Improvements in and connected with Arc Electric Lamps.
Year: 1894

page_text: Date of Application, 25th Oct., 1894
Complete Specification Left, 25th July, 1895-Accepted, 14th Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in and connected with Arc Electric Lamps.
We JAMES EGLINTON ANDERSON GWYNNE of Brooke Street Works Holborn
in the City of London Civil Engineer and RANKIN KENNEDY of 1 Clifton Villas
Camden Square Camden Town in the County of London Electrician, do hereby
declare the nature of this invention to be as follows:-
This invention relates to electric arc lamps especially to lamps used for photo-
graphic purposes and has for its objects the utilization of the energy now wasted
by passing the current through resistances (when such lamps are supplied from the
ordinary electric mains or supply circuits) in order to reduce the E.M.F. and
current in the lamp circuit and further to facilitate the focussing of the light upon
the subject and of the image in the camera.
When only one are lamp is used on a 100 volt circuit a resistance must be
placed in series. with it in order to dissipate or absorb sufficient energy to reduce
the E.M.F. of the current passing through the lamp to 60 volts or thereabouts but
if two lamps are placed in series each lamp can be adjusted to 45 or 40 volts so
that the two together (when connected in series) will take 80 to 90 volts leaving
from 10 to 20 volts only to be absorbed by the resistance.
Now according to this invention instead of using two lamps in series we provide
in one lamp two or more pairs of carbons connected so as to form two arcs in
series the movement of the two pairs of carbons being regulated by one electro-
magnetic apparatus.
The pairs of carbons are placed side by side so that the arcs are contiguous to
each other.
Only one pair of carbons are movable, and these are insulated from each other
and from the body of the lamp.
The other pair of carbons are fixed, and one of the said carbons is insulated
from the body of the lamp while the other is in electric connection therewith so
that the current enters one of the movable carbons passes across to the insulated
fixed carbon forming arc Number 1.
From the fixed carbon it passes along an insulated conductor to the other
movable carbon thence across to the other fixed carbon and from thence to the
exit terminal forming are Number 2.
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The mechanism we prefer to employ for regulating the movement of the carbons
is that commonly known as the "Pilsen regulator the two movable carbons
being carried on the lower end of the double tapered cores.
The carbou holders are attached to or from part of a cross head attached to a
square pin on the tapered core which pin fits loosely in a square hole in the cross
head a washer pressed against the cross head by means of a spring (the tension of
which may be regulated by a nut) prevents the cross head from oscillating freely
about the pin and yet allows sufficient play to ensure the proper distance apart of
each pair of carbons forming an arc.
For instance if one pair of carbons burnt away faster than the other and the
carbon holders were rigidly attached to the regulator the two arcs would not be
equal and after a time the light would be extinguished owing to the current being
unable to pass the distance between the two easily burnt carbons, the compensating
arrangement allows the distance between each pair of carbons to be adjusted to the
normal each time the arc is struck.

page_text: Although we have described our lamp as fitted with the Pilsen regulator, yet
we do not confine ourselves to this as any other suitable regulator may be
employed.
For focussing we combine with the arcs two or more incandescent lamps fixed in
the reflector (preferably in the front thereof) and connected with the source of
current by a separate switch so that the light may be focussed on the subject and
the image on the screen by means of the incandescent lamps alone before the ares
are switched on.
Dated this 25th day of October 1894.
and connected with Are Electric Lamps.
We JAMES EGLINTON ANDERSON GWYNNE of Brooke Street Works Holborn
in the City of London Civil Engineer and RANKIN KENNEDY late of 1 Clifton
Villas Cumberland Square Camden Town but now of The Phoenix Dynamo
Works Hubert Street Bradford in the County of York Electrician, 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 electric arc lamps and especially to lamps used for
photographic purposes and has for its objects the utilization of the energy now
wasted by passing the current through resistances (when such lamps are
supplied from the ordinary electric mains or supply circuits) in order to reduce
the E.M.F. and current in the lamp circuit and further to facilitate the focussing
of the light upon the subject and of the image in the camera.
When only one arc lamp is used on a 100 volt circuit a resistance must be
placed in series with it in order to dissipate or absorb sufficient energy to reduce
the E.M.F. of the current passing through the lamp to 50 volts or thereabouts
but if two lamps are placed in series each lamp can be adjusted to 45 or 40 volts
so that the two together (when connected in series) will take 80 to 90 volts leaving
from 10 to 20 volts only to be absorbed by the resistance.
Now according to this invention instead of using two lamps in series we provide
in one lamp two pairs of carbons connected in such a manuer as to form two
arcs in series the movement of the two pairs of carbons being regulated by one
electro-magnetic apparatus.
The two pairs of carbons are placed side by side so that the two arcs are
contiguous to each other. Only one pair of carbons (preferably the upper pair)
are movable and these are insulated from each other and from the body of the
lamp.
The other pair of carbons are fixed and one of these carbons is insulated from
the body of the lamp while the other is in electric communication therewith so
that the current enters one of the movable carbons passes across to the insulated
fixed carbon forming arc Number 1. From the fixed carbon the current passes
along an insulated conductor to the other movable carbon across to the other fixed
carbon forming are Number 2 and thence to the exit terminal or the current may
enter the fixed carbons and pass out through the movable ones.
The mechanism we prefer to employ for regulating the movement of the carbons
is of the type known as the "Pilsen" regulator and consists of one series and two
shunt solenoids each solenoid being provided with a tapered core the movable
carbons being carried in holders attached to the lower ends of the cores passing
through the shunt solenoids.

page_text: Figs. 4 5 and 6 are details hereinafter referred to.
The same letters denote the same parts in all the figs, the lamp shewn being
regulated on the "Pilsen" system by means of tapered cores passing through
solenoids. A. B. are the shunt solenoids through which pass the solf iron
cores C. C¹ moving freely within the solenoids. The cores may be laminated to
ensure cool working and the central portion of the cores may be made of non-
magnetic metal. To these central portions of the cores are secured the carbou
holders D. D' the said holders being insulated from the cores. P. P are guide
pulleys provided with flanges between which move the central plates of the
cores C. C. M is the series solenoid and N the core passing through it and sliding
freely in the metal tube O. K. is a cord one end of which is attached to the
core N'and the other end secured to a guide bar R. moving between the guile
pulleys P P P P¹. H is a pulley over which the cord K passes. Pivoted to the
guide bar by means of the square pin S. is the rocking lever Q from the ends of
which are suspended the cores C C₁ the said cores being provided with pins E E¹
which engage with slots formed in the ends of the lever Q.
The lower end of the guide bar R has a ratchet formed thereon which engages
with a pawl W to prevent the carbons from being two widely separated each time
the arc is struck. The lower carbons are secured in the stationary holders c and e
whereof C is insulated from the body of the lamp and e is in electric contact
therewith and with the tube O which tube is in electric communication with the
exit terminal (not shewn) of the lamp.
The positive terminal g is insulated from the carbon holders and from the body
of the lamp the current passes from the terminal g along wire a round solenoid M
down insulated wire b to carbon holders D¹ across arc No. 1. to fixed carbon
holder c along insulated conductor d to carbon holder D across arc No. 2 to carbon
holder e and along tube O to negative terminal.
Each shunt solenoid is connected across the arc to the carbon holder of its own
core so that if oue arc is longer than the other the core connected to the long arc

page_text: will be drawn in by the shunt solenoids and the rocking lever will oscillate slightly
on the pin S. shortening the long are and lengthening the short one until the arcs
are equal. If both arcs are long then both shunt cores will be drawn into the
solenoids and overpower the pull of the series solenoid on its core and the ares will
be shortened, but if both arcs are, too short then the series solenoid will become
sufficiently powerful to overcome the shunt solenoids and the arcs will be
lengthened. Thus by balancing the magnetic. pull of the series solenoid against
that of the shunt solenoids the lamp is fed and by balancing the magnetic pull of
one shunt solenoid against that of the other equality of the two arcs is maintained.
The weight of one shunt core with its attachments should be exactly equal to the
weight of the other shunt core and its attachments, and the weight of the two shunt
cores with their attachments guide bar and rocking lever should balance the weight
of the series core and its attachments. The solenoids. should be wound in such a
manner that the magnetic pull of the series solenoid on its core is equal to the
combined magnetic pull of the two shunt solenoids on their cores and the magnetic
pull of each shunt solenoid should be equal.
The cores of all solenoids should be guided and the weight thereof borne.by
antifriction rollers so as to enable the cores to move with as little friction as possible
and without shaking. An equalising pulley may be used instead of the rocking
lever. Instead of the shunt cores being attached to the rocking lever as shewn the
said lever may be placed below the cores and the carbon holders attached thereto
instead of to the cores.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In an electric are lamp the combination of two fixed carbon holders, with two
movable carbon holders actuated by one electro-magnetic apparatus whereby two
ares in series are maintained and equalised substantially as hereinbefore specified
and for the purpose stated.
2. In an electric arc lamp regulating two ares in series by one series solenoid and
tapered core in combination with two shunt solenoids with tapered cores carrying
carbon holders the shunt solenoid actuating each movable carbon being connected
across its own are substantially as hereinbefore specified.
3. An electric arc lamp having two arcs connected in series by means of two
fixed and two movable carbon holders the movable holder of one pair of carbons
forming an are being connected by means of an insulated conductor to the insulated
fixed carbon holder of the other pair of carbons forming the other arc the length of
the arcs being regulated by one electro-magnetic apparatus substantially as
hereinbefore specified.
4. In an electric arc lamp regulated on the "Pilsen system attaching the
carbon holders or the tapered cores carrying the carbon holders to a rocking lever
or equivalent thereof, substantially as hereinbefore specified and for the purpose
stated.
5. The construction of electric arc lamps having two arcs maintained in series in
one lamp substantially as herein before described and shewn by the accompanying
drawings.
6. In combination with a double carbon arc lamp constructed as hereinbefore
specified a reflector having two or more incandescent lamps therein the incandescent
lamps being connected with the source of current by a separate switch al
substantially as hereinbefore specified and for the purpose stated.
Dated this 25th day of July 1895.
T. E. HALFORD,
11 Furnival Street, Holborn, E.C., Agent for Applicants.