IMPROVEMENTS IN OBTAINING ELECTRIC LIGHT, AND IN THE APPARATUS TO BE EMPLOYED THEREFOR."
Year: 1881

page_text: LETTERS PATENT to Tom Ernest Gatehouse, of Camberwell, in the County
of Surrey, Electrician, for an Invention of "IMPROVEMENTS IN OBTAINING
ELECTRIC LIGHT, AND IN THE APPARATUS TO BE EMPLOYED THEREFOR."
"
PROVISIONAL SPECIFICATION left by the said Tom Ernest Gatehouse at
the Office of the Commissioners of Patents on the 25th July 1881.
TOM ERNEST GATEHOUSE, of Camberwell, in the County of Surrey, Electrician.
IMPROVEMENTS IN OBTAINING ELECTRIC LIGHT, AND IN THE APPARATUS TO BE
EMPLOYED THEREFOR."
This Invention relates to a method of electric lighting by the incandescence of
suitable material, and the regulation of the light giving substance by simple and
novel means; also to the increasing the durability of the incandescent material.
It is well known that the electrical resistance of metallic wires is increased by
the application of heat, and on the other hand that a rod of carbon or graphite
conducts better when hot.
When a wire, as for instance platinum, is used alone for the purpose of producing
an incandescent electric light, there is considerable risk of fusion upon any increase.
of current passing through. Regulators have been proposed to prevent this fusion,
but without any practical success. I propose to take advantage of the foregoing
and opposite properties of carbon and such like material and metallic wires, such as
platinum, iridium, and other suitable metals or alloys, to produce an incandescent
light, the carbon or like material acting as a regulator to the incandescent wire.
According to one arrangement I use the light giving material in conjunction or
combination with the carbon or such body in a parallel circuit, the two materials
having their lengths and sections properly proportioned, and therefor also their
respective resistances. The carbon rod may be moveable and adjustable, or both
materials may be so.
When a current of suitable strength is passed through the materials the greater
portion flows through the wire, rendering it incandescent and producing light.

page_text: A certain quantity however passes through the carbon, raising its temperature in
a slight degree. Now any increase of current will take effect on both inaterials,
but while the greater heating of the wire renders it more difficult for the current
to pass, the carbon rod on the other hand will by becoming warmer allow more
current to pass through than before, thus taking away the excess of current in a
greater proportion than does the wire, and keeping the latter from fusion. I also
for greater safety automatically adjust the length of carbon rod according to
the current strength by a sliding contact actuated by a solenoid or electro magnet
in the circuit.
According to a modified arrangement I use a light giving material, such as
carbon, platinum, iridium, and other suitable metals or alloys, and prevent its
fusion upon increase of current by automatically adjusting the length of such
material in proportion to the current strength by a sliding contact actuated as
above. The light producing substance may be in vacuo or not, according to the
material employed.
In connection with these arrangements an artificial resistance may be employed
in such a manner that if a lamp should break down or be extinguished the
remaining ones in the circuit shall not be affected. Individual or single lights
may be arranged on the system above described, or a number of lamps may be
regulated in a body in like manner. I further propose, with a view to increasing
the durability of the incandescent material in vacuo, such as a carbon filament or
metallic wire, to employ in combination or conjunction with the incandescent
material any metal or substance which has a greater affinity for oxygen than the
light giving material.
According to one mode of carrying out this part of my Invention I may use, for
example, a carbon filament in vacuo, with the contact terminals of this filament
bound with soft iron wire or other suitable metal or material, so that when the
carbon filament is rendered incandescent the soft iron wire also becomes heated in
a similar manner, and is then acted upon by any oxygen that may be inside or
leak through into the lamp, leaving the carbon filament comparatively unacted
upon. With the same object of preventing the carbon being acted upon by oxygen,
and also to maintain a perfect vacuum, I propose to employ a readily fusible
material for forming the joint or connection of the wires with the globe of the
lamp, and I so arrange the carbon filament that when incandescent it shall fuse
the said material in immediate contact therewith, and thus maintain and perfect
the air tight joint. I improve the construction of this class of lamp by suspending
an inner globe containing the light inside an outer globe by means of flexible
conductors.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Tom Ernest Gatehouse in the Great Seal Patent Office on the
25th January 1882.
"
TOM ERNEST GATEHOUSE, of Camberwell, in the County of Surrey, Electrician.
'IMPROVEMENTS IN OBTAINING ELECTRIC LIGHT, AND IN APPARATUS TO BE
EMPLOYED THEREFOR."
This Invention relates to a method of electric lighting by the incandescence of
suitable material, and the regulation of the light giving substance by simple
and novel means; also to the increasing the durability of the incandescent
material.
It is well known that the electrical resistance of metallic wires is increased by
the application of heat, and on the other hand that a rod of carbon or graphite
conducts better when hot.
When a wire, as for instance platinum, is used alone for the purpose of pro-
ducing an incandescent electric light, there is considerable risk of fusion upon any
increase of current passing through. Regulators have been proposed to prevent
this fusion, but without any practical success. I propose to take advantage of the
foregoing and opposite properties of carbon and such like material, and metallic
wires, such as platinum, iridium, and other suitable metals or alloys, to produce au
incandescent light, the carbon or like material acting as a regulator to the incan-
descent wire.
According to one arrangement I use the light-giving material in conjunction
or combination with the carbon or such body in a parallel circuit, the two materials
having their lengths and sections properly proportioned, and therefore also their
respective resistances. The carbon rod may be moveable and adjustable, or both
materials may be so.
When a current of suitable strength is passed through the materials, the greater
portion flows through the wire, rendering it incandescent and producing light.
A certain quantity however passes through the carbon, raising its temperature
in a slight degree. Now any increase of current will take effect on both materials,
but while the greater heating of the wire renders it more difficult for the current
to pass, the carbon rod, on the other hand, will by becoming warmer allow more
current to pass through than before, thus taking away the excess of current in a
greater proportion than does the wire and keeping the latter from fusion. I also
for greater safety automatically adjust the length of carbon rod according to the
current strength by a sliding contact actuated by a solenoid or electro-magnet in
the circuit.
In connection with these arrangements an artificial resistance may be employed
in such a manner that if a lamp should break down or be extinguished the
remaining ones in the circuit shall not be affected. Individual or single lights
may be arranged on the system above described, or a number of lamps may be
regulated in a body in like manner. I further propose, with a view to increasing
the durability of the incandescent material in vacuo, such as a carbon filament or
metallic wire, to employ in combination or conjunction with the incandescent
material any metal or substance which has a greater affinity for oxygen than the
light-giving material.
According to one mode of carrying out this part of my Invention I may use,
for example, a carbon filament in vacuo, with the contact terminals of this filament
bound with soft iron wire or other suitable metal or material, so that when the
carbon filament is rendered incandescent the soft iron wire also becomes heated

page_text: in a similar manner, and is then acted upon by any oxygen that may be inside
or leak through into the lamp, leaving the carbon filament comparatively unacted
upon. With the same object of preventing the carbon being acted upon by oxygen,
and also to maintain a perfect vacuum, I propose to employ a readily fusible
material for forming the joint or connection of the wires with the globe of the
lamp, and I so arrange the carbon filament that when incandescent it shall fuse
the said material in immediate contact therewith, and thus maintain and perfect
the air tight joint. I improve the construction of this class of lamps by suspending
an inner globe containing the light inside an outer globe by means of flexible
connectors.
And in order that my Invention may be the better understood, I now proceed to
describe the Drawings hereunto annexed, reference being had to the figures and
letters marked thereon.
Figure I shows a diagrammatic view of one of the simplest forms of my improved
arrangement. The platinum wire P is used as an incandescent light giving material,
in conjunction with the carbon C, in parallel or alternative circuits, having their
sections and lengths, and therefore their normal resistances properly proportioned.
I arrange in combination with the above the sliding contact spring S, movable
upon a metal bar B in such a manner as to shorten or increase the length of the
carbon in the circuit between the wires W and W1, the current at the same tine
passing through the platinum P.
Any increase of current will take effect then on both the platinum and the
carbon, but whilst on the one hand the greater heating of the wire increases its
resistance to the current, on the other hand the heating of the carbon causes it to
offer less resistance to the current and more electricity to pass through it than
before. The action of the current on the carbon is thus of a repeating or
reduplicating character, any excess of current serving to remove resistance by
heating, and thus to admit the passage of a further increase of current by that
very heating. It is obvious that by this arrangement the platinum or other
metallic wire may be heated to within a few degrees of its fusing point and yet be
safe under a great access of current, as the larger proportion will pass through the
carbon, almost entirely relieving the wire of any excess, as the resistance of the
latter is increased.
Without this carbon shunt a small excess of current would fuse the wire. I
propose to take advantage of these electrical properties of carbon and metals to
regulate any electric lamp_or_to_control_an_electro-magnetic-machine,-and-for-
electric lighting purposes generally.
Figure 2 shows my arrangement of both the metallic wire P and the carbon C,
enclosed in an exhausted glass globe G, and both used as incandescent lights. The
globe is hermetically sealed, and the wires W, W₁, are introduced in a special
manner. The wires W, W₁, are passed through the glass tube T which has a
pinched together neck and a turned over lip, as shewn in detail in Figure 3, so as
securely to hold the wires. The tube T is passed through a stopper or cork & of
conical shape, and is introduced into the neck of the globe, which is provided with
a special circular bulge g. Above the end of the cork and filling the bulging neck
of the globe is placed a quantity of an easily melted lump or powdered
composition F of similar carbonaceous character to that known as Chatterton's,
which is composed of a mixture of tar, resin, and gutta-percha. At the last stage
of exhaustion of the air, I apply heat to the neck of the globe and also make the
filament incandescent and melt the compound which runs into and fills up all the
pores in the stopper & and the interior of the tube T. The lip of the tube T and
the bulge g in the neck of the globe both serve to prevent the atmospheric pressure
from forcing either the tube or the composition into the globe. When the filaments
become incandescent, the composition at the top and in immediate vicinity to the
wires becomes slightly solvent, and thus tends to keep the joint good. The
composition is also slightly volatilized and the carbon vapour is precipitated upon
the incandescent filament, thus feeding the filaments and preserving them from

page_text: diminution. The joints at J are made with fine soft iron wire, or other material
having a greater affinity for oxygen or other gases likely to be present than either
the carbon or platinum; as part of this iron wire at J is also incandescent, it is first
acted upon by any gas accidentally present in the globe, and the filaments are
thus preserved. I apply this improved form of joint and the use of a readily
oxidisable material as above described to any kind of electric lamp whether with
one incandescent filament or more.
Figure 4 represents a lamp in which the carbon filament C is alone placed inside
a crescent shaped exhausted globe G, the platinum or other metallic incandescent
filament P being placed outside. I attach the two filaments together and support
thein in a metal holder M with clips H. The wire P is held by the spring
clips N, N, which open and release the wire when pressed together at the lower
part, or a taper screw clip may be used for the same purpose. W, W¹, are the
main wires.
Figure 5 shows a front elevation and Figure 6 a section of another form of
lamp, in which the platinum or other wire P connected to the main wires
W, W, is alone rendered incandescent. These wires are supported on the
insulating slab V, and are inside a globe G, which is almost air-tight, but not
exhausted. The carbon resistance C, Fig. 6, is arranged inside the top of the
standard A, and the adjustable contact brush S slides in a groove B, and so raises
and lowers the light in P. The action of the carbon and travel of the current is
the same as in Figure 1.
Figure 7, Sheet II. is a modification of Figure 5, the sliding arrangement
differing only in being operated by the rotation of a tap.
Figure 8 shows by a diagram the introduction of a resistance R into one of my
improved lamps, so that when the light is put out by the movement of the spring S,
the resistance R, equal to the former resistance of the lamp, is automatically
introduced by the springs into the circuit.
Figure 9 shows the incandescent wire P contained in a separate exhausted
globe supported on the flexible wires E within a second outer globe G. The
carbon resistance C is contained in the base, and is automatically adjusted as to its
length in the circuit by the solenoid M and the sliding contact rollers S. These
rollers are attached to the iron core I, which is drawn in and out of the coil by the
fluctuations of the main current through the solenoid and the reaction of the
spiral spring. Any increase of the main current from W shortens the length of
the carbon C, and the increase of temperature of the carbon also reduces its
resistance. A very sensitive automatic regulator of the current through the
wire P is thus provided.
Figure 10 shows the application of my carbon alternative circuit or shunt to the
regulation of a number of lamps, arranged either in series or in a parallel circuit.
The solenoid coil M and carbon rod C are arranged and operate as described in
Figure 9, but effect the regulation of the current through a series of lamps, and
prevents damage to the lamps by any unusual or sudden excess of electrical
current through the main circuit.
And having now fully described the nature and object of my Invention, be it
known that what I consider novel and useful, and desire to protect by my Letters
Patent is,
1st. The combination in electric light lamps or apparatus of a material, the
electrical resistance of which decreases by heating with a metal filament, the
electrical resistance of which increases by heating, in parallel or alternative circuits,
for purposes of control or regulation, substantially as described.
2. In electric light lamps the combination with the above claimed parallel
circuits of a sliding contact S on the carbon shunt C to regulate its length, and at
the same time the degree of light from the lanp, as shewn and described in
reference to Figures 1, 5, 6, & 7.
3. In electric light lamps the combination with Claim 1 of a solenoid M or
electro-magnet, to automatically regulate the carbon C in one lamp or in a series

page_text: of lamps according to the strength of current, as shewn and described in reference
to Figures 9 & 10.
4. In electric light lamps the combination with Claim 1 of a resistance R for the
purpose herein before described and shown in reference to Figure 8.
5. In incandescent electric lamps the combination with the light giving filaments
of a material J, also rendered incandescent, which shall have a priority of com-
bination (when incandescent) with any gases present, destructible to the luminous
filaments.
6. In electric light lamps with exhausted globes, the construction of the air
tight joint with an elastic, carbonaceous, fusible, volatilisable material F, as and
for the purposes shewn and described in reference to Figures 2 & 3.
7. The construction and general arrangement of the lamps, shewn and described
in reference to Figures 4, 5, 6, 7, and 9, consisting of a parallel circuit (claimed in
No. 1) in combination with alternative subsidiary apparatus.
In witness whereof, I, the said Tom Ernest Gatehouse, have hereunto set
my hand and seal, this Twenty fourth day of January, in the year of
our Lord One thousand eight hundred and eighty two.
In the presence of
S. P. WILDING,
23, Rood Lane,
London, E.Ç.,
Patent Agent.
TOM ERNEST GATEHOUSE. (L.S.)