ELECTRIC LAMPS."
Year: 1881

page_text: •
PROVISIONAL SPECIFICATION left by the said Charles Lever at the Office
of the Commissioners of Patents on the 18th August 1881.
CHARLES LEVER, of Bowden, in the County of Cheshire.
ELECTRIC LAMPS."
"IMPROVEMENTS IN
One object of my Invention is the providing of improved means of regulating
the voltaic arc for the production of the electric light.
The first part of the improvements to which the Invention applies is intended
to be used in connection with electric lamps where the light results from the
electric current passing between points or pencils of carbon. These improvements
are intended to effect automatically the following operations, viz. :-
First. To separate the carbon points to the required distance for the display of
the voltaic arc.
Second. To allow one of the carbon pencils to be fed forward to compensate for
the consumption which takes place when the electric current is passing between
the points or pencils of carbon.
Third. When the current is interrupted, to instantaneously bring the carbon
points into contact with each other.
I accomplish the first part of my Invention by allowing the force of an electro
magnet in circuit with the carbon points to act on armatures which can oscillate
on pivots, and provided with springs fixed to the armatures, but arranged
eccentrically to the axes on which the armatures are pivotted. These armatures
and springs are arranged on both sides of a carbon holder capable of sliding
through suitable bearings, so that when the electro magnet is excited it will attract
the armatures by means of polarised screws, hereinafter described, and consequently
[Price 8dı

page_text: the springs attached thereto will impinge on the sides of the movable carbon holder
carrying one of the carbon points, and by their eccentric motion will raise one of
the carbon points to the required distance for the display of the voltaic arc.
With regard to the second part of this Invention, the springs and armatures
are arranged on either side of the upper or movable carbon holder, so that when
the electro-magnet is not excited the upper carbon holder with its carbon pencil
will slide freely by the force of gravitation between the springs of the armatures,
and consequently the upper carbon pencil will rest on the lower carbon, thus
completing the electrical connection. But as when the current is passing the
resistance of the voltaic arc will increase as the carbons are consumed, the force
which the electro magnet will exert on the armatures will decrease until the upper
carbon holder will by its own weight overcome the force of the electro magnet
tending to keep it raised, and so by the force of gravity will fall, thus automatically
lessening the distance between the carbon points.
The polarised screws referred to consist of ordinary iron screws of a suitable
diameter and length, which pass through the poles of the electro magnet, and are
consequently polarised or rendered magnetic when the electro magnet is excited,
and are provided with milled heads, preferably of brass or other diamagnetic
material.
The part which these polarised screws is intended to play is, first, to attract in
virtue of their induced magnetism the armatures, and consequently to raise the
upper carbon pencil; and, secondly, to act as limits or stops for regulating the
distance between the carbon points for the production of the voltaic arc.
I provide an electro magnet with armatures above and the poles below same,
the section of which is preferably square in order that the electro magnet may be
fixed on a brass box, and secured by means of nuts to flanges cast on each side of
the box. A suitable piece of insulating material is employed, such as wood or
vulcanite, upon which the brass box carrying the electro magnet and the regulators
is fixed, and on to which are also fixed the binding screws and the conducting
frame carrying the lower carbon holder and carbon rod.
The brass box has a hole drilled in the top and bottom, through which slides
freely the upper carbon holder carrying the carbon rod, and which can be prolonged
through the armature if desired.
The regulators are constructed of two suitable pieces of iron, through which are
drilled eccentrically two holes to admit of two pivots which are secured to the
brass box, so that these pieces of iron or armatures will move freely on the pivots.
Two springs of a suitable tension are arranged semicircularly on the armatures,
but eccentrically to the axis on which each armature is pivotted, and these springs
can be fixed by means of small screws or in any other convenient manner.
The two regulators are so fixed by their pivots that when in their normal
position, that is, when the polarised screws passing through the poles of the
electro magnet are not magnetised, the upper carbon holder carrying the carbon
rod will slide freely by the force of gravity on to the lower carbon rod.
The action of this lamp is as follows:-
The current entering at the binding screw passes from thence through the coils
of the electro-magnets, then through the upper carbon holder and the carbon rod,
through the lower carbon rod and holder to the second binding screw, or vice
versa. When however the current flows through the coils of the electro magnet
the screws are polarised or magnetised and will consequently attract the armatures,
and the springs being arranged eccentrically to the axes on which the armatures
are pivotted will impinge on the sides of the upper carbon holder, and, will
therefore by this eccentric motion raise the carbon rod and so display the voltaic
arc, the length of which is adjusted by turning the polarised screws in one
direction or the other as may be required.
But as the resistance of the arc will increase as the carbons are consumed, the
current flowing through the coils of the electro magnet will decrease, consequently

page_text: the electro magnet and polarised screws will gradually loose their magnetism
until a point is reached, when the force which gravitation exerts on the upper
carbon holder will overcome the force exerted by the polarised screws on the
armatures tending to keep the upper carbon rod raised, and it will therefore be
lowered. But immediately this takes place the electro magnet and polarised screws
will regain their magnetic power because the resistance of the arc will have
diminished, and therefore the carbon rod will again be raised to the distance
regulated by the polarised screws, and these two actions will take place simul-
taneously until the carbons are consumed. Should the current be interrupted
from any cause whatsoever the upper carbon will instantly be brought into
contact with the lower carbon.
Screws, preferably of non-magnetic material, are used for the purpose of
preventing the ends of the armatures from falling out of the range of attraction
of the polarised screws when the upper carbon holder is falling, and should be so
adjusted that the upper carbon holder and carbon rod will just slide freely by the
force of gravity between the springs of the armatures.
A modification of regulator on the same principle as that already described is
where the springs are only fixed at one end of each armature.
In consequence of the peculiarity of this motion and the novel manner of
applying the force of the electro magnet to the armatures by means of polarised
screws and the sensitiveness of this regulator, it is believed that the regulation of
the voltaic are will be rendered more effectual by this Invention than by any other
at present in use.
When however a number of lamps are required to be placed in series or
single circuit, and where it is essential that the voltaic arc should be regulated
independently of the current flowing through the whole of the lamps thus arranged,
a device is employed wherein the lamps are arranged on the main circuit, and each
lamp placed in series is provided with a shunt circuit of high resistance, so that
according to the law of derived circuits the current flowing through this shunt
circuit of high resistance will be very small as compared with that flowing through
the main circuit and lamp of low resistance. But as the resistance of the are will
increase with the consumption of the carbons, more current will flow through the
shunt circuit, so that the electro magnet and the polarised screws will be demag-
netised more quickly than they would do if no shunt circuit was provided,
consequently the carbon will be lowered, which will decrease the resistance of the
are, whereupon more current will flow through the main circuit and lamp. It
will be seen then that by the simple arrangement of this shunt circuit of high
resistance a number of lamps can be placed in series or single circuit, because the
whole arrangement of each lamp and shunt will always represent a constant
resistance to the passage of the current.
In order to prevent an interruption in the main circuit caused by an accident,
such as the falling out of one of the carbon pencils, a device is employed where
the shunt circuit is made in the form of a solenoid, into the interior of which is
placed an iron core, so that when the current is passing through the solenoid the
iron core will become magnetic.
An armature is fixed to a spring of suitably elasticity, and a thick wire connects
the spring with the main circuit; a piece of ivory or other piece of insulating
material is fixed to the spring, and against which a metal spring presses very
lightly, and which spring is also fixed at one end.
As long as the are in the main circuit is established, the current flowing through
the shunt circuit of high resistance is very small, consequently the core is only
slightly magnetised and will not attract its armature. But should the connection
of the lamp in the main circuit be accidentally broken, then all the current will
flow through the solenoid shunt, the circuit being closed by the insulating piece,
and the iron core will become strongly magnetised and will instantaneously attract
the armature, thus forcing momentarily the metal spring aside by the forward

page_text: motion. But immediately this takes place the spring will touch the metal spring
and then the circuit will be opened, and so the current flowing through shunt will
be very small compared with that flowing through the circuit of low resistance,
whereupon the iron core will become demagnetised so that the spring will bring
the armature backwards, and by the combined tensions of the springs good contact
will be established between them. The action just referred to will take place
so quickly that there would scarcely be any perceptible flicker in the other
lamps which might be placed in the same circuit, and it would also take place so
quickly that there would be no dangerous rise of temperature in the fine wire of
the solenoid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Lever in the Great Seal Patent Office on the 18th February
1882.
CHARLES LEVER, of Bowden, in the County of Cheshire.
ELECTRIC LAMPS."
"IMPROVEMENTS IN
One object of my Invention is the providing of improved means of regulating
the voltaic are for the production of the electric light.
The first part of the improvements to which the Invention applies is intended to
be used in connection with electric lamps where the light results from the electric
current passing between points or pencils of carbon. These improvements are
intended to effect automatically the following operations, vis. :-
A. To separate the carbon points to the required distance for the display of the
voltaic arc.
B. To allow one of the carbon pencils to be fed forward to compensate for the
consumption which takes place when the electric current is passing between the
points or pencils of carbon."
C. When the current is interrupted, to instantaneously bring the carbon points
into contact with each other.
I accomplish the A part of my Invention by allowing the force of an electro
magnet in circuit with the carbon points to act on armatures which can oscillate on
pivots, and provided with springs fixed to the armatures, but arranged eccentrically
to the axes on which the armatures are pivotted. These armatures and springs are
arranged on both sides of a carbon holder capable of sliding through suitable
bearings, so that when the electro magnet is excited it will attract the armatures
by means of polarised screws hereinafter described, and consequently the springs
attached thereto will impinge on the sides of the movable carbon holder carrying
one of the carbon points, and by their eccentric motion will raise one of the carbon
points to the required distance for the display of the voltaic arc.
With regard to the B part of this Invention, the springs and armatures are
arranged on either side of the upper or movable carbon holder, so that when the
electro magnet is not excited, the upper carbon holder with its carbon pencil will
slide freely by the force of gravitation between the springs of the armatures, and
consequently the upper carbon pencil will rest on the lower carbon, thus completing
the electrical connection. But, as when the current is passing, the resistance of the
voltaic arc will increase as the carbons are consumed, the force which the electro
magnet will exert on the armatures will decrease until the upper carbon holder
will by its own weight overcome the force of the electro magnet, tending to keep it
raised, and so by the force of gravity will fall, thus automatically lessening the
distance between the carbon points.
The polarised screws referred to consist of ordinary iron screws of a suitable
diameter and length which pass through the poles of the electro magnet, and are
consequently polarised or rendered magnetic when the electro magnet is excited,
and are provided with milled heads, preferably of brass or other diamagnetic
material.
The part which the polarised screws is intended to play is, first, to attract in
virtue of their induced magnetism the armatures, and consequently to raise the
upper carbon pencil; and, secondly, to act as limits or stops for regulating the
distance between the carbon points for the production of the voltaic arc. I provide
an electro magnet with its armature and poles, the section of which is preferably
square; in order that the electro magnet may be fixed on a brass box and secured
by means of nuts to flanges cast on each side of the box. A suitable piece of
insulating material is employed, such as wood or vulcanite, upon which the brass
box carrying the electro magnet and the regulators is fixed, and on to which are
also fixed the binding screws and the conducting frame carrying the lower carbon
holder and carbon rod.
The brass box has a hole drilled in the top and bottom, through which slides

page_text: freely the upper carbon holder carrying the carbon rod or pencil, and which can be
prolonged through the armature if desired.
The regulators are constructed of two suitable pieces of iron, through which
are drilled eccentrically two holes to admit of two pivots which are secured to the
brass box, so that these pieces of iron or armatures will move freely on the pivots.
Two springs of a suitable tension are arranged semicircularly on the armatures, but
eccentrically to the axis on which each armature is pivotted, and these springs can
be fixed by means of sinall screws, or in any other convenient manner.
The two regulators are so fixed by their pivots that when in their normal
position, that is, when the polarised screws passing through the poles of the electro
magnet are not magnetised, the upper carbon holder carrying the carbon rod will
slide freely by the force of gravity on to the lower carbon rod.
And in order that this part of my Invention may be more fully understood, I
will now describe some modes of carrying it into effect, with reference to Figures 1,
2, 3, and 4 of the accompanying Drawings.
Figure 1 is a front elevation of an arc lamp constructed according to this part of
my Invention; E is an electro magnet, and A the armature, and c, c¹, the poles;
the section of the latter is by preference flat or square for the convenient fixing
of the electro magnet to flanges on the brass box or frame b by means of the
nuts n; I is a piece of insulating material, such as wood or vulcanite, and serving
conveniently as a base plate for the frame b and parts attached thereto. To this
plate I are also fixed the binding screws B, B', and the frame F carrying the lower
carbon holder T with its carbon rod or pencil C¹.
T¹ is the holder for the upper carbon C, and is made to pass through the bosses
shewn on the upper and lower part of the brass box b; the holder T¹ may be
prolonged through the armature A if desired.
a, a³, are the regulator armatures, which are bars of iron having each a hole
through for the reception of a pivot or fulcrum pin p, p, the said pivots being
eccentrically arranged as to the length of the bar. The pivots p, pl, have their
bearings in a cross bar p³ fastened to the two sides of the box 6; 8, 8³, are two
curved springs fastened at their ends to the armatures a, a', by means of
screws 7.
Figure 2 is a separate perspective view of one of the regulators.
P, P, are two polarized screws inserted through the pole pieces c, c¹, and are
magnetised when the current is flowing through the electro magnet E, E; 8³, 8³,
are set screws inserted through the sides of the box b, and serving to keep the
armatures a, a³, within the proper range of attraction of the polarized screws P, P¹ ;
these screws 83, 83, should be so set that the carbon holder T¹ will slide freely by
its gravity between the two springs 8, 8², of the armatures a, a¹; w, w, w, w, are
the connecting wires. In any given size or construction of lamps, when, the proper
distance between a polarized screw and a regulating armature has once been found,
any number of such lamps may be made without any adjustable polarized screws
or pole pieces. Also the fulcrum of the regulating armatures may be made
adjustable up and down, and thus more or less obviate necessity for adjusting the
polarized screws or pole pieces.
The action of this lamp is as follows:-
The current entering at the binding screw B passes from thence through the
coils of the electro magnet E, E, then through the upper carbon holder T¹ and the
carbon rod C, through the lower carbon rod C₁ and holder T to the second binding
screw B³, or vice versa. When however the current flows through the coils of the
electro magnet E, E, the screws P, P¹, are polarized or magnetised, and will con-
sequently attract the armatures a, a³, and the springs 8, s¹, being arranged eccen-
trically to the axes, on which the armatures a, a¹, are pivotted will impinge on the
sides of the upper carbon holder T¹, and will therefore by this eccentric motion raise
the carbon red C and so display the voltaic arc, the length of which is adjusted
by turning the polarized screws P, P¹, in one direction or the other, as may be
required.

page_text: But as the resistance of the arc will increase as the carbons are consumed, the
current flowing through the coils of the electro magnet E, E, will decrease, conse-
quently the electro magnet and polarized screws P, P¹, will gradually lose their
magnetism until a point is reached, when the force which gravitation exerts on the
upper carbon holder T¹ will overcome the force exerted by the polarized screws P, P',
on the armatures a, a¹, tending to keep the upper carbon rod C raised, and the
carbon holder T¹ will therefore be lowered. But immediately this takes place the
electro magnet E, E, and polarized screws P, P¹, will regain their magnetic power,
because the resistance of the are will have diminished, and therefore the carbon
rod C will again be raised to the distance regulated by the polarized screws P, P',
and these two actions will continually take place until the carbons are consumed.
Should the current be interrupted from any cause whatsoever the upper carbon C
will instantly be brought into contact with the lower carbon C¹.
A modification of regulator on the same principle as that already described is
where the springs 8, 81, are only fixed at one end of each armature. Figure 3
shews such an arrangement. 8, 81, are the regulator springs, each fixed at one end
to its armature a, a'; this Figure also illustrates a modification of the polarized
Screws P, P', instead of which I here shew adjustable pole pieces p, p, which pass
freely through the poles c, c³, of the electro magnet E, E, and can be fixed in any
desired position by means of set screws q, q².
Figure 4 shows a mode of adapting this principle of regulation to a lamp provided
with solenoids instead of an electro magnet; a, a, are the regulator armatures, and
J, J, are the solenoid cores connected thereto.
In consequence of the peculiarity of this motion, and the novel manner of
applying the force of the electro magnet to the armatures by means of polarized
screws, and the sensitiveness of this regulator, I find that the regulation of the
voltaic arc is rendered very effectual by this Invention.
The second part of my Invention is employed when a number of lamps are
required to be placed in series or single circuit, and where it is essential that the
voltaic arc should be regulated independently of the current flowing through the
whole of the lamps thus arranged. A device is then employed in which the lamps
are arranged on the main circuit, and each lamp placed in series is provided with
a shunt circuit of high resistance, so that the current flowing through this shunt
circuit will be very small as compared with that flowing through the main circuit
and lamp.
The first part which this shunt circuit performs is simply to offer another path
for the current in the main circuit and electric arc lamp, from which it is shunted
or derived, so that as the resistance of the arc increases the current, which
would flow through shunt circuit, would also increase, and it would therefore
weaken the force of the electro magnet or solenoid in the lamp, which sustains one
of the carbon points or pencils.
The electro magnet or solenoid would therefore allow its carbon rod to fall more
quickly than it would do if no shunt circuit were provided, thus lessening the
distance of the arc, or in other words, decreasing the resistance of the arc, where-
upon more current would, flow through the arc lamp and less through the shunt
circuit. It will be seen then that by simply forming from each electric arc lamp
a shunt or derived circuit, as described, a number of said are lamps can be worked
in series or single circuit, because the whole combination of the shunt circuit being
a constant resistance, and that of the arc which it shunts being a variable
resistance, will act precisely the same as would a constant resistance to the passage
of the current, for the amount of current which would flow through the shunt
circuit would always vary, or increase and decrease with the resistance of the arc
which it shunts. If desired the said shunt circuit can be placed at any convenient
distance from the arc lamp from which it is derived.
With reference to the second part which this shunt circuit performs, viz., that of
cutting out of circuit, the arc lamp which it shunts when the circuit through said
lamp is broken, the coil of fine wire forming the shunt circuit is preferably wound

page_text: over two iron cores connected at one end by a piece of iron or armature, so that
the combination will form an electro-magnet with two limbs, or it may be formed
as a bar electro magnet, or simply as a solenoid. The one first named is however
preferred for reasons stated hereinafter. The electro magnet thus formed has in
front of its two poles an armature which is capable of moving for a limited distance
around a pivot provided with means, such as a screw and screw head, the latter
being for the purpose of making the armature move somewhat stiffly. On the end
of the armature opposite to the pivot is fixed a piece of metal. Two metal studs
insulated and made flush with each other are also provided, so that the metal piece
can make contact with either one or the other metallic stud. The shunt circuit of
fine wire shunting the arc lamp is made through the coils of the electro magnet,
one end of which is connected to the metallic stud farthest away from the electro
magnet, and when the arc is burning, the metal piece attached to the armature is
made to rest on this stud, so that the shunt circuit is completed through the
contact with the said metallic stud. The other metal stud nearest the electro-
magnet has also a shunt circuit of low resistance shunting the arc lamp, but this
circuit is broken so long as the metal piece on the armature rests upon the
metallic stud farthest away from the electro-magnet, which completes the shunt
circuit of high resistance, as already described.
In its normal position, that is, when the electric arc is burning, or the con-
ductivity of the arc lamp is good, the metal piece of the armature always rests
upon the metal stud, completing the shunt circuit of high resistance, and which has
consequently not much current flowing through it, so that the electro-magnet of
which it forms part will only be feebly magnetised, and as the armature will have
been adjusted by the screwhead on the screwed pivot to move stiffly, it will not
be attracted by the electro-magnet. But should from any cause whatsoever the
conductivity of the arc lamp be destroyed, then it is quite clear that all the current
which originally flowed through the arc lamp will flow through the shunt circuit,
and therefore the electro-magnet will become powerfully magnetized, and will
attract its armature. By so. doing the metal piece attached to the armature will
leave the metal stud farthest away from the electro-magnet, and will in virtue of
the attraction of the armature rest upon the metal stud nearest the electro-magnet,
whereupon another circuit of low resistance will be brought into operation; the
shunt circuit and lamp will then be cut out of circuit, and the current from the
main will then flow through this new circuit. The action just referred to will, as
I have found in practice, take place so quickly, that there will be no perceptible
heating of the fine wire of the shunt circuit, and also so that there would scarcely
be any perceptible flicker in the other lamps in the series.
In order that this second part of my Invention may be better understood and
readily carried into practice, I will describe the annexed Drawings:
L, Figure 5, represents an electric arc lamp, the downward motion of one of the
carbons being caused for instance by gravity, and S is the shunt or derived circuit
of much greater resistance than that of the arc L; then the current which will flow
through S will be small compared with that which will flow through the arc L.
But as the resistance of the arc L will increase with the consumption of the
carbons, more current will flow through the shunt circuit S, consequently the force
of the electro-magnet or solenoid which sustains one of the carbon pencils in the
arc lamp L will be lessened, the shunt S having as it were drained off more current
from the arc lamp L, and the carbon rod will therefore be lowered, thus decreasing
the resistance of the arc L, whereupon less current will flow through the shunt S,
and correspondingly more through the arc L. By the simple addition of this shunt
circuit S, which can be placed at any desired distance from the arc lamp L, a number
of electric arc lamps can be worked in series or single circuit, because the whole
combination of shunt S and arc lamp L will act precisely the same as a constant
resistance to the passage of the current.
In order that this said shunt circuit, Figure 5, may cut out of circuit the arc
lamp L which it shunts, should the circuit through the said lamp be broken, the

page_text: coil of wire forming the shunt circuit is wound over the limbs of an electro
magnet e, e, as shown in front elevation and plan, Figures 6 and 7. f is an
armature which is capable of moving a limited distance round a pivot g, which is
provided with a screw and head g', the use of which will be described further on;
5 h is a peg or pieco of metal which passes through the armature f, and which by
being pressed on by a spring f', establishes contact with one of the metal studs /
or k.,, are binding screws fixed on to a suitable piece of insulating material,
upon which are also fixed the electro-magnet e, e, armature f, studs and k¹, and
pivot g. Two insulated wires of low resistance connect the binding screws and
to the electric arc lamp L. The ends of the coil of the electro-magnet e, e, forming
the shunt circuit are connected, one to the binding screw , and the other to the
metallic stud k¹. An insulated wire W of low resistance connects the metal stud k
with the binding screw 1, and another similar wire W₁ connects the pivot g with
the binding screw l'.
In its normal position, that is, when the circuit through the arc lamp L is
complete, the metal piece h makes contact with the metal stud k³, which is insulated
from the metal stud k by a suitable piece of insulating material i, the studs k
and k², and insulating piece i, being made flush with each other, so that the shunt
circuit is then completed through the coils of the electro-magnet metal stud k',
metal piece h, armature f, pivot g, wire W¹, or vice verad. The screw head g¹ is
then screwed down, so that the armature fmoves somewhat stiffly, and also so that
the small amount of current which will flow through the shunt circuit coil on the
electro-magnet e, e, will not magnetise it sufficiently to attract the armature f.
But should from any cause the conductivity of the arc lamp L be destroyed, then
all the current which previously flowed through the arc L in the main circuit will
flow through the shunt circuit coil on the electro magnet e, e, consequently it will
become magnetised very much more than it was when the circuit through the arc
lamp L was complete, and the armature ƒ will therefore be almost instantaneously
attracted, whereupon the metal piece will leave the metallic stud k¹, and will
make contact with the metal stud k. But immediately this takes place the arc
lamp L and shunt coil on the electro magnet e, e, will be cut out of circuit, and the
current will then flow through the new circuit of low resistance which has been
opened by the movement of the armature and metal piece h, from metal stud k' to
metal stud k, namely, from 7, wire W, metal stud k, metal piece h, armature ƒ,
pivot g, wire WI, and binding screw ', to the main circuit or vice versa.
Instoad of winding the coil of the shunt circuit over two limbs of an electro-
magnet it may be wound so as to form a bar electro-magnet, or it may be wound
simply as a solenoid. In the latter case however an iron core would have to be
fixed to the end of the armature f, and be made to move in the interior of the
solenoid, so that the solenoid would in this way act exactly the same as an electro-
magnet. The form of winding the coil of the shunt circuit, as illustrated, is however
preferred, because in this form a very high resistance can be obtained.
This regulating shunt may also be arranged to cut out the lamp in connection
with other devices than those here shown, which however have been found
efficient. I may thus, for instance, though not so efficently, make the shunt
circuit in the form of a solenoid, into the interior of which is placed an iron core,
which becomes magnetic when a current is flowing through the solenoid; an
armature is then fixed to a spring of suitable elasticity, and a thick wire connects
the spring with the main circuit, a piece of ivory or other insulating material is
fixed to the spring and another spring presses very lightly against the ivory piece;
this spring is also fixed at one end. As long as the arc in the main circuit is
established the current flowing through the shunt solenoid is very small, hence the
core is only slightly magnetised; but when the conductivity through the lamp is
destroyed then all the current will flow through the solenoid shunt, the circuit of
low resistance being broken by the insulating piece, and the core will become more
strongly magnetised and attract the armature, thus momentarily by its forward
motion forcing aside the metal spring which presses against the insulating piece.

page_text: But this spring will then at once. touch the other spring, and a new circuit will then
be opened, thus permanently, cutting out the lamp.
The mode described with reference to Figures 6 and 7 is however preferred,
'because with, the lamp herein described the main magnet E, E, Figure 1, can by
means of a piece of iron projecting from one of the poles be made to act on the
side of the arinature f, Figures 6 and 7, opposite to that on which the shunt
magnet acts. The object of this arrangement is to allow the electro magnet E, E,
Figure 1, to attract the armature ƒ by means of the said projecting piece of iron,
and thus keep the metal piece h, Figures 6 and 7, over the metal stud k³, and thus
complete the shunt circuit. If the conductivity of the lamp should be destroyed
the shunt magnet e, e, will of course cut out the lamp as already described. Should
however the conductivity of the lamp be again renewed, the projecting iron piece
will draw the armature ƒ down again on to the contact stud ¹, thus allowing the
arc to reappear.
Figure 8 shows a lamp complete, that is, with all the improvements hereinbefore
described, and with the regulating mechanism enclosed; e, e, is the shunt magnet
attached to the case in which the main magnet is enclosed; m is the piece of iron
which projects from one pole of the electro magnet E, E, and which is so placed
that it can attract the armature lever f; this latter is pivoted at the opposite end,
and the screw head g¹ may in this case be dispensed with. The thick wire shows
the connections of low resistance, and the fine wire those of high resistance.
Having thus described the nature of this Invention, and in what manner the
same is to be performed, I declare that I claim,-
First. In an electric arc lamp the application of pivoted armatures provided with
springs fixed eccentrically to the axes on which the said armatures are pivoted,
and actuated by an electro magnet or solenoid, all substantially as and for the
purposes set forth.
Second. In an electric arc lamp the application of polarized screws or other
adjustable pole pieces, which operate in combination with armature appliances for
raising one of the carbon pencils and adjusting the length of the arc, as set forth.
Third. In electric are lamps arranged in a series or single circuit, the combination
with each lamp of a regulating shunt circuit of a greater resistance than that of
the lamp which it shunts, the said shunt circuit simply offering another path for
the current from the said lamp, and thus weakening the force of the electro magnet
or solenoid which actuates one of the carbons and allowing the said carbon to drop,
substantially as described.
Fourth. In electric arc lamps arranged in series or single circuit, the combination
with each lamp of the regulating shunt, which will cut out the arc lamp which it
shunts, and form a circuit for the current outside the lamp, in case the circuit
through the said lamp should be broken, substantially as and for the purpose set
forth.
Fifth. In a combined regulating shunt and cut out device for electric arc lamps,
the armaturef having a contact piece h, in combination with the contact studs /
and k', with intermediate insulating piece i, the pivot g, with screw head g', and
the projecting pole piece m, all substantially as and for the purposes set forth.
Sixth. The combination of parts forming the improved shunt are lamp, as
described with reference to Figure 8.
In witness whereof, I, the said Charles Lever, have hereunto set my hand
and seal, this Thirteenth day of February, in the year of our Lord One
thousand eight hundred and eighty two.