IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1881

page_text: LETTERS PATENT to George Sylvester Grimston, of Holly Lodge, Brockley
Road, in the County of Kent, Mechanical Engineer, for an Invention of
"IMPROVEMENTS IN ELECTRIC LAMPS."
PROVISIONAL SPECIFICATION left by the said George Sylvester Grimston at
the Office of the Commissioners of Patents on the 16th April 1881.
GEORGE SYLVESTER GRIMSTON, of Holly Lodge, Brockley Road, in the County
of Kent, Mechanical Engineer. "IMPROVEMENTS IN ELECTRIC LAMPS."
One part of the present Invention relates to that description of electric lamps in
which the regulation of the carbons is effected by the differential action of two
coils or solenoids of different resistance, of which the coil of low resistance is in the
lamp circuit, while the coil of high resistance is connected to the external circuit
only. Such lamps were described in the Specifications to C. W. Siemens' Patents,
No. 4949, of 1878, and No. 2652, of 1879. According to the present improvements,
instead of effecting the feed of the upper carbon by mechanism, such as was
described in the said Specifications, the following arrangement is employed :-
The soft iron core or cores, which is or are acted upon by the two coils or
solenoids above referred to carries an arın or bracket, through apertures in which
passes the carbon holder, which can descend freely through the apertures unless
otherwise held.
To the bracket is pivotted an excentric or can shaped piece provided with a
projecting arm, the weight of which tends to turn the excentric or cam so as to
press the carbon holder against one side of the apertures, through which it passed,
and the carbon holder is thus held in the bracket, and can only move up or down
with the same, according as the core is actuated by the differential coils. When by
the burning away of the carbon, and the consequent increased action of the coil of
high resistance, the core has caused the bracket and carbon holder to descend to a
certain point, the arm of the cam or excentric comes in contact with a stationary
adjustable stop, and the further descent of the bracket consequently causes the
cam to be turned, so as to release the carbon holder, which then, descends by gravity
through the bracket.

page_text: On the current now passing to a greater extent through the coil of low resistance,
consequent on the near approach of the carbons, the core is actuated so as to raise
the bracket, and the arm of the cam being now again free to turn the cam so as to
nip the carbon holder, this is raised again with the bracket, so as to bring the
carbon to the proper distance for producing the electric arc. The said bracket is
by preference not directly attached to the soft iron core, but the latter has pivotted
to it one end of a lever mounted on a fixed fulcrum, and supporting the bracket
and carbon holder at its other end. In order to ensure that the carbon holder
shall descend gradually and without shock when released, as above described, and
shall also have an equable motion when acted upon by the differential coils, I prefer
to form its upper end into a tube or chamber, which is filled with a liquid, such as
glycerine, and in which is a piston or disc fitting it loosely, and held by a rod
passing up through the upper end of the tube, and fixed in any convenient manner,
so that on the movement of the carbon holder the liquid is forced to flow past the
piston or disc, as in a "cataract" apparatus. In the above described apparatus the
one or the other of the regulating coils can be replaced by springs, weights, or
similar contrivances.
According to another part of my Invention applicable to the above described or
any other kind of electric lamp in which the electric arc is produced between carbon
poles, instead of having only one pair of carbon poles I provide two or more pairs,
of which the upper carbons are all connected to one and the same holder, and are
consequently all moved simultaneously to and from the lower carbons.
By this arrangement, assuming that all the carbons are out of contact, and that
the electric arc is formed between one pair thereof, then on the upper carbon being
consumed to such an extent as to cause the carbon holder to descend, so as to bring
the other pair, or one of the other pairs of carbons, in contact, the current will
now pass through these, and the arc will be formed on the rising of the carbon
holder.
On the upper carbon of this pair burning away the downward motion of the
holder will bring the first named pair or another pair into contact, and the arc will
be transferred to that pair again, and so on continuously, until both or all the
upper carbon's have been consumed. The transference of the arc form the one pair
of carbons to the other takes place so rapidly that the interruption of the light is
scarcely perceptible. It will be seen that by the above described arrangement a
comparatively small total travel of the carbon holder will be required to enable
a lamp charged with two or more such pairs of carbons to burn for a considerable
length of time.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Sylvester Grimston in the Great Seal Patent Office on the
14th October 1881.
GEORGE SYLVESTER GRIMSTON, of Holly Lodge, Brockley Road, in the County
of Kent, Mechanical Engineer. "IMPROVEMENTS IN ELECTRIC LAMPS."
One part of the present Invention relates to that description of electric lamps
in which the regulation of the carbons is effected by the differential action of two
coils or solenoids of different resistance of which the coil of low resistance is in the
lamp circuit, while the coil of high resistance is connected to the external circuit
only. Such lamps were described in the Specifications to C. W. Siemens' Patents,
No. 4949 of 1878 and No. 2652 of 1879.
According to the present improvements instead of effecting the feed of the
upper carbon by mechanism, such as was described in the said Specifications, the
following arrangement is employed:-The soft iron core which is acted upon by
the two coils or solenoids above referred to carries an arm or bracket through
apertures in which passes the carbon holder, which can descend freely through the
apertures unless otherwise held. To the bracket is pivotted an excentric or cam
shaped piece provided with a projecting arm, the weight of which tends to turn
the excentric or cam, so as to press the carbon holder against one side of the
apertures through which it passes, and the carbon holder is thus held in the bracket
and can only move up or down with the same according as the core is actuated
by the differential coils. When by the burning away of the carbon and the
consequent increased action of the coil of high resistance the core has caused the
bracket and carbon holder to descend to a certain point, the arm of the cam or
excentric comes in contact with a stationary adjustable stop, and the further
descent of the bracket consequently causes the cam to be turned so as to release
the carbon holder, which then descends by gravity through the bracket. On the
current now passing to a greater extent through the coil of low resistance
consequent on the near approach of the carbons, the core is actuated so as to raise
the bracket, and the arm of the cam being now again free to turn the cam so as to
nip the carbon holder; this is raised again with the bracket so as to bring the
carbon to the proper distance for producing the electric arc. The said bracket is
by preference not directly attached to the soft iron core, but the latter has pivotted
to it one end of a lever mounted on a fixed fulcrum and supporting the bracket
and carbon holder at its other end. In order to insure that the carbon holder shall
descend gradually and without shock when released, as above described, and shall
also have an equable motion when acted upon by the differential coils, I prefer to
form its upper end into a tube or chamber, which is filled with a liquid such as
glycerine, and in which is a piston or disc fitting it loosely, and held by a rod
passing up through the upper end of the tube and fixed in any convenient manner,
so that on the movement of the carbon holder the liquid is forced to flow past the
piston or disc as in a "cataract" apparatus. In the above described apparatus
the one or the other of the regulating coils can be replaced by springs, weights, or
similar contrivances.
According to another part of my Invention applicable to the above described
or any other kind of electric lamp in which the electric arc is produced between
carbon poles, instead of having only one pair of carbon poles I provide two or
more pairs, of which the upper carbons are all connected to one and the same
holder, and are consequently all moved simultaneously to and from the lower
carbons. By this arrangement, assuming that all the carbons are out of contact-

page_text: and that the electric arc is formed between one pair thereof, then on the upper
carbon being consumed to such an extent as to cause the carbon holder to descend,
so as to bring the other pair or one of the other pairs of carbons in contact, the
current will now pass through these, and the arc will be formed on the rising of
the carbon holder. On the upper carbon of this pair burning away, the downward
motion of the holder will bring the first named pair or another pair into contact,
and the arc will be transferred to that pair again, and so on continuously until
both or all the upper carbons have been consumed. The transference of the arc
from the one pair of carbons to the other takes place so rapidly that the interruption
of the light is scarcely perceptible. It will be seen that by the above described
arrangement a comparatively small total travel of the carbon holder will be
required to enable a lamp charged with two or more such pairs of carbons to burn
for a considerable length of time
Fig. 1 of the acompanying Drawings shews a side elevation partly in section
Fig. 2 a front elevation, and Figs. 3, 4, and 5 sectional plans on lines X, X, Y, Y,
and Z, Z, of an electric lamp having the before described improvements applied
thereto. To the soft iron core A working up and down in the solenoids of low
and high resistance B, C, is pivotted one end of the lever D, which has its fulcrum
on the fixed bracket E at E¹, and has pivotted to its other end the suspended
frame F, which is guided at its lower end by a link connection M to a bracket M¹.
The frame F has two loops F1, F2, through which passes freely the carbon holder G,
this being held in the said loops by the action of an excentric locking piece H
pivotted to the frame and weighted by an arm H', so as to press the carbon holder
against the sides of the loops F1, F2. Thus as the core A rises, owing to the
increased attraction of the solenoid of high resistance C, consequent on the burning
away of the carbons S, the frame F, and with it the carbon holder and upper
carbon, will descend until the arm H' of the locking piece comes in contact with
the stop K, whereupon a slight further descent of the frame will cause the
excentric H to be turned by its arm H', so as to free the carbon-holder, which will
then descend by gravity through the loops F1, F2. The upper carbons being thus
made to approach the lower carbons sufficiently to cause a decreased action of the
solenoid C and an increased action of the solenoid B, the core A in descending will
raise the frame F again, and the arm H¹ being thus raised off the stop K the
eccentric H will again be caused to press the carbon holder against the loops, and
consequently the carbon holder and carbons will be raised with the frame until,
by the increased distance between the upper and lower carbons, the normal
resistance to the passage of the current through them is attained, whereupon the
core A. and frame will remain stationary, until by the burning away of the carbon
the resistance is again increased and the above described action is repeated.
Although it is preferred to provide the cam H with a weighted arm, as
described, yet it will be evident that this might be dispensed with, and the
weight of the cam alone with or without the aid of a spring be caused to
effect the nipping of the carbon holder. In this case the stop K would be
situated immediately beneath the cam, so as to release it on the descent of the
frame F. For the cam H a ring embracing the carbon holder so as to nip it
when in an inclined attitude may obviously be substituted. The carbon holder G
is formed tubular and contains a liquid, such as glycerine, and within it is a piston
L fitting it loosely and carried by a rod L' from a bracket L2 at the top of the
lamp by this arrangement the liquid has to be forced from the one side of the
piston to the other on the movement of the carbon holder, and consequently its up
and down motion as also that of the carbons is controlled and rendered gradual
and without shock. In order to diminish vibrations particularly when alternating
currents are employed, I prefer to bush with felt or other soft elastic material the

page_text: holes for the connections of the moving parts, such as the hole at A, and that for
the pin of H. The weight of the frame F and carbon holder with carbons being in
excess of that of the solenoid core A, the weight of the former is balanced to a
certain extent by means of a spring N connected at its upper end to an arm E² of
the bracket E, and at its lower end to the frame F. This spring N instead of
being attached directly to the frame F may be connected by a cord to a barrel
which unwinds the cord, thereby diminishing the strength of the spring as the
weight of the carbon diminishes. The current passes from the main circuit through
the contact screws O and P, and low resistance solenoid B to the bracket E, thence
through the metal strip Q to the frame F, from which it is led through the copper
cord R secured at R' to the frame to the top of the carbon holder G, and after
passing down through the upper carbons S or S¹, and lower carbons S2 or S³, it
flows through the flame T, T¹, and contact screw O¹ into the main circuit again.
At the same time a portion of the current passes through the body I of the lamp to
the one end of the solenoid C, the other end of which is connected by wire C₁ to the
contact screw P', from whence it flows through the contact screw O¹ into the main
circuit without passing through the poles of the lamp. When, owing to the
burning away of the carbons, the frame F descends so low as to bring an insulated
contact bar F3 carried by it into contact with the two screws P, P¹, the current
passes from 0 through P and P¹ direct to 01, thus throwing the lamp out of
circuit. U is a plate of insulating material, on the underside of which are con-
ducting plates V, VI, forming the connections respectively between O and P, and
between 0 and P¹. The rod T2 of the framing is in electric connection with the
plate V, and is insulated from the part T, while the rod T¹ is in electric connection
with T and with the plate V', so that the circuit wires can be connected either to
the screws 0, 0¹, or to the pinching nuts W, W₁, at the bottom of the framing.
The carbon holder G has a crosshead G¹, in which are secured two upper
carbons S, S¹, opposite two lower carbons S², S³. On first starting the lamp the
current will pass through the one or the other pair of carbons, say, S, S2, and on
the carbons burning away the downward motion of the carbon holder will cause
the carbons S¹, S3, to approach nearear than S, S2, (as indicated in Fig. 2) in
consequence whereof the current will be transferred to these, and on this pair
burning away S, S², will again be brought nearest together on the descent of the
carbon holder, causing the current to be transferred back to these. Thus the
current will alternately shift from the one pair of carbons to the other until both
pairs are consumed. It will be evident that three or more pairs of carbons may
operate in combination in the same manner, the current always passing through
that pair which on the descent of the carbon holder are brought nearest together.
It will be evident that this arrangement of carbons may be used with other
descriptions of electric lamps.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I claim,―
First. In an electric lamp, wherein the regulation of the carbons is effected by
the differential action of two solenoids or electro-magnets, or of a single solenoid
and a spring or weight suspending the one carbon holder on a lever actuated by
the movement of the solenoid core by means of a pinching cam or wedge piece,
which on being brought by the descent of the lever in contact with a stop is
caused to release the carbon holder and permit it to descend, substantially as herein
described.
Second. The combination of the core A, solenoids of high and low resistance B, C,
lever D, frame F, F1, F2, carbon holder G, eccentric or cam H, and stop K or its
equivalent, arranged and operating substantially as herein described.
Third: The arrangement in an electric lamp of two or more sets of carbons, so
that when one pair becomes partly consumed the current will on the descent of
the carbon holder be transferred to another pair of the carbons, substantially as
herein described.

page_text: Fourth. The improved construction of electric lamp with cam or excentric
regulation, and two or more pairs of carbons, herein described and shewn on the
accompanying Drawings.
In witness whereof, I, the said George Sylvester Grimston, have hereunto
set my hand and seal, this Thirteenth day of October, in the year of our
Lord One thousand eight hundred and eighty one.
GEORGE SYLVESTER GRIMSTON. (L.S.)