Improvements in Electric Arc Lamps.
Year: 1889

page_text: Date of Application, 2nd Nov., 1899
Complete Specification Left, 2nd Aug.. 1890-Accepted, 2nd Dec., 1890
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
1. HENRY HARPER, of 3, Cornwall Gardens, Queen's Gate, in the County of
Middlesex, Electrical Engineer, do hereby declare the nature of this invention to he
as follows:-
:
This invention relates to solenoid are lamps for electric lighting, and consists,
first, in improved means for regulating the feed of the carbons, secondly, in an
improved method of constructing the solenoid-core whereby it is rendered specially
adapted for use with alternating currents, and, thirdly, to certain devices for
enabling the carhons to be readily fixed and accurately centred and otherwise for
ensuring efficiency in the working of the lamp.
An are lamp constructed in accordance with this invention comprises a single
solenoid of a length determined by the number of hours the lamp is required to
burn continuously and composed of a single tube having two flanges; the tube
and flanges being split longitudinally to prevent heating by induced currents.
The frame forined by the tube and flanges is wound with a wire of sufficient size
to carry the current required for a given candle power. The solenoid when wound
is fixed to a base-plate. To the under side of the latter, and at a convenient
distance apart, are attached two longitudinally-grooved rods; the groove in one
rod facing the groove in the other rod. The lower ends of the rods are, to ensure
stability, joined together by a cross-piece, which also serves to support the gallery
for the globe. The grooved rods act as guides for the top and bottom carbon-holders.
The solenoid-core consists of a bundle of iron wires; each wire being insulated by a
covering of cotton, or by shellac, or in any other suitable manner. The respective
wires are placed lengthwise in a split tube of brass or in an unsplit tube of
vulcanite, fibre or other non-conducting material. To the lower end of the tube
appertaining to the solenoid-core is rigidly attached the cross-piece carrying the
upper carbon-holder, which comprises a socket fitted with a radial set-screw for
receiving and holding the carbon the socket being attached to the cross-piece by a
ball-joint in order that the carbon may have the desired freedom of movement. The
joint is preferably constructed in the following manner :-A vertical hole terminating
at its upper end in a cup-shaped cavity is formed in a boss in the centre of the cross-
piece. A screw with a ball-shaped head is then passed through the hole and firmly
screwed into the top of the socket; the head of the screw fitting within the cavity.
The bottom of the solenoid-core-tube, which is provided with a plug containing a
recess corresponding with the cup-shaped cavity, may then be screwed into the boss ;
the parts being thus securely held in position. The lower end of the upper carbon is
passed through and guided by a hole in a plate which is fastened to a cross-bar carried
by the grooved rods and is situated about three-quarters of an inch above the arc.
This plate is rendered removable, so that, should the guide-hole therein be too large
or too small, a plate containing a larger or a smaller hole may be substituted. The
extremities of the cross-piece to which the upper carbon-holder is pivoted are
furnished with guide-wheels which may be of brass and which run in the grooves
in the guide-rods. To the top of the solenoid-core is attached a two-eyed swivel to
which are connected cords running over two grooved pulleys mounted on the top of the
solenoid; these cords being in turn connected to two vertical rods fixed to the lower
carbon-holder cross-piece. The latter is provided at each end with a guide-wheel
formed of insulating material, held between two central brass plates or collars, through
which the brass pivot-pin is passed. For these guide-wheels, I prefer to employ mica,
which, besides being a good non-conductor, is well adapted to withstand the heat
radiated by the electric arc. The socket of the lower carbon-holder, in which the

page_text: lower carbon is held by a set-screw, is connected to its cross-piece by means of a
ball-joint of the following description:-A tapér pin with a ball-shaped head and a
screw-threaded extremity is passed from the under side through a central boss
projecting from the upper surface of the cross-piece and is screwed firmly into
the socket. A small cap is fastened by screws, over the head of the pin, to the cross-
piece in order to keep the parts in position vertically. Three radial adjusting screws
are screwed at equal distances apart through the boss and against the neck of the taper
in adjustment of the lower carbon-holder being by their means readily effected.
Dated this 2nd day of November 1889.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, HENRY HARPER, of 3, Cornwall Gardens, Queen's Gate, 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
This invention relates to solenoid are lamps for electric lighting, and consists, first,
in improved means for regulating the feed of the carbons, secondly, in an improved
method of constructing the solenoid-core whereby it is rendered specially adapted for
use with alternating currents, and, thirdly, to certain devices for enabling the carbons
to be readily fixed, accurately centred, and so guided as to ensure efficiency in the
working of the lamp,
In the accompanying drawings,
Fig. 1 represents, in vertical section, an arc lamp constructed in accordance with
this invention.
Figs. 2 to 11 are detail views drawn to larger scales. Fig. 2 is a vertical section
of the improved solenoid-core; Fig. being a corresponding horizontal section.
Fig. 4 is a vertical section of the base-plate; Fig. 5 being a corresponding plan.
Fig. 6 is a plan shewing the pulleys on the top of the solenoid. Fig. 7 is a plan of
the upper cross-piece; Fig. 8 being a corresponding side elevation. Figs. 9 and 10
are similar views of the lower cross-piece and carbon-holder. Fig. 11 is a plan of the
cross-piece employed for uniting the two grooved rods which serve as guides for the
carbon-holder cross-pieces.
The improved are lamp is provided with a solenoid A of a length determined
by the number of hours the lamp is required to burn continuously, and comprising
a tube a having two flanges a¹ and a² and gills a³; the tube, flanges, and gills being
split longitudinally to prevent heating by induced currents. The frame formed by
the tube, flanges, and gills is wound in series with the lamp circuit with wire of
sufficient size to carry the current required. An inner coil of fine wire in a shunt to
the lamp circuit is wound on the tube a*. The magnetizing influence of the current
.flowing through the outer coil of thick wire is diminished to an extent corresponding
with the current flowing through the inner coil of thin wire, as explained in my
Specification No. 13,389, of 1889. The tube a* and the inner coil may, when the
lamp is one of a set connected parallel, be dispensed with. The coils of wire are,.for
the sake of clearness, omitted from the drawing. The solenoid is fixed to a
base-plate B. To the under side of the latter, and at a convenient distance apart,
are, attached two longitudinally-grooved rods and C₁; the groove e in one rod
facing the groove c¹ in the other rod. The lower ends of the rods are, to ensure
stability, joined together by a cross-piece D, which also serves to support the
gallery E for carrying a globe. The grooved rods and act as guides for the
cross-pieces carrying the holders of the upper and under carbons.
The solenoid-core A', which is specially adapted for use with alternating currents,
comprises a bundle of iron wires a; each wire being insulated by a covering of
cotton, or by shellac, or in any other suitable manner. These wires are placed length-

page_text: wise in a split tube a of brass, or in an unsplit, tube of vulcanite, fibre or other
non-conducting material. To the lower end of the tube a' is rigidly attached the
cross-piece F carrying the upper carbon-holder G, which comprises a socket; g fitted
with a radial set-screw q for receiving and holding the carbon K; the sockety being
attached to the cross-piece F by a ball-joint in order that the carbon may have the
desired freedom of movement. The joint is preferably constructed in the following
manner: A vertical hole terminating at its upper end in a cup-shaped cavity is
formed in a boss f in the centre of the cross-piece. A screw g² with a ball-shaped
head g³ is then passed through the hole and firmly screwed into the top of the socket;
the lower part of the head of the screw fitting within the cavity. The bottom of the
solenoid-core-tube a, which is provided with a plug a containing a recess corre-
sponding with the cup-shaped cavity and fitting over the upper part of the head,
may then be screwed into the boss f; the parts being thus securely held in position.
The lower end of the upper carbon is passed through and guided by a hole in a
plate L, which is fastened to a cross-bar L' carried by the grooved rods Cand C,
and is situated about three-quarters of an inch above the arc. This plate is made
removable, so that, should the guide-hole therein be too large or too small, a plate
containing a larger or a smaller hole may be substituted. The extremities of the cross-
piece F are furnished with guide-wheels F1 and F, which may be of brass and which
run in the grooves c and c. To the top of the solenoid-core is attached a two-eyed
swivel a to which are connected cords as and a running over two grooved pulleys a¹º
and a mounted on the top of the solenoid; these cords being in turn connected to
two vertical rods mand m* fixed to the lower carbon-holder cross-piece M.
These rods pass through holes in the base-plate B, from which they are insulated
by perforated plates of non-conducting substance. The cross-piece is provided.
at each end with a guide-wheel M or M² formed of insulating material held
between two central brass plates or collars m³ or m², through which the brass
pivot-pin morm is passed. For these guide-wheels, I prefer to employ mica,
which, besides being a good non-conductor, is well adapted to withstand the heat
radiated by the electric arc. The socket n of the lower carbon-holder N, in which
the lower carbon K is held by a set-screw n¹, is connected to the cross-piece M
by means of a ball-joint of the following description:-A taper pin n² with a ball-
shaped head n³ and a screw-threaded extremity is passed from the under side through
a central boss m³ projecting from the upper surface of the cross-piece and is screwed
firmly into the socket n. A small cap m is fastened by screws m³, over the head n³
of the pin, to the cross-piece in order to keep the parts in position vertically. Three
radial adjusting screws ms are screwed at equal distances apart through the boss m
and against the neck of the taper pin n²; adjustment of the lower carbon-holder N
being by their means readily effected.
For use with a continuous current, a solenoid-core of the kind described and
claimed in my Specification No. 13,3898 may be substituted for the core A' above
described.
The positive wire from the generator is connected to the binding post O, whence the
current flows to the outer coil a of the solenoid. From the latter it passes into the
base of the rod o and along that rod, the top of which is electrically connected by a
flexible wire with the rod f' carried by the cross-piece F. From the rod f', the
current flows into the upper carbon K, thence into the lower carbon K', along the
rod m and through a flexible wire to the binding rod o' and thus to the binding
post O, to which the negative wire leading to the generator is connected.
The inner coil a' is connected in shunt as described in my Specification No. 13,389
of 1889.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. In an alternating current electric are lamp being one of a set connected parallel,
effecting the feed of the carbons by gravity acting in conjunction with a solenoid coil

page_text: on a core consisting of a number of insulated iron wires enclosed in a non-magnetic
tube and connected directly to the upper carbon substantially as herein described.
2. In an electric are lamp, the combination, with the holder G and screw g² having
a ball-shaped head g³, of the cross-piece F secured to the solenoid-core, substantially
as and for the purposes set forth.
3. In an electric are lamp, the combination, with the holder N.and pin n³ having a
ball-shaped head n³, of the cross-piece M, having a boss m furnished with set-screws m
and a cap me, substantially as and for the purposes set forth.
4. In an electric are lamp, for insulating the moveable cross-piece carrying one of
the carbons, guide-rollers made of non-conducting material, substantially as herein
described.
5. The electric are lamp constructed and operating substantially as described with
reference to the accompanying drawings.
Dated this 24th day of July 1890.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicant.