IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A M and
W Clark of 53, Chancery Lane, in the County of Middlesex, Patent Agents,
for an Invention of IMPROVEMENTS IN ELECTRIC LAMPS Communicated
to him from abroad by Hans Jacob Müller and Alexander Levett both of
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 24th July 1882.
ALEXANDER MELVILLE CLARK of the firm of A. M. &. W. Clark of
53 Chancery Lane in the County of Middlesex, Patent Agents, " IMPROVE-
MENTS IN ELECTRIC LAMPS" [Communicated to him from abroad by Hans
Jacob Müller and Alexander Levett both of New York City, United States of
America]
This Invention relates to improvements in the class of multiplex electric lamps
which are so constructed that when one set of carbons is completely consumed,
another set of carbons will be switched into the circuit automatically; and a further
object of the Invention is to facilitate the automatic regulation of the carbons. The
lamp is provided with two or more sets of carbons and corresponding helices or
solenoids above and in line with the positive carbon holder, there being a pivoted
armature and contact strip between each two solenoids so that the armature will
be in contact either with the solenoid or with the contact strip according as the
current is to pass through one solenoid or the other. The device for regulating
the carbons automatically consists of a lever actuated by the solenoid core and
engaging by means of a pawl with a ratchet wheel fast upon a shaft in gear with
a rack on one or both carbon holders. The Invention further consists in the
combination with the lower carbon holder for a focus-lamp, of a spring for drawing
this carbon holder upward. The Invention further consists of guides attached to
the lower carbon holder or to the lamp frame to prevent slender carbons slipping
past each other.

page_text: The lever of the automatic carbon regulating device is horizontal and is pivoted
to a standard on the bottom plate of the lamp frame. Its long arm is connected
by links with the lower end of the solenoid core, and the extremity of said arm is
located between adjusting screws which limit its motion. The short arm of said
lever is drawn upward by a spring attached to an adjusting screw on the top plate
of the lamp frame, and to this arm of the lever a spring pawl is pivoted which
engages with a ratchet wheel fast on a small horizontal shaft journalled in
standards on the bottom plate below the lever, said shaft also having fast upon it
two spur wheels of the proper relative diameters gearing with racks on the positive
and negative carbon holders respectively, the smaller wheel being insulated from
the shaft. The positive carbon holder passes through the tubular core of the
solenoid and through the latter, and has a piston at its upper end fitting in a
cylinder above it. The negative carbon holder is hollow and contains a spring
attached to the bottom of the carbon holder and to an insulated button resting on
a plate on a hollow stud rising from the top plate. This is the construction for a
focus lamp; for an ordinary lamp the gear and spring for the negative carbon
holder can be dispensed with and the holder made stationary.
The points of very slender carbons are liable to slip past each other and fail to
form a light are. To avoid this, two downwardly projecting arms are fixed to the
casing of the negative carbon holder (the upper arm being insulated therefrom)
said arms terminating in loops or eyes through which the carbons pass and are
guided.
So far the mechanism is applicable to a single lamp. In a multiplex lamp each
set of carbons must be provided with the above mechanism. Each solenoid is
provided with a pole piece at its lower end and an armature is pivoted to but
insulated from the top plate of lamp frame and is pendent alongside each solenoid
(except the last). A contact spring or strip is attached to but insulated from the
top plate of the frame adjoining each armature. The pole pieces of the solenoids,
the armatures and the contact strips are provided with contact buttons made from
gas retort carbon in its natural state, (i.c. as it comes from the retort without
admixture of other ingredients) which is much more durable and conductive than
prepared carbon and is not so rapidly destroyed by sparks. The negative terminal
of the lamp is electrically connected with the joint pin of the first armature which
is electrically connected with the upper end of the first solenoid, and the contact
piece adjoining this first armature is electrically connected with the upper end of
the second solenoid and with the joint pin of the second armature, and so on for
any number of solenoids. The lower end of each solenoid is connected with the
corresponding negative carbon holder and the positive carbons are connected
together electrically by wires or by the lamp frame. The last solenoid need not
have a pole piece.
The lower of the two adjusting screws which limit the motion of the automatic
carbon regulating lever as before described, is insulated and is electrically connected
with the negative terminal in order to cut out any damp without extinguishing the
others, so that when the lever drops the current will pass through said lever to the
negative terminal. This is in a single lamp. In a multiplex lamp a relay will
be required. The operation is as follows:-
If the arc is very small there is very little resistance in the circuit and the first
solenoid draws its core inward thereby oscillating the carbon regulating lever and
actuating the ratchet and gear wheels in such a direction that the positive carbon
holder is raised and the negative carbon holder lowered, thus separating the carbon
points. This causes a greater tension in the circuit and the lever can then be
oscillated in the opposite direction by its spring, the pawl then sliding over the
teeth of the ratchet. The above operation is repeated every time the carbons
approach each other too much. The rapid descent of the carbons is prevented by
the piston attached to the positive carbon holder. The weight of the upper carbon
and its holder acting on the gear wheels and shaft raises the lower carbon holder
assisted by the spring within the tubular stem of the latter.

page_text: As long as there are any carbons in the first lamp the current passes from the
positive terminal through the lamp frame to the positive carbon holder, the carbons,
the solenoid, the joint piece of its armature and the negative terminal, to the
generator. During this time the pole piece of the solenoid attracts its armature,
but as soon as the first set of carbons is consumed to such an extent that the circuit
will be interrupted, the armature is released and is pressed by a spring against the
contact strip in connection with the next solenoid. The current will now pass
through the second set of carbons and through the second solenoid causing its pole
piece to attract its armature thereby interrupting the circuit or connection with
the third solenoid. As soon as the second set of carbons is consumed, the second
solenoid releases its armature which is pressed by a spring against the contact strip
of the next solenoid. The current will now pass through the third set of carbons
and the corresponding solenoid. In the manner described a series of sets of carbons
can be united.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 24th January 1883.
"
ALEXANDER MELVILLE CLARK of the Firm of A, M, and W, Clark of
53 Chancery Lane in the County of Middlesex Patent Agents ❝ IMPROVE-
MENTS IN ELECTRIC LAMPS a communication to me from abroad by Hans
Jacob Müller and Alexander Levett both of New York City, United States of
America.
This Invention relates to improvements in the class of multiplex electric lamps
which are so constructed that when one set of carbons is completely consumed,
another set of carbons will be switched into the circuit automatically; and a
further object of the Invention is to facilitate the automatic regulation of the
carbons. The lamp is provided with two or more sets of carbons and corresponding
helices or solenoids above and in line with the positive carbon holder, there being a
pivoted armature and contact strip between each two solenoids so that the
armature will be in contact either with the solenoid or with the contact strip,
according as the current is to pass through one solenoid or the other. The device
for regulating the carbons automatically consists of a lever actuated by the solenoid
core and engaging by means of a pawl with a ratchet wheel fast upon a shaft in
gear with a rack on one or both carbon holders. The Invention further consists
in the combination with the lower carbon holder for a focus-lamp, of a spring for
drawing this carbon holder upward. The Invention further consists of guides
attached to the lower carbon holder or to the lamp frame to prevent slender
carbons slipping past each other.

page_text: In order that the Invention may be more readily understood I have illustrated
it in the accompanying drawings in which the same letters of reference indicate
corresponding parts in all the figures.
Figure 1 is a longitudinal elevation of the improved multiplex lamp, parts being
shown in section. Figure 2 is a sectional plan view of one half of the lamp on the
line xx Figure 1. Figure 3 is a longitudinal sectional elevation of the lower
carbon holder. Figure 4 is a detail longitudinal elevation of the spring pawl of the
carbon regulator. Figure 5 is a longitudinal elevation of the lower carbon holder
and its tubular casing. Figure 6 is a cross sectional view of the same on the line
y-y Figure 5. Figure 7 is a diagram of the lamp showing the first set of carbons
in the circuit. Figure 8 is a like diagram showing the second set of carbons in
the circuit. Figure 9 is a like diagram showing the third set of carbons in the
circuit.
A is the lever of the automatic carbon regulating device. It is horizontal and is
pivoted to a standard B' on the bottom plate B² of the lamp frame. Its long arm
is connected by links B with the lower end of the core C of solenoid D, and the
extremity A² of said arm is located between adjusting screws F' F' on a standard
Fs which limit its motion. The short arm A' of said lever is drawn upward by a
spiral spring C attached to an adjusting screw C2 passing through the top plate B³
of the lamp frame and provided with adjusting nuts C. To this arm of the lever
is pivoted a spring pawl E which is pressed upon by a flat spring E¹ attached to
lever A (as shown in Figure 4) and caused to engage with a ratchet wheel F fast
on a small horizontal shaft E journalled in the standards B below the lever A.,
said shaft also having fast upon it two spur wheels G G of the proper relative
diameters (about 2 to 1) gearing with racks H H on the positive and negative
carbon holders J₁ J2 respectively, the smaller wheel G2 being insulated from the
shaft. The positive carbon holder J' passes through the tubular core of the solenoid
D and through the latter, and has a piston at its upper end fitting in a cylinder
above it. The negative carbon holder J' is hollow and contains a spiral spring G
attached to the bottom of the carbon holder and to an insulated button H resting
on a plate J on a hollow stud G³ rising from the top plate. This is the construction
for a focus lamp; for an ordinary lamp the gear G2 H³ and spring G for the negative
carbon holder J2 can be dispensed with and the holder made stationary.. The
spring K serves to ensure electrical connection between the casing I and the carbon
holder J. The points of very slender carbons are liable to slip past each other and
fail to form a light arc. To avoid this, two downwardly projecting arms L' L² are
fixed to the casing I of the negative carbon holder (the upper arm being insulated
therefrom by a ring N) said arms terminating in loops or eyes M' M² through
which the carbons pass and are guided.
So far the mechanism is applicable to a single lamp. In a multiplex lamp each
set of carbons must be provided with the above mechanism.
In Figure 1 I have shown a duplex lamp, and in Figures 7. 8. and 9 I have shown
triplex lamps. Each solenoid D'D' &c is provided with a pole piece OO' &c at its
lower end and an armature P P¹ &c is pivoted to but insulated from the top plate
B³ of lamp frame and is pendent alongside each solenoid (except the last) and is
pressed away from it by a spring QQ &c. A contact spring or strip SS' &c is
attached to but insulated from the top plate B³ of the frame adjoining cach
armature. The pole pieces 0 0¹ &c of the solenoids, the armatures P P &c and the
contact strips S S¹ &c are provided with contact buttons T made from gas retort
carbon in its natural state (i.e. as it comes from the retort without admixture of
other ingredients) which is much more durable and conductive than prepared carbon
and is not so rapidly destroyed by sparks. The negative terminal R' of the lamp
is electrically connected with the joint pin of the first armature P (its hinge piece
and screw being insulated from plate B³) which pin is electrically connected with
the upper end of the first solenoid D, and the contact piece S adjoining this first
armature is electrically connected with the upper end of the second solenoid D' by
the wire band with the joint pin of the second armature P¹ by the wire c

page_text: and so on for any number of solenoids. The lower end of each solenoid is
connected by a wire a with the casing I of the corresponding negative carbon holder
J and the positive carbons are connected together electrically by wires d or by the
lamp frame. The last solenoid D² need not have a pole piece.
The holder for the lower one F2 of the two adjusting screws which limit the
motion of the automatic carbon regulating lever A as before described, is insulated
from standard F3 and is electrically connected with the negative terminal R¹ in
order to cut out any lamp without extinguishing the others, so that when the lever
A drops, the current will pass through said lever to the negative terminal. This is
in a single lamp. In a multiplex lamp a relay will be required. The operation is
as follows:-
If the light arc is very small, there is very little resistance in the circuit and
the first solenoid D draws its core C inward, thereby raising the end A¹ of lever A
as far as screw F¹ will permit and causing pawl E to engage with and turn the
ratchet wheel F a short distance. The pawl E then assumes the position shown
in dotted lines Figure 4, thereby raising the spring E' slightly, the stud y forming
a check for this movement of the pawl. The ratchet wheel F being thus rotated
the gear wheels G₁ G' will be also rotated in the direction of the arrow a¹ whereby
"the positive carbon holder J¹ is raised and the negative carbon holder J² lowered,
thus separating the carbon points. This causes a greater tension in the circuit and
the regulating lever A can then be oscillated in the opposite direction by its
spring C¹ overcoming the power of the solenoid, the pawl then sliding over the
teeth of the ratchet. The above operation is repeated every time the carbons
approach each other too much. The rapid descent of the carbons is prevented by
the piston attached to the positive carbon holder J. The weight of the upper
carbon and its holder J¹ acting on the gear wheels G¹ G and shaft E raises the
lower carbon holder J2 assisted by the spring G within the tubular stem I, which
spring supports a portion of the weight of the lower carbon holder and to that
extent reduces the force required to raise it. Hence the lower one is raised
quickly and easily when the upper one is lowered.
-
As long as there are any carbons in the first lamp, the current passes from the
positive terminal R through the lamp frame to the positive carbon holder, the
carbons, the solenoid D, the joint piece of its armature P, and the negative
terminal R¹ to the generator. This course is indicated by the signs + and
During this time the pole piece O of the solenoid attracts its armature P as shown
in Figures 1 and 7, but as soon as the first set of carbons is consumed to such an
extent that the circuit will be interrupted, the armature P is released and is pressed
by the spring Q against the contact strip S in connection with the next solenoid D¹.
The current will now pass through the second set of carbons and through the
second solenoid D₁ causing its pole piece O to attract its armature P¹ thereby
interrupting the circuit or connection with the third solenoid D². As soon as the
second set of carbons is consumed the second solenoid D¹ releases its armature P¹
which is pressed by the spring Q' against the contact strip S₁ of the next solenoid,
as shown in Figure 9. The current will now pass through the third set of carbons
and the corresponding solenoid. In the manner described a series of sets of
carbons can be united.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
1st In an electric lamp, the combination with the solenoid core of a lever
pivoted thereto and to suitable standards, a pawl pivoted to this lever, a ratchet
wheel acted upon by the pawl, a cog wheel which is fast on the same shaft with
the ratchet wheel, and a rack on the carbon holder, substantially as herein shown
and described, and for the purpose set forth.
2nd In an electric lamp, the combination with the solenoid D, of the core C, the
lever A pivoted to standards B', the pawl E, the ratchet wheel F, the cog wheel; GL
and G, all of said wheels being fast on the same shaft, and the racks H'H² on the

page_text: carbon holders J¹ J² substantially as herein shown and described and for the
purpose set forth.
3rd In an electric lamp, the combination with the solenoid D of the core C, the
lever A pivoted to standards B, the spring C, the pawl E, the ratchet wheel F,
the cog wheels G³ G³, all of said wheels being fast, and the racks H' H² on the
carbon holders J¹ J' substantially as herein shown and described and for the
purpose set forth.
4th In an electric lamp, the combination with the carbon holder J2 of the
spring G the insulating cap H, and the cap or plate J, substantially as herein
shown and described and for the purpose set forth.
5th In an electric lamp, the combination with the lever A, of the pawl E, the
spring E' and check, stud g, substantially as herein shown and described, and for
the purpose set forth.
6th In an electric lamp, the combination with two or more solenoids having pole-
pieces and two or more sets of carbons which are regulated in position by means
of said solenoids of as many pivoted armatures and corresponding contact strips,
minus one, as there are solenoids substantially as shown and described and for the
purpose set forth.
7th In an electric lamp, the combination with two or more solenoids having
pole-pieces and two or more sets of carbons which are regulated in position by
means of said solenoids of as many pivoted armatures P, pressure springs Q, and
contact-strips S, save one, substantially as herein shown and described, for the
purpose set forth.
8th In an electric lamp, the combination, with the tubular casing I of the arms
LL2 both attached to said casing, provided with eyes M' M² substantially as
herein shown and described and for the purpose set forth.
In Witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twenty fourth day of January, A.D. 1883.