IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1882

page_text: LETTERS PATENT to Edward Griffith Brewer of 33 Chancery Lane in the
County of Middlesex for an Invention of "IMPROVEMENTS IN ELECTRIC ARC
LAMPS" A communication to him from abroad by the "Société anonyme des
ateliers de construction mécanique et d'annareils électriques of Paris France
PROVISIONAL SPECIFICATION left by the said Edward Griffith Brewer at
the Office of the Commissioners of Patents on the 4th August 1882.
EDWARD GRIFFITH BREWER of 33 Chancery Lane in the County of Middlesex
"IMPROVEMENTS IN ELECTIC ARC LAMPS." (A. communication to me from abroad by
the "
Société anonyme des ateliers de construction inecanique et d'appareils
electriques" of Paris, France)
This invention refers to electric arc lamps and especially to the so called
"Cance" system wherein a screw serves to automatically produce the movement
of the regulator under the action of a nut motor which determines the bringing
together of the carbons or to remove them from one another when they are too
near, the throwing out of gear mechanism for regulation of the lamp being
produced by a suitable magnetic arrangement.
These improvements relate to the following points,—
First. To an arrangement of motor nut.
Second. To an arrangement of and for guiding the carbon holder.
Third. To arrangement of throwing out of gear mechanism.
Fourth. To an arrangement of the magnetic system which regulates the throwing
out of gear action.
Fifth. to a magnetic brake, for regulating the speed with which the carbons
approach one another.
Sixth. To the employment of two concentric globes and to the mode of
Buspending the same,
The lamp is composed of two parallel plates held together by four fixed columns
acting as guides and for the attachment thereto of the different parts of the
mechanism. The throwing out of gear screw carries at its ends pivots which turn
Din Q27

page_text: in a collar placed in the centre of each of the plates and it occupies the whole of
the space comprised between the plates.
The carbon holders are prolonged under the lower platform.
1. ARRANGEMENT OF THE NUT MOTOR.
The motor which serves at the same time to produce the approach of the carbons
and to turn the disengaging screw and to which the carbon holder is connected is
formed of a ring through which the screw passes freely and which carries
three arms each carrying a tail piece which engages into one of the threads
of the screw; this screw having preferably three threads there are three tail pieces
and consequently three arms. These tail pieces are threaded so that their pene-
tration into the threads of the screw may be regulated at will. The arms are
slotted and a tightening screw enables the tail piece to be fixed when it is brought
to the required position. A nut is thus obtained, the operation of which is very
certain, with the slightest possible friction and permits of reducing to a minimum
the weight of the element motor. This last may be made in a piece with, a cross
piece, hollowed out in its centre so as to allow the disengaging screw freely
to pass
This carbon
2. Arrangement for guiding the carbon holders. The upper carbon holder is
connected to the cross bar; this cross bar is put in electric communication with
the lamp by slotted tubes which slide with little friction on two of the columns
fixed between the plates which rest for this purpose free the whole of their length,
columns diametrically opposed are preferably chosen to improve the guiding. The
carbon carrier is formed of two rods held to the upper part by the cross piece above
mentioned and to the lower part by a second crosspiece which slides on the guiding
tubes of the lower carbon holder as will be explained further on.
holder besides passes through a lower plate of the lamp which also tends to guide
same. The lower carbon holder is composed of two rods united by a cross piece at
their lower ends and suspended by pulleys to cords which pass over the fixed guide
pulleys fixed to the upper platform of the lamp in order to be attached to the cross
bar of the motor nut. These rods are guided without friction the greatest portion
of their length by guide tubes sliding in other tubes fixed on the lower platform of
the lamp and from which they are electrically insulated by insulating collars placed
at suitable distances apart. The external tubes are prolonged a certain distance
below the lower platform of the lamp and carry an insulated socket which receives
the current for transmitting it to the carbon holder which there slides with very
little friction. Each of the carbon holders is provided with two centering socket
holders in which the carbon is adjusted; the two caps go into one another and the
internal piece is adjusted on a hollowed out part on the cross bar of the carbon
holder.
The two sockets and the crosspiece have a circular hole of a suitable size and to
the two ends of the same diameter two small half circular slots the stops of which
grip the carbons and hold then in the central line of the axis. Regulating screws
are placed in the head of each cap and abut against the cross piece enabling the
distance of the caps the one from the other to be regulated and adjusted.
It will be understood that if the motor nut is allowed to descend the two carbons
approach consequently the simultaneous displacement of the carbon holders takes
place, which are held between them by the above mentioned cords. It will also be
seen that the motor nut taking into the thread of the screw will stop as soon as the
screw is prevented turning.
3. Arrangement of the throwing out of gear mechanism.-This stop of the screw
is obtained by means of the throwing out of gear mechanism which serves at the
same time for regulating the advance of the carbons and to maintain constant the
length of the arc. It is arranged in the following manner. The upper end of the
screw carries a toothed wheel which is there keyed, and which gears with a pinion
keyed on an axis mounted in a frame. This frame is mounted loose on the axle

page_text: of the toothed wheel and is thus free to turn independently of that of the screw,
taking with it the small pinion around the circumference of the toothed wheel.
While the motor nut descends the screw in turning causes the toothed wheel to
turn with it which in its turn turns the pinion. If the two carbons approach one
another too much or touch, the magnetic system of the lamp operates, as will be
bereafter explained and turns the frame a certain distance, at the same time the
circular movement of the pinion is stopped as has been seen and as it is driven by
the circular movement of the frame it causes the toothed wheel to turn in the.
contrary direction to that of its normal motion by taking the screw with it on
which it is keyed and consequently causing the nut motor to ascend that is dividing
the carbons.
The pinion is stopped in the following manner, its axis carries a ratchet wheel
which turns with it; a spring catch fixed on the frame is placed opposite the teeth
ratchet without entering, a screw keeping it constantly out. But as soon as the
frame is open from its normal position by bringing the spring catch with it
opens it from the point of the screw and by reason of its elasticity the spring pawl
immediately engages in the teeth of the ratchet arresting its rotary motion outside
the pinion. When the arc after having regained its normal length tends to augment,
the magnetic system weakens and gradually makes the frame to return to the
point from which it started, and it is then that the spring pawl meets its abutment
being liberated from the teeth of the ratchet and allows the screw to turn and the
motor nut to descend until an exaggerated closing up of the carbons takes place
and the operations before described again take place. These then are the
movements of the frame which put into operation the disengaging gear, these
movements are produced as has been before said by the magnetic system produced
by a bobbin the core of which becomes displaced, according to the determined
variations in the intensity of the current which traverses spirals by the variations
of the length of the arc. The movements of the core cause a cam to oscillate, this
cam has, the form of a ratchet wheel and is fixed to the end of a bell crank lever
which carries. the lamp on its fixed part, a bent finger piece which is in a piece with
the frame is engaged in the ratchet and its shape as well as that of the cam is
calculated in order that if the cam oscillates the frame is forced to turn a certain
distance and return gradually to its first position, when the cam returns to it. The
oscillating movement of the cam is obtained by means of a crank in connection
with the core of the magnetic system above mentioned
4. Arrangement of the magnetic system which regulates the operation of the
lamp. The hollow bobbin of this magnetic system is surrounded by a wire of
suitable thickness into which passes all the current for the light. It is placed at
the side of the screw and not in the same axis in such manner that the length
required can be given to it without in any way losing the length of the screw and
without making the apparatus too long. In order not to exaggerate the dimensions
of the bobbin and to have nevertheless the desired power the bobbin is arrangeḍ
for two magnetic systems combined which aid one another, for this purpose two
cores are placed in the interior and extend about half the length; to the upper
part a fixed core is keyed in the bobbin tube, to the lower part a movable core is
arranged on a frame also movable and guided by pieces fixed to the bobbin. It is
to this frame that the connecting rod is attached which causes the cam to oscillate.
The upper core is magnetized and its two ends constitute two magnetic poles = the
same for the lower core the two middle poles being opposite there is between
them an attraction which tends to bring them together and which equalizes a
portion of the weight of the movable core; thus augmenting the sensibility of the
apparatus. The upper core is hollow to allow a guiding bar to pass being fixed to
the frame and attached to the lower core by a screwed part serving at the same
time to regulate the position of this lower core. When the currents are very intense
the lower core is farther from the fixed core while leaving the same magnetic power
to the system; in all these cases the position of the lower core is regulated with

page_text: its frame in such manner that the cores can never touch even at the end of the
course of the lower core.
A pressure screw fixes the lower core on the frame in
the position which has been arranged for such intensity, besides the adjusting screw
limits in the two directions the course of the movable core and thus regulates the
distance apart of the carbons, produces instantaneously the light by the magnetic
system which then receives all the action of the current, the arc not yet existing.
This system of bobbins with double core then becomes at the same time a
regulating system.
5. Employment of a special magnetic brake. In that case where the carbons
approach too rapidly in order to neutralize the acceleration of the speed of the
motor weight, a special magnetic brake is employed which is placed at the upper
part or at the lower part of the screw which is moved by the motor nut; this brake
may be composed of a short bobbin energized by a derivation of the light circuit
and of which the soft iron tubular core is formed, of a single piece or of a series; it
forms in these two cases a circular magnetic road on which revolve two rollers
carried by an axle which passes through the putting out of gear screw by a
rectangular opening sufficiently high to allow it to be vertically displaced and to
oscillate about a pin which keeps it in position; this pin passes into a lengthened
aperture formed in the middle of the axle in order not to interfere with the displace-
ments to which it may be subjected, the result of this arrangement is that the
rollers are brought along with the movement of the screw and retard this move-
ment with an energy as much greater than the current which passes into the bobbin
is more intense by reason of the coming together of the carbons, their end is
bevilled or thinned off in order that the contact with the revolving road shall be
as much reduced as possible. Another arrangement consists in replacing the vertical
rollers on a horizontal magnetic road by a horizontal disc keyed on the screw and
turning in the interior of a simple hollow bobbin; this disc should have relatively
to the bobbin a position, a diameter and a thickness in relation with the energy of
the current of the bobbin so as to obtain a brake of a determined power. These
brakes act magnetically and mechanically, as is made the immersion of a cylinder
in a liquid. A brake may also be employed made simply of one or several shoes
(sabot) jointed and kept applied against the periphery of a disc by a spring the
tension of which may be regulated at will; the employment of these special brakes
is optional, and their arrangement can be varied in many ways. From the foregoing
description it is easy to understand that by these arrangements a perfectly fixed
light is obtained.
6. Employment of two concentric globes-In order to still further increase the
steadiness of the are the inventors have attempted as much as possible to diminish
the draughts of air and specially draughts of hot air which are always produced
about the arc; for this purpose the arc is enclosed in a very small transparent globe
in which the air is very difficultly changed and consequently becomes rarefied the
consequence is to considerably diminish the consumption of the carbons; this small
globe is preferably ovoid to facilitate the falling of the cinders, it has two holes,
that at the top being just sufficient to allow the carbons to pass through, whilst
that at the bottom is a little larger to allow the cinders to pass out, these cinders
cannot get dispersed about when falling and moreover they are maintained in a
space sufficiently small to be completely burnt at the highest possible temperature,
that is to say, under the best conditions; this little globe always constructed of some
sort of transparent or translucent material and of different colours, glass, mica, is
simply suspended on the guiding columns of the carbon carriers. The external
globe being fitted in the ordinary manner is of any suitable material suspended
to the same columns. Its special object is to diffuse the light and to protect
the small internal globe which attains a high temperature against variations of
temperature.
There has been described a lamp in which the motor nut is put in operation by
a weight which is then intended to be placed vertically, this lamp can however be

page_text: reversed, that is to say, the movement being placed at the lower part all that is
necessary is to conveniently connect together the ends of the two carbon holders
moreover the mechanism remaining always vertical the carbons may be placed
horizontally above or below by arranging a suitable movement, besides the
mechanism itself may be placed horizontally, the movement of the motor nut being
then produced by any suitable motor. It is easy to understand that in all these
arrangements the fundamental principles always remain the same and that they
are consequently only simple varying forms. It is to be understood that the form
dimensions and materials; constituting the different parts may vary without
departing from this invention

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edward Griffith Brewer in the Great Seal Patent Office
on the 3rd February 1883.
"}
EDWARD GRIFFITH BREWER of 33 Chancery Lane in the County of Middlesex
"IMPROVEMENTS IN ELECTRIC ARC LAMPS A communication to me from abroad
by the "Société anonyme des ateliers de construction mecanique et d'appareils
Electriques" of Paris, France.
This Invention refers to electric arc lamps and especially to the so called
Cance" system wherein a screw serves to automatically produce the movement
of the regulator under the action of a nut motor which determines the bringing
together of the carbons or to remove them from one another when they are too
near, the throwing out of gear mechanism for regulation of the lamp being
produced by a suitable magnetic arrangement. These Improvements relate to the
following points.
1st To an arrangement of motor nut.
2nd To an arrangement of and for guiding the carbon holder.
3rd To an arrangement of throwing out of gear mechanism
4th To an arrangement of the magnetic system which regulates the throwing out
of gear action.
5th To a magnetic brake for regulating the speed with which the carbons
approach one another.
6th To the employment of two concentric globes and to the mode of suspending
the same.
The accompanying drawings show a lamp constructed according to this Invention
and arranged so as to be placed vertically.
Figure 1 is an elevation of the apparatus.
Figure 2 is a section of the upper part of the lamp.
Figures 3, 4 and 5 are horizontal sections.
Figure 6 is a detached section of the magnetic system.
Figures 7 and 8 are detached views of the centreing guides for the carbon
carriers.
Figures 9 and 10 are detail views of the suspension pulleys and guide cords of
the lower carbon holder.
Figure 11 is a section on a larger scale of the guiding tube of the lower carbon
holder.
As seen by reference to the drawing.
The lamp is composed of two parallel plates held together by four fixed columns
acting as guides and for the attachment thereto of the different parts of the
mechanism. The throwing out of gear screw carries at its end pivots which
turn in a collar placed in the centre of each of the plates and it occupies the
whole of the space comprised between the plates.
The carbon holders are prolonged under the lower platform.
1. ARRANGEMENT OF THE NUT MOTOR.
The motor nut which serves at the same time to produce the approach of the
carbons and to turn the disengaging screw and to which the carbon holder is
connected is formed of a ring a through which the screw passes freely and which
carries three arms beach carrying a tail piece c which engages into one of the

page_text: tail pieces and consequently three arms. These tail pieces are threaded so that
their penetration into the threads of the screw may be regulated at will. The
arms bare slotted and a tightening screw enables the tail piece to be fixed when it
is brought to the required position. A nut is thus obtained the operation of which
is very certain with the slightest possible friction and permits of reducing to a
minimum the weight of the element motor. This bolt may be made in a piece
with a cross piece e as shown in the drawing hollowed out in its centre so as to
allow the disengaging screw d freely to pass.
2. ARRANGEMENT FOR GUIDING THE CARBON HOLDERS.
The upper carbon holder f is connected to the cross bar this cross bar is put in
electric communication with the lamp by slotted tubes g which slide with little
friction on two of the columns h fixed between the plates which rest for this
purpose free the whole of their length-Columns diametrically opposed are
preferably chosen to improve the guiding. The carbon carrier is formed of two
rods held to the upper part by the cross piece above mentioned on to the lower
part by a second cross piece i which slides on the guiding tubes of the lower
carbon holder as will be explained further on. This carbon holder besides passes
through a lower platej of the lamp which also tends to guide same. The lower
carbon holder is composed of two rods k united by a cross piece at their lower ends
and suspended by pulleys to cords which pass over the fixed guide pulleys m fixed to
the upper platform n of the lamp in order to be attached to the cross bar of the
motor nut. These rods are guided without friction the greatest portion of their
length by guide tubes o sliding in other tubes p fixed on the lower platform of
the lamp and from which they are electrically insulated by insulating collars q
placed at suitable distances apart. The external tubes p are prolonged a certain
distance above the lower platform of the lamp and carry an insulated socket r
which receives the current for transmitting it to the carbon holder which then
slides with very little friction. Each of the carbon holders is provided with two
centreing socket holders s t in which the carbon is adjusted the two sockets go
into one another and the internal piece is adjusted on a hollowed out part on
the cross bar of the carbon holder as seen in the drawing.
The two sockets and the cross piece have a circular hole of a suitable size and
the two ends of the same diameter two small half circular slots the edges of which
grip the carbons and hold them in the central line of the axis. Regulating screws
are placed in the head of each socket and abut against the cross piece enabling the
distance of the sockets the one from the other to be regulated and adjusted.
It will be understood that if the motor nut is allowed to descend the two carbons
approach consequently the simultaneous displacement of the carbon holders takes
place which are held between them by the above mentioned cords. It will also be
seen that the motor nut taking into the thread of the screw will stop as soon as
the screw is prevented turning.
3. Arrangement of the throwing out of gear mechanism. This stop of the screw
is obtained by means of the throwing out of gear mechanism which serves at the
same time for regulating the advance of the carbons and to maintain constant the
length of the arc. It is arranged in the following manner. The upper end of the
screw d carries a toothed wheel u which is there keyed and which gears with a
pinion keyed on an axis mounted in a frame w; this frame is mounted loose on
the nave of the toothed wheel u and is thus free to turn independently of that of
the screw, taking with it the small pinion around the circumference of the
toothed wheel u. While the motor nut descends the screw in turning causes the
toothed wheel u to turn with it which in its turn turns the pinion v. If the two
carbons approach one another too much or touch, the magnetic system of the lamp
operates as will be hereafter explained and turns the frame a certain distance, at
the same time the circular movement of the pinion is stopped as it will be seen
and as it is driven by the circular movement of the frame it causes the toothed

page_text: wheel u to turn in the contrary direction to that of its normal motion by taking
the screw with it on which it is keyed and consequently causing the nut motor to
ascend, that is dividing the carbons.
The pinion is stopped in the following manner, its axis carries a ratchet
wheel which turns with it; a spring catch y fixed on the frame w is placed
opposite the teeth of ratchet without entering; a screw z keeping it constantly out.
But as soon as the frame is open from its normal position by bringing the spring
catch with it it opens it from the point of the screw and by reason of its elasticity
the spring pawl immediately engages in the teeth of the ratchet arresting its
rotary motion outside the pinion. When the arc after having regained its normal
length tends to augment, the magnetic system weakens and gradually makes the
frame to return to the point from which it started and it is then that the spring
pawl meets its abutment being liberated from the teeth of the ratchet and allows
the screw to turn and the motor nut to descend until an exaggerated closing
up of the carbons takes place and the operations before described again take
place. These then are the movements of the frame which put into operation the
disengaging gear, these movements are produced as has been before said by the
magnetic system produced by a bobbin the core of which becomes displaced
according to the determined variations in the intensity of the current which
traverses spirals by the variations of the length of the arc. The movements of the
core cause a cam a' to oscillate, this cam has the form of a hook and is fixed to
the end of a bell crank lever which carries the lamp on its fixed part, a bent
finger piece b', which is in a piece with the frame is engaged in the hook and its
shape as well as that of the cam is calculated in order that if the cam oscillates
the frame is forced to turn a certain distance and return gradually to its first
position when the cam returns to it. The oscillating movement of the cam is
obtained by means of a connecting rod c' in connection with the core of the
'magnetic system above mentioned.
4. Arrangement of the magnetic system which regulates the operation of the
lamp. The hollow bobbin d' of this magnetic system is surrounded by a wire of
suitable thickness into which passes all the current for the light. It is placed
at the side of the screw and not in the same axis in such manner that the length
required can be given to it without in any way losing the length of the screw and
without making the apparatus too long. In order not to unnecessarily increase the
dimensions of the bobbin too much, and to have nevertheless the desired power,
the bobbin is arranged for two magnetic systems combined which aid one another,
for this purpose two cores are placed in the interior and extend about half the
length; to the upper part a fixed core f¹ is keyed in the bobbin tube; to the lower
part a movable core e¹ is arranged on a frame g¹ also movable and guided by pieces
fixed to the bobbin. It is to this frame that the connecting rod c¹ is attached
which causes the cam to oscillate. The upper core is magnetized and its two ends
constitute two magnetic poles = the same for the lower core = the two median
poles being opposite there is between them an attraction which tends to bring them
together and which equalizes a portion of the weight of the movable core, thus
augmenting the sensibility of the apparatus. The upper core is hollow to allow a
guiding bar to pass being fixed to the frame and attached to the lower core by
a screwed part serving at the same time to regulate the position of this lower core.
When the currents are very intense the lower core is farther from the fixed core
while leaving the same magnetic power to the system; in all these cases the
-position of the lower core is regulated with its frame in such manner that the
cores can never touch even at the end of the course of the lower core. A pressure
screw fixes the lower core on the frane in the position which has been arranged
for such insensity. Besides the adjusting screw limits in the two directions the
course of the movable core and thus regulates the distance apart of the carbons
produces instantaneously the light by the magnetic system which then receives all
the action of the current the arc not yet existing. This system of bobbins with
double core then becomes at the same time a regulating system.

page_text: 5. Employment of a special magnetic brake. In that case where the carbons
approach too rapidly in order to neutralize the acceleration of the speed of the
motor weight, a special magnetic brake is employed which is placed at the upper
part or at the lower part of the screw which is moved by the motor nut This
brake may be composed of a short bobbin energized by a derivation of the light
circuit and of which the soft iron tubular core is formed of a single piece or of a
series, it forms in these two cases a circular magnetic road on which revolve two
rollers carried by an axle which passes through the putting out of gear screw d by
a rectangular opening sufficiently high to allow it to be vertically displaced and to
oscillate about a pin which keeps it in position this pin passes into a lengthened
aperture formed in the middle of the axle in order not to interfere with the
displacements to which it may be subjected. The result of this arrangement is
that the rollers are brought along with the movement of the screw d and retard
this movement with an energy as much greater than the current which passes in
the bobbin is more intense by reason of the coming together of the carbons. Their
edges are bevelled or thinned off in order that the contact with the revolving road
shall be as much reduced as possible. Another arrangement consists in replacing
the vertical rollers on a horizontal magnetic road by a horizontal disc keyed on
the screw and turning in the interior of a simple hollow bobbin. This disc should
have relatively to the bobbin, a position a diameter and a thickness in relation
with the energy of the current of the bobbin so as to obtain a brake of a deter-
mined power.
These brakes act magnetically and mechanically as would be done
by the immersion of a cylinder in a liquid. A brake may also be employed made
simply of one or several shoes (sabot) jointed and kept applied against the
periphery of a disc by a spring the tension of which may be regulated at will.
The employment of these special brakes is optional and their arrangement can be
varied in many ways. From the foregoing description it is easy to understand
that by these arrangements a perfectly fixed light is obtained.
6. Employment of two concentric globes.
In order to still further increase the steadiness of the arc the inventors have
attempted as much as possible to diminish the draughts of air and specially
draughts of hot air which are always produced about the arc; for this purpose the
arc is enclosed in a very small transparent globe in which the air is very
difficultly changed and consequently becomes rarefied the consequence is to
considerably diminish the consumption of the carbons; this small globe is
preferably ovoid to facilitate the falling of the cinders; it has two holes, that at the
top being just sufficient to allow the carbons to pass through whilst that at the
bottom is a little larger to allow the cinders to pass out. These cinders cannot get
dispersed about when falling and moreover they are maintained in a space
sufficiently small to be completely burnt at the highest possible temperature, that
is to say, under the best conditions, this little globe always constructed of some
sort of transparent or translucent material, and of different colours, glass, mica, is
simply suspended on the guiding columns of the carbon carriers. The external
globe being fitted in the ordinary manner and of any suitable material is
suspended to the same columns as seen by the drawing. Its special object is to
diffuse the light and to protect the small internal globe which attains a high
temperature against variations of temperature.
There has been described and represented in the drawing a lamp in which the
motor nut is put in operation by a weight which is then intended to be placed
vertically. This lamp can however be, reversed, that is to say, the movement
being placed at the lower part all that is necessary is to conveniently connect
together the ends of the two carbon holders. Moreover the mechanism remaining
always vertical the carbons may be placed horizontally above or below by
arranging a suitable movement. Besides the mechanisin itself may be placed
horizontally, the movement of the motor nut being then produced by any suitable
motor. It is easy to understand that in all these arrangements the fundamental
principles always remain the same and that they are consequently only simple

page_text: varying forms. It is to be understood that the form dimensions and materials
constituting the different parts may vary without departing from the Invention.
And having now described the nature of the said Invention and in what manner
the same is to be performed I declare that I claim as the aforesaid Improvements in
electric-arc lamps.
"
First In combination with the screw employed for regulating automatically the
position of the carbons, the employment of a motor nut constructed substantially as
before described for reducing to a minimum the friction in threads of the screw.
Second-The arrangement before described of guiding tubes for the lower carbon
holder these tubes at the same time serving to guide the upper carbon holder
and also the means employed for fixing and centreing the carbons substantially as
set forth.
Third: The mode of construction of the throwing out of gear mechanism of the
hook shaped cam actuating it, when the lamp is set in action by acting on a curved
contact finger on the frame, and of a spring ratchet fixed on the frame all arranged
and operating as herein before described and with reference to the accompanying
drawings.
Fourth-The arrangements for regulating the working of the lamp, composed of
the double core bobbin one being fixed and the other movable the distance apart
which can be regulated in the manner and for the purpose described.
Fifth The employment with or without the beforementioned system of a
magnetic brake consisting of rollers running on a magnetic road or track or a core
disc revolving in a hollow bobbin or of shoes frictioning against a revolving dise
in order to reduce the speed of the descent of weights and consequently regulating
the motion of the screw all substantially as described.
Sixth-The employment of two concentric globes the internal globe being made
of any suitable transparent or translucent material and of any desired colours and
of very small sizes and having apertures of the required dimension in the manner
and for the purpose described together with the external globe for protecting the
beforementioned globe against the sudden change of temperature and to diffuse
the light.
Seventh-The new or improved system of electric regulator at a luminous
fixed point substantially as before described and illustrated in the accompanying
drawings.
In witness whereof I the said Edward Griffith Brewer have hereunto set my
hand and seal this Second day of February in the year of our Lord one
thousand eight hundred and eighty-three.
EG BREWER (L.S.)