IMPROVE- MENTS IN OR RELATING TO ELECTRIC LIGHTS
Year: 1882

page_text: LETTERS PATENT to Thomas John Handford of 42 Southampton Buildings
in the County of Middlesex Patent Agent for an Invention of "IMPROVE-
MENTS IN OR RELATING TO ELECTRIC LIGHTS" Communicated to him 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 Thomas John Handford
at the Office of the Commissioners of Patents on the 19th August 1882.
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, Patent Agent, "IMPROVEMENTS IN OR RELATING TO ELECTRIC LIGHTS
a communication to me from abroad by Thomas Alva Edison of Menlo Park,
in the State of New Jersey United States of America,
»
The object of the present Invention is to produce simple and efficient means
for regulating the feed of the upper or positive carbons, of arc-lamps, more
especially designed and adapted for such lamps when arranged in separate multiple
arc circuits, and having the cross or multiple arc circuits completed only through
the electrodes of the lamp
These lamps are or may be run from the same conductors as incandescent
electric lamps, the regulating mechanism being constructed and arranged to
separate the carbon electrodes the proper distance to give the desired resistance
at the arc.
Two
With a multiple arc arrangement a constant electromotive force is maintained
in the main conductors or those from which the lamp circuits are taken.
opposing electro-magnets or solenoids may be used for the regulating mechanism
located one in a main conductor and the other in the cross or lamp circuit in
which case, the former acts simply as a constant force opposing the action of the
latter. This constant opposing force can be efficiently produced by a retracting
spring or weight.
Or a single electro-magnet or solenoid located in the lamp circuit and an
armature or core and retractor may be used to regulate an arc lamp arranged in
a multiple arc circuit by the employment of a gripping eye or similar device, but

page_text: it is preferred to use for the purpose two electro-magnets, or solenoids both located
in the lamp circuit, and acting together to regulate the feed of the upper or positive
carbon, and to raise it in establishing the arc.
The two electro-magnets, or solenoids are thus arranged in series with the carbon
electrodes, and they may either be in series, or have a multiple arc relation with
each other.
Electro-magnets are preferably used for the purpose, but solenoids may be
employed; the term electro-magnets when hereinafter used will be understood as
including solenoids as equivalent devices.
One electro-magnet operates a locking device, which locks and releases the
holding rod of the upper carbon electrode; the other electro-magnet works through
this locking device to raise the carbon electrode in establishing the arc and in
enlarging the distance between the electrodes if need be during the burning of
the lamp.
The armature lever of the locking electro-magnet, has a forked or notched arm
pivotted thereto, and pressed by the electro magnet against the carbon holding-
rod. The armature lever and the forked arm are drawn back by a retracting
spring which is nicely adjusted so that when the arc is normal the arm will press
against the holding-rod with just sufficient force to prevent the further descent
of the carbon, and when the arc increases a definite small extent the holding-rod
will be released and again instantly locked. The movement of this locking arın is
limited by a stop, and the retracting spring of the armature lever is provided with
means for permitting adjustment of its tension.
The other or lifting electro-magnet has an armature lever, retracted by an
adjustable spring, and carrying a sleeve, box, or loop, through which the forked
arm of the locking armature lever works.
The lifting electro-magnet is not so sensitive as the locking electro-magnet,
the retracting spring of its armature lever being adjusted to overcome the magnetic
attraction except when there is a marked increase in the current.
Both electro-magnets being in the cross or multiple arc circuit in which the
carbon electrodes are located, they will both be strongly energized when the
circuit to the lamp is first completed. The locking magnet acting first will force
the notched arm against the holding rod of the upper or positive carbon, when
the lifting magnet will raise the said arm, and the upper carbon establishing the
arc. As the arc increases the armature lever of the lifting magnet drops until it
rests on its back contact. The locking magnet then controls the further downward
feeding of the carbon. It being very sensitive and its action being exceedingly
quick, it will release and lock the carbon holding-rod with a short and rapid-
movement making a regular feed and preventing flicker in the light. In order
to prevent a too rapid descent of the carbon electrode a retarding device may
be employed, such as a ratchet wheel and reed, or pendulum, or other form of
escapement.
A circuit controller is placed in each arc lamp circuit, and also in the circuit
of each incandescing lamp operated from the same conductors, so that every lamp
in the system, whether arc, or incandescing, is independent of all others, and can
be lighted, and extinguished without affecting other lamps
The Invention has further for its object providing a safety device to be used
with arc lamps arranged in multiple arc circuits for preventing a dangerous flow
of current when the carbon electrodes touch each other,
The touching of the carbon electrodes would form a short circuit, and the
conductor would be heated by the abnormal flow of current, destroying insulation,
and setting fire to wood work with which such conductors may be in contact.
The other lamps would also be affected by this short circuit.
The means for preventing the formation of this short circuit consists of a
resistance, which is cut out of circuit when the arc is normal, but which is thrown
into series with the carbon electrodes by means of an electro-magnet when the
flow of current increases to a definite extent.

page_text: Another electro-magnet is provided to throw such resistance into series with the
carbon electrodes when the circuit is broken.
The resistance may be arranged in series with the carbon electrodes, and the
electro-magnets be also placed in the lamp circuit in series with such electrodes.
A shunt circuit is formed around the resistance, passing to the back contact of
one armature lever of such electro magnets and to the front contact of the other
lever. The two levers are connected electrically together, and form part of the
shunt circuit.
The retracting springs of these levers are so adjusted that the lever making
its back contact normally will be drawn away from such contact by the magnet
when there is a definite increase in the flow of the current and the lever making
its front contact normally will break contact when the circuit is broken.
The movement of either lever away from its normal contact opens the shunt and
throws the resistance into series with the carbon electrodes. This safety device
may be used to adapt any arc lamp for, a multiple are arrangement.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas John Handford in the Groat Seal Patent Office on the
17th February 1883.
33
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent "IMPROVEMENTS IN OR RELATING TO ELECTRIC LIGHTS
A communication to me from abroad by Thomas Alva Edison of Menlo Park
in the State of New Jersey, United States of America
The said invention of improvements in or relating to Electric lights has reference
to arc lights arranged in cross or multiple arc circuits and it consists
First, In an arc light arranged in a cross or multiple arc circuit which is
completed through the electrodes of the lamp only, the combination of a lower
stationary electrode, an upper movable electrode fed downwardly by gravity,
a locking and releasing or feed regulating electro magnet or solenoid, and a lifting
or arc-forming and regulating electro magnet or solenoid, such electro magnets
or solenoids being located in series with the electrodes and opposed by retractors.
Second, Of the combination with an arc lamp located in a cross or multiple arc
circuit, of means hereinafter described for preventing the formation of a short
circuit when the electrodes come into or are in contact.
And in order that the said invention may be perfectly understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the accompanying drawing which is a view partly diagrammatic of an arc lamp
embodying the invention and shewing a multiple arc arrangement of both are and
incandescing lamps in the same system.
1, 2, represent main conductors connected by cross or multiple arc circuits 3-4
and 5-6. In 3-4 is shewn located an incandescing electric lamp A of any
In
suitable pattern, the circuit being made and broken by a circuit controller a.
the circuit 5-6 are arranged the carbon electrodes B, C, of an arc lamp, this
circuit is made and broken by a circuit controller b. The upper or positive
carbon B is carried by a sliding rod D and is fed downwardly by its own weight
and that of the rod D. E, F, are two electro magnets both located in the lamp
circuit 5-6 in series with the carbon electrodes such circuit being completed
through the electrodes only.
The electro_magnet E operates a locking device which locks and releases the
holding rod D of the upper carbon electrode B; the electro magnet F works
through this locking device to raise the carbon electrode B, in establishing the
are and in enlarging the distance between the electrodes B, C, if need be during
the burning of the lamp. The locking device consists of a forked or notched arm e
pivoted to the armature lever c of the locking electro magnet E, and pressed by
the electro-magnet against the carbon-holding rod D close to the long stationary
bearing for between the two bearings. The armature lever c and the forked
arm e are drawn back by a retracting spring d which is nicely adjusted so that
when the arc is normal the arm will press against the holding rod D with just
sufficient force to prevent the further descent of the carbon B and when the arc
increases a definite small extent the holding rod D will be released and again
instantly locked. The movement of this locking arm is limited by a stop c' and
the retracting spring d of the armature lever c is provided with means for
permitting adjustinent of its tension.
The other or lifting electro-magnet F has an armature lever g retracted by an
adjustable spring h and carrying a sleeve, box or loop i through which the forked
arme of the locking armature lever c works.

page_text: The lifting electro-magnet F is not so sensitive as the locking electro magnet E
the retracting spring h of its armature lever g being adjusted to overcome the
magnetic attraction except when there is a marked increase in the current.
Both electro-magnets being in the cross or multiple arc circuit 5-6 in which
the carbon electrodes B, C, are located, they will both be strongly energized when
the circuit to the lamp is first completed. The locking magnet E acting first will
force the notched armi e against the holding rod D of the upper or positive carbon B
when the lifting magnet F will raise the said arm, and the upper carbon B thereby
establishing the arc.
As the arc increases the armature lever g of the lifting magnet F drops until
it rests on its back contact h' as shewn in the drawings. The locking magnet E
then controls the further downward feeding of the carbon B.
It being very
sensitive and its action being exceedingly quick, it will release and lock the carbon
holding-rod D with a short and rapid movement making a regular feed and
preventing flicker in the light. In order to prevent a too rapid descent of the
carbon electrode B a retarding device may be employed, such as a ratchet wheel
and reed or pendulum or other form of escapement as will be well understood.
It is obvious that the locking and lifting electro magnets may have a multiple
arc relation to each other instead of being in series as shewn and still be located
in series with the carbon electrodes of the arc lamp.
A circuit controller is placed in each arc lamp circuit, and also in the circuit of
each incandescing lamp operated from the same conductors, so that every lamp in
the system, whether arc or incandescing, is independent of all others, and can be
lighted and extinguished without affecting other lamps.
With are lamps arranged in multiple arc circuits there is a liability of a
dangerous flow of current taking place when the carbon electrodes come into
or are in contact, a short circuit being formed causing an abnormal flow of current
which heats the conductors destroying insulation and setting fire to wood-work
with which such conductors may be in contact, the other lamps being also affected
by this short circuit.
Now the said Invention also relates to means for preventing the formation of
this short circuit. For this purpose a resistance R is provided which is cut out
of circuit when the arc is normal but is thrown into series with the carbon
electrodes when the flow of current increases to a definite extent these actions
being controlled by an electro magnet G with its armature k acted upon by a
spring m. Another electro magnet H is provided, the armature lever of which,
acted upon by a spring n, throws such resistance into series with the carbon
electrodes when the circuit is broken.
These results are accomplished in the following manner viz.
A shunt circuit 7-8 is formed around the resistance R passing to the back
contact 9 of the armature lever k of the electro magnet G and to the front
contact 10 of the armature lever of the electro magnet H. The two levers kl
are connected electrically together and form part of the shunt circuit.
The retracting springs m, n, of these levers are so adjusted that the lever k
normally making its back contact 9 will be drawn away from such contact by
the magnet G when there is a definite increase in the flow of the current; and
the lever normally making its front contact 10 will break contact when the
circuit is broken.
The movement of either lever away from its normal contact opens the shunt
and throws the resistance into series with the carbon electrodes, such resistance
being sufficient to prevent a dangerous flow of current, but allowing the regulating
mechanism to act and reestablish the arc. The parts are represented in the
drawings in their normal position the resistance R being cut out of circuit.
This safety device may be used to adapt any arc lamp for a multiple arc
arrangement.
In the arrangements hereinbefore described solenoids may be substituted for
electro magnets as equivalent devices.

page_text: Having now described and particularly ascertained the nature of the said
invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the invention secured to me by the hereinbefore in part
recited Letters Patent is :-
First In an arc lamp arranged in a cross or multiple are circuit which is
completed through the electrodes of the lamp only, the combination of a lower
stationary electrode, an upper movable electrode fed downwardly by gravity, and
locking and lifting electro-magnets or solenoids located in series with the electrodes
and opposed by retractors, substantially as hereinbefore described.
Second. The combination with an arc lamp located in a cross or multiple arc
circuit, of means for preventing the formation of a short circuit when the electrodes
come into or are in contact, substantially as hereinbefore described.
In witness whereof I the said Thomas John Handford have hereunto set my
hand and seal this seventeenth day of February in the year of our Lord
One thousand eight hundred and eighty three.
MTTA
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