IMPROVEMENTS IN ELECTRIC LAMPS AND IN THE METHOD OF MANUFACTURING THE SAME
Year: 1880

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME WE THE EDISON
ELECTRIC LIGHT COMPANY of London LIMITED send greeting WHEREAS Her
most Excellent Majesty Queen Victoria by Her Royal Letters Patent under the Great
Seal of Great Britain and Ireland bearing date at Westminster the Tenth day of
February in the year of our Lord One thousand eight hundred and eighty in
the forty-third year of Her reign did for Herself Her heirs and successors give and
grant unto Thomas Alva Edison of Menlo Park in the State of New Jersey United
States of America his executors administrators and assigns especial licence full
power sole privilege and authority that he the said Thomas Alva Edison his
executors administrators or assigns and every of them by himself and themselves
or by his and their deputy and deputies servants or agents or such others as he
his executors administrators or assigns should at any time agree with and no others
from time to time and at all times thereafter during the term therein expressed
should and lawfully might make use exercise and vend within the United
Kingdom of Great Britain and Ireland the Channel Islands and the Isle of Man
an Invention of "IMPROVEMENTS IN ELECTRIC LAMPS AND IN THE METHOD OF
MANUFACTURING THE SAME for and during the term of fourteen years thence
next ensuing And whereas in pursuance and performance of a proviso in the said
Letters Patent contained the said Thomas Alva Edison did within six calendar
months next after the date of the said Letters Patent cause a Specification
in writing under his hand and seal purporting to particularly describe the nature
of the said Invention and in what manner the same was to be performed to
be duly filed in the Great Seal Patent Office And whereas by indenture bearing
date the Sixth day of April One thousand eight hundred and eighty two and
made between the said Thomas Alva Edison of the first part Edward Griffith
Brewer of the second part Peter Jensen of the third part Anthony I
I
Drixel
Pierpoint Morgan Egisto Paolo Fabbri and I Hood Wright of the fourth part
Egisto Paolo Fabbri and Grosvenor Porter Lowry of the fifth part and the Edison
Price 4d1

page_text: ก
Electric Light Company of the sixth part The said Thomas Alva Edison as beneficial
owner with the concurrence and by the direction of the said parties thereto of the
fourth and fifth parts as beneficial owners granted and assigned and the said parties
thereto of the fourth and fifth parts as beneficial owners assigned and confirmed.
unto the said company their successors and assigns absolutely the said hereinbefore
recited Letters Patent and the full and exclusive benefit and advantages thereof
And whereas since the date of the said assignment we have been advised that the
subject matter of claims 3 and 4 is of doubtful novelty and we are also advised
that claims 5, 6, 8, 10, 11, 12, 13, 16, and 17 are either for matters which are already
claimed by other claims in the said Specification or are for matters which are not of
sufficient importance to render it desirable to retain them in the said Specification.
NOW KNOW YE that we the said Edison Electric Light Company Limited by
and with the leave of Her Majesty's Solicitor General for the reasons afore-
said do alter and amend the said Specification in manner following that is to say:
. We strike out of the Specification printed by the Queen's Printers and published
at the Great Seal Patent Office in One thousand eight hundred and eighty that
"If a definite area
portion of the said Specification commencing with the words
in line 35 of the same
in line 5 of page 5 and ending with the word "necessary
page, also we strike out the portion of the said Specification commencing with the
words and figures "Figures 6, 7," in line 5 of page 7 and ending with the word
"obstacles" in line 37 of page 7 also we strike out the portion of the said Specifi-
cation commencing with the words "the maximum light" on page 8 line 18, and
ending with the letters and word "v and y" on page 8 line 20, also we strike out
the whole of the third fourth fifth sixth eighth tenth eleventh twelfth thirteenth
fifteenth sixteenth and seventeenth claiming clauses at pages 8 and 9 of the said
Specification also we strike out the word "seventh" in line 49 of page 8 and
substitute therefor the word "third" also we strike out the word "ninth " in
line 54 of page 8 and substitute therefor the word "fourth," also we strike out
the word "fourteenth" in line 12 of page 9 and substitute therefor the word
"fifth"
And in order that the effect of the Disclaimer and Memorandum of
Alteration as aforesaid may be clearly understood we annex hereto a copy of the
said Specification as it will appear when so altered and amended the preamble and
testing clause being omitted.
وو
For an electric lamp I prefer to use an incandescent conductor of high resistance
hermetically sealed in a glass chamber.
Great difficulty has always been experienced in so sealing a glass vacuum globe
or chamber that a complete union of the parts was had and danger of opening or
separation avoided.
In all vacuum sealing of which I am cognizant there has never been a complete
union of the parts where the parts were attempted to be joined in vacuo. There
might be a union forming a tight joint lasting an indefinite time under ordinary
conditions, yet critical examination always revealed a line shewing incomplete
juncture when under the influence of heat or conditions present in an electric lamp
an opening would occur.
One part of my Invention therefore relates to a method of manufacturing lamps
so that a stable vacuum may be maintained therein.-In manufacturing my lamps
a glass bulb is formed with a long small tube extending therefrom by which the
bulb is to be attached to the air pump, and it is preferably curved so that several
may be attached to one pump. Upon the opposite side from the tube is formed a
supporting neck of a size sufficient to permit the introduction through it into the
body of the bulb of the carbon arc. A piece of tubing is formed into a round head
at one end smaller than the neck referred to for receiving the supporting and
conducting wires of the arc. The tube a little below this head is made as large as
the neck. A part of the head where the platinum wires pass may be formed of
white Enamel Glass having a greater conductivity for heat than the main part of
the vessel, or it may be of plain glass.-The glass through which the platinum

page_text: wires pass is melted and sealed around them by fusion, the Glass extending some
little distance above the general surface of the head around the wires or vice versa
on the outside of the bulb.
The platinum wires are joined to copper or alluminium wires which pass out
through the lower or open end of the tube.
Clamps for holding the incandescent conductor are secured to the upper ends of
the platinum wires and the incandescent conductors secured therein. The head is
then passed into the neck until the lower edge of the neck and the enlargement of
the tube below the head meet and the two are there joined together by fusion. The
lamp is now ready for exhaustion and for this purpose it is attached by the tube
aforesaid to an air pump. After the proper degree of vacuum has been reached the
tube is closed by fusion at the point of juncture with the pump and the lamp
removed from the pump. The tube is then sealed by fusion at or near the plane
of the bulb; there is now the same degree of vacuum upon each side of the last
seal. The vacuum in the tube is now destroyed and the tube again sealed just
above the seal at or near the plane of the bulb. The vacuum in the bulb is now
protected by two sealings, one in vacuo and one in air. I find that this double
sealing makes a complete and perfect union of the parts, so that a stable vacuum
may be maintained.
In manufacturing these lamps I use within the vacuum chamber only such
material as when subjected to influences within the chamber consequent upon the
light do not affect the light. For instance, iron or steel under the influence of
heat in a vacuum vaporize to a slight extent and form carburet of iron while
platinum in its ordinary state always contains some air. I therefore use platinum
or metals of that group prepared and treated by heat in vacuum as heretofore
announced by me or else aluminium for the supporting clamps and for all metallic
parts within the vacuum chamber. As a necessary part of any practical system of
electric lighting for domestic uses it is essential that the electric lamp should be
simple in construction and complete within itself, requiring no skill in placing in
position or in manipulating it.
To provide for this an insulating ring is secured upon the lower end of the neck
of the lamp and upon the opposite side of this ring are placed two contact springs
one of the conductors leading from the incandescent conductor being secured to
each. A cup shaped holder is made of insulating material ornamented as desired,
the bottom being fashioned, so as to be secured in any suitable support, such as a
bracket or chandelier,-On the interior of the cup which is of a size to receive
the neck of the lamp, are two metallic plates, opposite to but insulated from each
other. To one is fastened a conductor leading directly or indirectly from the
source of electricity and upon the exterior of the holder is a metallic nut to which
the other main conductor leads. A screw passes through this nut and may be
made to impinge against the other metallic piece so as to electrically connect the
nut and plate The main conductors may pass to the holder through ordinary
gas or other tubing and through the bracket or chandelier arm or in any other
suitable way.
From this description it is evident that a lamp holder may be so made that the
lamp may be placed in position in or removed from the holder without any skill
or manipulation of binding posts or fastening devices and that the current for
lighting is turned off or on by simply turning the screw that presses upon one of
the plates. It is evident that the portion of the neck of the lamp entering the
socket may be round or square or many sided and provided with a feather lugs
or spliner the holder being correspondingly hollowed out. It is also evident that
the neck and holder may be made of such relative size that the neck shall slide
upon and over instead of within the holder. In a prior application for Letters
Patent I have stated how fibrous material capable of carbonization may be coiled
in a spiral in order that a large resistance may be had with comparatively small
radiating surface. I have also shown how an incandescent conductor of small
radiating surface with large resistance may be made of paper properly carbonized

page_text: I have since discovered that an incandescent conductor of very high resistance in
comparison to the radiating surface may be made of such natural fibres as are
capable of carbonization. I prefer to use the single fibre of bleached manilla
hemp although any of the fibres which are large round and filamentary instead of
cellular may be used as hereafter set forth. In using these fibres I wind the ends
with tissue paper and then carbonize them the tissue paper wrapping forming an
enlarged end which gives a good bearing for the supporting clamps.
Figures 1, 2, 3, 4 and 5 illustrate the method of manufacturing my improved
lamp showing the steps therein successively.
A piece of tubing the size of c is taken on which is blown or otherwise formed
the bulb 6 whose upper portion is drawn out into the tube h curved so that several
bulbs may be attached to one air exhausting pump The part c is left unchanged
in order to form a supporting neck for the lamp in forming this from tubing
however the lower end is often drawn out as shown in Figure 1. this small end is
removed on the line x. x leaving the globe neck and tube as shown in Figure 2
f is a piece of glass tubing of a size somewhat less than c upon its upper end is
formed the bulb d and the two seals p p for the wires Below d the enlargement e
is formed in the tube fits exterior diameter being the same or nearly so as that
of c
Platinum wires ww joined to conductors 1, 2, are passed through openings
in the projections p p which projections are then fused by heat around the wires ww
so as to seal the wires hermetically in the glass said seals extending around the
wires above the general surface of the bulb & Clamps h¹¹ are attached to the
wires and the incandescent conductor fastened in the clamps. It is to be here
remarked that the clamps or wires within the globe must be of some material not
so affected by any influences existing within the globe when the proper vacuum
has been attained as to interfere with the light or its proper dissemination
If iron be used it is so acted on that it is gradually destroyed with an ensuing
deposit on the glass obscuring the transparency of the globe and also acting on the
carbon uniting with it and finally destroying it. In order to prevent this and to
guard against any injurious influences whatever the clamps h¹ h¹ and wires within
the globe should be of platinum or some metal or metals of the platinum group
treated by the vacuum and heating process described by me in a prior application
for a Letters Patent. The arc a and bulb d are inserted in the neck c until the
end of the neck c rests against the enlargement e when the two are securely
and hermetically joined by fusion of the glass at that point. The tube c is large
enough to allow the carbon arc which is slightly flexible to pass through it. The
lamp is attached by the tube to an exhaust pump of any suitable character and
after the proper degree of exhaustion has been reached the tube h is sealed by
fusion of the glass at i and removed from the pump and a second seal is made in
the tube immediately above the globe b This last sealing is made entirely
in vacuo and the degree of vacuum in 6 and in h between land i is the same.
I have found however that a perfect and durable seal cannot be made when all the
portions of the glass which unite to form the seal are in a vacuum when the seal is
made hence the seal i at the end of the tube h The tube h is now sealed by fusion
at m or it may be broken off at m and a drop of molten glass placed therein and the
parts melted to form the seal The seal Figure 5 is therefore the result of two
sealings at in vacuo and at m in air.
I have found that such a seal is lasting under all conditions and that by the
method here indicated a globe is so constructed and sealed that a vacuum perfectly
stable is maintained therein. The wires and 2 for attachment to devices for
completing the circuit pass out of the end of the tube f and in order to prevent
their accidental crossing or displacement a plug n of cork plaster of Paris or other
insulating material is put in the end off securing the wires therein.
An incandescent conductor of very high resistance in proportion to its radiating
surface may be made of any natural fibre capable of carbonization especially such
as are large and filamentary instead of cellular. A preferable one for this purpose
is a single fibre of bleached manilla hemp A fibre is taken its ends wound with

page_text: tissue paper and then carbonised the carbonization uniting the fibre and paper
wrapping the latter forming an enlarged end which gives a good bearing for the
supporting clamps. Figures 12 and 13 show my lamp manufactured as herein-
before described with additions and modifications rendering it a separate and
complete article adapted. for attachment to a suitable support Upon the lower
end of the part c is secured a cylinder of any suitable insulating material
provided on opposite sides with metallic springs or contact pieces 13 and 14 From
the clamps h¹¹ which hold and support the incandescent arc a the conductors 1, 2
lead to the contact pieces 13 and 14 adapted to complete the electrial circuit when
the lamp is placed in position in the holder here-after described.
This construction forms a separate electric lamp which may readily be removed
from or placed. upon or within a suitable holder the act of placing the lamp in
position completing without adjustment or attention the necessary connection of
the circuit to the light giving portions is a socket or holder for receiving the
lamp It is made of suitable insulating material shaped and ornamented as may
be desired receiving and supporting the neck of the electric lamp and fashioned at
one end so as to be fastened into a gas fixture or other suitable support as shown.
The cylindrical cup or socket for the lamp is at the top and a screw threaded™
aperture in the base allows the holder to be attached to a standard a bracket or a
chandelier armt Upon the interior are the metallic plates u v insulated from
each other Upon the exterior of the holder, is a metallic nuts in which works the
metallic screw y A conductor 5 leads to the plate u and a conductor 6 to the
nut 8 upon turning the screw y electric connection between the plate v and nut 8.
is either completed or broken dependent upon the direction of turning. The con-
ductors 56 lead directly or indirectly from the source of electricity and may be
placed inside of gas or other suitable pipes or tubing as shown in Figure 12 or
they may be brought to the lamp in any convenient manner. From this it may
be seen that if the lamp be placed in the socket r as shown in Figure 12 one
spring 13 bears against and forms electrical contact with one plate say u while
the other spring 14 bears against and forms electrical contact with the other
plate v.
If the screw y be turned so as to impinge firmly on plate va complete circuit is
formed via wire plate a spring 13 wire 2 incandescent arc d wire 1 spring 14
plate v screw y nuts and wire G.
From the description it is evident that the lamp is an article complete in itself
capable of being placed in position for use without any attention or adjustment
While I have shown contact springs upon the cylinder q or the neck of the lamp
and contact plates upon the interior of the socket or holder it is evident that the
relation could be reversed the plates being placed on the neck of the lamps and the
springs in the socket without departing from the spirit of my Invention or
requiring any further Invention It is also evident that the lamp can be 80
constructed that the neck will embrace the holder instead of being placed therein.
What I claim as my Invention is :-
First. The method of forming electric lamps consisting in separately forming the
enclosing globe and the supporting bulb for the incandescent conductor attaching
the wires and incandescent conductor thereto and then herinetically uniting the
parts prior to the formation of the vacuum substantially as set forth.
Second. The method of hermetically sealing a vitrified vacuum chamber which
consists of first sealing in vacuo and then sealing in the air substantially as
described.
Third. An incandescent conductor formed of a single carbonized fibre sub-
stantially as described.
Fourth A separate electric lamp adapted to be readily removed from or placed
or replaced upon or within a suitable holder substantially as herein described.
Fifth A socket or holder for electric lamps consisting of an insulating cylinder
formed to receive and support the lamp and provided with two contact plates and

page_text: a circuit controlling device for controlling the circuit to one of the contact plates
substantially as herein set forth.
Limited
In witness whereof The Edison Electric Light Company▲ of Lendon have
caused their Common Seal to be hereunto affixed the Second day of June
One thousand eight hundred and eighty two.
Notice of the application for leave to file this Disclaimer and Memorandum of
Alteration having been advertized in accordance with my directions :-
--
I hereby grant my Fiat giving leave to the above named Edison Electric Light 1
Company Limited (the assignees and now legal and equitable owners of the above
recited Letters Patent) to file in the Great Seal Patent Office with the Specification
to which the same relates the above written Disclaimer and Memorandum of
Alteration.

page_text: LETTERS PATENT to Thomas Alva Edison, of Menlo Park, in the State of New
Jersey, United States of America, for an Invention of "IMPROVEMENT IN
ELECTRIC LAMPS, AND IN THE METHOD OF MANUFACTURING THE SAME.'
"
PROVISIONAL SPECIFICATION left by the said Thomas Alva Edison at the
Office of the Commissioners of Patents on the 10th February 1880.
THOMAS ALVA EDISON, of Menlo Park, in the State of New Jersey, United
States of America. "IMPROVEMENT IN ELECTRIC LAMPS, AND IN THE METHOD
OF MANUFACTURING THE SAME.
"
For an electric lamp I prefer to use an incandescing conductor of high resistance
hermetically sealed in a glass chamber.
Great difficulty has always been experienced in so sealing a glass vacuum globe
or chamber that a complete union of parts was had, and danger of opening or
separation avoided. In all vacuum sealing of which I am cognizant there has
never been a complete union of the parts where the parts joined were attempted to
be joined in vacuo. There might be a union forming a tight joint lasting some
indefinite time under ordinary conditions, yet critical examination would always
reveal a line showing incomplete juncture, where, under the influence of heat or
conditions present in an electric lamp, an opening would occur.
One part of my
Invention therefore relates to a method of manufacturing electric lamps so that a
stable vacuum may be maintained therein.
In manufacturing my lamps a glass bulb is formed with a long but small tube
extending therefrom, by which the bulb is to be attached to the air pumps, and it
is preferably curved so that several may be attached to one pump.
Upon the opposite side from the tube is formed a supporting neck of a size
sufficient to permit the introduction through it into the body of the bulb of the
carbon arc.
A piece of small tubing is formed with a round head at one end, smaller than the
neck referred to, for receiving the supporting and conducting wires of the arc. The
tube, a little below this bead, is enlarged to the size of the neck.
Upon the head a part of the glass where the platinum wires pass is formed of
white enamel glass having a greater conducticity for heat than the main part of the
vessel. The enamel glass through which the platinum wires pass is then melted and
CD 01

page_text: sealed around them by fusion, the glass extending some little distance above the
general plane of the head around the glass, or vice versa. On the outside of the
bulb the platinum wires are joined to copper or aluminium wires which pass out
through the lower or open end of the tube. Clamps for holding the incandescent
conductor are secured to the upper ends of the platinum wires, and the incandescent
conductor secured therein. The head is then passed into the neck until the lower
edge of the neck and the enlargement of the tube below the head meet, when the
two are there joined together by fusion.
The lamp is now ready for exhaustion, and for this purpose it is attached by the
tube referred to to an air pump. When the proper degree of vacuum has been
reached the tube is closed by fusion at the point of juncture with the pump, and
the lamp removed from the pump. The tube is then sealed by fusion at or near
the plane of the bulb. There is now the same degree of vacuum upon each side of
this last seal that is in the bulb and in the tube between the two seals made.
The vacuum in the tube is now destroyed, and the tube again sealed just above
the seal at or near the plane of the bulb; the vacuum in the bulb is now protected
by two sealings, the one in vacuo and one in air. I find that this double sealing
makes a complete and perfect union of the parts, so that a stable vacuum may be
maintained.
In manufacturing these lamps I use within the vacuum chamber only such
materials as when subjected to influences within the chamber consequent upon the
light do not injuriously effect the light. For instance, iron or steel under the
influence of heat vaporize to a slight extent, and platinum in its ordinary state
always contains some air or gas. I therefore use platinum or metals of that group
prepared and treated by a process hitherto announced by me, or aluminium may
be used for the supporting clamps and for the metallic parts within the vacuum
chamber.
If a definite area of radiating surface be raised to a definite temperature a
definite amount of light is the result, a definite electro motive force, or as I have
termed it, "pressure of current is required, and the conductors or mains are
proportioned to all these conditions.
"
I have discovered that if the resistance of the light giving medium be increased,
its radiating surface remaining the same, the same amount of light will be produced,
but the conductors may be diminished in size proportionally to the increase of
resistance, much less proportionate increase of pressure of current however being
required.
For example, let all the lamps in circuit have incandescent conductors of 100
ohms. resistance each, and 1000 pounds of copper conductor be used in the main
conductors, and 100 volts. be required to keep the lights up. If now the radiating
surface of each lamp be unchanged, but the resistance of each be raised to 200
ohms., 500 pounds of copper conductor will answer for main conductors, and 140
volts. will be required to keep the lights up to the same point, hence by doubling
the resistance of the lamp one half of the prime cost of the conductors will be saved,
the amount of energy expended remaining the same, about 3000 foot pounds being
required to maintain the light in either case, which is entirely independent of the
resistance.
Another part of my Invention therefore relates to utilizing this discovery by so
adjusting the radiating surface resistance and pressure relatively to each other
that great economy in conductors may result. In one form I increase the resistance,
the resistance in the light, by taking a filament of carbon long enough to give twice
the ordinary resistance, and double it upon itself, keeping the two surfaces
electrically apart. In this case the contiguous sides radiate little if any light, each
obscuring the other, but I obtain the increased resistance necessary to enable me to
use small conductors.
A number of arcs may be connected together as a series in one lamp, in which
event an increase of resistance (equal to number used) and of radiating surface

page_text: would be secured with a proportionate decrease in the amount of conductor
necessary.
As a necessary part of any practical system of electric lighting for domestic uses
it appears to be essential that an electric lamp should be simple in construction and
complete within itself, requiring no skill in placing in position or in manipulation.
To provide for this upon the lower end of the lamp, as described under the first
head, an insulating ring is secured, upon the opposite sides of which are placed two
contact springs, one of the conductors leading from the incandescent conductor
being secured to each.
A holder is made by hollowing out a piece of insulating material shaped or
ornamented, as desired, the bottom being fashioned so as to be secured in any
suitable support, say, a bracket or chandelier arm. On the interior of the hollow
(which is of a size to receive the neck of the lamp) are two metallic pieces insulated
from each other; to one is fastened a conductor leading directly or indirectly from
the source of electricity, opposite the other piece, and upon the exterior of the
holder is a metallic nut, to which the other main conductor leads. A screw passes
through this nut, and may be made to impinge against the interior plate so as to
electrically connect the nut and plate. The main conductors may pass to the
holder through ordinary gas or other tubing, and through the bracket or chandelier
arms, or in any other suitable way.
From this description it is evident that a lamp holder may be so made that the
lamp may be placed in position in or removed from the holder without any skill or
manipulation of binding posts or fastening devices, and that the current for
lighting is turned off or on by simply turning the screw connecting one plate and
the nut.
It is evident that the portion of the neck of the lamp entering the socket may
be round or square, or many sided, or provided with a feather, lugs, or splines, the
holder being correspondingly hollowed out.
It is also evident that the neck and holder may be made of such relative size
that the neck shall slide upon and over instead of within the holder.
In an
In a prior application, filed by me on the 10th November 1879, I have stated how
fibrous material capable of carbonization may be coiled in a spiral in order that a
large resistance may be had with comparatively small radiating surface.
application, filed by me on the 15th December 1879, I have shown how an
incandescent conductor of small radiating surface with large resistance may be
made of paper properly carbonized.
I have since discovered that an incandescent conductor of very high resistance
in comparison to the radiating surface may be made of such natural vegetable
fibres as are capable of carbonization. I prefer to use the fibre of bleached manilla
hemp, although any vegetable fibres which are large, round, and filamentary, instead
of cellular may be used. In using these fibres I wind the ends with tissue paper
and then carbonize them, the tissue paper wrapping forming an enlarged end,
which gives a good bearing for the supporting clamps.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Alva Edison in the Great Seal Patent Office on the 10th
August 1880.
THOMAS ALVA EDISON, of Menlo Park, in the State of New Jersey, United
States of America. "IMPROVEMENT IN ELECTRIC LAMPS, AND IN THE METHOD
OF MANUFACTURING THE SAME."
For an electric lamp I prefer to use an incandescent conductor of high resistance
hermetically sealed in a glass chamber.
Great difficulty has always been experienced in so sealing a glass vacuum globe
or chamber that a complete union of the parts was had, and danger of opening or
separation avoided.
In all vacuum sealing of which I am cognizant there has never been a complete
union of the parts where the parts were attempted to be joined in vacuo.
There
might be a union forming a tight joint lasting an indefinite time under ordinary
conditions, yet critical examination always revealed a line shewing incomplete
juncture, when under the influence of heat or conditions present in an electric lamp
an opening would occur.
One part of my Invention therefore relates to a method of manufacturing lamps
so that a stable vacuum may be maintained therein. In manufacturing my lamps
a glass bulb is formed with a long small tube extending therefrom by which the
bulb is to be attached to the air pump, and it is preferably curved so that several
may be attached to one pump. Upon the opposite side from the tube is formed a
supporting neck of a size sufficient to permit the introduction through it into the
body of the bulb of the carbon arc. A piece of tubing is formed into a round
head at one end, smaller than the neck referred to, for receiving the supporting and
conducting wires of the arc. The tube a little below this head is made as large as
the neck. A part of the head where the platinum wires pass may be formed of
white enamel glass having a greater conductivity for heat than the main part of
the vessel, or it may be of plain glass. The glass through which the platinum wires
pass is melted and sealed around them by fusion, the glass extending some little
distance above the general surface of the head around the wires, or vice versa, on
the outside of the bulb.
The platinum wires are joined to copper or alluminium wires which pass out
through the lower or open end of the tube.
Clamps for holding the incandescent conductor are secured to the upper ends of
the platinum wires, and the incandescent conductors secured therein. The head is
then passed into the neck until the lower edge of the neck and the enlargement of
the tube below the head meet, and the two are there joined together by fusion.
The lamp is now ready for exhaustion, and for this purpose it is attached by the
tube aforesaid to an air pump. After the proper degree of vacuum has been
reached the tube is closed by fusion at the point of juncture with the pump, and
the lamp removed from the pump. The tube is then sealed by fusion at or near
the plane of the bulb; there is now the same degree of vacuum upon each side of
the last seal. The vacuum in the tube is now destroyed, and the tube again sealed
just above the seal at or near the plane of the bulb. The vacuum in the bulb is
now protected by two sealings, one in vacuo and one in air. I find that this
double sealing makes a complete and perfect union of the parts, so that a stable
vacuum may be maintained.
In manufacturing these lamps I use within the vacuum chamber only such
material as when subjected to influences within the chamber consequent upon the
light do not affect the light. For instance, iron or steel under the influence of
heat in a vacuum vaporize to a slight extent and form carburet of iron, while

page_text: platinum in its ordinary state always contains some air. I therefore use platinum
or metals of that group prepared and treated by heat in vacuum, as heretofore
announced by me, or else aluminium for the supporting clamps and for all metallic
parts within the vacuum chamber.
If a definite area of radiating surface be raised to a definite temperature a
definite amount of light is the result, a definite electro motive force of electricity,
or, as I have termed it, "pressure" of current being required therefor, the conductors
or mains being proportioned to all these conditions.
I have discovered that if the resistance of the light giving body be increased, its
radiating surface remaining the same, the same amount of light will be produced,
but the conductors may be diminished in size proportionally to the increase of
resistance, much less proportionate increase of pressure of current however being
required. For example, if all the lamps in circuit have incandescent conductors of
one hundred ohms. resistance, each then one thousand pounds of copper conductor
should be used in the main conductors, and one hundred volts. will be required to
maintain the lights. If now the radiating surface of each lamp be unchanged, but
the resistance of each be raised to two hundred ohms., five hundred pounds of
copper conductor will answer for main conductors, one hundred and forty volts.
however being required to keep the lights up to the same point, so that by doubling
the resistance the prime cost of one half the conductors is saved, the amount of
energy expended remaining the same, about three thousand foot pounds being
required to maintain the light in either case, which is entirely independent of the
resistance.
"
Another part of my Invention therefore relates to utilizing this discovery by 90
adjusting the radiating surfaces, resistances, and pressure relatively to each other
that great economy in conductors may be obtained. In one form I increase the
resistance by taking a filament of carbon long enough to give twice the ordinary
resistance, and double it upon itself, keeping the two surfaces electrically apart.
In this case the contiguous sides radiate but little light, as each obscures the other,
but I obtain the increased resistance necessary to enable me to use the smaller
conductors.
A number of arcs may be connected together as a series in one lamp, in which
event there is an increase of resistance equal to the number used, and radiating
surfaces are secured with a proportionate decrease in the amount of conductor
necessary. As a necessary part of any practical system of electric lighting for
domestic uses it is essential that the electric lamp should be simple in construction,
and complete within itself, requiring no skill in placing in position or in manipu-
lating it.
To provide for this an insulating ring is secured upon the lower end of the neck
of the lamp, and upon the opposite side of this ring are placed two contact springs,
one of the conductors leading from the incandescent conductor being secured to
each. A cup shaped holder is made of insulating material, ornamented as desired,
the bottom being fashioned so as to be secured in any suitable support, such as a
bracket or chandelier. On the interior of the cup, which is of a size to receive the
neck of the lamp, are two metallic plates opposite to but insulated from each other.
To one is fastened a conductor leading directly or indirectly from the source of
electricity, and upon the exterior of the holder is a metallic nut, to which the other
main conductor leads. A screw passes through this nut, and may be made to
impinge against the other metallic piece, so as to electrically connect the nut and
plate. The main conductors may pass to the holder through ordinary gas or
other tubing, and through the bracket or chandelier arm, or in any other suitable
way.
From this description it is evident that a lamp holder may be so made that the
lamp may be placed in position in or removed from the holder without any skill
or manipulation of binding posts or fastening devices, and that the current for
lighting is turned off or on by simply turning the screw that presses upon one of
the plates. It is evident that the portion of the neck of the lamp entering the

page_text: socket may be round, or square, or many sided, and provided with a feather, lugs,
or spliner, the holder being correspondingly hollowed out. It is also evident that
the neck and holder may be made of such relative size that the neck shall slide
upon and over instead of within the holder. In a prior application for Letters
Patent I have stated how fibrous material capable of carbonization may be coiled
in a spiral in order that a large resistance may be had with comparatively small
radiating surface. I have also shown how an incandescent conductor of small
radiating surface with large resistance may be made of paper properly carbonized.
I have since discovered that an incandescent conductor of very high resistance in
comparison to the radiating surface may be made of such natural fibers as are
capable of carbonization. I prefer to use the single fiber of bleached manilla
hemp, although any of the fibers which are large, round, and filamentary instead of
cellular may be used, as hereafter set forth. In using these fibers I wind the ends
with tissue paper and then carbonize them, the tissue paper wrapping forming an
enlarged end, which gives a good bearing for the supporting clamps.
Figs. 1, 2, 3, 4, & 5 illustrate the method of manufacturing my improved lamp,
showing the steps therein successively.
A piece of tubing the size of c is taken, on which is blown or otherwise formed
the bulb b, whose upper portion is drawn out into the tube h curved so that several
bulbs may be attached to one air exhausting pump. The part c is left unchanged
in order to form a supporting neck for the lamp; in forming this from tubing
however the lower end is often drawn out as shown in Fig. 1; this small end is
removed on the line x, x, leaving the globe neck and tube as shown in Fig. 2;
f is a piece of glass tubing of a size somewhat less than c; upon its upper end is
formed the bulb d and the two seals p, p, for the wires. Below d the enlargement e
is formed in the tube f, its exterior diameter being the same or nearly so as that
of c.
Platinum wires w, w, joined to conductors 1, 2, are passed through openings
in the projections p, p, which projections are then fused by heat around the wires
w, w, so as to seal the wires hermetically in the glass, said seals extending around
the wires above the general surface of the bulb d. Clamps h', h³, are attached to
the wires, and the incandescent conductor fastened in the clamps. It is to be here
remarked that the clamps or wires within the globe must be of some material not
so affected by any influences existing within the globe when the proper vacuum
has been attained as to interfere with the light or its proper dissemination. If
iron be used it is so acted on that it is gradually destroyed with an ensuing deposit
on the glass obscuring the transparency of the globe, and also acting on the carbon,
uniting with it, and finally destroying it. In order to prevent this, and to guard
against any injurious influences whatever, the clamps ¹, h¹, and wires within the
globe should be of platinum or some metal or metals of the platinum group, treated
by the vacuum and heating process described by me in a prior application for a
Letters Patent. The arc a and bulb d are inserted in the neck c until the end x, x,
of the neck crests against the enlargement e, when the two are securely and
hermetically joined by fusion of the glass at that point. The tube c is large enough
to allow the carbon arc, which is slightly flexible, to pass through it. The lamp is
attached by the tube h to an exhaust pump of any suitable character, and after the
proper degree of exhaustion has been reached the tube h is sealed by fusion of the
glass at i and removed from the pump, and a second seal is.made in the tube /
immediately above the globe b. This last sealing is made entirely in vacuo, and
the degree of vacuum in band in h between 1 and i is the same. I have found
however that a perfect and durable seal cannot be made when all the portions of
the glass which unite to form the seal are in a vacuum when the seal is made,
hence the seal i at the end of the tube h. The tube h is now sealed by
fusion at m, or it may be broken off at m and a drop of molten glass placed therein,
and the parts melted to form the seal. The seal l, Fig. 5, is therefore the result of
two sealings, at in vacuo, and at m in air.
I have found that such a seal is lasting under all conditions, and that by the
method here indicated a globe is so constructed and sealed that a vacuum perfectly

page_text: stable is maintained therein. The wires 1 & 2 for attachment to devices for com-
pleting the circuit pass out of the end of the tube f, and in order to prevent their
accidental crossing or displacement a plug n of cork, plaster of Paris, or other
insulating material is put in the end off securing the wires therein.
Figs. 6, 7, 8, 9, 10, and 11 show modifications in which the resistance of the
incandescent are is increased. In Fig. 6 b is the enclosing globe. Several incan-
descent conductors a, each of the standard resistance, are united at their ends in a
series by conducting clamps k, the terminal ends of the series connecting to
clamps h¹, h', to which are attached the wires w, w. The series are supported
upon d in circular form by wires or other supports 3, 3. In this case the current
entering by 1 traverses one carbon and passes by clamp k to the next, and so on
through the series to conductor 2. Five of these carbons are shown in Figs. 6 and 7.
As each incandescent portion a is of standard resistance, and gives a standard light,
the object of this arrangement is to group a number of such lights, and to light a
much larger area than one light would, at the same time the total resistance of the
lamp being proportionately increased the size of the conductors or street mains is
proportionately lessened, there being consequently great economy in the laying
thereof, and the number of street lamps required being lessened it is practicable to
light thinly settled highways and streets.
In Figs. 9, 10, and 11, a strip a of carbonized material is employed of standard
resistance for a given length, but of twice the ordinary length, and the same is
doubled upon itself. At the point of bending back an insulating block o is intro-
duced, so that the folded carbonized strip is kept apart. To the free ends are
attached the clamps h¹, h¹, and conductors w, w. Each inner contiguous surface is
partially hidden by the other, so that the outer surface is the portion that radiates
light, and this is to be equal to the total surface of an ordinary or undoubled carbon;
but the increase of length has doubled the resistance, hence there is a double
resistance with little change in the radiating surface. This double resistance
however enables a smaller conductor to be used, the amount of metal in this
instance being diminished one half. This ability to diminish the amount of metal
in conductors is of great importance, as in many instances, notably in thinly
settled localities, it may determine the practicability of a system of electric lighting,
It also enables localities far distant from a central station or source of electric
energy to be supplied with electric energy for purposes of light and power when
under ordinary conditions, or under conditions which have usually existed, the
first cost of conductors and the cost of maintenance would prove insurmountable
obstacles.
An incandescent conductor of very high resistance in proportion to its radiating
surface may be made of any natural fiber capable of carbonization, especially such
as are large and filamentary instead of cellular. A preferable one for this purpose
is a single fiber of bleached manilla hemp. A fiber is taken, its ends wound with
tissue paper and then carbonized, the carbonization uniting the fiber and paper
wrapping, the latter forming an enlarged end, which gives a good bearing for the
supporting clamps. Figs. 12 and 13 show my lamp manufactured as herein before
described with additions and modifications, rendering it a separate and complete
article adapted for attachment to a suitable support. Upon the lower end of the
part c is secured a cylinder q of any suitable insulating material, provided on
opposite sides with metallic springs or contact pieces 13, 14. From the clamps
h, h, which hold and support the incandescent arc a, the conductors 1, 2, lead to
the contact pieces 13, 14, adapted to complete the electrical circuit when the lamp
is placed in position in the holder hereafter described.
This construction forms a separate electric lamp, which may readily be removed
from or placed upon or within a suitable holder, the act of placing the lamp in
position completing without adjustment or attention the necessary connection of
the circuit to the light giving portions. r is a socket or holder for receiving the
the lamp. It is made of suitable insulating material, shaped and ornamented as
may be desired, receiving and supporting the neck of the electric lamp, and

page_text: fashioned at one end so as to be fastened onto a gas fixture or other suitable
support, as shown. The cylindrical cup or socket for the lamp is at the top, and
a screw threaded aperture in the base allows the holder to be attached to a
standard, a bracket, or a chandelier arm t. Upon the interior are the metallic
plates u, v, insulated from each other. Upon the exterior of the holder is a metallic
nut 8 in which works the metallic screw y. A conductor 5 leads to the plate u,
and a conductor 6 to the nut 8; upon turning the screw y electric connection
between the plate v and nut s is either completed or broken dependent upon the
direction of turning. The conductors 5, 6, lead directly or indirectly from the
source of electricity, and may be placed inside of gas or other suitable pipes or
tubing, as shown in Fig. 12, or they may be brought to the lamp in any convenient
manner. From this it may be seen that if the lamp be placed in the socket r, as
shown in Fig. 12, one spring 13 bears against and forms electrical contact with one
plate, say u, while the other spring 14 bears against and forms electrical contact
with the other plate v.
If the screw y be turned so as to impinge firmly on plate va complete circuit is
formed via wire 5, plate u, spring 13, wire 2, incandescent arc a, wire 1,
spring 14, plate v, screw y, nut 8, and wire 6, the maximum light, a dim light, or
no light, being due respectively to a fine contact, a slight contact, or no contact
between and y.
From the description it is evident that the lamp is an article complete in itself,
capable of being placed in position for use without any attention or adjustment.
While I have shown contact springs upon the cylinder q or the neck of the lamp,
and contact plates upon the interior of the socket or holder, it is evident that the
relation could be reversed, the plates being placed on the neck of the lamps, and
the springs in the socket without departing from the spirit of my Invention,
or requiring any further Invention. It is also evident that the lamp can be so
constructed that the neck will embrace the holder instead of being placed therein.
What I claim as my Invention is,-
First. The method of forming electric lamps, consisting in separately forming the
enclosing globe and the supporting bulb for the incandescent conductor, attaching
the wires and incandescent conductor thereto, and then hermetically uniting the
parts prior to the formation of the vacuum, substantially as set forth.
Second. The method of hermetically sealing a vitrified vacuum chamber, which
consists of first sealing in vacuo and then sealing in the air, substantially as
described.
Third. The clamps and wires made of platinum or metals of the platinum group
or conductors of electricity not affected by influences within the lamp, substantially
as described.
Fourth. In a system of generation, distribution, and translation of electricity for
purposes of light, the method of diminishing the amount of metal required in a
given length of main conductors by increasing the resistance of the lamps,
substantially as described.
Fifth. An incandescent conductor formed of several separate conductors joined
together, substantially as set forth.
Sixth. An incandescent conductor formed of a long strip doubled upon itself, so
as to increase the resistance and maintain a given radiating surface, substantially
as set forth.
Seventh. An incandescent conductor formed of a single carbonized fiber,
substantially as described.
Eighth. An incandescent conductor having a body formed of a single fiber with
enlarged ends made of paper wrapped upon the ends of the fiber and carbonized,
substantially as set forth.'
Ninth. A separate electric lamp adapted to be readily removed from, or placed,
or replaced upon or within a suitable holder, substantially as herein described.
Tenth. The combination of a separate removable electric lamp and a suitable
holder, substantially as herein described.

page_text: Eleventh. The combination of a separate removable lamp, a suitable holder, and
electric conductors, which complete the circuit when desired to said lamp, but are
not attached thereto, substantially as herein described.
Twelfth. An electric lamp consisting of a glass globe, substantially of one piece
of glass, hermetically sealed, and enclosing in a vacuum material capable of being
rendered incandescent by an electric current, and provided at its base with contact
pieces, substantially as herein described.
Thirteenth. The combination in an electric lamp of a glass globe enclosing in a
vacuum material capable of being rendered incandescent by an electric current, an
insulated base, spring contacts, and conductors therefrom to the incandescent.
material, substantially as herein described.
Fourteenth. A socket or holder for electric lamps consisting of an insulating
cylinder formed to receive and support the lamp, and provided with two contact
plates and a circuit controling device for controling the circuit to one of the contact
plates, substantially as herein set forth.
Fifteenth. The combination with a bracket or chandelier arm of a socket or
holder adapted to receive and support an electric lamp, substantially as herein set
forth.
Sixteenth. The combination of a holder, bracket, or chandelier arm with a socket
or holder adapted to be received thereon, and to receive and support an electric
lamp and conductors passing through the arm to contact plates in the holder,
substantially as herein set forth.
Seventeenth. The combination with a socket or holder provided with suitable
contact plates of a lamp provided with corresponding contact springs upon its
exterior, substantially as herein set forth.
In witness whereof, I, the said Thomas Alva Edison, have hereunto set my
hand and seal, this 29 day of June, A.D. 1880.
Witnesses,
S. L. GRIFFIN,
FRANK MCLAUGHLIN.
THOMAS ALVA EDISON. (LS.)