IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1877

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
ELECTRIC LAMPS." A communication from abroad by Siegfried Marcus and
Bela Egger, both of Paris, France.
Sealed the 11th January 1878, and dated the 31st July 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 31st July 1877.
"
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. 'IMPROVEMENTS IN ELECTRIC LAMPS." [A communication from
abroad by Siegfried Marcus and Bela Egger, both of Paris, France.]
This Invention relates to improved means of maintaining the proper interval
between the carbon points or electrodes of electric lamps to compensate for their
waste or consumption and ensure the constancy of the light.
It is generally admitted that the best means of regulating the carbon electrodes is
by the influence of a current passing through a coil on a movable core of soft iron
within said coil; but in consequence of the limited movement of the core and the
variable degree of force at different positions of the core, nechanism has been
introduced in electric lamps hitherto constructed to enable carbons of considerable
length to be fed towards one another, through distances greater than that traversed
by the core, and as uniformly as possible.
The object of this Invention is to dispense with this mechanism, and to effect the
regulation of carbons directly by the influence exerted by a series of coils traversed
by the current on a core of soft iron placed therein.
I will proceed to describe the Invention with reference to the annexed Drawings,
in which Figures 1 and 2 show a series of helices or coils combined in such manner
as to exert the maximum effect on a soft iron core, and admit of the latter traversing
a course of any required extent.

page_text: The regulator is composed of a series of short independent coils a, b, c, d, e, f, g,
connected together end to end, the ingress and egress ends of the several coils being
respectively connected to separate metallic contact plates m, m³, m², m³, m¹, and
n, n', n², n³, n, screwed upon strips of india-rubber or other insulating material o, o¹.
The current passes into and out of the coils by contact rollers h, h', carried by
metallic springs i, i, and rolling along the plates m to m* and n to n. As each pair
of opposite plates m, n, comprises between them, say, but three coils, the current will
pass through three only out of the whole series of coils, these particular coils varying
as the contact rollers rise or fall, as will be readily understood from inspecting the
Drawing.
The springs i, i, are connected to a metal cross bar L fixed on rod F attached to
the core E, which occupies such a position with regard to the coils traversed by the
current (about a third of the core projecting beyond these coils) that the maximum effect
is produced; this relation of the core to the effective coils remaining unvariable in
all positions of the core, so that the latter will exert a uniform power at all points
of its course.
R is a double barrel or pulley for the purpose of causing the upper
electrode to be fed downwards at a rate equal to that of its consumption, which,
compared to that of the lower electrode, should be in the proportion of 1 to 2. The
pulley R has two grooved peripheries, the diameters of the two parts of the pulley
being in the proportion of 1 to 2. A small chain or band attached to and wound on
the larger part of the pulley passes down over a guide pulley and is connected to
the core E, while a similar connection wound on the smaller part of the barrel
supports the rod T which moves freely in the hollow pillar S, being guided by an
arm projecting horizontally at its upper end.
It will be evident that at each upward or downward movement of the core E the
rod T is moved to one half the extent in the opposite direction, and as the lower
carbon x' is connected by its holder u' to the core E, the upper one x to the rod T by
its holder stud u on the cross arm Q, both the electrodes are simultaneously fed or
moved at the proper rate. This arrangement of double grooved pulley forms a
simple substitute for the complicated gearing hitherto employed for the purpose.
The weighted part and the small flat weights 2, 21, 2¹¹, serve in part to
balance the two electrodes with their supports and partly and especially to maintain
the electrodes at the most suitable distance apart, according to the power of the current,
which may be readily ascertained by the application or removal of the weights. The
coils, standard S, and binding screws K, K, are mounted on a base plate B, and the
lower part of the lamp may be enclosed in a casing.
The working of the lamp is as follows:-The rod T having been loaded just
sufficiently to bring the two carbon points into contact, the wires from a powerful
battery are connected to the binding screws K, K'. The course of the current varies
according to the position of the core E, as shown in the Drawing, the current passes
from K through standard S, rod T, carbons x, x', to the one spring i¹ (the insulator M
preventing its passage to the other spring i) thence by contact roller h' and plate m111
through the three coils f, e, d, comprised between said plate ml at the corresponding
opposite plate n; thence by the other contact roller h and a plate y (shewn in
Figure 3) alongside plates n to K. The passage of the current through the coils a,
as above described, has for its object to cause the core E to be slightly drawn down-
wards in order to separate the carbons sufficiently to produce the arc of light. The
core is drawn downwards with a force increasing commensurately with the intensity
of the current, whereby the distance between the carbons is increased, whereas as the
force of the the current diminishes it is overcome by the weight and the distance is
reduced, the lamp being thus regulated in a perfectly automatic and reliable manner.
The following are the advantages of this Invention :-
1st. Simplicity of construction.
2nd. Small cost of manufacture.
3rd. Certainty of action.
4th The friction being reduced to a minimum the regulator responds to every

page_text: 5th. The regulation is continuous instead of in jerks, as when gearing is employed.
6th. A constant steady flame is obtained without flickering.
7th. The luminous point always remains stationary in the focus of the reflector.
The above advantages render this lamp especially adapted for illuminating
workshops, squares, and other public places, vessels, lighthouses, and particularly for
railway signalling and lighting up trains, as the apparatus is not liable to become
disarranged by shocks or vibration.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
30th January 1878.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN ELECTRIC LAMPS." A communication from
abroad by Siegfried Marcus and Bela Egger, both of Paris, France.
This Invention relates to improved means of maintaining the proper interval
between the carbon points or electrodes of electric lamps to compensate for their
waste or consumption and ensure the constancy of the light.
It is generally admitted that the best means of regulating the carbon electrodes is
by the influence of a current passing through a coil on a moveable core of soft iron
within said coil, but in consequence of the limited movement of the core and the
variable degree of force at different positions of the core, mechanism has been
introduced in electric lamps hitherto constructed, to enable carbons of con-
siderable length to be fed towards one another as uniformly as possible, through
distances greater than that traversed by the core, but experience has shown that this
mechanism is very liable to get out of order and cause the light to be extinguished.
The object of this Invention is to dispense with this mechanism and to effect the
regulation of the carbons directly by a series of any number of coils, through some
only of which the current passes at any one time, according to the position of the soft
iron core, so that the latter is always subject to the maximum influence of the coils,
whatever may be its position, and it may be made to travel any required distance by
increasing the number of coils.
I will proceed to describe the Invention, with reference to the annexed Drawings,
n which Figures 1 and 2 show a regulator composed of a series of short independent
helices or coils a, b, c, d, e, f, g, connected together end to end in one continuous coil,
the ingress and egress ends of the several coils being also respectively connected to
separate metallic contact plates m, m', m³, m³, m², and n, n¹, n², n³, n³, screwed upon
strips of india-rubber or other insulating material o, o¹, the connections being as
follows, or otherwise, as preferred:-The ingress ends of coils c, d, e, f, g, are
respectively connected to plates m, m', m², m³, m³, and the egress ends of coils a, b,
c, d, e, are respectively connected to plates n, n', n³, n³, n¹.
The current passes into and out of the coils by contact rollers h, h¹; carried by
metallic springs i, i, and rolling along the plates m to m* and n to n¹. As each
pair of opposite plates m, n, &c., comprises between their connection, say, but three
coils, the current will pass through three only of the whole series of coils, these
particular coils varying as the contact rollers run upwards or downwards, as will
be readily understood by inspecting the Drawings.
The springs i,., are connected to a metal cross bar L fixed on rod F attached to
the core E which occupies such a position with regard to the coils traversed by the

page_text: current (about a third of the core projecting beyond these coils), that the maximum
degree of attraction is exerted on the core, this relation of the core to the effective
coils remaining unvariable in all positions of the core, so that the attractive power
is uniform at all points of its course. R is a double barrel or pulley for the purpose
of causing the upper electrode to be fed downwards at a rate equal to that of its
consumption, which, compared to that of the lower electrode, should be in the
proportion to 1 to 2. The pulley R has two grooved peripheries, the diameters at the
two parts of the pulley being in the proportion of 1 to 2. A small chain or band attached
to and wound on the larger part of the pulley passes down over a guide pulley and
is connected to the core E, while a similar connection wound on the smaller part of
the barrel supports and is attached to an arm projecting from the lower end of a rod
T, which is free to slide in the hollow pillar S, and is guided by an arm projecting
horizontally at its upper end.
It will be evident that at each upward or downward movement of the core E the
rod T is moved to one half the extent in the opposite direction, and as the lower
carbon x is connected by its holder u¹ to the core E, and the upper one x to the rod
T by its holder on the cross arm Q, both the eloctrodes are simultaneously fed or
moved at the proper rate. This arrangement of double grooved pulley with chains
or bands forms a simple substitute for the complicated gearing hitherto employed
for the purpose.
The weighted head vand the small flat weights 2, 21, 22, serve in part to balance
the two electrodes with their supports, and partly and especially for adjusting the
electrodes at the most suitable distance apart, according to the power of the current,
which may be readily ascertained by the application or removal of the weights. The
coils, standard S, and binding screws K, K¹, are mounted on a base plate B, and the
lower part of the lamp may be enclosed in a casing.
The working of the lamp is as follows:-The rod T having been loaded just
sufficiently to bring the two carbon points into contact, the wires from a powerful
battery are connected to the binding screws K, K'. The course of the current varies
according to the position of core E, in the position shown in the Drawing, the current
passes from K¹ through standard S, rod T, carbons x, x², to the one spring (the
insulator M preventing its passage to the other spring i), thence by contact roller
h¹ and plate m³ through the three coils f, e, d, comprised between said plate m³ at
the corresponding opposite plate n³, thence by the other roller h and a long plate
y alongside platen, with which said roller is also in contact, as shown in Figure 3,
to k. The passage of current through the coils a, as above described, has for its
object to cause the core E to be slightly drawn downwards in order to separate the
carbons sufficiently to produce the light. The core is drawn downwards with a
force increasing commensurately with the intensity of the current, thus augmenting
the distance between the carbons, whereas as the force of the current diminishes it is
overcome by the weights and the distance is reduced, the lamp being thus regulated
in a perfectly automatic and reliable manner.
The following are the advantages of this Invention :-
1st. Simplicity of construction.
2nd. Small cost of manufacture.
3rd. Certainty of action.
4th. The friction being reduced to a minimum, the regulator responds to every
variation in the currents.
5th. The regulation is continuous instead of in jerks, as when toothed gearing is
employed.
6th. A constant steady flame is obtained without flickering.
7th. The luminous point always remains stationary in the focus of the reflector.
The above advantages render this lamp especially adapted for illuminating work-
shops, squares, and other public places, vessels, lighthouses, and particularly for
railway signalling and lighting up trains, as the apparatus is not liable to become
disarranged by shocks or vibration.
Having described the nature of the said Invention and the manner of

page_text: performing the same, I declare that what I claim as the Invention to be protected by
the herein-before in part recited Letters Patent is,―
1st. The general arrangement of electric lamp regulator, substantially as herein
set forth, and shown in the Drawing.
2nd. The combination of one or a series of coils a, b, c, d, e, f, g, connected together,
and to metallic contact plates m, m³, m², m³, mt, contact rollers h, h¹, and parts in
connection therewith, substantially as and for the purpose above set forth, and shown
in the Drawings.
3rd. The double or differential pulley R for feeding the carbons at the required
rate in the proportion of 1 to 2, as specified, and represented in the Drawings.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Thirtieth day of January, in the year of our Lord
One thousand eight hundred and seventy-eight.