IMPROVEMENTS IN ELECTRIC LAMPS, AND IN CARBONS OR INCANDESCING CONDUCTORS THEREFOR, AND IN MEANS FOR AND METHODS OF MANUFACTURING THE SAME
Year: 1880

page_text: LETTERS PATENT to Edward Griffith Brewer, of 33, Chancery Lane, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN ELECTRIC
LAMPS, AND IN CARBONS OR INCANDESCING CONDUCTORS THEREFOR, AND IN
MEANS FOR AND METHODS OF MANUFACTURING THE SAME." A communication
from abroad by Thomas Alva Edison, of Menlo Park, in the State of New
Jersey, United States of America.
PROVISIONAL SPECIFICATION left by the said Edward Griffith Brewer at
the Office of the Commissioners of Patents on the 16th September 1880.
EDWARD GRIFFITH BREWER, of 33, Chancery Lane, in the County of Middlesex.
"IMPROVEMENTS IN ELECTRIC LAMPS, AND IN CARBONS OR INCANDESCING
CONDUCTORS THEREFOR, AND IN MEANS FOR AND METHODS OF MANUFACTURING
THE SAME." (A communication from abroad by Thomas Alva Edison, of Menlo
Park, in the State of New Jersey, United States of America.)
As is now generally known, the inventor prefers to use in his system of electric
lighting an electric lamp consisting essentially of an incandescing conductor sealed
hermetically in a glass enclosing globe.
In manufacturing carbons for such, and for all classes of electric lamps, the
practice, so far as the inventor knows, has been to make them of as low resistance
as possible, a porous carbon having been used which was dipped or soaked in some
cabonizable liquid until its pores were filled and then subjected to recarbonization,
which process was repeated until the pores of the original carbon were filled with
carbon.
By this process the resistance of the carbon is lessened, while its liability to
disintegration under high heat is increased.
Such carbons are unfit for use in electric lamps giving light by incandescence.
For such lamps the inventor has discovered that the incandescing material
should have the highest possible resistance in a very small bulk, and be capable of
resisting the disintegrating effects of very high heats in the absence of atmospheric
pressure, and further that carbons, which are purely structural in character, alone
possess these qualities. By purely structural is meant a carbon wherein the

page_text: natural structure, cellular or otherwise, of the original material is preserved
unaltered, that it is not modified by any treatment which tends to fill up the cells
or pores with unstructural carbon, or to increase its density, or to alter its
resistance.
One object of this Invention therefore is to provide such carbons, and means
and methods for their manufacture.
In practice the incandescing conductor of a lamp should be of about one hundred
ohms resistance, while this may be varied within certain limits; the resistance
stated is a preferable one, and is a very high resistance compared to the carbons
referred to as previously used.
It is essential that this high resistance should be had without increase of
radiating surface, that is, only the radiating surface necessary to give a certain
standard amount of light at the proper degree of incandescence should be used.
The inventor has discovered that incandescing conductors possessing the qualities
enumerated may be made of such natural fibres or fibrous bodies as are capable of
carbonization, especially such as are large, filamentary, and cellular in character.
Of such there are several varieties, of some of which a single fibre or several fibres
aggregated together artificially are used, of some a piece composed of numerous
elementary fibres is used.
'The inventor has found that the preferable single fibres are those of which jute,
bast, manilla, hemp, and-such like, are good-types, the-most preferable one being a
fibrous grass from South America called "monkey bast" fibre, each blade of which
is generally round and composed_of_a_great_number of elementary fibres held
together by a natural cement or resin, which carbonizing locks all the elementary
fibres-together into a homogeneous filament. The treatment next-berein described-
applies however to all the fibres of this class.
These blades vary somewhat in size and also are slightly tapering. "It being
necessary that the conductors should be of a uniform size are reduced, and also
any other fibres varying in size to uniformity by passing them through a cutting
die, which shaves off the extraneous matter; or a revolving cutter may be passed
along the fibres, or they may be reduced in any other practical way.
When desired several blades of the above named grass, or several of any other
natural fibres, may be taken, and after bunching them together they are dipped
into a solution of sugar or other carbonizable liquid and then carbonized as one
fibre, the carbonized cementing liquid binding them firmly together into a large
filament of higher resistance, but of no greater radiating surface than the
carbonized paper incandescing conductor heretofore described by the inventor.
Upon the ends of the fibre, whether simple or compound, are fixed prior to
carbonization clamps made of any suitable carbonizable material, lignum vitæ, box
wood, or equivalent, being well adapted therefor.
They may be made flattened or square, but preferably are cylinders.
A small hole is bored through the centre and the fibre inserted therein.
It is advantageous to moisten these inserted ends of the fibre with a solution of
sugar or with other carbonizable liquid; pieces of platinum wire are inserted into
the clamps. Upon carbonization the material of the clamps shrinks around and
upon the wires and fibre, binding thein tightly together, which result is aided by
the carbonization of the liquid applied as before suggested to the inserted ends of
the fibre.
Of course materials wherein the piece necessary to form a conductor is composed
of a large number of fibres. The inventor has discovered that excellent results
pertain to the use of the plants of the family arundensria, or gigantic grasses,
commonly known as bamboo or cane, or cane bamboo. In such the primary fibres
making up the mass of the material extend from end to end parallel to each other,
increasing the strength and obviating danger of breakage from cross or oblique
grain.
Of the bamboo cane the hard glossy exterior is the best to use, and the softer or
pithy interior part should be rejected.

page_text: To produce the best results in giving light it is essential that the carbon should
be of uniform size throughout the portion that is to be rendered incandescent in
order that radiating surface and resistance be regular and uniform, ensuring even
heating and incandescence.
To accomplish this the cane, bamboo, or other material used is treated as follows
and by the following means :-
The cane is split into pieces somewhat wider than necessary and the inner or
pith portion removed. The material chosen (either the cane or bast, or other if
desired) cut into strips is passed through a shaving device in which a cutting or
shaving knife is fixed, the material being forced against the knife by a movable
block provided with an adjustable stop screw, by which the distance of the block froin
the knife can be regulated, regulating in turn the thickness to be given to the slip.
In this device the slip or filament is shaved on both sides until the proper thickness
is attained.
It is then placed in a clamp composed of two halves of a length equal to the
desired length of the slip. In one half a shoulder or offset is made at a distance
from the edge greater than the desired width, upon which one edge of the fibre
rests, which is then clamped between the two halves and the protruding portion
carefully shaved off, which may be done by hand or by a cutting blade moved by
machinery.
On the opposite side of the clamp is an offset in one half at a distance from the
edge exactly equal to the width to be given the slip.
As it is desirable to form the extended bearing upon which take the clamps
securing the carbon to metallic conductors, homogeneous and in one pieco with the
body, provision is made therefor.
Upon the side last referred to of the clamps and at the ends are small projections
of the exact shape and size to be given the broadened ends of the carbons.
The slip shaved upon both sides and one edge is transferred to the opening in
the clamps, and the extra material shaved or cut off.
The slip is now of uniform size throughout its body and with enlarged ends
formed upon it.
These enlarged ends are entirely upon one edge, instead of the enlargement
being equally distributed upon both edges, as elsewhere shown.
This construction enables the slips when placed on edge, the straight edge, in
the carbonizing flask to move therein, as they are contracted in the process of
carbonization.
Good natural and purely structural carbons may be made of wood, as the wood
is an example of the class of material alluded to, in which the mass of material is
composed of a number of elementary fibres naturally bound together.
In all instances the wood is first to be formed into the shape of what is generally
known in the inventor's system as the loop or "horse shoe "and then carbonized,
and not to be subjected to any further processes which will tend to fill up its pores
and alter its density or resistance.
The wood may be prepared by several methods; for instance, it can be shaped
by cutting or stamping by a die.
A thin veneer of wood, preferably smoother and brought to the desired thickness,
is taken and laid upon a mould or bed plate, a cutting die is then forced down upon
it, cutting out a piece in the shape desired for the incandescing material, and
with thickened ends for attachment to the clamps, or a number of vencers may be
taken and secured together, and then cut into proper shape by a band, gig, or
circular saw.
Another method is as follows:-
A block of wood is taken and cut or formed so that its centre shall be a web,
bounded at the sides by thicker portions. The grain of the wood is from side to
side, and the thickness of the web is about the desired breadth of the carbon.
From the block so fashioned pieces whose width approximates the desired
hickness of the carbon are split, shaved, or cut off. These pieces are then

page_text: sufficiently softened by moisture and heat so as to be bent into a circular or horse
shoe or oval form, and they are retained in such shape in a proper carbonizing
flask and carbonized.
Another method is as follows:-
A block of wood is taken and cut in a milling machine or lathe for turning 5
irregular forms until its shape is that of an elongated oval, of which about one
third, including an end, is cut upon somewhat larger axis than the remainder in
order to provide for the clamps.
The interior is then reamed out in a suitable machine, so that the block then
resembles a series of carbon horse shoes with closed ends piled upon each other.
The length of the oval is with the grain of the wood.
The block is then split or sawed into very thin layers or strips, each forming
ultimately one horse shoe carbon.
10
The slips are then carbonized, preferably in a nickel flask. After carbonization
the greater portion of the bronder end of the slip is cut off, leaving the horse shoe 15
in shape for use. This broader end, which connects what are afterwards tho ends
of the horse shoe, may, if desired, be cut off prior to carbonization; but as the
broader connecting end tends to support and keep in shape the portions afterwards
forming the horse shoo, it is better to leave it on until after carbonization.
-Either before-or-after-carbonization, preferably before, and before the slips are 20
sawed or split from the block, small holes are made in the broad end, through
which pass the clamp screws.
It is desirable in manufacturing carbon slips or filaments of the styles-generally-
known-as-the-"horse-shoe" carbons,-for-use-as-the-incandescing-conductors in.
electric lights, that they should be carbonized evenly and uniformly, and that their 2
shape should be preserved that the carbonization should be effected without
warping or twisting the body of the carbon.
As however the inaterial contracts largely in the process of carbonization, means
are required which, while holding the inaterial in position to avoid twisting or
warping, shall at the same time guarantee even and thorough carbonization, and 3
permit the material to move, so that the inevitable contraction during the process
may proceed without danger of rupturing or otherwise damaging the carbons.
The means and methods for this object are as follows:-
For fibres of the class where a single fibre is used and clamps are secured thereto
a carbonizing flask is used, in the bottom of which is cut a groove approximating 3
in form the shape desired for the finished carbon, but somewhat longer, in which
groove is laid the fibre with its attached clamp. A heavy metallic cover is then
laid thereon, confining the fibre in place, so that it preserves its shape during
carbonization, while at the same time it is free to contract.
The cover may in turn be grooved and receive another fibre, and a series be 4
used, so that many may be carbonized at once in one flask. This flask and all its
parts should be made of nickel, which is best adapted to stand the high heats
necessary to thorough carbonization.
The result is what is now known as the "horse shoe" carbon, made as a single
fibre with carbon clamps and proper conductors securely attached thereto by the
process of carbonization.
As these carbon clamps from their much larger size relatively contain a large
quantity of deleterious gases, which come out very slowly when under the action
of the vacuum pumps, it is preferable that clamps be used which have first been
carbonized and subjected in vacuo to heat sufficient to produce a high degree of
incandescence. When such are used a very small amount of sugar applied to the
ends of the fibres serves, by its carbonization, to bind them securely together.
The carbons made of the other materials set forth have enlarged ends made
upon them for offering a large and certain connection with the clamps, as set
forth. For their carbonization a flask constructed in either of the following
methods is used :-
These various forms are unitary in principle, in that they confine and support

page_text: the material during the carbonization, preventing any distortion, while at the same
time provision is made for contraction, and they differ only slightly in the details
by which these results are attained.
In one form a plate is provided with a groove or recess of the shape and size
lesired for the carbons. At one end of the groove is a recess just large enough to
receive one of the enlarged ends of the strip, a pin being used to secure that end
therein. At the other end of the groove is an elongated recess, the excess of length
of which is equal to the contraction of the material during carbonization, in which
rests the other end of the filament, to which may be attached, or on which may be
placed, a small weight to keep it straight.
During carbonization this end is drawn up in its elongated recess, the other end
remaining fixed.
In another form a groove or recess is made of the elliptical form desired with
recesses at the ends just sufficient to admit of the enlarged ends of the filament
placed sideways therein.
The top or apex of the groove is enlarged in this case, one boundary edge being
upon a curve equal to the length of the uncarbonized material, while the other is of
the length and shape desired for the filament after carbonization.
In another form a recess is cut in a plate of the form desired for the carbon, but
of a size that will accommodate the uncarbonized material.
In the recess fits and slides a plate slightly smaller than the recess, so that when
the plate is laid in the recess a groove is left sufficient in size to just receive the
filament.
.
Upon the outer edges of the recess and at the proper points aro made side recesses
just large enough to receive the enlarged ends of the filament. The filament is
laid in the groove formed between the recess and its plate, the enlarged ends laying
in the recesses provided therefore, weights being laid upon the latter to confine
them therein.
During carbonization, as these ends are fixed, contraction draws down the bow
portion which carries the plate with it, the upper portion of the plate preserving
the shape of the material.
The means described ensure the preservation of the proper shape of the material
during carbonization.
It is also essential that they should be carbonized evenly and equally throughout
their entire mass.
This may be accomplished by a furnace of the following description:
==
Preferably a nickel flask is used composed of two parts, a base plate provided
with numerous legs so as to support the same and permit the heat to reach the
bottom, and a case, or which sets thereon. A series of plates constructed as
before described is placed upon the bottom so as to form a pile, and the box or caso
placed thereon, its edges resting upon the bottom.
This flask is then placed in an oven of a size sufficient to leavo a spaco on overy
side of the flask.
The oven is provided with a top in which is a peep hole having a removable
cover for inspection of the interior.
A pipe connected to a source of supply of any gaseous combustible passes around
the oven in several branches, inlet pipes therefrom carrying the gas in as many
places as necessary to the interior of the oven for comsumption there.
A pipe connected to a suitable air blast passes around the oven in the same
manner, from which lead branch pipes, one passing into each inlet pipe of the gas
supply, so that air under suitable pressure is mingled with the gas at the point of
combustion, furnishing the proper blast for ensuring the necessary high degree of
heat.
The gas and air pipes are furnished with proper valves, so that the relative
supply of each may be regulated.
By this means the supply may be so regulated that at first the flask is subjected

page_text: Ordinarily this radiating surfaco has been that with which the standard pressure
or electro motive force and the standard resistance should give a light equal to 16
candles.
Sometimes however it is desirable in some part of the system to use lamps which
each give a much less amount of light, for instance, in chandeliers, where it is
desired to divide the total amount of light produced among a larger number of
lamps than ordinary, that is, that the light of one standard, say, 16 candle lamp, be
divided between two, three, or four lamps, each of eight, five, and one third or
four candle power respectively.
This result may be obtained in the following way:-
In a derived circuit are placed two lamps, each being carefully provided with an
incandescing conductor of one half the resistance and one half the radiating surface
of the incandescing conductor of the standard lamp of the system.
A single circuit breaker is provided for both lamps, in order that both shall be
turned off or on simultaneously.
When desirable, the two lamps may be arranged in one holder, which may form a
bracket or a section of a group of lamps or of a chandiler.
Instead of two lamps as instanced, any number may be used, care being taken
that the resistance of each be a fractional part of the standard resistance of one
ordinary lamp, the denomination of the fraction being the number of smaller lamps
in the one derived circuit.
In the lamp generally used in my system and referred to hereinbefore, the light
is produced by the incandescence of a conductor in an hermetically sealed vessel;
the incandescing conductor being the small carbon now generally designated as the
horse shoe carbon."
Such however are designed for small lamps, usually fifteen to eighteen candle
power, and the conductor required therefor being small is hermetically sealed in
glass.
When it is desired to produce on the same principle a much greater light, say,
one hundred candles power, the conductor thereto must also be much larger.
While the inventor has succeeded in satisfactorily sealing somewhat larger

page_text: conductors: hermetically in the glass, it is generally not so effective or desirable
a method of passing large conductors into the bulb as where small conductors are
used, wherefore there seems to be a necessity for some other method, which, in the
case of large conductors, shall pass the conductors in the bulb of the lamp without
contact with the glass thereof, and at the same time furnish an effective and lasting
hermetical senl.
This the inventor has succeeded in doing by the employment in the lamp of
two colums of mercury sustained in tubes attached to the lamp bulb at ordinary
barometric hight by the pressure of the atmosphere, and serving both as seals to
preserve the vacuum in the lamp bulb, and as parts of the circuit through the
incandescent conductors.
A glass globe or bulb is blown of proper size, having an annular opening in its
base of a size to admit of the passage into the globe of an insulating base supporting
the carbon.
After this base is put in the globe the annular opening is closed, and two tubes
connecting with the interior of the globe are connected hermetically thereto of a
length somewhat greater than the barometric column of mercury.
From the clamps of the carbon conductors pass one from each clamp into the
proper tube.
The lower ends of the tubes aro placed in proper mercury reservoirs insulated
from each other, one reservoir being connected to one pole of the source of
electricity, the other to the other pole.
The air being exhausted from the globe, the mercury rises in the columns or
tubes forming a seal for the vacuum, and also forming a circuit to the conductors
attached to the clamps.
The lamp is supported upon or by a frame, the standards of which are provided
with adjusting screws, so that its height may be regulated on the lovelling of the
stand secured.
Hitherto in manufacturing the lamp the carbon, having been prepared from
paper, wood, or other suitable fibre, was placed in the lamp, whose parts were then
sealed, the lamp was then exhausted of air, a current being applied during the
process of exhaustion, heating the carbon.
Prior to sealing in the lamp and the process of exhausting the completed lamp
the carbons were not heated, and prior to heating any defects therein could not be
discovered.
It is practicably impossible to produce all the loops or slips of absolute
uniformity or homogenity, or to carbonize all of them absolutely uniform throughout
their entire mass.
When heated to redness, generally throughout their length, some show spots
either less red or of a brighter red than the average of the carbons, indicating for
the first time faults in the carbons.
Where there is a bad fault in the carbon a white incandescent appears
determining the life of the lamp and also affecting its resistance.
Such lamps are unfit for use, and the entire cost of their manufacture has proved
a loss.
The inventor now employs a simple and easy method and means of testing the
carbons before they are put in the lamp proper, and so prevent defective or
unsuitable carbons from being embodied in completed lamps, to be only thrown
away upon discovery of the faults, increasing in fact the net cost of the faultless ones.
This is accomplished by a preliminary heating of the carbons in vacuum, which
by the following means can be cheaply, rapidly, and effectually done.
What may be called a temporary lamp is formed of a globe or chamber of proper
size, with an aperture at its top of a size sufficient to admit of the passage of a
carbon and its supporting base. The neck of the supporting base passes tightly
through a soft rubber cork which fits into the aperture in top of the globe. The
cork is so sized that its upper side is a little distance below the top edge of the
aperture, so that when the cork is in position a chamber is formed on top.

page_text: On one side of the wall of the aperture is an opening having a tube upon its
exterior, the opening being into the chamber referred to as formed above the cork.
A mercury reservoir is connected to the opening by a flexible tube.
When the cork is put into place the reservoir is elevated and the mercury flows
thence, forming a seal over the cock, per contra the reservoir being depressed the
mercury flows back into the reservoir, leaving the cork exposed.
The globe is connected to a proper exhaust tube, several springle drops being
simultaneously used.
By this means a carbon may be placed in the globe, and sealed and exhausted
quickly, and the current applied for testing the carbon, and if found perfect it may
be placed in a permanent lamp.
If the carbon proves defective it is discarded, the only loss being the labor and
material, which are small, involved in the manufacturo of the carbon, and not as
hitherto, the material and great labor necessary to make a complete lamp.
It is evident that several carbons may be tested at once in the proving chamber
or temporary lamp.
One of the objects in giving a very high resistance to the incandescing
conductors used in my system of lighting is to attain economy of material in the
conductors therefor.
-The resistance. usually given them is sufficient for any desired economy. in
ordinarily thickly settled localities. For use, however, in sparsely settled neigh-
borhoods, as say, the outskirts or suburbs of a town or city, it may be desirablo
to have a lamp by the use of which-still-greater-economy-of-conductor.is.attained.
--In-such-localities,-in order to lessen the number of lights needed in streets, it
may be also desirable to have a lamp in which the volume of light is increased, in
order that economy in the erection of lamp posts, for example, may be subserved,
and it may also be desirable to use lamps in which the volume of light may be
increased in other localities.
As there is eventually a limit to the effective life of the carbon used, it is desirable
to so arrange a lamp that the operative life of the lamp may be prolonged beyond
the average life of a carbon, to the end that the cost of the labor expended in
embodying a carbon in a lamp may be reduced.
Both or either of these results are obtained in the following way :-
In a globe made and put together in the manner usually employed and hitherto
described, two or more carbons are used.
In using two to the end of ono conductor passing into and sealed in the globe
is by its single limb fastened, a double clamp of Y shape to each of the double
limbs, a carbon being attached. At their other end each carbon is attached to an
individual clamp, each clamp being attached to a conductor passing and scaled into
the globe.
The conductors (in this instance three in number) pass to a circuit closer con-
necting them to the conductor from the source of electricity.
This circuit closer is so constructed as to be capable of closing the circuit
simultaneously through both, and so that, as desired, they may be either in one
circuit, as a series, or each be in its own derived circuit, or the circuit may be closed
through either one separately.
When both are used in multiple arc, it is evident that the net resistance
of the circuit is one half the resistance of one, and a certain sized conductor is
required.
If both are used in series the resistance is double that of one, and four times
that of the multiple arc, in which case the conductor may be diminished three
fourths.
As the volume of light is that of two ordinary lamps, it is evident that a much
less number may be used with the same light giving results. Thus economy in
laying main conductors and in the erection of lamps is secured.
It is evident that, as one carbon only may be used at a time, that by so using
one only at a time, the life of a manufactured lamp is practically doubled, for where

page_text: one carbon has reached its effective limit the circuit there-through is transferred to
the other, thus saving the oxpense involved in sealing ono carbon in its globo, the
cost of a globe, and its exhaustion.
It is evident that more than two carbons may be sealed in one globe, one conductor
boing provided with the corresponding number of clamps, and each carbon provided
with a separate return wire, for which proper connections are made by enlarging the
circuit closing key, on the principle shown.
In electric lamps formed by sealing an incandescing conductor hermetically in a
glass enclosing globe, there may be danger sometimes that the glass and wire will
separate at the point where the conducting wires pass through and are sealed into
the glass globe. This is due to the fact that the conducting wires near the
incandescing material become very hot by conduction, and that the co-efficient of
expansion of the glass and wire are so different.
In the lamp made on this plan, owing to the high resistance of the incandescing
material, such small conductors are used that the danger referred to has been of
minor or the very least importance.
It may be desirable, however, to provide means which reduce the danger to a
minimum, while affording at the same time tho necessary support for the very small
and delicate conductors and incandescing material.
To accomplish this, a small glass bulb is blown of a little larger diameter than
the distance apart of the ends of the carbon.
Through this globe are passed and scaled therein the conductors leading to tho
carbon, each conductor being scaled therefore in two places, one contiguous to
the clamps for receiving and supporting the carbon, the other soal being almost
diametrically opposite.
The carbon and clamps being placed in position, this small globe is placed in an
aperture left for the purpose in the larger enclosing globe, and sealed thereto at
about the meridian line of the smaller bulb.
The larger bulb is provided with a tube by which it is attached to the air
axhausting apparatus, and where it is sealed after the vacuum is produced; con-
nected to this tube is a branch tube leading from the smaller bulb, so that both are
simultaneously exhausted.
As very small small conductors are used, it is necessary for stability that they be
supported near the carbon, which is done at the sealings on top of the smaller globe,
but if either of these, from their proximity to the light, is over so heated as to
crack, it will still subserve its function as a support, while the vacuum is preserved
by the seals more distant from the clamps.
Sometimes it may be desirable to make a lamp in which a less permanent seal is
used, involving a less expensive method of sealing, and which may be taken apart
readily for the substitution of a carbon, or for other purposes.
This may be done as follows:-
Upon a tube closed at one end is supported a carbon, the conductors therefrom
passing through the tube, and being sealed hermetically in the top thereof.
The enclosing globe is made with a neck somewhat larger than the tube, so that
the carbon may be passed there-through.
A rubber packing is interposed between the outer walls of the tube and inner
walls of the neck securing the two together, the ends of the tube projecting beyond
the end of the neck.
This projecting portion of the tube passes through the base of a rubber cup, the
base of the neck resting upon the bottom of the interior of the cup. At the top of
the cup a rubber packing fills the space between the exterior of the neck and the
interior of the cup.
The space in the cup is filled with mercury, which is retained in place in the
cup by the packing last referred to, forming with the rubber a good seal for any
temporary use.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Griffith Brewer in the Great Seal Patent Office on the
16th March 1881.
EDWARD GRIFFITH BREWER, of 33, Chancery Lane, in the County of Middlesex,
"IMPROVEMENTS IN ELECTRIC LAMPS, AND IN CARBONS OR INCANDESCING
CONDUCTORS THEREFOR, AND IN MEANS FOR AND METHODS OF MANUFACTURING
THE SAME." A communication from abroad by Thomas Alva Edison, of Menlo
Park, in the State of New Jersey, United States of America.
As is now generally known said Edison prefers to use in his system of electric
lighting an electric lamp consisting essentially of an incandescing conductor sealed
herinetically in a glass enclosing globe.
In the manufacturing carbons for such and for all classes of electric lamps, the
practice so far as known has been to make them of as low resistance as possible,.a
-porous carbon. having been used which was dipped or soaked in some carbonizable
liquid until its pores were filled and then subjected to recarbonization, which-
process was repeated until the pores of the original carbon wero filled with
By_this_process_the_resistance or
w
disintegration under high heat is increased. Such carbons are unfit for use in
electric lamps giving light by incandescence.
For such lamps said Edison has discovered that the incandescing material should
have the highest possible resistance in a very small bulk, and be capable of
resisting the disintegrating effects of very high heats and the absence of atmos-
pheric pressure, and further that carbons which are purely structural in character
alone possess these qualities. By purely structural is meant a carbon wherein the
natural structure, cellular or otherwise, of the original material is preserved
unaltered, that is, not modified by any treatment which tends to fill up the cells
or pores with unstructural carbon, or to increase its density, or to alter its
resistance.
One object of this Invention therefore is to provide such carbons and means
and methods for their manufacture.
In practice the incandesing conductor of a lamp should be of about one hundred
ohms resistance. While this may be varied within certain limits the resistance
stated is a preferable one, and is a very high resistance compared to the carbons
referred to as previously used. It is essential that this high resistance should be
had without increase of radiating surface, that is, only the radiating surface
necessary to give a certain standard amount of light at the proper degree of
incandescence should be used.
Said Edison has discovered that incandescing conductors possessing the qualities
enumerated may be made of such natural fibers or fibrous bodies as are capable of
carbonization, especially such as are large, filamentary, and cellular in character.
Of such there are several varieties, of some of which a single fiber or several
fibers aggregated together artificially are used, of some a piece composed of
numerous cleinentary fibres are used.
The preferable single fibres are those of which jute, bast, manilla, hemp, etc., are
good types, the more preferable one being a fibrous grass from South America
called "monkey bast" fibre, each blade of which is generally round and composed
of a great number of elementary fibres held together by a natural cement or
resin, which carbonizing locks all the elementary fibers together into a homogeneous
filament. The treatment next herein described applies however to all the fibers
of this class. These blades vary somewhat in size and are also slightly tapering.
It being necessary that the conductors should be of an uniform size they are

page_text: reduced, and also any other fibers varying in size to uniformity by passing them
through a cutting die which shaves off the extraneous matter, or a revolving cutter
may be passed along the fiber, or they may be reduced in any other practical
way.
When desired, seveal fibers of the above named grass or several of any other
natural fibers may be taken, and after bunching them together dip them into a
solution of sugar or other carbonizable liquid and then carbonize as one fiber,
the carbonized cementing liquid binding them tightly together into a large
filament of higher resistance, but of no greater radiating surface than the carbonized
paper incandescing conductor heretofore patented by said Edison. So far as
capable of illustration this part of the Invention is shown in Figs. 1, 2, & 3.
Upon the ends of the fiber A, whether simple or compound, are fixed prior to
carbonization, the clamps B mado of any suitable carbonizable material, lignuin
vitae, box wood, etc., being well adapted therefor. They may be made flattened or
square, but preferably are cylinders. A small hole is bored through the center and the
fiber inserted therein, as shown in Fig. 2. It is advantageous to moisten the
inserted ends of the fiber with a solution of sugar or with other carbonizable
liquid. Pieces of platinum wire c, c, are inserted into the clamps, as shown
in Fig. 1. Upon carbonization the material of clamps B, B, shrinks around,
and upon the wires and fiber binding them tightly together, which result is
aided by the corbonization of the liquid applied, as before suggested, to the
inserted ends of the fiber. Of those materials wherein the piece necessary to form
a conductor is composed of a large number of fibers, excellent results pertain to the
use of the plants of the family arundeneria or gigantic grasses commonly known
as bamboo or cane or cane bamboo. In such the primary fibers making up the
mass of the material extends from end to end parallel to each other, increasing the
strength and obviating danger of breakago from cross or oblique grain. Of the
bamboo cane the hard glossy exterior is the best to use, and the softer or pithy
part should be rejected.
To produce the best results in giving light, it is essential that the carbons should
be of uniform size throughout the portion that is to be rendered incandescent, in
order that the radiating surface and resistance be regular and uniform, ensuring
even heating and incandescence. To accomplish this, the cane, bamboo, or other
material used is treated as follows, and by the following means:-The cane is split
into pieces somewhat wider than necessary, and the inner or pith portion removed.
The inaterial chosen (either the case or bast, or other if desired) cut into strips, is
passed through a shaving device, in which a cutting or shaving knife is fixed, the
material being forced against the knife by a movable block provided with an
adjustable stop screw, by which the distance of the block from the knife can be.
regulated, regulating in turn the thickness to be given to the slip. In this device
the slip or filament is shaved on both sides until the proper thickness is attained.
It is then placed in a clamp composed of two halves, of a length equal to the
desired length of the slip. In one half a shoulder or offset is forined at a distance
from the edge greater than the desired width upon which one edge of the fiber rests,
which is then clamped between the two halves, and the protruding portion carefully
shaved off, which may be done by hand or by a cutting blade moved by machinery.
On the opposite side of the clamps is an off-set in one half, at a distance from the
edge exactly equal to the width to be given the slip. As it is desirable to formn
the extended bearing, upon which take the clamps securing the carbon to metallic
conductors, homogeneous and in one piece with the body, provision is made therefor.
Upon the side last referred to of the clamps and at the ends are made projections of
the exact shape and size to be given the broadened ends of the carbons. The slip
shaved upon both sides, and one edge is transferred to the opening in the clamps,
and the extra material shaved or cut off. The slip is now of uniform size throughout
its body, with enlarged ends formed upon it. The enlarged ends are entirely upon
one edge instead of the enlargement being equally distributed upon both edges.
This construction enables the slips when placed on edge, the straight edge in the

page_text: carbonizing flask to move therein as they are contracted in the process of carbon-
ization. This part of the Invention is illustrated in Figs. 4, 5, 6, 7, and 8, in which
Fig. 4 is a top view, and Fig. 5 is a side view of the device used for shaving the
sides; Fig. 6 is an end view, and Fig. 7 is a side view of the clamps used in shaving
the edges. Fig. 8 is a view of a complete filament.
In these Figures, A is a suitable base, having upon it supports a, a, for the
working devices, these supports leaving an open space between them in which such
working devices are mainly located. In front of a' is fixed a block B fashioned at
one end to receive and support at the proper angle the knife or plane b. In front
of a is a block Cattached to screw D sliding in a, and caused to rotate so as to
move C by disk E, working in a slot in a, D, being prevented from rotating by
screw & taking into a feather cut in its side. Upon the side of C is lug G, through
which passes the scrow g, which is set to strike against B, and consequently limit
the movement of C, keeping it at any desired distance from B, which distance is the
thickness to be given the slip. The slip s is placed between B and C, and
drawn through between them, being forced by C against the edge of the knifo
until one side is smoothed. It is then taken out and replaced with the shaved side
next to c, and the operation repeated.
By these operations and means the slip is reduced to an uniform thickness.
The clamp for reducing to an uniform width is. made of two parts H, I, of a
length equal to the length to be given to the slip, and held together by pieces
one-at-each-end,-having.a.slot_o in one end so as to permit of a limited movement
_of_the_parts_H, I, from each other.
length,
The part I is formed with shoulders-or-off-sets-v,-w,_along_its_entire
taking into a corresponding recess in H, forming when the two parts are in position
slots along the entire length of the clamp, the off sets v, w, forming the bottom of
the slots. Upon one side at each end of each part are formed the lugs or
projections h, h, the size and shape of the enlarged ends of the finished carbons.
In h, h, the small recesses i, i, for the purposes hereinafter set forth.
The slip S of a greater width than the widest portion of the finished slip is
placed in the clamp in the slot, whose bottom is the off set v, the clamps tightened
and the protruding portion removed down to the surface of the clamps. The edge
thus prepared forms a straight edge or gage for the finishing, the slip being placed
in the clamp in the slot whose bottom is the off set w, and the extra material
removed on the line formed by the surface of the clamp and the projections h, h.
The result is
This being done a saw or knife is run through the recesses i, i.
the slip shown in Fig. 8 having an uniform body with the enlarged clamps for
securing the carbon in the clamps, and provided with the recesses i, which are of
use in securing the slip in the carbonizing flask, and afterwards for permitting
the clamping screws to pass through. Sometimes it is desirable to form the ends
thicker in both directions. In such cases the preliminary cutting in the first
machine simply reduces the slip to dimensions equal to the desired width and
thickness of the ends, and it is then finished off in the clamps, one set of clamps
being made with shallow grooves so that the slip may be laid flatwise therein. Good
natural and purely structural carbons may be inade of wood, as wood is an example
of the class of materials alluded to, in which the mass of material is composed
of a number of elementary fibers naturally bound together. In all instances the
wood is first to be formed into the shape of what is generally known in Edison's
system, as the loop or "horse shoe," and then carbonized, and not to be subjected
to any further processes which will tend to fill up its pores and alter its density
or resistance.
The wood may be prepared by several methods, for instance, it can be shaped by
cutting or stamping by a die. A thin vencer of wood properly smoothed and
brought to the desired thickness is taken and laid upon a mold or bed plate,
a cutting die is then forced down upon it cutting out a picce in the desired shape
for the incandescing material, and with thickened ends for attachment to the
clamps, or a number of veneers may be taken and secured together, and then cut

page_text: into proper shape by a band, jig, or circular saw. This is illustrated in Fig. 9,
which is a section of the cutting dio and mold with a veneer in position, and in
Fig. 10, which shows the resultant pieco ready for carbonization. In these Figures
A is a cutting or stamping die provided with the cutting or stamping edge a
projecting from the face of A, and of the same size and contour as the wooden horse
shoe E; B is the mold or bed-plate having a groove or recess D, whose upper edge
is of a size and shape just sufficient to receive a, but increasing in size towards tho
base to permit the ready escape of anything which may be forced in at the top.
C is a piece of veneer in position for the operation of the stamp or die A. Upon
force being applied to A shoe E is cut from the wood, with the broadened ends e
for attachment to the clamps homogeneous and unitary therewith. This in then
taken and placed in a suitable carbonizing flask fully illustrated herein. The result
is a porous structural carbon of high resistance excellently fitted for use in lamps
intended to give light by incandescence, and not needing any further treatment
which might alter or modify its purely natural structure. Another method is as
follows: A block of wood is taken and cut or formed so that its center shall be a
web bounded at the sides by thicker portions. The grain of the wood is from side
to side, and the thickness of the web is about the desired breadth of the carbon.
From the block so fashioned pieces whoso width approximate the desired thickness
of the carbon are split, shaved, or cut off. These picces are then sufficiently
softened by moisture and heat, so as to be bent into a circular, or horso shoe, or
oval form, and they are retained in such shape in a proper carbonizing flask and
carbonized. This method is illustrated in Figs. 11, 12, & 13, in which Fig. 11
represents a block formed as before described; Fig. 12, a picco split, cut, or shaved
therefrom, and Fig. 13 the same after carbonization, in which A is the web of the
block, the center of the block being reduced in thickness, while the ends a, a, are
left broad or thickened for fastening to the clamps. This block is split, cut, or shaved
into pieces like Fig. 12, which are then bent into the shape shown in Fig. 13, or
into any other desired shape, and then carbonized while in such form. The result
is a carbon with broadened ends for clamping unitary with itself, and which is
porous, structurally unaltered, of high resistance, and with a minimum tendency to
disintegration under high heat. It is evident that the block shown in Fig. 11 could
be made of disintegrated fibers, paper pulp, papier mache, etc., by powerful pressure,
and the individual carbons then cut off from such block; but in practice it is
so far preferred to make the block and resultant carbons of wood. Another
method is as follows:-A block of wood is taken and cut in a milling machine or
lathe for turning irregular forms, until its shape is that of an elongated oval, of
which about one third, including an end, is cut upon somewhat larger axes than the
remainder in order to provide for the clamps. The interior is then reamed out in
a suitable machine, so that the block then resembles a series of carbon horse shoes
with closed ends piled upon each other. The length of the oval is with the grain
of the wood. The block is then split or sawed into very thin layers or slips,
forming ultimately one horse shoe carbon. These slips are then carbonized,
preferably in a nickel flask or a description shown herein; after carbonization the
greater portion of the broader end of the slip is cut off, leaving the horse shoe in
shape for use. This broader end which connects what are afterwards the ends of
the horse shoe may if desired be cut off prior to carbonization, but as this broader
connecting end tends to support and keep in shape the portions afterwards forming
the horse-shoe, it is better to leave it on until after carbonization. Either before or
after carbonization, preferably before, and before the slips are sawed or split from
the block small holes are made in the broad end through which pass the clamp
screws. This is illustrated in Figs. 14, 15, and 16, of which Fig. 14 is a
perspective view of the block partially turned in proper shape.
Fig. 15 is a front view of a carbon after carbonization; Fig. 16 is a side view of
a carbon properly secured in clamps. In these Figures, A is a block of wood,
which in a proper machine is turned so that its exterior shape is that of an oval
composed of two ovals B, C, of different axes, thereby forming a broader portion

page_text: for the clamps, the interior being reamed out to present a uniform smooth
surface F. This block so shaped is then split or sawed into very thin layers or
slips of a thickness sufficient for one carbon horse shoe, as seen in Figs. 15 and 16.
These slips are then carbonized and a portion of C broken or cut off at c, c, as shown
in dotted lines in Fig. 15. At some stages in the process, preferably while in the
shape shown in Fig. 14, holes d, d, are drilled for the reception of the
screws e, which fasten the clamps D to the carbon. It is desirable in manu-
facturing carbon slips or filaments of the style generally known as the horse shoe
carbons for use as the incandescing conductors in electric lights that they should be
carbonized evenly and uniformly, and that their shape should be preserved, that
the carbonization should be effected without warping or twisting the body
of the carbon. As however the material contracts largely in the process of
carbonization, means are required which, while holding the material in position
to avoid twisting or warping, shall at the same time guarantee even and
thorough carbonization and permit the material to move, so that the inevitable
contraction during the process may proceed without danger of rupturing or
otherwise damaging the carbons. For this purpose means and methods as follows
are used :-
For fibers of the class where a single fiber is used and clamps or enlarged portions
for-clamps are secured thereto, a carbonizing flask is used, in the bottom of which
is cut a groove approximatiúg in form the shape desired for the finished carbon,
but somewhat longer, in which groove is laid the fiber with its attached clamps. A
heavy metallic cover is then laid thereon-confining-the-fiber-in-place,.so_that_it_
preserves-its-shape-during-carbonization,_while_at_the_same_time it is free to
contract. The cover may in turn be grooved and receive another fiber, and a series
be used so that many may be carbonized at once in one flask. This flask and all
its parts should be made of nickel, which is best adapted to stand the high heats
necessary to thorough carbonization.
This task is illustrated in Fig. 17, in which D is a flask or box of metal capable
of withstanding a high degree of heat, having a groove E of the desired shape cut
in its bottom, as shown in Fig. 17. As fibrous material contracts or shrinks in the
process of carbonization, it is necessary to provide for the movement attendant
thereon, care being taken at the same time to prevent any movement which would
allow of warping or distortion. This is effected by the groove E which allows a
longitudinal movement but prevents any other. In this groove the fiber with its
attached ends is placed, a cover F being then laid over it. A corresponding groove
may he cut in the upper surface of the cover F and another fiber laid therein, and
a number of such covers, limited by the capacity of the flask or box D, may be
used, so that many may be carbonized at one operation. When the flask or box D
is full the lid F is fastened tightly thereon, and the whole placed in any suitable
furnace for carbonization. The result is what is now known as the horse shoo
carbon made as a single fiber with carbon clamps and proper conductors securely
attached thereto by the process of carbonization. As these carbon clamps from
their much larger size relatively contain a large quantity of deleterious gases, which
come out very slowly when under the action of the vacuum pumps, it is preferable
that clamps be used which have first been carbonized and subjected in vacuo to
heat sufficient to produce a high degree of incandescence. When such are used a
very small amount of sugar applied to the ends of the fibers serves by its carboni-
zation to bind them securely together.
The carbons made of the other materials set forth have enlarged ends made upon
them for affording a large and certain connection with the clamps, as set forth. For
their carbonization a flask constructed in either of the following methods is used:-
These several forms are unitary in principle in that they confine and support the
material during its carbonization, preventing any distortion, while at the same time
provision is made for contraction, and they differ only slightly in the details by
which these results are attained. In one form a plate is provided with a groove
or recess of the shape and size desired for the carbon. At one end of the groove is

page_text: a recess just large enough to receive one of the enlarged ends of the strip, a pin
being used to secure that end therein.
At the other end of the groove is an elongated recess, whose excess of length is
equal to the contraction of the material during carbonization, in which rests the
other end of the filament, to which may be attached or on which may be placed a
small weight to keep it straight. During carbonization this end is drawn up in its
elongated recess, the other end remaining fixed. In another form a groove or recess
is made of the elliptical form desired, with recesses at the ends just sufficient to
admit of the enlarged ends of the filament placed sideways therein. The top or apex
of the groove is enlarged in this case, one boundary edge being upon a curve equal
to the length of the uncarbonized material, while the other is of the length and
shape desired for the filament after carbonization.
In another form a recess is cut in a plate of the form desired for the carbon, but
of a size that will accomodate the uncarbonized material. In the recess fits and
slides a plate slightly smaller than the recess, so that when the plate is laid in the
recess a groove is left sufficient in size to just receive the filament. Upon the outer
edge of the recess, and at the proper points, are made side recesses just large enough
to receive the enlarged ends of the filament. The filament is laid in the groove
formed between the recess and its plate, the enlarged ends laying in the recesses
provided therefor, weight being laid on the latter to confine them therein. During
carbonization as these ends are fixed, contraction draws down the bow portion
which carries the plate with it, the upper portion of the plate preserving the shape
of the material. These plans may be better understood by reference to Figs. 18,
19, 20, 21, 22, 23, 24, 25, and 26, in which Figs. 18, 21, 24, and 25 are plan views
of carbonizing plates, unitary in principle but differing slightly in detail. Figs. 20
and 23 are an edge and side view respectively of a slip or filament ready for car-
bonization. Figs. 19, 22, 26, and 27 are details more fully hereinafter referred to.
A is the nickel plate in which is cut the groove a of the shape desired for the
finished carbon, and of a depth sufficient to receive the slip or filament s.
The co-efficient of contraction of the fiber is determined by experiment, and the
length of the groove is made equal to the length desired for the finished carbon,
plus the contraction of the material during the process of carbonization. In
Fig. 18 this extra length is at one end of the groove, enlarged at one end into a
Sinall chamber just sufficient to receive one of the enlarged ends c of the filament,
which is secured therein by a pin e. A small wedge may also be placed in the
chamber to assist in keeping the enlarged end in shape, the pin e passing through c
and f. The other end of the groove a is made with a long chamber b, whose length
is equal to or greater than the amount of contraction in length of the filament in
carbonization. Upon the free end of the slip or tilament & the clamp d is
secured.
The plate A with the slip or filament secured in position, as described, is covered
by a smooth plate, or a series may be used piled one upon another, the smooth
under surface of one forming the cover to the one underneath. They are then
placed in a suitable nickel case, and on being subjected to the first low heat
carbonization and contraction proceed evenly and equally throughout each slip or
filament, the contraction drawing up the loose end in the chamber b, until at the
conclusion of the process the end d is exactly opposite c. The cases and plates
used are made of nickel as no other metal stands the high heat necessary in the
final stage of carbonization.
In Fig. 21 the groove a is shown formed with a chamber a' at the bow of the
horse shoe.
In this case the slip & is laid flatwise in the groove, the ends c, c, fitting into
chambers at the end of the groove, upon which weights o are laid. By this means
the ends are held in position during carbonization, while the contraction is
from x to during the process. Fig. 24 shows the same construction and method
of operation as in Fig. 1S, except that while in Fig. 18 the slip is placed edgewise
in the groove, in Fig. 24 it is placed flat or sideways in the groove. In Fig. 25

page_text: the plate A is formed with a chamber, in which slides a plate C smaller than the
chamber by the size of the filament or strip, so that when the plate C is placed in
the chamber a groove shall be left in which is placed the filament or strip, the
ends c, c, resting in chambers fitted for them, and held in place therein by weights
9, g, laid thereon, in chambers made therefor.
As the filament is thus fastened at the ends, as carbonization proceeds, the
ensuing contraction pulls the bow towards the ends forcing the plate C towards
the end B of A. In all theso plans, however, the filament is kept under strain
during carbonization with one or more points fixed against moving, and the
contraction proceeds against the strain which constantly keeps the filament against
or in contact with a former, preserving its shape and obviating any risk of warping
or twisting. In all provision is made for keeping flat and in their proper relative
position the enlarged ends of the carbon.
It is also essential that they should be carbonized evenly and equally throughout
their entire mass. This may be accomplished by a furnace of the following
description-Preferably a nickel flask is used composed of two parts, a base plate
provided with numerous legs so as to support the same and permit the heat to
A series of plates,
reach the bottom, and a case or box which sets thereon.
constructed as before described, is laid upon the bottom so as to form a pile, and
the box or case placed thereon, its edges resting upon the bottom. The flask is
then placed in an oven of a size sufficient to leave a space on every side of the flask.
The oven is provided with a top, in which is a peep-hole, having a removable cover
for inspection of the interior-A-pipe-connected to a source of supply of any
gaseous combustible-passes_around the oven in several branches,-inlet-pipes..
therefrom carrying the gas in as many places as necessary-to-the.interior_of the
oven for consumption there.
A pipe connected to a suitable air blast passes around the oven in the same
manner, from which lead branch pipes, one passing into each inlet pipe of the gas
supply, so that air under suitable pressure is mingled with the gas at the point of
combustion, furnishing the proper blast for ensuring the necessary high degreo
of heat. The gas and air pipes are furnished with proper valves, so that the
relative supply of each may be regulated. By this means the supply may be so
regulated that at first the flask is subjected to a comparatively moderate heat only,
which is then gradually brought up to the highest degree necessary.
The carrying into effect of this part of the Invention may be more clearly
understood by reference to Figs. 28, 29, and 30, of which Fig. 28 is a view of a
carbonizing plate grooved to receive a filament; Fig. 29 is a perspective view of
a series of the plates in the carbonizing flask; Fig. 30 is a perspective view of the
carbonizing oven. In these Figures, A is a carbonizing plate grooved to receive a
filament, and to have it secured therein. The carbonizing flask is composed of two
portions, B and C; B is a base provided with numerous legs b, b, b, b, in order to
raise it above the bottom of the oven to permit the free passage of heat there
around. Upon B is arranged a series of the plates A, each containing a filament,
and over the series is placed a cover C, securing thein all upon the base and within
the flask. The flask so filled is placed within the oven D, provided with the
cover E, an exit e for the escape of the products of combustion being provided. A
peep hole may be provided, which is closed by cover F, through which the condition
of the flask may be observed. A pipe G, connected to a source of supply of any
gaseous fluid, passes around the oven in several branches, inlet branches g, g,
therefrom conveying the gas in as many places as necessary to the interior of the
oven for consumption; H is an air tube connected with a suitable blast and passing
around the oven in the same manner as G, from which lead branch pipes h, h, h,
one passing into each branch inlet g, so that air under pressure is mingled with the
gas at the point of combustion, furnishing a supply of air for proper combustion,
and ensuring the necessary high degree of heat. Both G and H are provided with
ordinary stop cocks or valves, by which the supply of either air or gas absolutely
or relatively to each other may be regulated. The oven D is of such a size that

page_text: when the flask is placed in position therein there is a space on every side between
the flask and the oven. The flask, filled with plates and filaments, is placed in the
oven and the fire kindled by lighting the gas. By means of the valve before
mentioned, the supply of fuel may be so regulated that at first the flusk is subjected
to a moderate heat, which may be gradually brought up to the required point.
The blast ensures a high degree of heat directed immediately upon the flask, and
evenly distributed thereon.
When heated for a sufficient time the gas is turned off, and the flask may be
allowed to cool down in the oven. During the process of carbonization there is
sometimes danger that the material under treatment may be oxydized to such an
extent as to interfere with proper carbonization. This oxydation is due to the
oxygen in the air present in the flask, and to the oxygen eliminated from the wood
itself at the commencement of the process. If desired to prevent this, an auxiliary
tube may be used, passing into the flask, through which is introduced therein prior
to firing, and during the burning, an atmosphere of hydrogen, or of some hydro
carbon, or of some other element which will take up the oxygen and prevent its
action upon the filaments.
In a system of electric lighting, such as proposed by said Edison, in which
soparate electric lamps devoid of regulating devices are used at the places of
consumption, the entire regulation for all the lamps being performed at the central
station as with water or gas supply, it is essential that a constant electro motive
force or pressure be maintained. And as in such a system the lamps are arranged
upon the multiple arc or derived circuit system it is essential that there should be
a certain standard resistance in each derived circuit. This has been attained by
placing one lamp of such standard resistance in each derived circuit. It is desirable
that all lamps should be of equal lighting value, each giving a certain standard
amount of light. This has been attained by giving each a certain definite or
standard amount of radiating surface.
Ordinarily this radiating surface has been that with which the standard pressure
or electro motive force and the standard resistance should give a light equal to
sixteen candles. Sometimes however it is desirable iu some parts of the system to
use lamps which each give a much less amount of light; for instance, in chandeliers
where it is desirable to divide the total amount of light produced among a larger
number of lamps than ordinary, that is, that the light of ono, say, standard sixteen
candle lamp, be divided between two, three, or four lamps, each of eight, five
and one third, or four candle power respectively. This result may be attained
in the following way :-
In a derived circuit are placed two lamps, each being carefully provided with
an incandescing conductor of one half the resistance and one half the radiating
surface of the incandescing conductor of the standard lamp of the system. A
single circuit breaker is provided for both lamps in order that both shall be turned
off or on simultaneously. When desirable the two lamps may be arranged in one
holder, which may form a bracket or may form a section of a group of lainps or of
a chandelier. This part of the Invention is shown in Figs. 31, 32, and 33, wherein
Fig. 31 is a diagram showing one standard lamp and two half lamps in derived
circuits from the same main conductors; Fig. 32 is a view of two half lamps
arranged in one holder; and Fig. 33 is a diagram showing the connections in such
holder. In these Figures C, C, are the main conductors leading to and from any
suitable source of electric energy at the central station. In the multiple are 1
thereto is a lawp A of standard resistance and radiating surface. In the multiple
are 2 are the two lamps B, B, each of which has just one half the radiating surface
and one half the resistance of A. One circuit breaker b is provided controling the
circuit through both lamps. As a consequence, with an uniform standard electro
motive force or pressure, each of these lamps will each give one half the light
which A would give. If it is desired to increase the number the same proportion
between the number used and the standard resistance and radiating surfaco should
exist. For two, three, or more lamps a suitable holder F of insulating material is

page_text: made, sockets & being made therein for each lamp. To each socket metallic
conducting plates are placed on opposite sides, as at c, c, d, d, for forming contact
with metal slips or pieces on the necks of the lamps. The socket may be provided
with a plain or screw threaded aperture E, by which it may be attached to the wall
as a bracket or to a framing so that it may constitute a portion of a group of
lamps or of a chandelier. Upon the socket is a circuit breaker consisting of a
metallic screw D secured in a seat h, and which may be turned to impinge upon or
be cleared from contact with a metal block e. The conductor C passes through c, c',
to e, and the conductor C' through d, d, to the metal seat h of the screw D.
Instead of two lamps as instanced, any number may be used, care being taken
that the resistance of each be a fractional part of the standard resistance of one
ordinary lamp, the denominator of the fraction being the number of smaller lainps
in the one derived circuit. If more than two are used, the block e and screw D are
placed somewhere in the circuit, lending through all the lamps in order that all may
be turned on or off simultaneously, all the divided lamps being used as one
standard lamp. In the lamps generally used in said Edison's system, and referred
to herein before, the light is produced by the incandescence of a conductor in an
hermetically sealed vessel, the incandescing conductor heing the small carbon now
generally designated as the "horse shoe carbon." Such, however, are designed for
small lamps usually, say, fifteen to eighteen candle power, and the conductor
required therefor being small is hermetically sealed in glass. Wlien it is desired to-
produce-on-the-same-principle a much greater light, say, one hundred candle power,
the conductor thereto must also be much larger. While-said-Edison.has succeeded
satisfactorily in sealing somewhat larger-conductors_hermetically in the glass, it is
generally not so effective or desirable a method of passing large conductors into the-
bulb as where small conductors are used. Wherefore, there seems to be a necessity
for some other method, which in the case of larger conductors, shall pass the
conductor into the bulb of the lamp without contact with the glass thereof, and at.
the same time furnish an effective and lasting hermetical seal. This is accomplished
by the employment in the lamp of two columns of mercury sustained in tubes
attached to the lamp bulb at ordinary barometric hight by the pressure of the
atmosphere, and serving both as seals to preserve the vacuum in the lamp bulb and
as parts of the circuit through the incandescent conductors. A glass globe or bulb
is blown of proper size, having an annular opening in its base of a size to admit of
the passage into the globe of an insulating base supporting the carbon. After this
base is put in the globe, the annular opening is closed, and two tubes connecting with
the interior of the globe are connected hermetically thereto, of a length somewhat
greater than the barometric column of mercury. From the clamps of the carbons,
conductors pass one from each clamp into the proper tube. The lower ends of the
tubes are placed in proper mercury reservoirs insulated from each other, one reservoir
being connected to one pole of the source of electricity, the other to the other pole.
The air being exhausted from the globe, the mercury rises in the columns or tubes,
forming a seal for the vacuum, and also forming a circuit to the conductors attached
to the clamps. The lamp is supported upon or by a frame, whose standards are
provided with adjusting screws, so that its hight may be regulated, or the leveling
of the stand secured.
This part of the Invention is shown in detail in Fig. 34, which is a view of a
lamp embodying this part of the Invention, shortened somewhat in proportion to
its hight, as indicated in the dotted line. A glass globe or bulb A is blown, having
an annular opening in its base of a size to admit of the base a, a, passing there-
through. The line of this opening is indicated at i, i. Upon the top of the bulb is
formed a tube, the continuation of the projection N by which the lamp is attached
to the air pump. Upon a suitable base a, a, of insulating material are fastened by
proper devices, the clamps b, b, holding and supporting the horse shoe B, the clamps
being connected to metallic conductors e, c', passing a little distance, say, several
inches, below the base a, a. Two glass tubes c, c', each of a diameter several times
greater than that of e or e¹, and several inches longer than a column of mercury

page_text: supported in vacuo by atmospheric pressure, are united near their top as at m, and
their united tops formed into a circle, the diameter of or slightly larger than the
diameter i, i, of the opening in A. The base a, a, supporting the carbon and with
its attached conductors is introduced into A, and tho tubes c, c, are then secured
by sealing at i, i, to A; the conductor e projecting downwardly into c, and e¹ into c'.
For supporting the lamp thus formed a stand is employed consisting of an
insulating top E and base E¹ united by metallic standards F, F', which are
connected to the base E' by adjustable screw connections g, g', so that, as
circumstances require, the top may be raised, lowered, or inclined. Upon the metal
standards F, F', are binding screws, whereby conductors 1, 4, to and from the
source of electricity are attached. The top E is provided with a central aperture,
or it may be annular, permitting the tubes c, c', to pass through and below it while
supporting the globe. Upon the base E is located a vessol made of insulating
material not affected by mercury divided into compartments D, D¹, or two separate
distinct vessels inay be used.
The tube c passes into one D to near its bottom, while c passes into D¹. A
wire 2 connects D and F and a wire 3 connects D' and F. The parts being placed
in position, as shown in the Figure, the vessels D, D', are filled with mercury,
and the tube continuation of N, before mentioned, fastened to the pumps.
As the air is exhausted from the bulb the mercury rises in c and c'. During
this operation care must be taken that the compartments D, D¹ are kept supplied.
with mercury and that upon the completion they are still full. Upon the proper
degreo of vacuum being attained the bulb is sealed at N and the tube removed.
At this stage the mercury has risen to and remains at x, x, the hight at which
atmospheric pressure sustains a column of mercury in vacuo, the inercury contacting
with e, e', and passing a little distance above their ends. The columns C, C', should
he of such a diameter as to give no greater resistance to the current than does
either of the conductors e, e¹, 2 or 3.
For high candle power incandescent lamps this arrangement makes a very
reliable and durable seal, obviating any danger there may be of seal breakago
arising from difference of expansion coefficient likely to exist where a large metallic
conductor is sealed directly to or in glass. For such reason in large lamps this
method may prove preferable to that of sealing direct.
Hitherto in manufacturing the lamp the carbon having been prepared from
paper, wood, or other suitable fiber, was placed in the lamp, whose parts are then
sealed; the lamp was then exhausted of air, a current being applied during the.
process of exhaustion heating the carbon.
Prior to sealing in the lamp and the process of exhausting the completed lamp
the carbons were not heated, and prior to heating any defects therein could not be,
discovered. It is practically impossible to produce all the loops or slips of absolute.
uniformity or homogenity, or to carbonize all of them absolutely uniform throughout
their entire mass. When heated to redness generally throughout their length some
show spots either less red or of a brighter red than the average of the carbons,
indicating for the first time faults in the carbons. Where there is a bad fault in
the carbon a white incandescence appears, determining the life of the lamp and
also affecting its resistance. Such lamps are unfit for use and the entire cost of
their manufacture has proved a loss.
It is now proposed to furnish a simple and easy method and means of testing the
carbons before they are put in the lamp proper, and so prevent defective or
unsuitable carbons from being embodied in completed lamps to be only thrown
away upon discovery of the faults, increasing, in fact, the net cost of the faultless
ones. This is accomplished by a preliminary heating of the carbons in vacuo,
which by the following means can be cheaply, rapidly, and effectually done. What
may be called a temporary lamp is formed of a globe or chamber of proper size,
with an aperture at its top of a size sufficient to admit of the passage of a carbon
and its supporting base. The neck of the supporting base passes tightly through a
soft rubber cork which fits into the aperture in top of the globe. The cork is so

page_text: sized that its upper side is a little distance below the top edge of the aperture, so
that when the cork is in position a chamber is formed on top. On one side of the
wall of the aperture is an opening having a tube upon its exterior, the opening
being into the chamber referred to as formed above the cork. A mercury reservoir
is connected to the opening by a flexible tube. When the cork is put into place
the reservoir is elevated and the mercury flows thence, forming a scal over the
cork; per contru, the reservoir being depressed, the mercury flows back into the
reservoir baring the cork. The globe is connected to a proper exhaust tube, several
sprengel drops being simultaneously used. By this means a carbon may be placed
in the globe, it sealed and exhausted quickly, and the current applied testing the
carbon, which standing the test may be placed in a permanent lamp.
Suitable mechanism for carrying this part of the Invention into effect is shown in
Fig. 35, which is a sectional view of the preliminary proving or testing lamp,
in which Fig. Q is the usual glass carbon support, which is sealed to the glass globe
in the completed lamp at r. a is the carbon to be proved, secured thereto in the
usual way. C is the temporary proving lamp, having at its upper end an aperture
sufficiently large to admit the carbon and its support, and provided with a soft
rubber cork B, through which the neck of the carbon support Q passes. The
cork B fits tightly in the aperture, the sealing being further rendered secure by a
mercury scal E, a mercury reservoir & being elevated- when necessary, so that the
mercury therefrom flows down through a tube cover the top of the cork. From
the bottom-of-the-proving-lamp-C_proceeds two two tubes, one n connecting with a
-McLeod-gage; the other tube blends to and connects with the vacuum apparatus:
In operation the carbon to be tested is placed in-the-proving-chamber.or lainp C,
and the mouth hermetically sealed. The stop cock in tube bis then opened,
giving free communication between the chamber C and the vacuum apparatus.
When the proper degree of exhaustion is attained circuit is closed through carbon a,
heating it to incandescence, causing defects if any to be visible. If the carbon proves
defective it is discarded, the only loss being the labor and material, which are small,
involved in the manufacture of the carbon, and not as heretofore the labor and
materials, which were many times greater, necessary to a completed lamp. It is
evident that several carbons may be tested at once in the proving chamber or
temporary lamp.
One of the objects in giving a very high resistance to the incandescing con-
ductors used in said Edison's system of lighting is to attain economy of material
in the conductors therefor. The resistance usually given them is sufficient for any
desired economy in ordinary thickly settled localities. For use however in sparsely
settled neighborhoods, as, say, the outskirts or suburbs of a town or city, it may be
desirable to have a lamp by the use of which still greater economy of conductor is
attained. In such localities, in order to lessen the number of lights needed in
streets, it may also be desirable to have a lamp in which the volume of light is
increased, in order that economy in the erection of lamp posts, etc., may be
subserved; and it may also be desirable to use lamps in which the volume of light
may be increased in other localities. As there is eventually a limit to the effective
life of the carbon used, it seems desirable to so arrange a lamp that the operative
life of the lamp may be prolonged beyond the average life of a carbon, to the end
that the cost of the labor expended in embodying a carbon in a lamp may be
reduced. Both or either of these results are attained in the following way:
An enclosing globe is used, made and put together in the usual manner, in the
lamps herein described. To the inner end of one of the conductors leading into the
lamp is fastened a double clamp, that is, one that is Y shaped, a carbon being
fastened to each limb of the Y clamp. At the other end each carbon is fixed in
an individual clamp, each clamp having its own conductor leading outside of the
lamp. The wires leading out of the lainp and the wires leading from a suitable
source of electricity are united at a circuit controling device, constructed so that it
may close the circuit through either carbon, the circuit through the other remaining
open; or it may close the circuit through both, as carbons in a series; or it may

page_text: close a circuit through each, the circuit through them being derived or multiple arc
circuits. This part of the Invention is moro clearly shown in Fig. 36, in which A
is a glass globe, and B the supporting neck united at a, b. Through the neck B
passes the conductors 6, 7, 8, which are scaled therein. Upon the inner terminal
of 6 is the shaped clamp D, in each leg of which is fixed a carbon e or g. The
other ends of these carbons are in separate clamps, e being fastened in the clamp &
of conductor S, and g in clamp d' of conductor 7. The conductors 6, 7, and 8 und
the circuit conductors 5, 9, are connected to a key E composed of metal contact
points 1, 2, 3, 4, and anvils x, 8, , as follows:-Circuit conductor 5 is connected to
point 1, contacting with a, and to anvil 8, on which 2 contacts, while 9 is connected
to anvils, with which both 3 and 4 may make contact. Conductor 6 is connected
to anvil ; 7 to point 4, which contacts with ; and 8 to 2, which contacts
with 8; and to 3, which contacts with s. If points 1 and 3 bo put in contact
with their anvils x, z, a circuit is formed, 5, via 1, x, 6, D, e, d, 8, 3, 2,
to 9, the circuit through g being open. If 1 and 4 be closed on 20
and, the circuit is formed 5, via 6, D, g, d, 7, 4, z to 9, the circuit through e
being open, and g alone in circuit and use. If 2 & 4 be closed on 8 and 2, the
circuit is from 5, via 8, 2, 8, e, D, g, 7, 4, 2, to 9, and both e and g are in one
circuit, that is in scries. If 1, 3, and 4, be closed on 2, 8, and 2, the circuit is
from 5, via 1, x, 6, to D, where two paths are formed, the current consequently
dividing one circuit being D, e, 8, 3, 2, to 9, the other D,g, 7, 4, &, to 9, both carbons
being in circuit, but each having its own circuit, which is a derived one, so far as
the main circuit is concerned. When both are used in multiple arc it is evident
that the net resistance of the circuit is one half the resistance of one, and a certain
sized conductor is required. If both are used in series the resistance is double that
of one and four times that of the multiple arc, in which case the conductor may be
diminished three fourths. As the volume of light is that of two ordinary lamps, it
is evident that a much less number may be used with the same light giving result.
Thus economy in laying main conductors and in the erection of lamps is secured.
It is evident that as one carbon only may be used at a time, that by so using one
only at a time, the life of a manufactured lamp is practically doubled, for where
one carbon has reached its effective limit, the circuit therethrough is transferred to
the other, thus saving the expense involved in sealing one carbon and its globe, the
cost of a globe, and of its exhaustion. It is evident that while only two carbons
are shown, that more may be sealed in one globe D, being provided with the same
number of clamps, and each carbon provided with a separate return wire, for which
proper connections are made by enlarging key E on the principle shown. It is also
evident that E may be provided with lever contacts instead of the screw contacts
used to explain the principle of this Invention.
In electric lamps formed by sealing an incandescing conductor hermetically in a
glass enclosing globe, there may be danger sometimes that the glass and wire will
separate at the point where the conducting wires pass through and are sealed into
the glass globe. This is due to the fact that the conducting wires near the
incandescing material become very hot by conduction, and that the co-efficient of
expansion of the glass and wire are so different. In the lamp made on the plan
herein aforementioned, owing to the high resistance of the incandescing material,
such small conductors are used that the danger referred to has been of minor or
the very least importance. It may be desirable, however, to provide means which
reduce the danger to a minimum, while affording at the same time the necessary
support for the very small and delicate conductors and incandescing material. One
part of this Invention has for its object the provision of such means, which is done
as follows:-A small glass bulb is blown of a little larger diameter than the
distance apart of the ends of the carbon. Through this globe are passed and sealed
therein the conductors leading to the carbon, each conductor being sealed therefore
in two places, one contiguous to the clamps for receiving and supporting the carbon,
the other seal being almost diametrically opposite. The carbon and clamps being
placed in position, this small globe is placed in an aperture left for the purpose in

page_text: the larger enclosing globe, and sealed thereto at about the meridian line of the
smaller bulb. The larger bulb is provided with a tube by which it is attached to
the air exhausting apparatus, and where it is sealed after the vacuum is produced.
Connected to this tube is a branch tube leading from the smaller bulb, so that both
are simultaneously exhausted. This is shown in detail in Fig. 37, in which A is the
glass enclosing globe formed with the tube a for attachment to the exhausting
apparatus. A small bulb B is made attached to the supporting neck C, and formed
with a tube b. Through the bulb B the conductors 1, 2, are passed and sealed
therein, 1 being sealed at c, c', and 2 at e, e'. The bulb B is then sealed into A at
the lines, 2, and the tube b connected to the tube a, the bulb B practically forming
the seal to A. The tube a is then connected to the exhaust apparatus. It is
evident that a vacuum is created in both A and B. When a proper degree of
exhaustion is reached the tube b is sealed off at y, after which the tube a is sealed
off at x, x.
The vacuum in globe A is thus protected by two sealings of each wire
c, e, and c¹, e¹, to only one set of which is there any danger, c¹, e¹, the other set, c, e,
from its distanco from the heated portion of the lamp, never heating sufficiently to
be affected. As very small conductors are used it is necessarry for stability that
they be supported near the carbon, which is done at the sealings c¹, e¹; but if either
of these from their proximity to the light is ever so heated as to crack, it will still
subserve its functions as a support while the vacuum is preserved by the seals c, e,
more distant from the clamps. Sometimes it may be desirable to make a lamp in
which a less permanent seal is used, involving-a-less-expensivo_method_of_sealing,
and-which-may-be-taken-apart-readily_for_the_substitution of a carbon or for other
purposes. This may be done as follows:-Upon a tube closed at one end is sup-
ported the carbon, the conductors therefrom passing through the tube and being
Bealed hermetically in the top thereof. The enclosing globe is made with a neck
somewhat larger than the tube, so that the carbon may be passed therethrough.
A rubber packing is interposed between the outer walls of the tube and inner walls
of the neck, securing the two together, the ends of the tube projecting beyond the
end of the neck. This projecting portion of the tube passes through the base of a
rubber cup, the base of the neck resting upon the bottom of the interior of the cup.
At the top of the cup a rubber packing fills the space between the exterior of the
neck and the interior of the cup. The space in the cup is filled with mercury,
which is retained in place in the cup by the packing last referred to, forming with
the rubber a good seal for any temporary uses. Fig. 38 shows a lamp embodying
this portion of the Invention. A is the enclosing globe made with a long neck A¹,
through which may be passed the carbon B attached to clamps b, b, connected to
conductors 1, 2, which are sealed in the top of a tube C at c, c, the tube C being
somewhat smaller than the neck A. Around the base of C is a soft rubber plug D,
which fits into the lower part of the neck A, forming a tight joint between the
two, supporting C and the carbon in position in A' and A; F is a socket or cup
through the bottom of which by a tight joint passes the end of C, the end of D
resting in the cup. At the top of the cup a washer E of soft rubber fills tightly
the space between A¹ and the inner wall of the cup F, the space in the cup being
filled with mercury H or other suitable liquid. The lamp so put together is
exhausted, and then sealed at u in the usual manner, the combination of the cup F,
plugs or washers D and E, and the mercury H forming a reliable seal.
Having thus described the Invention, what is claimed is hereby declared to be as
follows:-
First. An incandescing conductor formed of one or more carbonized natural fibers,
substantially as set forth.
Second. A carbon clamp for uniting the incandescing and the metallic conductors
formed of a carbonizable material, substantially as set forth.
Third. The method of uniting the incandescing and the metallic conductors,
which consists in inserting both in clamps made of carbonizable material, and then
carbonizing the whole together, substantially as set forth.
Fourth. The slip for carbonization having enlarged ends formed in one piece,

page_text: and homogeneous therewith upon one edge, or one side and one edge, the
remaining edge and side being straight, substantially as set forth.
Fifth. The method of forming a slip or filament for carbonization, consisting in
securing a blank in clamps or holders, having the configuration desired for the
carbon, and shaving or cutting away the superfluous material, substantially as set
forth.
Sixth. A slip or filament for forming on carbonization the incandescing conductor
of an electric light made of bast or fiber, like cane and bamboo, substantially as
set forth.
Seventh. A slip or filament for forming by carbonization the incandescing
conductor of an electric light made of a material composed of fibres laying parallel
through the length of the slip or filament, substantially as set forth.
Eighth. A slip or filament for carbonization provided with slots or holes in its
enlarged ends for holding it in the carbonizer and for passage of the clamping screws
when placed in a lamp, substantially as set forth.
Ninth. The combination of the shaving knife, the block C, and means for moving
it, and the adjustable limiting screw, substantially as set forth.
Tenth. The clamp formed of two portions, one being provided with off-sets or
shoulders forming the bottom of slots acting as straight edges or gages to the slip
under treatment, substantially as set forth.
Eleventh. The clamp provided with slotted projections at the ends for forming
the broadened or thickened ends of the slip and the slots therein, substantially as
set forth.
Twelfth. The method of forming carbons for electric lamps, which consist in
forming the wood into the shape desired for the carbon, and then carbonizing the
same, substantially as described.
Thirteenth. The method of forming carbons for electric lamps, which consists in
cutting or stamping from a veneer a piece of wood with thickened or broadened
ends and of the shape desired, and then carbonizing the same, substantially as
described.
Fourteenth. The horse-shoe with thickened or broadened ends for attachment to
the clamps formed or cut from one piece of wood, substantially as set forth.
Fifteenth. The method of forming carbons for electric lamps, which consists in
shaping a block of wood as described, then cutting, splitting, or shaving into
straight pieces adapted for single carbons, then bending such pieces into the desired
form, and carbonizing in such form, substantially as described.
Sixteenth. The block for the manufacture of carbons for electric lamps, consisting
of the central web and thickened or broadened ends, substantially as set forth.
Seventeenth. The method of forming carbons for the incandescing conductors of
electric lights, consisting in first cutting or turning a block of wood into the shape
of an oval having a broadened portion, then carbonizing, and then removing a
portion of the broadened part, substantially as described.
Eighteenth. A carbon horse-shoe composed of a filamentary body with broadened
ends turned from one piece of wood, and then carbonized, substantially as
described.
Nineteenth. The method of manufacturing carbons for incandescent electric
lamps, uniform and regular in shape and carbonization, consisting in carbonizing
filaments while one or both ends are secured in a certain definite position relatively
to the amount of contraction, so that when carbonized and contracted the ends
shall be in proper position to each other, substantially as set forth.
Twentieth. The method of manufacturing carbons for incandescent electric lamps,
consisting in maintaining the slips or filaments under constant strain, and with
one or both ends fixed while in process of carbonization, substantially as set forth.
Twenty first. The method of manufacturing carbons for incandescent electric
lamps, consisting in carbonizing the slips or filaments while in grooves, which
maintain the shape and provide for contraction during carbonization, substantially
as set forth.

page_text: Twenty second. The carbonizing plate provided with a groove for shaping the
material, and a chamber or chambers permitting contraction during carbonization,
substantially as set forth.
Twenty third. A carbonizing flask and the plates thereof made of nickel, substan-
tially as set forth.
Twenty fourth. The carbonizing flask or box provided with grooves for the
reception of the fiber, substantially as set forth.
Twenty fifth. The carbonizing oven consisting of a case and a system of gas and
air supply pipes combined, substantially as described and for the purposes set
forth.
Twenty sixth. The combination of a case or cover therefor provided with an
inspection aperture and cover, means for supplying gaseous fuel to the interior of
the case, and means for mingling air under pressure with the fuel, substantially as
set forth.
"
Twenty seventh. The combination with one derived circuit of a multiple are
system of two or more lamps, each of a fractional resistance and radiating surface
of the resistance and radiating surface of the standard lamp of the system, the
fraction being the number used, substantially as set forth.
Twenty eighth. The combination with one socket or holder and one derived
circuit-of-one-circuit_controller, and two or more lamps each of a fractional
resistance and radiating surface of a standard lamp, substantially as set forth.
Twenty ninth. The combination with the incandescing conductor of an electric.
lamp, of two fluid columns-sustained by atmospheric pressure, and forming both a
part of the circuit and a hermetical seal to the lamp, substantially_as_set_forth.
Thirtieth. The combination with the incandescing_conductor and the fluid
columns of reservoirs connected to the source of electricity, and into which-the-
columns dip for the maintenance of the columns and the completion of the circuit
therethrough, substantially as set forth.
Thirty first. The combination with an electric lamp of the stand or support
therefor, consisting of an insulating base and top connected by adjustable standards,
substantially as set forth.
Thirty second. The combination with a globe or chamber of a much larger
chamber or reservoir connected to air exhausting apparatus, which maintains
therein a high degree of exhaustion, substantially as set forth.
Thirty third. The combination of a proving chamber or globe, a mercury
reservoir for sealing the saine, and exhaust reservoir or chamber, and means for
exhausting the same, substantially as set forth.
Thirty fourth. The combination of a globe or chamber, a second and much larger
globe, chamber, or reservoir, a valved tube connecting them, means for maintaining
a high degree of exhaustion in the larger reservoir or chat iber and connected
thereto, and a gage for determining the degree of exhaustion, substantially as set
forth.
Thirty fifth. The combination with the globe or chamber of a proving lamp, of a
mercury reservoir connected to the globe or chamber, so that the stopper thereof
may at will be covered or not covered by mercury, substantially as set forth.
Thirty sixth. The method of testing carbons, consisting in subjecting them to the
action of a current in a temporarily exhausted globe or receiver prior to their
embodyment in completed lamps, substantially as set forth.
Thirty seventh. The combination in one electric lamp of two or more incan-
descing conductors, and means for connecting them in the electric circuit, either in
series or multiple arc, substantially as set forth.
Thirty eighth. The combination in one electric lamp of two or more incandescing
conductors, and means for making or breaking an electric circuit through either one
as may be desired, substantially as set forth.
Thirty ninth. The combination in one electric lamp of two or more incandescing
conductors, and means for completing the circuit through either, or through both,
substantially as set forth.

page_text: Fortieth. The combination of contact points 1, 2, 3, 4, anvils x, 8, ≈, and circuit
connections, substantially as set forth.
Forty first. In an electric lamp, the combination with the enclosing globe or
chamber of a second chamber through and into which the conducting wires pass
and are sealed, both chambers being hermetically sealed together and exhausted,
substantially as set forth.
Forty second. The method of sealing the enclosing globe or chamber of an electric
lamp by sealing an auxiliary or secondary globe or chamber in the opening of the
first or enclosing globe, substantially as set forth.
Forty third. The method of preserving the vacuum in the enclosing globe of an
electric lamp, consisting in sealing the conducting wires at two points in a vacuum
globe hermetically sealed to the enclosing globe, substantially as set forth.
Forty fourth. The combination with the neck of the enclosing globe and the
carbon supporting tube of a cup containing a liquid receiving the end of the neck
of the enclosing globe, and through which passes the carbon supporting tube, and
washers or plugs filling the space between the neck and cup and the neck and tube,
substantially as set forth.
In witness whereof, I, the said Edward Griffith Brewer, have hereunto set
my hand and scal, this Fourteenth day of March, in the year of our
Lord One thousand eight hundred and eighty one.