Improvements in Electric Arc Lamps.
Year: 1893

page_text: Date of Application, 23rd Mar., 1893
Complete Specification Left, 23rd Dec., 1893-Accepted, 17th Feb., 1894
Improvements in Electric Arc Lamps.
I, ALFRED LYSTER SHEPARD, 8 West Kensington Gardens, in the County of
Middlesex, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
In my improved arc lamp I provide means whereby the carbon pencils are
controlled by two suitable electrical devices both aiding one another to regulate
the lamp, one governed by the main current adapted to strike the arc and also to
rapidly adjust the carbons to compensate for sudden changes in the current flowing
in the circuit of the lamp, and the other governed by a current shunted on the arc
designed to allow the carbons to feed slowly together when the potential on the arc
has reached the desired amount.
In carrying my said invention into practice in one type of my lamp the carbons
are operated by a chain which passes over and gears with a toothed wheel, the
carbon-holders being fixed at either extremity of the said chain. The upper
carbon-holder is weighted so as to ensure its falling and drawing up the lower
holder when released. The said toothed wheel carries the centre-wheel of a set of
differential gear wheels, made up of three bevel wheels working together; the two
outside wheels are connected respectively to a ratchet wheel worked by the solenoid
or electromagnet in the main circuit, and to an escapement wheel the releasing
catch of which is worked by a coil solenoid, electromagnet, or other suitable
On this latter
controlling device energized by a current shunted from the arc.
wheel I prefer to use some suitable device such as a pendulum escapement to check
the speed of rotation. In place of the bevel wheels above described I may employ
other suitable gear.
For the main regulating device I prefer to employ a solenoid wound with thick
wire and having a cylindrical plunger or core, the weight of which can be partially
balanced by an opposing spring or weight. I prefer to make the said core of a
number of thin strips of soft iron of V-section arranged radially around the centre
rod of metal, and insulated from each other by a suitable coating, the ends of the
said strips being so shaped that when the cylinder is completed, the two ends
present concentric grooves or projections adapted to engage with similar concentric
grooves or projections formed in the substance of two insulating caps of vulcanized
fibre or other suitable material, the said caps being clamped up from either end by
nuts threaded on the central rod serving thereby to keep the soft iron strips in
place. I prefer moreover to use in connection with the main solenoid core a
suitable one-way dash-pot where such is necessary that will prevent the carbons,
through the solenoid core and ratchet wheel from being separated too quickly, but
which will allow the solenoid. core to move unimpeded in a direction to bring the
carbons together.
For the shunt regulating device I sometimes use a similar solenoid and core, and
I sometimes prefer to make use of the expansive properties of a fine metallic wire
One extremity
when heated by passing through it a current shunted from the arc.
of the wire is rigidly held and the other, to which is attached a suitable spring to
take up the slack, operates the release catch of the feeding wheel. The said
metallic wire, which is composed of platinum or other suitable metal, in some cases
passes down one of the guide rods of the carbon holders and up the other, passing
over insulating pulleys. As the heat of the arc as distinguished from the heating
effect of the shunted current would affect the accurate working of the apparatus

page_text: provide a duplicate wire similarly situated to the first and insulated from it so as to
be equally affected by the heat of the arc; no current is passed through this wire
which is so arranged as to have an opposite effect on the releasing catch thereby
compensating for the external heat.
In another type of my lamp I prefer instead of a chain to use a rack-rod or
rack-rods to carry the carbons; in this lamp moreover the disposition of the parts
is different; in a single carbon non-focussing lamp of this type the rack-rod
carrying the positive carbon gears with a suitable cog upon the spindle of a toothed
wheel of considerably larger diameter; this latter wheel is the first of a train of
three or more wheels so arranged that the last wheel rotates at a considerably
higher speed than the first, which gears direct with the rack-rod and is pivoted on a
lever at a point between the fulcrum and the point of application of the power.
The second wheel is pivoted at a point which coincides with the fulcrum, the third
wheel the periphery of which is suitably formed to act as an escapement or release
wheel is pivoted on a suitable bracket fixed to the frame of the lamp and which
may or may not carry the fulcrum.
A core and solenoid of similar construction to that hereinbefore described,
operated by the main current actuates the end of the lever, to draw it upwards
when the current is turned on: a similar device to those hereinbefore described or
a suitable electro magnet operated by a current shunted from the arc is used to
actuate an escapement or release which controls the movement of the third wheel.
The operation of this lamp is as follows; when no current is passing through the
lamp the carbons are together, the lever being so arranged that when it is at its
lowest point it breaks the shunt circuit and also releases the escapement wheel,
thereby allowing the carbons to come together. Directly the carbons touch each
other the main current flowing in the solenoid draws up the core and the lever, and
at the same moment that the catch comes into operation the train of wheels is
arrested and the rack-rod is consequently raised and strikes the arc. When the
arc is of sufficient length the shunt device releases the third wheel and the weight
of the rack rod causes it to descend and feed the upper carbon downwards. The
core of the main solenoid while the lamp is burning takes up different positions
relative to the same in accordance with the current fluctuations, adjusting the
carbons rapidly to compensate for such sudden fluctuations while the shunt device
causes the carbons to feed slowly at a fixed point. When using this lamp as a
double carbon lamp in which when one pair of carbons is consumed the second pair
automatically come into use, I provide each of the two rack rods carrying the
upper carbons with similar trains of wheels mounted on two pivoted levers which
are both under the control of one main solenoid or magnet, and so arranged that
when the current is turned on, ene rod is lifted before the other, the pair of carbons
which are separated last being the first to burn. The third wheel or escapement
on the second pair is meanwhile held by a catch to prevent them from coming in
contact until required, when the rack-rod of the first side releases the catch, and
allows the second side rack to descend and start the arc on the new pair of
carbons.
Although I have hereinbefore described convenient and advantageous means of
carrying my said invention into practice, it is obvious that I can somewhat modify
the construction of my apparatus without however in any way departing from the
nature of my said invention.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: Improvements in Electric Are Lamps.
I, ALFRED LYSTER SHEPARD, of 8 West Kensington Gardens, in the County of
Middlesex, Electrical Engineer, 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 electric arc lamps and comprises the improvements
hereinafter indicated.
According to my invention I construct an improved arc lamp wherein I provide
means whereby the carbon pencils are controlled by two suitable electrical devices,
both aiding one another to regulate the lamp, one governed by the main current
adapted to strike the arc and also to rapidly adjust the carbons to compensate for
sudden changes in the current flowing in the circuit of the lamp, and the other
governed by a current shunted on the arc designed to allow the carbons to feed
slowly together when the potential on the arc has reached the desired amount.
In another part of my invention I provide improved means for regulating an arc
lamp which means may be used inɛtead of the ordinary regulating electro magnet
if desired, such means comprises a metallic wire through which the current passes,
the expansion of the wire serving to raise a detent and so allow the wheels of a
wheel train to rotate, and the upper carbon which is in gear with said wheel train,
to descend. I provide in addition to the aforesaid wire through which the current
passes a second similar wire which does not carry any current, said second wire is
located in a position similar to that of the first wire and is subject to the same
external conditions but is arranged to act on the detent of the wheel train in the
opposite sense to that in which the first wire acts. I thereby compensate for
variations in the length of the first wire when such variations are not due to the
current passing through the same.
Furthermore provide improved laminated iron cores for electromagnets used in
arc lamps.
In order that my invention may be clearly understood I will now describe the
same with reference to the accompanying drawing in which
Figure 1 is a diagrammatic perspective view shewing the essential portions of
one type of my improved lamp.
Figure 2 is a front view shewing a part of Figure 1 drawn to a larger scale.
Figure 3 is a front view in detail of another form of my improved arc lamps.
Figure 4 is a portion of a side view of the same.
Figure 5 is a similar view to Figure 4, partly sectional and shewing a modified
construction.
Figure 6 is a view shewing my improved arrangement of wires for regulating the
lamp without the use of a shunt coil.
Figure 7 is a view similar to Figure 4 shewing a modified form of escape-wheel
and detent.
Figure 8 is a sectional view of my improved iron core.
Like letters denote corresponding parts throughout the drawings.
A is the base of the lamp, B is the main or series coil, C the upper carbon-rod,
D the lower carbon-rod, and E is the wheel train.
Referring now to Figures 1 and 2 the carbons are operated by a chain L' which
passes over and gears with a toothed wheel L, the carbon-holders C, D, being fixed
at either extremity of the said chain. The upper carbon-holder C is weighted so
as to ensure its falling and drawing up the lower one when released. The toothed
wheel L carries the centre wheel U of a set of differential gear wheels, made up.
of three bevel wheels U, U', U2 working together, the wheel U₁ is connected to a
ratchet wheel Es worked by the solenoid or electromagnet B in the main circuit.

page_text: The core B of the solenoid B is attached to a lever G which has its fulcrum
coincident with axes of the wheels E8, U1, U2, L' and E. On said lever I provide
a pawl G' which when the lever is lifted by the core B' rotates the ratchet wheel E.
The other bevel wheel U2 is connected to an escapement wheel E the releasing
catch J of which is worked by a coil, solenoid, electromagnet, or other suitable
controlling device energized by a current shunted from the arc. On this wheel E'
I prefer to use some suitable device such as a pendulum escapement to check the
speed of rotation. The centre wheel U is arranged to turn on an axis U³ inside
the chain wheel L. For the main regulating device I prefer to employ a solenoid
wound with thick wire and having a cylindrical plunger or core, the weight of
which can be partially balanced by an opposing spring or weight, and which is
preferably connected with one-way dash-pot that will prevent the carbons from
being separated too quickly, but which allows the solenoid core to move unimpeded
in a direction to bring the carbons together. These details will be hereinafter
more fully described.
The principle of the operation of this lamp is as follows. When the circuit of
the lamp is broken the wheel E is locked by the catch J. As soon as current is
turned on to the lamp the main coil B is energized and attracts its core B₁ this lifts
the lever G and by the pawl G' rotates wheel E8 and bevel wheel U. The bevel
wheel U is rotated by wheel U' and the wheels U2 and E being locked is forced
to run round said wheel U2 thus rotating the chain wheel L. This chain wheel
then moves the chain L' which separates the carbons and strike the arc. When
the arc grows long the detent J is raised by the shunt electro-magnet or other
suitable means from the wheel E" thereby allowing the chain wheel to be rotated
by the weight of the upper carbon holder in the opposite direction to the one in
which it was rotated at first thus the carbons are fed together. It is clear that the
main coil B cannot turn the chain wheel L' unless the wheel E is locked by the
detent and also that if the wheel E be locked and the main coil B allows its
core B to drop that the weight of the upper carbon-holder will cause the carbons
to feed together as the chain wheel is able to rotate the wheel U' through the bevel
wheel U.
Referring now to Figures 3 and 4, Fis the regulating magnet coil which is joined
as a shunt to the arc. The series coil B is carried on a standard A' secured to the
base A and is furnished with an iron core B₁ carried by a spring H which is
adjustably supported by the screwed rod H¹ carried by the standard A¹. The
core B' supports the pivoted lever G and is also connected with a one-way dash-
pot B2 which prevents the core from being drawn up quickly but offers no impediment
to the movement of the core in the other direction. I thereby ensure that the are
shall be struck slowly without interfering with the rapidity with which the carbons
can come together. The core B is also connected by a pin and slot connection to
a pivoted lever B3 which is joined by a rod B' to the arm J2 for a purpose herein-
after explained. The upper carbon holder C moves up and down in a guide tube 1
attached to the base A having a slot I through which slot the rack C on the
carbon holder can gear with the pinion E' mounted in bearings in the lever G.
The pinion E communicates the motion of the carbon holder C by means of wheels
and pinions E, E³, E, E to the escapement wheel E which is adapted to engage
with a stop or detent J as hereinafter described.
The shunt electro-magnet F is supported by the base A. and is provided with an
armature which is carried by a spring F2 attached to the standard A2. The
armature F¹ carries the detent J and also a weighted arm J¹ which tends to make
the detent engage with the teeth of the escapement wheel E' and so prevent it and
the other wheels of the wheel train from rotating. The lever G is pivoted on an
axis coincident with the axle of the wheel E. This is effected by securing the end
of the lever to a sleeve which can turn on the axle of said wheel. It results from
this arrangement that when the lever is turned on its fulcrum the wheel E2 which
is mounted on lever G turns round the pinion E without being put out of gear
therewith. Thus the rotation of the pinion E¹ is always controlled by the detent J

page_text: acting on wheel E irrespective of the position of lever G. The lower carbon-rod D
slides up and down in a sleeve K fixed to the base A and is connected with the
upper carbon-rod C by a flexible metallic cord L which passes over a pulley L
pivoted on a standard L' secured to the base A.
The said cord L is insulated from the carbon-rods by insulation as shewn
at L, L.
The electrical connections of the lamp are as follows: M, N are the terminals
of the lamp fixed in but insulated from the base A. From the terminal M a wire
is led direct to the series coil B the other end of said coil being connected by a
wire M' to the bearing of the wheel L₁ and thereby to the wire L connected to
wire C to upper carbon holder. The main current also passes from the arc
through the lower carbon holder, spiral wire D², terminal D³, to the terminal N.
The shunt coil on the magnet F is connnected by one end to terminal N and
by other to the bearing of wheel L'. When the lamp is used for direct currents M
is the positive terminal and N the negative, hence wire L is positive and D' is
negative.
The operation of my improved lamp is very simple. When no current is
passing through the lamp the coil B₁ drops to its lowest position and by the
lever B³ and rod B lifts the detent J from the wheel E. The upper carbon
holder is now free to descend by rotating the wheel train and the carbons are
brought into contact. When the current is switched on the series coil B draws up
its iron core B' and lifts the lever G. This lifting of the core B' allows the
rod B and detent J to fall and stop the wheel E. The train of wheels being
locked by the detent the lever G lifts the carbon-rod through the action of the
pinion E which cannot rotate, and the rack C₁. When the arc grows long the
shunt coil F being sufficiently energized attracts its armature F¹ and raises
the detent J releasing the wheel train. The weight of the upper carbon-holder
then feeds the carbons together, the wheels of the train rotating until the arc is
short enough, when the detent J is dropped by the shunt magnet and the wheel E
stopped the feed of the carbons then ceases. The core B₁ of the main coil B
while the lamp is burning takes up different positions relatively to the same in
accordance with the fluctuations of the current, adjusting the carbons rapidly to
compensate for such fluctuations while the regulating device, in this case the
shunt coil F, causes the carbons to feed slowly at a fixed point. I prevent the
core from dropping too far when the current is cut off from the lamp by a
spring A³. I also provide a handle A which can be operated so as to depress the
core B and lever G against the force of said spring and so release the pinion E
from the rack C. The carbon-rods can then be moved up and down freely
without rotating the wheels of the train. This is more especially useful when
lamp is being trimmed.
In Figure 5 I shew a modified form of part of the lamp. In this modification
I provide in addition to the shunt magnet a series coil P which is adapted to act
on the detent J in the following manner. The said coil P is provided with a
loose iron core P' and the detent-arm J2 has at the end thereof a piece of iron J³.
As soon as any current is sent round the coil P the core P' is attracted and sticks
to the iron part Ja thereby weighting the detent-arm and opposing the pull of the
shunt inagnet F. When however the circuit of the lamp broken the core P
drops off the detent-arm J and owing to the weight of the armature F' the
detent J is lifted out of engagement with the wheel E and so permits the carbons
to come together. By using this device I am enabled to dispense with the lever B³
and link B and the permanent weight on the arm J¹.
In Figure 6 I have illustrated my improved device for regulating the lamp
without the use of a shunt coil. E' is an escapement wheel of a wheel train and J
a detent therefor, these parts being similar to those hereinbefore described. The
detent arm J is pivoted on a bracket T secured to the frame or base of the lamp.
The detent arm is controlled by a fine wire R and spring R' which work against or
in the opposite sense to a wire S and spring St. The wires R and S are the same

page_text: length and thickness and are preferably placed in the tubes K, K which support
the bottom carbon-holder, said carbon holder in this lamp therefore is stationary.
In any case however the wires R and S are placed in similar positions with
regard to the arc. The wire R carries a current shunting the arc and the wire S
is insulated and carries no current. When the arc grows too long the wire R
expands owing to the increase in the shunt current passing through. It therefore
allows the detent J to rise and release the escapement wheel E the upper carbon
being thereby caused to feed. When the current in the wire R diminishes the
wire regains its normal length and the detent again brakes the escapement wheel.
The wire S ensures that the raising of the detent shall only occur through an
increase in length of the wire R due to the rise of the shunt current passing
therethrough. This is the case, for any lengthening of the wire R due to heat
radiated from the arc will have its effect on the detent arm counteracted by the
lengthening of the wire S from the same cause. The springs R', S' are provided
with suitable adjusting screws as shewn. I can apply the above principles, namely
the employment of two wires one of which carries a current and the other of which
does not, to other forms of arc lamp regulating mechanism than that herein
described.
Figure 7 shows a modified form of escapement wheel and detent. The wheel E
is provided with pins E' instead of teeth and the detent arm J2 is furnished with a
projecting part J. The detent arm J2 and wheel E and the intermediate parts
are so arranged that when no current is passing through the shunt the part J is
below the pins E7 and does not engage with said pins. The wheel E is therefore
free to rotate as long as the lamp circuit is broken so that the lamp carbons will
come together. When the arc is the proper length and what I will call a normal
current passing through the shunt coil F, the armature F¹ is attracted so far that
the projection J engages with the pins E' and the carbons can not feed. When
however the arc lengthens more current flows through the shunt and the armature F¹
is strongly attracted until the part J comes above the pins E. The wheel E can
then revolve and allow the carbons to feed until the arc is the right length and
the shunt current has become normal again, the attraction on the armature F¹
being thereby diminished the part J again engages with the pins E7 and stops
the feed.
My improved iron core is shewn in Figure 8 in longitudinal section. B' are thin
strips of soft iron of V-section arranged radially round a central rod B³. The
said strips are insulated from each other by a suitable insulating coating such as
shellac varnish for instance and the ends thereof are shaped so as to engage with
grooves Q, Q on the two end washers Q', Q' as shewn. The washers QQ' are
made of vulcanite or vulcanized fibre or the like and are kept in position clamping
the strips in place by a nut Q, screwed on the central rod 13. The washers QQ
are preferably provided with orifices Q3 Q3 which admit of air circulating through
the core as shewn by the arrows. The strips of iron may or may not be too
narrow to reach to the central rod, and in the former case 1 sometimes fill the
intervening space with insulated iron wires.
1 may make the ends of the strips of a form so as to engage with projections in
the washers Q1, Q, instead of making them of the design shewn, or modify the
shape of said strips in various other ways.
My improved lamp may if desired be used as a double carbon lamp in which
when one pair of carbons is consumed, a second pair automatically comes into use.
In this case I provide each of the two rack rods which carry the upper carbons
with a train of wheels mounted on two pivoted levers. Said levers are both under
the control of one main solenoid or electro-magnet and are so arranged that when
the current is turned on to the lamp, one of the rack rods is lifted before the
other. The are will then be struck between the pair of carbons which were last
separated. The third wheel or escapement in the wheel train belonging to the
second pair of carbons is held by a catch during the burning of the first pair of
carbons so that said second pair can not feed. When however the first pair of

page_text: carbons is consumed the rack rod of the upper carbon releases the aforesaid catch
and allows the second pair to feed together so as to make contact and start a
second arc.
Although I have herein shewn two types of lamp in which I make use of a lever
whose fulcrum coincides with the axis of one of the wheels of the train I do not
confine myself to the exact details shewn. It is obvious that the point of
application of the lifting force due to the core of the main or series coil being
drawn up may be applied at other parts of the lever and not necessarily at the
opposite end thereof as shewn in Figures 1 and 3 of the drawings. In short I
may use levers of different orders provided that the fulcrum is as aforesaid
coincident with the axis of one of the wheels of the train.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. An electric are lamp in which two independent controlling devices are
provided, one of which devices actuates a pivoted lever to give a rapid motion to
the carbons, and the other of said devices controls a train of wheels to regulate
the gradual feeding of the carbons, said wheels being carried by the aforesaid
lever in such a manner that the pivot of the lever coincides with the axis of one of
the wheels, substantially as described.
2. In an electric arc lamp a train of wheels adapted to work in connection
with a rack rod said wheels being carried by a lever the fulcrum of which is
coincident with the axis of one of the wheels, so that when the lever is moved
about its fulcrum beyond a certain limit the wheel train will become disconnected
from said rack rod, substantially as, and for the purposes, specified..
3. An electric arc lamp constructed substantially as described with reference to
Figures 1 and 2 or to Figures 3 and 4 or to Figure 5 of the accompanying
drawings and operating as specified.
4. An electric arc lamp having its feed regulating device controlled by the
differential expansion of two wires, one of which carries a current shunting the
arc and the other of which carries no current, substantially as described.
5. In an electric arc lamp the combination with the regulating coil, of an
escapement or detent wheel as described with reference to Figure 7 of the accom-
panying drawings for the purposes specified.
6. The improved iron core composed of a cylinder of insulated iron strips, with
or without iron wires filling the interior thereof, substantially as described.
Dated this 23rd day of December 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.