Improvements in or relating to Arc Lamps.
Year: 1889

page_text: Date of Application, 12th Sept., 1889
Complete Specification Left, 7th June, 1890-Accepted, 26th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in or relating to Arc Lamps.
I, WILFRID SWANWICK BOULT, of 24 King's Mount, Birkenhead, in the County of
Chester, Civil Engineer, do hereby declare the nature of this invention to be as
follows: -
To strike and maintain the arc in an arc-lamp I employ a motor, constructed by
preference on the uni-polar principle, (a convenient form being the "Sturgeon's
Wheel "), the pull of which is balanced by weight or spring-pressure when the arc is
of the desired length.
Thus, in the case of a lamp working with constant potential at the terminals, having
the motor and lamp in series:-When no current is passing, the carbons will be
caused by gravity, springs, &c., to touch each other at their points; but, as soon as
the current is turned on, the motor begans to withdraw the carbons so as to form the
arc. When the carbons are separated to the required distance, the resistance offered
by the arc causes the current flowing through the motor to be reduced, so that the
effort of the motor to continue revolving and further separating the carbons is
neutralized by the opposing force of gravity, &c.; and, if the carbons were not con-
sumed, no further motion would take place. When, by consumption of the carbons,
the arc has somewhat increased in length, the resistance is increased and the volume
of current so far diminished that the motor is unable longer to maintain its position,
and is forced backwards, allowing the carbons to approach each other a little so that
the strength of current may be correspondingly enforced.
As long as the lamp is kept alight, this forcing back of the motor, and consequent
feeding of the carbons, is continued. When the current is discontinued, the carbons
run together and are ready for again striking the arc.
It is not necessary that both carbons should be movable: one may be held in a
stationary holder, and the movement of the other correspondingly increased.
Instead of a rotating motor, one giving a straight pull over a limited range may be
used, and may conveniently be formed of a three-poled field-magnet in the shape of
a trident or three-pronged fork and an armature in the shape of a solenoid slipped
over the central pole of the field-magnet; or the central pole may be surrounded by
a cylindrical casing leaving an annular space for the solenoid-shaped armature or
other modifications may be adopted.
The current may traverse the whole length of the solenoid armature or only a part-
say just opposite the poles of the field-magnet, or other portion as may be advisable
for regulating purposes.
This armature may be attached directly to one of the carbon-holders, and, to com-
pensate for the loss of weight in the carbons due to consumption, may be wound more
openly, or with wider pitch, at one end than the other, the variation from end to end
being by preference regular and gradual.
Whatever kind of motor is used, the lamp may be adapted, by well-known methods
of winding and connecting up conducting wires, for working with either constant
potential or constant current; or otherwise either in parallel or in series.
Another modification of the apparatus consists in the use of:-A solenoid through
only part of which the current of electricity flows at once; a core to pass up and
down the solenoid as necessary, and by its motion to adjust the relative position of
the carbons; and contact-brushes or rollers or equivalent to slide or roll along the
solenoid as the core rises or falls and afford a passage to the current from one brush
to the other through the intervening portion of the solenoid, such "live" portion of
the solenoid extending beyond the movable core and thus attracting it with a uniform
pull in all positions, if the pitch of the solenoid windings is constant.

page_text: To balance the variation in weight of the carbons as they are consumed, I prefer to
lay the solenoid windings somewhat closer together at one end of the coil, and
gradually increase the distance apart towards the other end.
For series working a shunt coil may be carried by the solenoid core or carbon
holder to act upon the live portion if the series coil or solenoid either within or around
which it moves with the carbon holder.
Instead of a long solenoid only part of which is in use at once, I may employ a
short solenoid the whole of which is constantly active, and which is automatically
lowered to the required extent as the carbons are consumed.
This is conveniently effected as follows:-To the upper side of the solenoid is fixed,
in bearings in which it can rotate, a spindle or shaft carrying a ratchet-wheel or
equivalent. On this shaft is wound a chain or cord by which the solenoid is sus-
pended from the frame of the lamp; the ratchet-wheel being prevented in the usual
manner from rotating and allowing the cord to unwind by means of a pawl or
equivalent.
The position of the core carrying the carbon-holder is so arranged that, when the
solenoid is in a position suitable to the length of carbon at any time in the lamp, a
hook or equivalent attached to the top of the core is held clear of the pawl or some
lever or mechanism in connection therewith. As the carbons are consumed, the core
drops and eventually pulls the pull off the ratchet-wheel thus allowing it to revolve
and the solenoid to drop until the next tooth of the ratchet encounters the pawl.
To allow for the necessary amount of play between the solenoid and its core while
the latter is still exerting the same lifting power on the carbon-holder it will be
advisable that the cross-section of metal in the core shall diminish towards its upper
end either by coning or hollowing or both, the well-known effect being to equalise
the attraction between core and solenoid over a more or less considerable range.
To supply the current to this movable solenoid I may employ sliding connections
similar to those commonly used for leading the current to the carbons, and allow for
variation in weight of the carbons by means of stationary re-enforcing coils which act
the more strongly on the core the higher it stands.
The shunt coil for series working may be wound directly on the main solenoid to
which one end is attached, the other connection being by means of a flexible con-
ductor to one of the slides of the cross-bar carrying the upper carbon-holder and
solenoid-core.
Instead of the sliding connections and stationary re-enforcing coils just described,
I may use for conducting the current to and from the suspended solenoid extensible
coils which will act both as conductors and as re-enforcing coils for the solenoid,
acting the more strongly in the latter capacity the higher the solenoid stands.
Dated this 31st day of August 1889.
WILFRID S. BOULT.
COMPLETE SPECIFICATION.
Improvements in or relating to Arc Lamps.
I, WILFRID SWANWICK BOULT of 24 King's Mount, Birkenhead in the County of
Chester, Civil 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 :-
To strike and maintain the arc in an arc-lamp I employ a solenoid (or solenoids)
acting on a core attached directly to one of the carbon-holders, the said solenoid being
movable along the frame-work of the lamp, and having its position automatically
regulated in accordance with the length of carbons in the lamp.
One way of carrying out my invention is shown in figs. 1.and 2. of the accompany-
ing drawing and a modification of this design in fig. 3. I will first describe the
arrangement shown in figs. 1 & 2, which are a side and front elevation respectively;
the solenoid in the latter being shown in section.

page_text: In these, A and B are two vertical guides forming part of the main framework of
the lamp in accordance with the usual custom, C is the upper carbon-holder and C¹
the lower one, both being by preference insulated. As shown, only C is movable ;
but by well-known gearings the two carbon-holders, being made movable, may be
connected so as to maintain the arc more or less accurately in the same position, or
render the lamp "focusing." D is an iron core attached to C, and entering the
compound solenoid E F, in which E is a series coil of stout wire and F an opposing
shunt coil of fine wire as commonly used in arc-lamps. It is not essential that F
should be placed inside E: it may be outside or on top or below, as in the case of
other arc-lamps, or for parallel working, be dispensed with altogether. G is a sleeve
attached to E F and capable of sliding on the guide-rod A; H is a short sleeve or jaw
also attached to E F and embracing guide B with an easy fit so as to prevent E F
from swinging round A as an axis, but by preference not otherwise touching B, C
similarly slides on the guides A and B which pass through the sleeves J and K.
L M is a dash-pot arrangement consisting of an annular trough or "cylinder" M and
a loosely fitting piston, of 1 section, L; the latter attached to the solenoid E F.
Glycerine, oil, mercury, air, or other suitable fluid, placed in the trough M prevents
sudden jerky movement of C.
The solenoid E F is suspended from the top of the lamp frame by the cord or
chain N the lower portion of which is wound on the spindle O. Spindle O rotates in
bearings P on pedestals Q (carried by E F) and carries the ratchet-wheel R. S is a
pawl held against R by the spring T, and capable of being pulled back by the link U.
Interlocked with U, but capable of some vertical movement therein, is another link or
hook V, fixed to the end of the iron core D. This connection of D to S is capable of
very numerous modifications of detail; as for instance the use of a short length of
chain or cord, or side pressure of D upon a bell-crank shaped lever. Or the pawl
may be pulled from the ratchet-wheel by means of an electro-magnet, excited by a
circuit closed when D has sunk to a certain position. Current of suitable electro
motive force for this purpose may be obtained by tapping the coil F in suitable
places.
Electrical connection is made through the insulated terminals + and
-
- by means
of the insulated flexible conductor W to the bracket X, thence through the solenoid
coil E and flexible conductor Y to C, through the carbons to C', and by the insulated
wire Z up the inside of B to terminal The shunt circuit through F (W₁, fig. 2)
starts from a junction with the main circuit near the bracket X, and on leaving F, is
continued by the insulated flexible wire a, (for convenience laid round the flexible
conductor W), to the terminal With the circuits thus arranged in insulated con-
ductors the handling of the lamps is rendered much safer than when the framework
forms a part of the circuit as commonly is the case in arc-lamps, and as may be in
this lamp.
The action of the feeding apparatus is as follows:-When no current is passing,
the carbons lie together, but as soon as the current is switched on, the cord D is
sucked into the solenoid E F, and the are thereby struck.
As the arc increases in length, the effective power of the compound coil diminishes
in the usual way and the upper carbon is lowered until the link V, coming into
contact with U, withdraws the pawl S from the ratchet-wheel R. E F, with all it
carries, now drops by its own weight; but, in doing so, by the intervention of cord N,
causes R to rotate: simultaneously it releases S which consequently engages with the
next tooth of R. This movement is repeated at intervals as long as the lamp is
alight.
In order to lessen the weight to be lifted by E F (and consequently to enable the
size of coils to be kept as small as possible), and to keep the load constant notwith-
standing the consumption of the upper carbon, the device shown principally in fig. 1
may be employed. The lever b, (also shown in section in fig. 2), is hinged at one
end to the link c and is pulled up at the other end by the spring d. At about its
centre it partially takes the weight of C, D, &c., the amount of upward pressure
depending upon the pull of d. To the upper end of d is attached the cord e, the upper

page_text: portion of which is wound on the spindle f, which also carries the toothed-wheel g in
gear with the pinion h on spindle O. As this last rotates, step by step, as explained
above, it slowly rotates g and f, paying out the cord e and consequently lessening the
pull of d on b.
To wind up the lamp for the reception of fresh carbons, the cord j and winding
barrel are provided.
Fig. 3 is a front elevation showing a method of lowering the solenoid by means of
a rack and pinion instead of a suspending cord. In this fig. the same letters have the
same signification as in figs. 1 & 2. Also, is a pinion on spindle O in gear with a
rack A¹ on guide bar A. The action of the ratchet-wheel and pawl is exactly as
already described. The lamp is "wound" by simply pushing up the carbon holder, &c.
A different arrangement of lifting-spring and compensating-gear is shown. m is the
spring, its lower end being attached to the sleeve J and its upper end to the tongue n
proceeding from the sleeve o. To prevent
o from turning round on the rod B, the
tongue n passes through a guide p on the sleeve H. From o a cord q is led over the
pulley to the barrel s on the shaft O. The diameter of s is such that, as the solenoid
descends, a length of q is paid out rather greater than twice the corresponding
movement of the solenoid. It will be an advantage in all cases where cords are
wound on barrels or shafts that a screw cut or channel be formed therein for the
cord to lie in.
Instead of the barrel s, cord q, and pulley r, the following arrangement may be
adopted for governing the movement of sleeve o-Spindle O may be geared, either
directly by a very small pinion on its end, or by intermediate.gearing, with a rack on
sleeve o, so that as E F descends, sleeve o is gradually brought nearer to sleeve H.
The details shown in the drawings and described above are capable of great variation
without departing from the spirit of my invention.
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. In an Arc Lamp, for striking and regulating the are, a movable solenoid capable
of automatically accommodating its position to the length of carbons remaining in the
lamp, substantially as described and illustrated in the accompanying drawings.
2. In an Arc Lamp, for lowering a suspended solenoid such as named in claiming-
clause No. 1 above, the use of a cord or equivalent, such as wound on a shaft or
barrel, such as O, which by means of a ratchet-wheel or equivalent (for instance a
brake-wheel and brake), such as R and S, is prevented from turning, until released
by the dropping of the carbon-holder, substantially as described and illustrated in the
accompanying drawings.
3. In an Arc Lamp, (winding-gear such as j, k, for raising the solenoid and carbon-
holder for the reception of fresh carbons, substantially as described and illustrated in
the accompanying drawings.
4. In an Arc Lamp, for lowering a movable solenoid such as named in claiming-
clause No. 1 above, a ratchet-wheel or equivalent, such as R, pinion, such as l, and
rack, such as A³, actuated substantially as described and illustrated in the accom-
panying drawings.
5. In an Are Lamp, relieving or balancing springs and connections substantially as
described and illustrated in the accompanying drawings.
6. In an Arc Lamp, an annular or other shaped dash-pot formed directly between
the movable solenoid and the crosshead forming or carrying the movable carbon-
holder.
7. The combination and arrangement of parts forming the complete Arc Lamp sub-
stantially as described and illustrated in the accompanying drawings.
Dated this Sixth day of June 1890.
WILFRID S. BOULT.