Improvements in Arc Electric Lamps.
Year: 1893

page_text: Date of Application, 21st Mar., 1893-Accepted, 6th May, 1893
COMPLETE SPECIFICATION.
Improvements in Arc Electric Lamps.
We, JAMES EGLINTON ANDERSON GWYNNE, Civil Engineer, and RANKIN
KENNEDY, Engineer, both of Brooke Street Engineering Works, Brooke Street,
Holborn, in the County of London, 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 :-
Our invention relates to electric arc lamps in which the regulation of the
movement of the carbon holders is effected directly by the movement of the core or
cores of one or more solenoids without the aid of clockwork clutches or other
mechanism and has for its objects, firstly to increase the duration of the lighting
or burning period, relatively to the lengths of the solenoids and cores of an arc
electric lamp, and secondly to adapt such lamps to work effectively with alternating
currents as well as with continuous currents.
In order that our invention may be clearly understood we have appended the
accompanying sheets of drawings in which :
Figure 1, Sheet 1 is a front elevation of a lamp shewing the gearing and method
of suspension Figure 2 is a side elevation and Figure 3 a plau diagram shewing
relative position of coils and carbon holders.
Figure 1 on Sheet 2 is a front elevation of a lamp in which the gearing for
extending the lighting period is dispensed with, but suitable cores for alternating
currents are adapted thereto.
Figures II and III are front and side views of the cores aforesaid drawn to a
larger scale.
Similar reference letters are used on each sheet to indicate corresponding parts in
the several views.
In carrying our invention into effect we place a spindle a Figures 1, 2, and 3
Sheet 1 at the top of the lamp frame, above the shunt and series solenoids A and B.
Said spindle a carries two grooved wheels b and c which are of different dimension
radially the ratio being determined by the required length of carbon feed
relatively to the effective range of travel of the cores within the solenoids. The
smaller wheel b supports by means of a cord or equivalent d the tapered cores ƒƒ'
within the magnetic fields of the solenoids A and B.
Normally, when the lamp is set ready for use, one core is withdrawn to the full
extent, and that within the series solenoid is correspondingly immersed, and the
duration of the feed depends upon the range of said cores in reversing their order
of position. The larger grooved wheel c carries a cord or equivalent which is
attached at each end to the upper carbon holder C with its guide 9 and the lower
holder D with guide g'. The effect of the interposition of this gearing is that in
the preliminary striking of the arc, and in all the movements incidental to the
automatic regulation of the feed of said carbons, a very small movement of the
cores suffices to effect the desired purpose. The relative movements of the cores
and the carbon holders are in direct ratio to the difference of the radii of the
wheels b and c.
We may without departing from our said invention vary the position of the
wheels and we may also in certain cases employ any greater number than two for
further increasing the duration of the lighting period relatively to the travel of
the cores.
The second part of our invention relates to the adaptation of arc electric lamps
to circuits traversed by alternating currents. It is well known that the rapid
magnetization and demagnetization due to the reversal of polarity at each
alternation tends to heat the core and other adjacent parts, by reason of the rapid
molecular action due to magnetism as aforesaid and partly to the development of

page_text: eddy currents in the mass. Referring to Figures II and III Sheet 2 a tapered
core is shewn, which acts effectively as a regulator when used in an alternating
current circuit, without becoming unduly heated.
A plate i preferably of non-magnetic metal or material is made of such width as
to freely fit the bore or magnetic field of the solenoid, and therefore act as a guide,
and also as a means for suspension. Upon each side of the oblong plate i we attach
by rivetting or other equivalent means a series of soft iron plates j which are
tapered, so that the magnetic and mechanical effects due to the use of a tapered
core are produced independently of the fact that the plate i approximately fits the
hollow field.
These cores may be used as shewn by Figure 1 Sheet 2 upon a double solenoid
lamp in which the carbon holders C and D are directly attached to the plates i of
the cores suspension being effected by a cord or equivalent d passing over a
grooved wheel b suitable guides 9 g' being used to reduce friction and promote
a steady and uniform feed of the carbons.
Although we have shewn in the drawings the laminated tapered core adapted to
a lamp in which the carbon holders are directly attached to said cores, we wish it
to be understood that said cores may also be adapted with equal facility and
efficiency to a differential gearing as herein before described, rendering it applicable
to an alternating current circuit. Therefore that part of our invention relating to
said gearing for increasing the duration of the lighting period of an arc electric
lamp is applicable to continuous current circuits when a solid core or cores is or are
used, and to alternating current circuits when a laminated tapered core as herein-
before described, is used, and that part of our invention relating to said core is
applicable to any kind of lamp, whether the carbon holders are directly attached
thereto or by the interposition of gearing.
In order to equalise the pull of the cores on the carbon holders we may place a
sprocket wheel m on the spindle of the differential gear and cause the revolution of
the same to lift a chain n it being understood that when fresh carbons are inserted
in the holders the weight of the chain to be raised acts against the pull of the core
in the shunt solenoid.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that
what we claim is :-
I. In an arc electric lamp the combination of multiple gearing with a tapered
core or cores and carbon holders substantially as herein described with reference to
Figures 1, 2 and 3 Sheet 1 and for the purpose stated.
II. In an arc electric lamp the combination of a laminated tapered core or cores
with a carbon holder or holders substantially as herein described.
III. In an arc electric lamp the combination of a laminated tapered core or cores
with an arrangement of differential gearing and carbon holders, substantially as
herein described.
IV. In an electric arc lamp in which the length of the arc is regulated by
moving tapered cores the combination of a compensating chain and pulley with the
said cores as and for the purpose set forth.
Dated this 21st day of March 1893.
FREDK. WALKER,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicants.