Electric Incandescent Lamp.
Year: 1899

page_text: Date of Application, 7th Dec., 1899-Accepted, 20th Jan.,
1900
Electric Incandescent Lamp.
I, CHRISTOPHER VAN DEVENTER, Electrical Engineer, of 626, Lexington
Avenue, Borough of Manhattan City, County and State of New York, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My invention relates to that class of electric lamps in which refractory non-
electric conductors cold, and electric conductors hot, like kaoline, magnesia, and
several other materials are employed as the principal source of light in the
lamp.
The general object of my invention is to produce a lamp of this character
adapted to fulfil by its cheapness of manufacture and convenience in operation,
all the requirements of a commercial and practical electric lamp. More parti-
cularly, the object is to dispense with the other forms of energy like heat from
gas for heating the light giving substance to the temperature of proper con-
ductivity and to heat the conductor effectually, by means of the electric current.
I am enabled to accomplish the results sought, by a simple combination con-
sisting in means adapted to impart all its heat, which is produced electrically,
to the refractory material, said means being for this purpose, an electric heater
embedded entirely within the mass of the substance. The form of electric.
heater which I have adopted thus far, consists of a coil of wire wound around
an ordinary clay pipe stem, or its equivalent, which may be any substance
adapted to withstand heat. The electric conductor of this heater serves not
only as a primary heater, for raising the temperature of the light giving sub-
stance which I call a finger, but it performs also, a secondary, but equally
important function, for it serves the purpose of one pole or terminal of the
invention. Any number of conductors lying at another portion of the inven-
tion, preferably upon the outside and in contact therewith, form the other ter-
minal of the finger, and consequently, after the finger is heated by the electric
heater, the current can be switched so as to pass through the heater, through
the finger, and through the terminals on the outside of the finger.
Drawings are annexed and described.
Figure 1, is a general elevation of the lamp on a small scale, shown applied
in use in one of the usual ways, by being suspended from the ceiling by a
flexible electric conductor.
Figure 2, is a diagram of the circuits from a given generator through the
lamp and switches, and back again to the generator, so that the complete opera-
tion of the lamp may be understood. The drawing in Figure 2, is made on a
much larger scale than that in Figure 1.
Figure 3. is an enlarged elevation of one of the important details of the con-
struction shown in mere outline in Figure 2.
a is a finger of magnesia or other substance which has the property of having

page_text: an enormously high resistance when at the natural temperature, and a compara-
tively low resistance being about the right resistance for an electric lamp,
when at a comparatively high temperature. I have shown it in the form of a
rod, and to easily identify it, I call it a finger, but it is evident that shape, in
this invention, has little to do with the principles or claims of the invention.
Located entirely within the finger is an electric heater consisting of a coil of
wire b, shown by a full zig zag line passing around the cylinder c, of refractory
material, and through the whole length of said cylinder, as shown by a line d,
made of dots and dashes. The refractory cylinder c, and conductors b, and d,
are so located, as to be completely surrounded by the material of the finger a,
so that when the electric heater is under operation, said finger will be quickly
raised to the proper temperature at which it becomes of a sufficiently low
resistance to conduct a comparatively low voltage current after being made
incandescent. It is unnecessary to specify the materials to be used in the
electric. heater, as this department of art is well known, but the wire b, and d,
should be made of such a resistance as to withstand the proper temperature
without fusion. The cylinder c, may be hollow or solid and may consist, for
example, of a section of an ordinary clay pipe stem, or it also may be made of
the same substance as the finger a. Again, my invention is broad enough to
permit the omission of the cylinder c, without departing from the spirit thereof,
as this element of the invention consists essentially of an electric heater located
in the interior of the finger a.
On the outside of the finger and on opposite sides thereof, there are located
several conductors e, extending preferably, throughout the whole length of the
finger a, and these conductors, only two being shown in the drawing for the
sake of illustration, are made of a material which will not fuse by heat, and if
the finger is outside of a vacuum, they should be made of incombustible material.
f, represents a glass globe or bulb, which may be evacuated or not, according
to the circumstances, but, as far as the invention is concerned, it is immaterial
as to what kind of, and how much gas surrounds the finger.
During the first part of the operation of the lamp, the electric heater only,
is in circuit, and when the temperature of the finger is sufficient, the current
is switched so as to pass over the electric heater, through the finger a, to the
outside and then through the filaments e.
In order to carry on this operation, I provide a row of insulated contacts 9, .h, i,
and . The contacts g, and i, are the terminals of the filaments e, and they are
separated by the insulated contact 7, which is merely an idle piece serving as
an insulator. j, is a similar piece between the contacts i, and k, which latter
is one of the terminals of the electric heater, namely, of the conductor d. The
terminal of the other conductor b. of the electric heater, connects permanently
with the dynamo 7, while the other pole of the dynamo is connected to the
switches m and n, which are respectively normally or at starting the device,
located in contact with the terminals k and h. The current can, therefore, go
from the pole 2, of the dynamo through the switch m, through the contact or
terminalk, through the conductor d, through the conductor b, and thence to
the pole q, of the same dynamo 7. In a second or two, the electric heater, by
means of the current which passes over the above outlined circuit.
raises the temperature of the finger a, to the proper increment. The next step
consists in turning the switches m and n, to the left so that two currents can
pass as follows:-The one from the pole p, to the switch m, to the contact i, to
the filament e, to the conductor b, and thence to the pole g: and the other current
passes from the pole p, to the switch n, to the terminal g, to the filament
or other conductor e, to the conductor b, and thence to the terminal q. These
two currents therefore, pass between the electric heater in the interior of the
finger a, and the filaments e, on the exterior thereof, and consequently, the
finger is no longer heated by conduction of heat, as when heated by the electric
heater, but is now heated directly by the current conducted through the finger,

page_text: and consequently, in view of the high efficiency of the finger in generating
ight by an electric current is made use of.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. An electric lamp consisting of the combination of a finger of refractory
material, a source of heat located in the interior of the finger, and conductors
and switches so arranged as to be adapted to conduct a current through the
material of said finger.
2. An electric lamp consisting of the combination of a mass of refractory
material, an electric heater located within the same, electric conductors in con-
tact with said mass and out of contact with said heater, and means for switching
the current from the heater so as to pass from said conductors through said
mass, to said heater.
3. An electric lamp consisting of the combination of a finger of refractory
material, electric conductors located respectively inside and outside of said
finger, and switches for conducting the current in a predetermined order and
direction through the conductors.
4. An electric lamp consisting of the combination of a finger of refractory
material, a refractory cylinder within the material, an electric conductor pass-
ing through the interior of the cylinder and helically around the exterior,
filaments upon and in contact with the outside of said finger, and an electric
switch adapted in one phase, to conduct a current through said conductor only,
and in another phase from said conductor to said filaments through the material
of said finger.
5. An electric lamp consisting of the combination of a finger of refractory
material, being a nonconductor cold, and a conductor hot, an electric conductor
embedded in said mass substantially throughout the length thereof and forming
a heating circuit from one end of the finger to the other and back again, con-
ductors on the exterior of the finger and in contact therewith throughout the
length, said electric conductors being located inside and outside so as to be
adapted to permit an electric current to flow from the interior to the exterior
of the finger.
.
.
Navamber 1899.