Improvements in Alternating Current Aro Lamps.
Year: 1893

page_text: Date of Application, 1st Feb., 1893
Complete Specification Left, 30th Oct., 1893-Accepted, 20th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Alternating Current Aro Lamps.
I JAMES EGLINTON ANDERSON GWYNNE Civil Engineer of Brooks Street
Holborn London, E.C. England do hereby declare the nature of this invention to
be as follows:
-
This invention relates to improvements in electric arc lamps and more especially
to that class, workable by alternating electric currents, and suitable for photographio
and other purposes.
This invention has for its object the construction of an are lamp for photographic
and other purposes suitable for working with alternating currents.
According to this invention the lamp is constructed so that the regulator works
freely when the lamp is inclined at an anglo of about forty-five degrees. The
regulator consists of a tapered laminated iron core moving freely through a solenoid
carrying the main current, this core is balanced by a cord passing over a grooved
pulley and carrying a counter weight.
The core is made about four ounces heavier than the counter weight so that the
core moves forward by gravity and to prevent the core being pulled too far into
the solenoid at any time when striking the are the grooved pulley is cut with
ratchet teeth into which a pawl fits, for the purpose of preventing motion in one
direction further than that required to form a good aro, this motion is regulated in
extent by a screw attached to a pin acting on a tail piece attached to the rocker
carrying the pawl.
The solenoid is wound on a spool of insulating material and consists preferably
of stranded copper wire of large section.
The laminated tapering core is built up of thin strips of soft iron each strip out
a little shorter than the one laid on previously, this core is tapered only in one
way and the middle rib is built up with parallel edges the whole length of the core.
The upper carbon holder is carried on the lower or thick end of the core, and the
upper end of the core is fixed to a cord passing over a ratchet wheel and to a
counter balancing weight.
In photographic use the lower carbon holder is made to slide on a tube so that
it can be moved by hand to any desired distance from the upper holder.
In operating the lamp the alternating current energizes the thick wire solenoid
and pulls the core into it. As the carbons part from cach other the arc is formed
and the current reduced in strength, and as it burns away the current is still
further reduced until the weight of the core and carbon holder overpowers the pull
of the solenoid at this point the carbon slides down a sufficient distance to
re-establish the proper length of are.
A choking coil is not necessary with this lamp, the solenoid and core act as a
choking coil besides acting as the regulator of the lamp.
The ratchet wheel and pawl prevent the drawing of too long an arc at the
instant of switching on or in the event of the carbons coming suddenly together.
For ordinary purposes the lamp is built as a Pilsen lamp with a main and shunt
coil have two tapering laminated cores one in each coil, and the upper carbon
holder is attached to the core in the main coil, the lower carbon holder is attached
to the core in the shunt coil the cores are hung on the ratchet pulley by a cord.
The main coil pulls the carbons apart while the shunt coil feeds them together.
Dated this 30th day of January 1893.

page_text: Improvements in Alternating Current Aro Lamps.
I, JAMES EGLINTON ANDERSON GWYNNE, of Brook Street, Holborn in the
City and County of London, Civil Engineer do hereby declare the nature of this
invention and in what manner the same is to be performed, to bo particularly
described and ascertained in and by the following statement :-
My invention relates to certain improvements in are electric lamps, and especially
to those adapted to alternating currents, and suitable for photographic and other
purposes, and has for its object the production of a steady feeding and reliable
lamp for the purposes set forth.
In order that my invention may be the better understood, I have appended the
accompanying two sheets of drawings, in which
Figure 1 Sheet 1 represents a lamp with a single solenoid and core, and
Figures 2 and 3 upon the same sheet are respectively front and end clevations of
a double solenoid lamp based upon the principles embodied in my said invention.
Figures 4 and 5, Sheet 2 are respectively front and end olovations of a means
for suspending said lamp for ready adjustment, and Figures 6 and 7 upon the same
sheet represent front and end clovations of a portable and adjustable carriage for
the same purpose.
In carrying my invention into effect I proforably construct the lamp so that its
regulator works freely when said lamp is inclined at an angle of about 45°, said
regulator consisting of a tapered laminated iron core, within the field of a
solenoid, with a counterweight suitably arranged to balance it, as hereinafter
described.
When a single solenoid is used, as in Figure 1, indicated by A, it is preferably
wound upon a tube or spool of insulating material, the winding consisting preferably
of stranded copper or other conducting wire of such sectional area as to present a
negligible resistance when connected in series to the main circuit.
The laminated tapered core a is preferably built up of strips of soft iron, each
strip being cut shorter than the one previously laid in position, and the centre
portion is preferably made of Gorman silver, or other non-magnetic metal or
material, and shaped to fit the tube forming the internal bore of the solenoid A,
thereby acting as a guide, and as a means for suspension of the magnetic portion
of the tapered core a. The upper carbon holder is attached to, or carried by the
lower or thicker end of the core a, the upper end of the same being fixed to a
cord or equivalent, c which passes over a grooved pulley provided with a ratohet, d;
and thence to the counterbalancing weight within the tube
The core a and its carrier bis preferably made to weigh in excess of the
counterweight e, so that the former is moved forward by gravity, and also to
prevent its being drawn into the solenoid A too suddenly when striking the arc,
and the grooved wheel or pulley d is cut upon one or both sides of its grooved
face with ratchet teeth, into which a pawl 'g engages, so as to limit the motion in
one direction in which said wheel may move when striking the arc, the distance
or length of which may be predetermined or regulated by a screw projecting
from a tail piece extending from the rocker carrying the pawl g. In this form of
lamp the lower carbon holder B is made to slide within or upon a tube f so that it
may be moved into any required position by hand. The operation of this lamp
may be described as follows, that is to say ;-
When the passage of the electric current energises the solenoid A, it draws
the core a into it, thereby parting the carbons and forming the arc, and as the
consumption of the carbons increases, the current passing through the coils of A
is reduced by reason of the increased resistance of the are, allowing the upper

page_text: carbon, carried by the core a to descend sufficiently to maintain said are at its
normal or predetermined length.
The action of the core and solenoid in this case obviates the use of a choking
coil since the regulation is thoroughly effected by these means.
A modification of the foregoing device according to my said invention is shewn
by Figures 2 and 3, Sheet 1, representing respectively front and end elevations of
a double solenoid lamp. In this caso, the series, or thick wire solenoid A. is placed
in the same axial plane with a shunt or fine wire solenoid A', a core a fixed to a
German silver, or other magnetic strip & boing placed within its field, and upon the
same strip b, which is common to both cores, is fitted a second core a¹ preferably of
smaller sectional area, so as to be within the field of the shunt coil A'. The upper
end of the strip or picce & forming at once the foundation and guide for the two
cores a and a', is connected to a cord or the like c passing over the pulley or
ratchet wheel d, which is controlled by the pawl g, which is regulated by the
screw fitted to an extension of the rocker carrying said pawls. The balance
weight e fixed to the free end of the cord c, is made to slide freely within the
tube which carries the fixed lower carbon holder B, and the concentrator or
reflector D. Said tube f. forms the base or foundation of the structure of the
lamp, which is preferably inclined when in uso, and wheels or rollers j are
provided to reduce the friction of the weight e. The weight of the upper carbon
holdor C is borne by a wheel or roller K working upon the inner surface off.
The action of this modification may be described as follows, that is to say ;-
When the main, or series coil A is energised by the current passing round it, the
two cores a and a' are moved upwards, since they are attached to a common base
or foundation b. The arc is thus established, its longth being regulated by the
adjustment of aud upon the wheel d. As the carbons are consumed the
energy of the solenoid A is decreased and that of A' is correspondingly increased,
thus maintaining with the constant gravitating force of the weight e a regular
and steady feed.
.
In order to render the lamps made in accordance with my invention portable
and adjustable in all cases of adaptation I employ the devices shewn by
Figures 4, 5, 6, and 7, Shoot 2. Referring to Figuro 4, which represents a means
for suspension, Figure 5 upon the same sheet being an end elevation thereof
similarly altered, a rod E carries the lamp with its reflector J at one end, and a
counterweight K at the opposite end, said rod E working freely through a socket F
from a point of suspension G. A joint at H carrying a gimbal frame I allows of
lateral adjustment from this point which is practically the third point of
suspension, adjustment being easily effected at each. The actual position of the
lamp is shewn by Figure 5, the shade or reflector J being shewn in section for that
purpose. Figures 6 and 7 shew front and end elevatious respectively of a portable
carriage or frame, made preferably of tubes or metallic piping, and mounted upon
rubber or elastic tyred wheels L L', a pointed knob M similarly capped or tipped
serving to maintain the rigidity of the portable lamp when once placed in position.
The lamp, carried by the gimbal I is supported by a cord o passing over a
pulley N, and attached to a winch P for vertical adjustment, and to further
enlarge the range of said adjustment the members R R R" of the frame may be
so constructed as to be capable of telescopic movement.
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 :-
First. In an are electric lamp the employment of a laminated tapered core or
cores, within one or more solonoids carrying a carbon holder at one end, and being
supported by a counter weight at the other, over a grooved pulley with a ratchet
and pawl substantially as herein described with reference to the appended
drawings.
Second. In an electric arc lamp the construction and use of a laminated tapered

page_text: core a upon a non magnetic base & in combination with a series solouoid A,.a.
counterweight ratchet pulley d and pawl o substantially as herein described with:
especial reference to Figure 1 of the appended drawings.
Third. In an electric arc lamp the construction and use of two laminated
tapered cores, fixed upon one non magnetic base, and operating within two
solenoids respectively series and shunt, with the main circuit, in combination with
a ratchet pulley and pawl, and counterweight, substantially as lierein described
with especial reference to Figures 2 and 3 of the appended drawinge.
Dated this 23rd day of October 1803
FREDK. WALKER,
73, St. Stephen's Road, Upton Park, London, E.C.,
Agent for the Applicant.