this process, but I do not wish to be confined to the particular apparatus
shown, as the process may be performed with equal facility with other forms of
apparatus.
This part of the Invention is illustrated in Figures 10, 11, and 12; Figure 10 is
a longitudinal vertical section of the said apparatus.
Figure 11 is a plan or top view, and Figure 12 shows a carbon conductor as it
appears before and after carbonization.
A is a carbonizer or retort for holding the material to be charred; 133 is a
carburetter containing gasoline or other volatile hydro carbon oil; a' is a pipe
leading from the carburetter to the carbonizer, and b is a gas-supply pipe; C is a
sheet of metal placed in the carbonizer, and supported a short distance above the
bottom of it by short posts c¹, c¹.
A sheet of tissue paper is placed upon the plate C, and a layer of the forms of
material is placed upon this sheet enclosed between pieces of cardboard, and
another sheet of tissue paper is spread over the layer thus formed. Other sheets
of metal and layers of material are added until the carbonizer is full, and the whole
is then covered with sand.
The sheets of metal are made somewhat smaller than the inside of the carbonizer,
so as to leave a space for the escape of the gas, and this space is covered with
cotton batting or the like to prevent the sand from sifting down into it.
The carbonizer thus filled is placed over a gas-flame or upon a stove, and beated
to a temperature sufficiently high to expel the aqueous vapor contained in the pores
of the material, but not sufficiently high to char the material to any considerable
extent, and the carburetted gas is admitted to the carbonizer through the pipe a
and ignited, where it escapes through the sand at the top. After the material has
been subjected to this heating for a considerable time. say, ten or twelve hours, the
carbonizer is placed in a muffle-furnace and raised to a whito heat, and kept there
until all the material is thoroughly charred, the gas being all the time supplied to
the carbonizer through the pipe a', and circulating about the forms so as to envelop
them on all sides. Ordinary coal gas may be used for this purpose, but unless it is
rich in carbon it should be carburetted with gasoline or some other volatile hydro
carbon oil, and I prefer to carburet it in all cases. The carburetter B³ is of
convenient form for this purpose; the pipe b' for supplying coal-gas opening below
the surface of the oil.
The function of the gas during the first part of the process is to all appearance
to permeate the pores of the material and drive out the aqueous vapor and air
contained in them as far as possible; and its function during the latter or
charring part of the process seems to be to protect and consolidate the carbon
of the material. When the hydrogen and other constituents are disassociated
from the carbon of the material by the heat of the furnace, the surrounding
hydrocarbon vapor or gas is also apparently decomposed, and some part of the
carbon thus liberated especially that which is contained in the pores of the material
is apparently deposited upon the carbon of the forms and serves to consolidate it.
The hydrogen when liberated does not corrode the carbon of the forms, but if it
has any tendency to again take up carbon probably unites with some part of the
free carbon liberated from the gas or vapor.
In this manner nearly if not quite all of the carbon of the carbonized material
is preserved, and as carbon liberated from a gas or vapor at high temperatures has
a tendency to deposit upon any solid carbon present, the carbons of the forms
may apparently be built up to a considerable extent by maintaining the white heat
for a sufliciently long period and keeping up the supply of gas. I prefer however
to remove the carbonizer from the furnace soon after the forms have become
thoroughly carbonized, and before any considerable amount of carbon from the gas

page_text: has been deposited upon them. I find that two or three hours is usually sufficient
for this purpose, and the carbonizer is then removed from the furnace and allowed
to cool. The current of gas is kept passing through the carbonizer until it is so far
cooled that it will not ignite dry saw-dust; 1 thus prevent access of air to the forms
while they are hot.
I find that carbon made by this process is more dense and tough than any
made by other processes, and the forms shrink less than when carbonized in the
usual way. The essential feature of the process is the enveloping of the forms
in an atmosphere or current of hydro-carbon gas or vapor during the carbonizing
and the preliminary heating, and the subsequent passage of the gas through the
carbonizer are not essential, although I find that better results are secured by so
conducting the process.
I have considered the process above described as especially applicable to making
conductors for electric lamps, but it may obviously be used to make carbon for
other purposes where a similar quality of carbon is desired, and I do not wish to be
limited to any particular application of the process.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I am aware that trains of gearing in connection with detents of various forms
operated by clectro-magnets placed in the circuit have heretofore been used in
voltaic-are lamps for feeding the upper carbon to the focus and regulating its
Imovement, and I do not claim such combination of parts irrespective of the
particular devices described. I am also aware that a glass globe scaled about the
electrical connections has been used to enclose the conductors of incandescent
lamps, and that a more or less perfect vacuum has been produced in such globes by
means of an air-pump, and I do not claim such surrounding globe or a vacuum so
produced therein.
I am further aware that carbon conductors for such lamps have heretofore been
nade by carbonizing wood, paper, pith of trees, and other carbonaceous substances
at a high temperature, and I do not claim carbonizing such materials independently
of the particular process described, but I claim,-
First. The combination in an electric lamp of a carbon-feeding device consisting
of a racked spindle and a train of gearing with a regulating device consisting of a
stationary detent and an axial magnet, and a movable core having an extension
carrying the said feeding device, the said core and its extension being suspended
on springs, all substantially as and for the purpose specified.
Second. The combination in an electric lamp of a gravitating carbon-carrier
supporting the upper carbon and the device for regulating the movement of the
same, with a support for the said carbon-carrier and regulating device suspended
upon springs and adapted to be raised and lowered by variations of strength in the
current, substantially as set forth.
Third. The combination in an electric lamp of the magnet, the core, and the
train of gearing mounted upon the core-extension with the springs T, T₁, and I,
the spring I having one or more adjusting screws to regulate its tension,
substantially as and for the purposes set forth.
Fourth. The combination in an electric lamp of the magnet with the movable
core C, and the springs T, T¹, suspending the said core free from frictional contact
with the stationary part of the lamp, substantially as and for the purpose
specified.
Fifth. The combination in an electric lamp, of a swinging armature bearing a
gear-train and escapement actuated by the gravitating carbon-carrier with an
electro-magnet in the light-generating circuit, substantially as and for the purpose
specified.
Sixth. The combination in an electric lamp, of a swinging armature bearing a
gear-train for feeding the carbons, and an escapement actuated by the gravitating
carbon-carrier with a fixed detent for arresting the gear-train when the armature
is raised, substantially as herein described.

page_text: Seventh. The combination in an electric lamp of a movable magnet-core hung
on springs and carrying the carbon foeding and rogulating devices, with the
hook L for locking the same, substantially as and for the purposes set forth.
Eighth. The combination in an electric lamp of a globe-holder with telescopic
supporting rods or arms, and catches, or other suitable fastenings for holding the
same in place, substantially as and for the purposes set forth.
Ninth. In an electric lamp having a continuous incandescent conductor, the
employment of a highly attenuated atmosphere of hydro-carbon vapor or gas
surrounding such conductor and enclosed in a sealed glass globe, substantially as
and for the purposes specified.
Tenth. The production and utilization of a vacuum or highly attenuated atmos-
phere of hydrocarbon vapor in the globe of an electric lamp having a continuous
incandescent conductor, and a sealed glass globe enclosing the same.
Eleventh. The combination of the globe with the platinum connections, and the
capillary spaces filled with gum or wax, substantially as and for the purpose
specified.
Twelfth. The combination of the base carrying the plug with the sub-base and
the ring, substantially as and for the purpose specified.
Thirteenth. The combination in an electric lamp of a continuous carbon conductor,
metallic electrical connections for the same, and one or more washers of soft
carbon interposed between the said conductor and each metallic connection,
substantially as described.
Fourteenth. The combination in an electric lamp of the carbon-conductor, the
support C having the flattened end, the washers mi, m, and h, and the pin o, and
nut t, substantially as and for the purpose specified.
Fifteenth. The process of carbonizing carbonaceous substances and of making
carbon conductors for electric lamps by exposing the same to a high temperature
in the presence of hydrocarbon gas or vapor, substantially as above described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty-first day of October, in the year of our Lord
One thousand eight hundred and eighty.