IMPROVEMENTS IN ELECTRIC LAMPS AND IN CIRCUITS FOR THE SAME
Year: 1881

page_text: LETTERS PATENT to Peter Jensen, of 33, Chancery Lane, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN ELECTRIC LAMPS AND IN
CIRCUITS FOR 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 Peter Jensen at the Office
of the Commissioners of Patents on the 24th February 1881.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex.
"IMPROVE-
MENTS IN ELECTRIC LAMPS AND IN CIRCUITS FOR THE SAME." (A communication
from abroad by Thomas Alva Edison, of Menlo Park, in the State of New Jersey,
United States of America).
It is now well known that in said Edison's system of electric lighting lamps are
used consisting of an exhausted glass globe, in which is hermetically sealed to
conducting wires passing through the glass a carbon filament which is heated to
incandescence by the electric current.
In said system a lamp is adopted as a standard, that is, one having a definite
area of radiating surface and a definite resistance, so that with a current of a
definite electro-motive force or "pressure "the standard candle power of light
shall be given by a definite amount of energy for each lamp; all the lamps used
in the system being made to approximate the conditions of the standard an
approximately uniform result is obtained.
In such a system each lamp is placed in its own separate derived or multiple arc
circuit; and experience has shown that a lamp giving a light equal to about a 16
candle power gas jet is the best adapted to average general use.
It is desirable however sometimes to connect in one multiple arc or derived
circuit a series of lamps, each giving the same amount of light as the standard lamp
of the system, say, 16 or 18 candle power, so that all the lamps in the circuit, say, a
chandelier circuit, could be controlled by one circuit closer.
The object of this Invention is to furnish a method and means for accomplishing
this result

page_text: To this end it consists, generally speaking, in making the density of the carbons
where a series of lamps are to be used proportionately greater than that of the
standard lamp, their conductivity increasing and resistance decreasing propor-
tionately, so that with the standard amount of energy and the standard amount of
electro-motive force or pressure, each lamp of such series shall give the standard
amount of light; the radiating surfaces of each remaining approximately at the
area of radiating surface of the standard lamp.
The proportions in which the density or conductivity must be increased and the
resistance diminished, when it is desired to connect a series of lamps in one
multiple arc or derived circuit of a system, may be expressed approximately by a
fraction whose numerator is one and whose denominator is the square of the
number desired to be so connected.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Jensen in the Great Seal Patent Office on the 24th
August 1881.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex: "IMPROVE-
MENTS IN ELECTRIC LAMPS, AND IN CIRCUITS FOR THE SAME." A communication
from abroad by Thomas Alva Edison, of Menlo Park, in the State of New Jersey,
United States of America.
ور
It is now well known that in said Edison's system of electric lighting lamps are
used consisting of an exhausted glass globe, in which is hermetically sealed to
conducting wires passing through the glass a carbon filament which is heated to
incandescence by the electric current. In said system a lamp is adopted as a
standard, that is, one having a definite area of radiating surface and a definite
resistance, so that with a current of a definite electro motive force or "pressure
the standard candle power of light shall be given by a definite amount of energy
for each lamp; all the lamps used in this system being made to approximate the
conditions of the standard an approximately uniform result is attained. In such a
system each lamp is placed in its own separate derived or multiple arc circuit, and
experience has shown that a lamp giving a light equal to about a sixteen candle
power gas jet is the best adapted to average general use. It is desirable however
sometimes to connect in one multiple arc or derived circuit a series of lamps, each
giving the same amount of light as the standard lamp of the system, say, sixteen or
eighteen candle power, so that all the lamps in such circuit, say, a chandelier
circuit, could be controlled by one circuit closer.
The object of this Invention is to furnish a method and means for accomplishing
this result. To this end it consists, generally speaking, in making the density of
the carbons where a series of lamps are to be used proportionately greater than
that of the standard lamp, their conductivity increasing and resistance decreasing
proportionately, so that with the standard amount of energy and the standard
amount of electro motive force or pressure each lamp of such series shall give the
standard amount of light, the radiating surfaces of each remaining approximately
at the area of the radiating surface of the standard lamp.
The proportions in which the density or conductivity must be increased and the
resistance diminished when it is desired to connect a series of lamps in one
multiple arc or derived circuit of a system may be expressed approximately by a
fraction whose numerator is one, and whose denominator is the square of the
number desired to be so connected. The drawing represents diagrammatically a
number of multiple arc circuits. 1, 2, are the main conductors; 3, 4, 5, and 6, are
multiple arc circuits. In 3 is shown one lamp A which would have the standard
conditions of the system. In 4, 5, and 6, two, three, and four lamps respectively
in series are shown. Applying the rule before stated the density of the carbons
in B, B', should be such that their resistance is one-fourth that of the standard A,
while the resistance of the three C, D, E, in circuit 5, and the four F, G, H, I, in
circuit 6 should be one ninth, and one sixteenth that of A respectively. By thus
changing this one condition of the standard of the system, radiating surface and
electro motive force remaining unchanged, it is possible to place in one multiple
arc a series of lamps, each giving the standard candle power of light, and all
capable of being controlled by one circuit closer, which is typified by 8, in each of
the multiple arc circuits, but which may be placed in any desired and convenient
position for operation. It is evident though, that when desired, a circuit controller
or key may be placed at each lamp, and arranged so that the operation of any one
shall control all the lamps in the circuit. From this it appears that the condition
to be changed is the density or mass of the incandescent conductor.

page_text: This may be effected in several ways, for instance, standard carbons may be
taken and carbon deposited therein from carbon vapours by heat, in the manner
well known from the researches and experiments of Berthollet upon the deposition
of carbon from carbides of hydrogen and other decomposible carbon compounds
until their density be so increased that their resistance is brought down to the
desired degree.
Carbons may be dipped in syrups or other carbonaceous material, and then
recarbonized; the process being repeated until the required density is attained;
and the number of dippings or soakings in a solution of a given strength, and
re-carbonizations to produce a definite result may be accurately determined, so
that this process may be carried on with great certainty. Where very dense
carbons of great electrical conductivity are required they may be made of graphitic
carbon, sometimes called plumbago, moulded under great pressure, or they may be
cut by a punch and die from a sheet of moulded graphite of proper thickness. It is
evident that the density or mass and resistance may be varied in many other ways,
any of which may be used in practicing this Invention. It is also evident that for
the result of increased conductivity for the purposes herein set forth an increase in
area of cross section is equivalent to increase of density, though the latter is
preferable unless the former can be practiced without materially affecting the area
of radiating surface.
The arrangement herein described is conducive also to economy, in that owing
to the greater mass or density per unit of incandescing surface of the carbons their
life is lengthened.
What is claimed is,―
First. The combination with one multiple arc or derived circuit of two or more
incandescent electric lamps arranged in series therein, the density and electrical
conductivity of the carbons of the lamps being increased proportionately, sub-
stantially as set forth.
Second. The method of arranging a series of incandescent lamps in a multiple
arc or derived circuit, consisting in increasing the density and electrical conductivity
of the individual carbons approximately in the proportion to the number to be
placed in the one circuit, substantially as set forth.
Third. The combination with one derived circuit of two or more lamps, each of a
fractional resistance of the resistance of the standard lamp, but with approximately
the same radiating surface, substantially as set forth.
Fourth. In a system of electric lighting the combination with a main circuit of
several multiple arc or derived circuits, some containing a standard lamp and some
containing a series of lamps, two, three, or more; the electrical conductivity and
density of the carbon in any one derived circuit in the latter instance increasing
as the number of lamps used in such circuit increases, substantially as set forth.
Fifth. The combination with one derived circuit and one circuit controller of
two or more lamps, each of a fractional resistance of the resistance of a standard
lamp, but with approximately the same radiating surface, substantially as set
forth.
Sixth. An incandescing conductor for electric lamps, made of compressed
graphitic carbon, substantially as set forth.
In witness whereof, I, the said Peter Jensen, have hereunto set my hand
and seal, this Twenty third day of August, in the year of our Lord
One thousand eight hundred and eighty one.