IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Tom Ernest Gatehouse of No 35 Flaxman Road
Camberwell in the County of Surrey and Harry Robert Kempe of Rowland
Villa Barnet in the County of Middlesex for an invention of IMPROVEMENTS
IN ELECTRIC LAMPS.
PROVISIONAL SPECIFICATION left by the said Tom Ernest Gatehouse &
Harry Robert Kempe at the Office of the Commissioners of Patents on the
31st May 1882.
TOM ERNEST GATEHOUSE of No 35 Flaxman Road Camberwell in the County of
Surrey and HARRY ROBERT KEMPE of Rowland Villa Barnet in the County of
Middlesex "IMPROVEMENTS IN ELECTRIC LAMPS"
Our invention relates to apparatus for automatically regulating the Distance of
the carbons or electrodes of electric lamps so as to maintain approximate uniformity
in the voltaic are and to provide for the feed of the electrodes as they are consumed.
For this purpose we arrange in the framing of the lamp a solenoid or electro-
magnet, the core or armature of which is drawn away by an adjustable spring.
By means of a make and break arrangement of any known kind we cause:
intermittent electrical currents either from the lamp circuit or from another source:
to pass through the coils of this solenoid or electromagnet, so that its core or
armature is alternately moved one way by the magnetic attraction and the other
way by the spring, thus giving continuous reciprocating movement to an arm
jointed to the core or armaturę. To this reciprocating arm there is jointed the
core of another solenoid the axis of which is perpendicular or nearly so to the
reciprocating arm, and the core of this, which we may term the deflecting solenoid,
is drawn away by an adjustable spring. The end of the reciprocating arm has a
tooth on each side and it moves to and fro between two ratchet wheels without
touching either of them unless when it is deflected to the one side or the other by
the attraction of the deflecting solenoid exceeding the force of the spring, or con-
versely. On the axes of the two ratchet wheels are fixed rollers which bear against
one side of the lamp carbon, another roller being pressed against the other side of

page_text: the carbon by a spring, so that the carbon is clamped between the rollers and is
caused to move in the one direction or the other according as the one or the other
of the two rollers on its one side is caused to turn in the one or the other direction.
Sometimes instead of thus clamping the carbon between rollers, we fix it in a tube
having on its side rack teeth engaging with the teeth of pinions which are fixed,
instead of, the rollers, on the axes of the ratchet wheels. Instead of employing
two ratchet wheels as above described, a single toothed wheel may be employed;
the reciprocating arm being made with anchor teeth which can be engaged on the
one side or the other of the wheel according as it is deflected the one way or the
other by the deflecting solenoid. When the carbons of the lamp are vertical, it is
preferred to balance them by weights attached to cords passing over pullies, and
instead of employing separate weights for this purpose the lower carbon and its
holder may be conveniently arranged as the counterpoise for the upper carbon and
its holder. The pullies over which the cords pass may be so proportioned that the
carbon which is the more rapidly consumed has to move through a distance greater
than that moved through by the other carbon and thus the focal position of the
are between the carbons can be maintained approximately constant. The deflecting
solenoid whose core acts laterally on the reciprocating arm may be arranged in
either of two ways. According to the one arrangement, its coil forms part of the
lamp circuit, and the action is then as follows. When the carbons are too near
each other, the solenoid attracts its core deflecting the reciprocating arm so that its
tooth engages with one of the ratchet wheels, which it turns step by step in such
direction as to withdraw the carbons from one another; when on the other hand,
the carbons are too far apart, the spring overcoming the attractive power of the
solenoid deflects the reciprocating arm in the opposite direction so that its tooth
engages with the other ratchet wheel which it turns step by step in such direction
as to advance the carbons towards each other. When the solenoid is thus arranged
in the lamp circuit, we apply to the lamp a shunt of any known kind so as
automatically to complete a by pass and maintain the general circuit in case of the
extinction of the lamp. We prefer however to arrange the deflecting solenoid, not
in the lamp circuit, but in a by-pass circuit, making this by-pass one of considerable
resistance by including in it a carbon filament fixed in a vacuous bulb, as in an
incandescent electric lamp, not for the purpose of illumination but for an object
which we will now explain. The electrical resistance of a carbon filament is
lessened when the filament is heated. Thus when, owing to too great separation
of the electrodes of the lamp, the resistance of the are becomes too great, a con-
siderable portion of the lamp current has to find its way through, the by-pass
which includes the solenoid coil and the carbon filament.
The filament becoming heated offers less resistance and consequently permits the
passage of a greater portion of the current, and thus the deflecting solenoid is
rapidly and forcibly excited attracting its core and so causing approach of the lamp
electrodes and lessening the resistance of the lamp circuit. This use of a carbon
filament for the purpose of rapidly varying the resistance of a circuit is obviously
applicable generally to electric lamps in which there is a by-pass circuit including
a solenoid coil or electromagnet for regulation of the arc.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Tom Ernest Gatehouse & Harry Robert Kempe in the Great
Seal Patent Office on the 30th November 1882.
TOM ERNEST GATEHOUSE of No: 35 Flaxman Road Camberwell, in the county
of Surrey and HARRY ROBERT KEMPE, of Rowland Villa Barnet in the county of
Middlesex IMPROVEMENTS IN ELECTRIC LAMPS
Our invention relates to apparatus for automatically regulating the distance of
the carbons or electrodes of electric lamps so as to maintain approximate uniformity
in the voltaic arc and to provide for the feed of the electrodes as they are consumed.
For this purpose we arrange in the framing of the lamp a solenoid or electro-
magnet, the core or armature of which is drawn away by an adjustable spring.
By means of a make and break arrangement of any known kind we cause inter-
mittent electrical currents either from the lamp circuit or from another source to
pass through the coils of this colenoid or electro-magnet so that its coil or armature
is alternately moved one way by the magnetic attraction and the other way by the
spring, thus giving continuous reciprocating movement to an arm jointed to the
core or armature. To this reciprocating arm there is jointed the core of another
solenoid the axis of which is perpendicular or nearly so to the reciprocating arm,
and the core of this, which we may term the deflecting solenoid, is drawn away by
an adjustable spring. The end of the reciprocating arm has a tooth on each side
and it moves to and fro between two ratchet wheels without touching either of
them unless when it is deflected to the one side or the other by the attraction of
the deflecting solenoid exceeding the force of the spring or conversely, On the
axes of the two ratchet wheels are fixed rollers which bear against one side of the
lamp carbon, another roller being pressed against the other side of the carbon by
a spring, so that the carbon is clamped between the rollers and is caused to move
in the one direction or the other according as the one or the other of the two
rollers on its one side is caused to turn in the one or the other direction. Some-
times, instead of thus clamping the carbon between rollers, we fix it in a tube
having on its side rack teeth engaging with the teeth of pinions which are fixed
instead of rollers, on the axes of the ratchet wheels. Instead of employing two
ratchet wheels as above described, a single toothed wheel may be employed, the
reciprocating arm being made with anchor teeth which can be engaged on the one
side, or the other of the wheel, according as it is deflected the one way or the
other by the deflecting solenoid and spring. When the carbons of the lamp are
vertical, it is preferred to balance them by weights attached to cords passing over
pullies, and instead of employing separate weights for this purpose the lower
carbon and its holder may be conveniently arranged as the counterpoise for for
the upper carbon and its holder. The pullies over which the cords pass may be so
proportioned that the carbon which is the more rapidly consumed has to move
through a distance greater than that moved through by the other carbon, and thus
the focal position of the arc between the carbons can be maintained approximately
constant. The deflecting solenoid whose core acts laterally on the reciprocating
arm may be arranged in either of two ways. According to the one arrangement,
its coil forms part of the lamp circuit, and the action is then as follows. When the
carbons are too near each other, the solenoid attracts its core, deflecting the reci-
procating arm so that its tooth engages with one of the ratchet wheels, which it
turns step by step in such direction as to withdraw the carbons from one another;
when on the other hand, the carbons are too far apart, the spring overcoming the
attractive power of the solenoid deflects the reciprocating arm in the opposite-

page_text: direction, so that its tooth engages with the other ratchet wheel, which it turns
step by step in such direction as to advance the carbons towards each other.
When the solenoid is thus arranged in the lamp circuit, we apply to the lamp a
shunt of any known kind, so as automatically to complete a by-pass and maintain
the general circuit in case of the extinction of the lamp. We prefer however to
arrange the deflecting solenoid not in the lamp circuit, but in a by-pass circuit,
making this by-pass, one of considerable resistance by including in it a carbon
filament fixed in a vacuous bulb as in an incandescent electric lamp, not for the
purpose of illumination but for an object which we will now explain. The
electrical resistance of a carbon filament is lessened when the filament is heated.
Thus when, owing to too great separation of the electrodes of the lamp, the
resistance of the arc becomes too great, a considerable portion of the lamp current
has to find its way through the by-pass which includes the solenoid coil and the
carbon filament. The filament becoming heated offers less resistance and conse-
quently permits the passage of a greater portion of the current, and thus the
deflecting solenoid is rapidly and forcibly excited attracting its core and so causing
approach of the lamp electrodes and lessening the resistance of the lamp circuit.
This use of a carbon filament for the purpose of rapidly and considerably varying
the resistance of a circuit is obviously applicable generally to electric lamps in
which there is a by-pass circuit including or not a solenoid coil or electro-magnet
for the regulation of the arc.
Fig 1 of the accompanying drawings is an elevation partly in section of an
electric lamp according to our invention, Fig 2 is a plan on X X. The upper
carbon K is pressed against two hollowed rollers R R¹ by an opposite roller r
mounted on a spring, or. it might be otherwise pressed by a spring or by a weight.
On the axes of the rollers R R are fixed finely toothed ratchet wheels W. W¹.
having their teeth sloped opposite ways. An arm A is jointed to the core of a
horizontal solenoid B, and a point in this arm is linked to the core of a vertical
solenoid C. The coil of the solenoid B is connected through any convenient make
and break arrangement with the lamp circuit or with another circuit, so that the
solenoid is intermittently excited attracting its core in opposition to a spring, a
reciprocating to-and-fro movement being thus given to the arm A. The coil of the
solenoid C is of high resistance and is connected in a shunt or by-pass to the
main circuit of the lamp and its core is drawn upwards by an adjustable spring D.
When the carbons are too near each other and consequently when the resistance of
the arc is too small, the solenoid C is very weak and the spring D raises the arm A
so that a tooth at its end engages as a pawl with the teeth of the upper wheel. W.
By the reciprocation of the arm A, this wheel is caused to turn in the direction of
the arrow on it raising the upper carbon K and so increasing the length of the arc.
When on the other hand, the carbons are too far apart and consequently the
resistance of the arc is too great, the solenoid C becomes more powerful and draws
down the arm A so that its end tooth engages with the lower wheel W₁, and
thereupon the reciprocation of A turns the wheel Win the direction of the arrow
on it, so as to lower the carbon K, and šo diminish the length of the arc. The
regulating apparatus may be modified as shewn by the part elevation Fig 3. In
this case there are two rollers 7 pressing the carbon K against a single roller R on
the axis of which is fixed a toothed wheel W. The reciprocating arm A is made
in the form of an escapement anchor which engages either the teeth on the under
side of the wheel W or those on its upper side causing it to turn in the one direction
or the other and so to raise or lower the carbon K.
Figs 4 and 5 are diagrams illustrating the arrangement according to our
invention of the shunt or by-pass circuit which may be employed to include the
coil of C in the lamp above described, or the high resistance coil used in other
electric lamps either as part of the regulating apparatus or merely as an alternative
for the lamp circuit to maintain the current when the lamp is extinguished.
Assuming CC in Fig: 4 to represent the two carbons of any are lamp and R to
represent a very considerable resistance such as a solenoid coil of fine wire in a

page_text: by-pass to the main circuit L. L. then when the resistance of the arc is excessive,
the current instead of passing as usual mostly through the carbons finds its way
through R. Such is the usual arrangement which we modify as illustrated by
fig: 5. We substitute for a considerable part of the resistance R a resistance in
the form of a carbon filament I as in an incandescent lamp, and we thus utilize
the property possessed by such a filament of having its electrical resistance
lessened by heat. When the main circuit of the lamp presents moderate
resistance very little current passes through I and R, and I remaining comparatively
cold has considerable resistance. When, however, owing to increased resistance of
the main circuit, more current is caused to take the by-pass course, then the
filament I becoming heated has lessened resistance and thus the total resistance of
the by-pass is diminished. By thus introducing carbon as part of the by-pass, the
resistance of the by-pass may be made so great that very little current will pass
that way when the main circuit is in operation, but that when the main circuit is
impeded, the current will have greater freedom to follow the by-pass course owing
to the diminution of resistance resulting from the heating of the carbon by the
passage of the current. When the by-pass is employed as in many lamps to excite
a regulating solenoid or electro-magnet, this diminution of resistance renders the
regulating apparatus much more sensitive:
Having thus described, the nature of our said invention and in what manner
the same is to be performed, we claim :-
First Regulating automatically the distance of the carbons in an electric arc
Lamp by causing a roller pressed against one of the carbons to be turned in the
one direction or the other by the action of a reciprocating pawl, the engagement of
which with the teeth to drive the roller is controlled by an electro-magnet or
solenoid, having its attractive force determined by the resistance of the arc,
substantially as herein described
Second Introducing a carbon filament in a resisting by-pass circuit as part of
the resistance thereof, as and for the purposes herein set forth
In witness whereof, we the said Tom Ernest Gatehouse and Henry Robert
Kempe have hereunto set our hands and seals this Twenty ninth day of
November in the year of our Lord, one thousand eight hundred and
eighty two
TOM ERNEST GATEHOUSE (L.S.)
HARRY ROBERT KEMPE (L.S)