IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Benjamin Joseph Barnard Mills of the firm of Harris and
Mills of 23 Southampton Buildings in the County of Middlesex Patent
Agent for an Invention of IMPROVEMENTS IN ELECTRIC LAMPS Com-
municated to him from abroad by William Maulsby Thomas of Cincinnati,
Hamilton County, in the State of Ohio in the United States of America
PROVISIONAL SPECIFICATION left by the said Benjamin Joseph Barnard
Mills at the Office of the Commissioners of Patents on the 9th August 1882..
BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex Patent Agent IMPROVE-
MENTS IN ELECTRIC LAMPS A communication to me from abroad by William
Maulsby Thomas, of Cincinnati, Hamilton County, in the State of Ohio, in the
United States of America
The improvements are especially intended for arc-electric lamps, such as those
described in the Specification of Letters Patent N° 578 granted to me and dated
7th February 1882 and the present invention, as to its principal feature, is designed
for the equalization of such lamps when used "in series."
It is well known that no two arc-electric lamps employed in series, behave
precisely alike. In one lamp the magnetic "lift" incident to increased current-
flow takes place more promptly and with greater facility, with a consequently
greater arc-interval than in the others. Such disproportionate increase of arc
interval in one lamp necessarily weakens the current throughout the series, and
thus detracts from the lifting power of all, but most so from those of most sluggish
movement. The heavier working lamps thus dwindling in illuminative action,
cease, one by one, to respond to the continually waning magnetic energy. In strong
contrast with, and at the expense of, this enfeebled action of the weaker lamps, the
arc of the most susceptible or easiest working lamp continues to expand until it
practically monopolizes the effective activity of the entire circuit.
The remedy for such unequal action lies in a provision whereby when the
arc resistance in any given lamp becomes higher than normal, the current is

page_text: "
automatically diverted from the arc of that lamp to the next lamp of the series or
to " "line or "generator" as the case may be, and whereby such overflow current
is, at the same time, utilized either to reduce or counteract to a greater or less
extent the belix-suction upon the core or armature of the lamp thus regulated so
ns to restore its arc interval to normal length, and, at the same time, by diminution
of its arc resistance, to secure resumption of normal current flow throughout the
series.
In the present invention, illuminative equilibrium throughout a given series of
arc-electric lamps is secured by the mechanical force due to the current repulsion of
the carrier of the shunted current or overflow of each respective lamp.
With this object in view, a portion of the overflow-wire having a resistance
which renders it comparatively inert during normal action, is so wound upon a non-
magnetic bobbin attached to and travelling with the positive electrode-holder, as
to surround without touching, the prime helix, and, when carrying off overflow, to
conduct the current in a direction reverse to that of the said helix. This overflow
current-carrier (hereinafter called "the differential") has electrical connection, by
its lower end, with the positive electrode, and by its upper end with "line "beyond
the negative electrode, so as whenever called into action to "shunt" or " short-
circuit" the arc.
In this arrangement of differential, the polarity of the regulating core or
armature, is not sensibly affected but its mechanical potency is, during abnormal
activity of such lamp, counteracted to a greater or less extent, commensurate with
the overflow, by the opposing downward pull of the excited differential.
As above intimated, these movements operate in a two-fold capacity, namely by
reducing to normal length the arc of the individual lamp and by reinstating the
normal current flow and equal illuminative action throughout the series.
The lamp proper, irrespective of the equalizing attachment, may be substantially
as described in the Specification of Letters Patent aforesaid in which the positive
wire or rheophore from the generator (or from "line" or a preceding lamp, as the
case may be) connects by binding post upon non conducting collar with a stationary
coil or helix of insulated wire which is wound around a non-magnetic metal bobbin
whose ends are secured in non-conducting collars.
A metallic pendant attached to the lower collar supports and has electrical con-
nection with the lower or negative electrode, which may be either of refractory
metal or of carbon.
A metallic stem is surmounted by a soft iron core or armature, that has capacity
for longitudinal vibration coincident with the axis of the stationary helix and that
terminates below in a clamp, for a rod of "carbon" that constitutes the positive
electrode.
One or more chains attached to top of core pass over as many sheaves to counter-
poises whose aggregate weight is such' as to nearly balance that of the core and
its attachments, the weight of the chains being such as to compensate for the
diminishing weight of the gradually consuming carbon by the transfer of successive
portions of the chains from the outside to the inside of the helix.
Fastened by set screw to the stem is a metallic cross-bar from whose extremities
arise two slender rods of spring brass in whose upper ends are journalled brass
wheels whose peripheries, by virtue of the elasticity of the rods press moderately
against the periphery of the stationary helix on diametrically remote sides
thereof.
Along the narrow paths or lines of contact traversed by these wheels the
insulating envelope of the helix-wire is removed so as to expose naked tracks
which bring the wheels into direct electrical communication with the wire at the,
for the time being, points of contact.
One side of pendant has electrical communication, by one strip with the non-
magnetic metal bobbin which, by another strip communicates with the negative 5
binding post on the upper collar whence the current escapes, by wire to the next
lamp in the series, (or to line or the generator, as the case may be.)

page_text: Where the said bobbin is thus made to do duty as a portion of the channel or
he escaping current, collars, upon the armature servo to insulate the armature
from the bobbin.
The rheophore-wires may consist, for a part of their length in copper cables
whose lower ends are secured in their respective binding posts by means of
screws. These cables may pass over sheaves journalled in hangers attached
to a non-conducting slab which may be secured to ceiling or other fixture.
Binding posts on said hangers enable the attachment of the line-wires or
rheophores proper. To the other extremities of said cables may be suspended
a counterpoise.
Posts connecting the upper and lower collars may receive glass panes, and glazed
openings in collar may admit light while excluding dust and moisture from the
parts above said collar.
A reflector may be attached to the lower collar.
The carbons may be grasped by split tubes or holders tightened upon them by
sliding or screwing sleeves.
The socket may be pierced to permit insertion and adjustment of the negative
carbon-holder, which may be secured by a set screw.
The positive and negative binding posts may be attached to a single metallic
base which is itself attached to a wooden or other non-conducting collar the
positive binding post being, in that case, insulated by a vulcanite washer.
The upper collar may be metallic and insulation of the pendant be secured by
means of vulcanite bushings.
Carbon may be employed for both electrodes, the pendant (and the globe where
one is used) being made long enough to accommodate the travel of the point of
light incident to the consumption of the negative electrode.
The counterpoises may be guided to a vertical path by rods which extend from
collar to collar and one of these rods may be made available as a portion of the
channel of the escaping current; being, for this purpose, connected by strips with
the lower and upper negative binding posts respectively.
The pressure of the wheels upon their tracks may be enhanced by means of
springs.
The wire of the prime or stationary helix is preferably flat in transverse section,
with its greatest thickness in direction radial to the helix.
The lamp is adapted for use in series by means as follows.
Attached at any desired height to the positive electrode holder by screw-clamps
is a light non-magnetic tube or bobbin preferably of brass.
A very fine insulated wire wound on the bobbin (called in this specification
"the differential") whose lower extremity has electrical connection with the
positive electrode, through its holder, and whose upper extremity is connected to
circuit beyond the electrodes, is of such resistance as to be comparatively inert
during normal action, but such as to become an active current carrier in proportion
to the checking of the current by the elongation of the arc-interval of the lamp
thus regulated
Said insulated wire is so wound upon the bobbin as that, whenever active its
current shall flow in reverse direction to the neighbouring current of the prime
helix, so as to subject said differential helix to a downward current repulsion
proportionate to the activity of the overflow.
A consequence of this mutual repulsion is that the differential, whenever
energized by an overflow, tends to move in the opposite direction to the armature
suction, and, both differential and armature being rigidly attached to the positive
electrode holder, it follows that-without sensibly diminishing the armature-
magnetism―said differential exerts a mechanical pull which, to the extent of its
force, for the time being, neutralizes, to a greater or less degree, the "lift" of the
armature.
Negative connection of the differential, without sensibly impeding its vertical

page_text: movement is secured in any desired way such for example-as by giving the
connecting wire a convoluted form.
It will be seen that the differential preserves throughout its movements up and
down a constant relative position to the other appendages of the positive electrode
and the points of contact of the wheels being preferably about mid-height of the
differential the bobbin is at its mid-length, left bare of wire except a single
filament to connect its upper and lower bundles and has slots on its diametrically
remote sides to permit said wheels contact with the bared tracks
The differential may be restricted to its proper vertical movement by rods which
extending from upper, collar to lower collar through orifices in the flange of the
bobbin are held taut by means of nuts and, inasmuch as the differential bobbin is
rigidly secured to the rods the wheels are thus retained to their proper vertical path
upon the tracks.
The following modification of the suction core may be employed. Instead of
using a soft iron armature, a solenoid may be employed that consists of a helix
of insulated wire similar to that of the prime helix and so coiled as for its current
to flow in the same direction as the neighbouring current of the prime helix. Said
helix is connected below with bar by means of a brass tube and is connected above
with a brass rod which extending axially downward through the helix and tube
from which it is insulated by collars is, at its lower extremity provided with the
proper clamp or holder for the positive electrode or carbon.
It will be seen that, in this form of the invention both the normal and the
differential regulations are secured by the attractive and repellant energies of
simple helices or current-carriers without the use of any ferro-magnetic element or
magnetized mass.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Benjamin Joseph Barnard Mills in the Great Seal Patent Office
on the 9th February 1883.
"
BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex Patent Agent. "IMPROVE-
MENTS IN ELECTRIC LAMPS (A communication to me from abroad by William
Maulsby Thomas of Cincinnati, Hamilton County in the State of Ohio in the
United States of America)
The improvements are especially intended for arc-electric lamps such as those
described in the Specification of Letters patent N° 578 granted to me and dated
7th February 1882. and the present invention, as to its principal feature, is designed
for the equalization of such lamps when used," in series."
"
It is well known that no two arc-electric lamps employed in series, behave
precisely alike. In one lamp the magnetic "lift incident to increased current-
flow takes place more promptly and with greater facility with a consequently
greater arc-interval than in the others. Such disproportionate increase of arc-
interval in one lamp necessarily weakens the current throughout the series, and
thus detracts from the lifting power of all but most so from those of most sluggish
movement. The heavier working lamps, thus dwindling in illuminative action,
cease, one by one, to respond to the continually waning magnetic energy. In
strong contrast with, and at the expense of, this enfeebled action of the weaker
lamps, the arc of the most susceptible or easiest working lamp continues to expand
until it practically monopolizes the effective activity of the entire circuit.
The remedy for such unequal action lies in a provision whereby when the arc-
resistance in any given lamp becomes higher than normal; the current is auto-
inatically diverted from the arc of that lamp to the next lamp of the series or to
"line" or "generator" as the case may be, and whereby such overflow-current is, at
the same time, utilized either to reduce or counteract, to a greater or less extent,
the helix-suction upon the core or armature of the lamp thus regulated so as to
restore its arc-interval to normal length, and, at the same time, by diminution of
its arc-resistance, to secure resumption of normal current-flow throughout the
Beries.
In the present invention, illuminative equilibrium throughout a given series of
arc-electric lamps is secured by the mechanical force due to the current-repulsion of
the carrier of the shunted current or overflow of each respective lamp.
With this object in view, a portion of the overflow-wire having a resistance
which renders it comparatively inert during normal action, is so wound upon a
non-magnetic bobbin attached to and travelling with the positive electrode-holder,
as to surround without touching, the prime helix and, when carrying off overflow,
to conduct the current in a direction reverse to that of the said helix. This over-
flow current-carrier (hereinafter called "the differential") has electrical connection,
by its lower end, with the positive electrode, and by its upper end, with "line"
beyond the negative electrode, so as whenever called into action-to "shunt" or
"short-circuit" the arc.
In this arrangement of differential, the polarity of the regulating core or
armature is not sensibly affected but its mechanical potency is, during abnormal
activity of such lamp, counteracted to a greater or less extent, commensurate with
the overflow, by the opposing downward pull of the excited differential.
As above intimated, these movements operate in a two-fold capacity, namely, by
reducing to normal length the arc of the individual lamp and by reinstating
the normal current flow and equal illuminative action throughout the series.

page_text: And in order that the said Invention may be more clearly understood and readily
carried into effect I will proceed aided by the accompanying drawings more fully
to describe the same.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a front elevation of an arc-electric lamp provided with the equalizer.
Figures 2 and 3 are sections on lines 1-1 and 2-2 respectively.
Figures 4 and 5 are, respectively, a front elevation and a side elevation of the
helices and their immediate adjuncts, portions of the main and differential helices
being broken away to expose the sliding contact.
Figure 6 is a section in the plane of the geometrical.axis common to the helices
and armature.
Figure 7 is an axial section, at right angles to figure 6 showing the mode of
counterbalancing the armature.
Figure 8 shows another mode of connecting the armature with its stem.
Figure 9 is a front and Figure 10 a side elevation of a form of the lamp adapted
for use with two carbons.
I
Figure 11 is a section on the line 3, 3, Figure 9.
Figure 12 represents, to a larger scale, the upper part of the prime helix and its
connection with the positive binding post.
Figure 13 is an enlarged section of one of the two insulating joints by which the
pendant is attached to the lower collar.
Figure 14 is an enlarged section of one of the counterpoises.
Figure 15 represents the carbon-holders to a larger scale.
Figure 16 represents a modification in which the suction-core instead of being a
soft iron armature consists of a solenoid connected at its upper end to the electrode
holder and coiled in the same direction as the prime helix.
"
The lamp-proper, irrespective of the equalizing attachment may be substantially
as described in the Specification of Letters Patent aforesaid in which the positive
wire or rheophore A from the generator (or from "line or a preceding lamp, as
the case may be) connects, by binding post B upon non-conducting collar E with
a stationary coil or helix C of insulated wire which is wound around a non-
magnetic metal bobbin D whose ends are secured in the non-conducting
collars E, F.
A metallic pendant G attached to the lower collar F supports and has electrical
connection with the lower or negative electrode, which may be either of refractory
metal as at I figure 1 or of carbon as at J figures 9 and 10.
A metallic stem L is surmounted by a soft iron core or armature K that has
capacity for longitudinal vibration coincident with the axis of the stationary helix C
and that terminates below in a clamp M for a rod of "carbon" N that constitutes
the positive electrode.
One or more chains O attached to top of core K pass over as many sheaves P
to counterpoises whose aggregate weight is such as to nearly balance that of
the core and its attachments, the weight of the chains being such as to compensate
for the diminishing. weight of the gradually consuming carbon by the transfer of
successive portions of the chains from the outside to the inside of the helix.
Fastened by set-screw R to the stem L is a metallic cross-bar S from whose
extremities arise two slender rods T of spring-brass in whose upper ends are
journalled brass wheels U whose peripheries, by virtue of the elasticity of the
rods T press moderately against the periphery of the stationary helix C on
diametrically remote sides thereof.
Along the narrow paths or lines of contact traversed by these wheels U the
insulating envelope of the helix-wire is removed so as to expose naked tracks c
which bring the wheels into direct electrical communication with the wire at the,
for the time being, points of contact.
4
4
E
One side of pendant G has electrical communication, by strip H with hobbin D 5
which by another strip H' communicates with the negative binding post X on the

page_text: upper collar E whence the current escapes, by wire Y to the next lamp in the
series (or to line or the generator as the case may be).
$
Where the bobbin D is thus made to do duty as a portion of the channel of the
escaping current, collars K' upon the armature K serve to insulate armature from
the bobbin.
The rheophore-wires may as shown in Figures 1, 4, 5, 9 and 10 consist for a part
of their length in copper cables whose lower ends are secured in their respective
binding posts by means of screws p. These cables may pass over sheaves q
journalled in hangers attached to a nonconducting slab 8 which may be secured
to ceiling or other fixture. Binding posts t on said hangers enable the attachment
of the line-wires or rheophores proper. To the other extremities of said cables may
be suspended a counterpoise U.
Posts connecting the upper and lower collars E F may receive glass panes w
and glazed openings fin collar F may admit light while excluding dust and
moisture from the parts above said collar.
A reflector (see dotted lines x) may be attached to the lower collar F.
The carbons may be grasped by split tubes or holders Z¹ Z" tightened upon
them by sliding or screwing sleeves M'.
The socket Z may be pierced to permit insertion and adjustment of the negative
carbon-holder which may be secured by a set-screw 2¹.
The positive and negative binding posts B and X may be attached to a single
metallic base V which is itself attached to the wooden or other non-conducting
collar E, the positive binding post B being, in that case, insulated by a vulcanite
washer B'.
The collar F may be metallic and insulation of the pendant be secured by means
of vulcanite bushings G¹.
Carbon may be employed for both electrodes, as shown in figures 9 and 10, the
pendant (and the globe where one is used) being made long enough to accommodate
the travel of the point of light incident to the consumption of the negative
electrode.
The counterpoises Q may be guided to a vertical path by rods y which extend
from collar to collar and one of these rods may be made available as a portion of
the channel of the escaping current; being for this purpose, connected by
strips H H with the lower and upper negative binding posts respectively.
The pressure of wheels U upon their tracks may be enhanced by means of
springs &.
The wire of the prime or stationary helix is preferably flat in transverse
section with its greatest thickness in direction radial to the helix as shown in
figure 12.
The lamp is adapted for use in series by means as follows:-
11
Attached at any desired height to the positive electrode-holder by screw-clamps a
is a light non-magnetic tube or bobbin 6 preferably of brass.
A very fine insulated wire d wound on the bobbin b (called in this specification
"the differential") whose lower extremity has electrical connection with the
positive electrode through its holder, and whose upper extremity is connected to
circuit beyond the electrodes, is of such resistance as to be comparatively inert
during normal action, but such as to become an active current-carrier in proportion
to the checking of the current by the elongation of the arc-interval of the lamp
thus regulated.
Said wire d is so wound upon the bobbin b as that, whenever active its current
shall flow in reverse direction to the neighbouring current of the prime helix so as
to subject said differential helix to a downward current repulsion proportionate
to the activity of the overflow.
A consequence of this mutual repulsion is that the differential, whenever
energized by an overflow, tends to move in the opposite direction to the armature
suction, and, both differential and armature being rigidly attached to the positive
electrode holder, it follows that-without sensibly diminishing the armature-

page_text: magnetism said differential exerts a mechanical pull which, to the extent of its
force, for the time being, neutralizes, to a greater or less degree, the "lift" of the
armature.
Negative connection of the differential, without sensibly impeding its vertical
movement is secured in any desired way such for example-as by giving the
connecting wire the convoluted form shown at d¹.
It will be seen that the differential preserves throughout its movements up and
down a constant relative position to the other appendages of the positive electrode
and the points of contact of the wheels U being preferably about inid-height of the
differential the bobbin bis at its mid-length, left bare of wire except a single
filament to connect its upper and lower bundles and bas slots b' on its diametrically
remote sides to permit said wheels contact with the bared tracks c.
The differential may, as in figures 9 and 10 be restricted to its proper vertical
movement by rods e, which extending from collar E to collar F through orifices in
the flange of the bobbin b are held taut by means of nuts fand, inasmuch as the
differential bobbin is rigidly secured to the rods T at a, the wheels U are thus
retained to their proper vertical path upon the tracks c.
At Figure 16 is shown a modification of the suction core in which is used
instead of a soft iron armature, a solenoid that consists of a helix K" of insulated
wire similar to that of the prime helix and so coiled as for its current to flow in the
same direction as the neighbouring current of the prime helix. Said helix K" is
connected below with bar S by means of a brass tube j and is connected above
with a brass rod L which extending axially downward through the helix K" and
tube j from which it is insulated by collars -is at its lower extremity provided
with the proper clamp or holder M for the positive electrode or carbon.
It will be seen that in this form of the invention both the normal and the
differential regulations are secured by the attractive and repellant energies of
simple helices or current-carriers without the use of any ferro-magnetic element or
magnetized mass.
Having thus described the nature of the said Invention and the mode in which
the same is carried into effect I would have it understood that what I claim is
First. In an arc-electric lamp in series, having a fixed helix in a main circuit
that includes the electrodes, a helix of high resistance surrounding said fixed helix
in a circuit derived from said main circuit and attached to the positive electrode
and a simultaneously movable core common to both helices whereby the feed and
position of the electrode are controlled and equal action maintained throughout the
series, by the joint action of two opposing electric forces, substantially as and for
the purposes set forth.
Second. In an arc-electric lamp in series, a stationary helix in the circuit which
includes the electrodes in combination with a surrounding movable helix in a
circuit derived from said main circuit and a simultaneously movable core common
to both of said helices and adapted and arranged to be lifted by electric influence
from the stationary helix and to be subject to depression by repulsion upon the
attached differential helix which surrounds said main helix so as to maintain
uniform arc lengths throughout the series in the manner set forth.
>
:11
Third. In an arc-electric lamp in series, a stationary helix in a circuit which
includes the arc, in combination with a shifting positive electrode to which are
attached a suction-core which occupies an axial position within said helix and is
attracted upward thereby and an overflow helix of high resistance that encircles
said stationary helix and is in a circuit derived therefrom, and, when energized, acts
in mechanical opposition thereto, in proportion to the overflow substantially as and
for the purposes set forth.
Fourth. In an arc-electric lamp in series, the combination of a stationary helix
in communication with the positive rheophore and the following members attached
to and moving with the positive electrode, to wit; a sliding conductor upon a bared
track on said helix's peripliery-an interior suction core and an exterior concentric
differential shunt, substantially as and for the purposes set forth.

page_text: Fifth. In an arc-electric lamp, in series, a shifting conductor which is rigidly
attached to and which travels with the consuming electrode upon a longitudinal
bared track on the exterior periphery of a stationary helix, said conductor together
with the portions of said helix thus brought into circuit constituting the electrical
communication from the generator to said electrode, so as to shift the said helix's
magnetic field and to maintain a practically constant magnetic equipoise to the said
electrode, there being also attached to said shunt a counterpoise and a suction core
and differential overflow coil which are concentric with and respectively interior
and exterior to said helix substantially as and for the purposes set forth.
Sixth. In an arc-electric lamp in series, a shifting conductor which is rigidly
attached to and travels with the consuming electrode upon a longitudinal bared
track on the periphery of the prime helix and which constitutes the electrical com-
munication from the generator to the said electrode so as to shift the helix's
magnetic field and to maintain a practically constant magnetic equipoise to the
said electrode, in combination with a similarly attached and travelling suction-core
and a differential coil that surrounds said helix and is so wound with a wire of
higher resistance than the normal arc and so connected with line beyond it, as to
divert the overflow and to counteract the core-suction in proportion to such overflow
substantially as and for the purposes set forth.
Seventh. In an arc-electric lamp in series, the combination with a stationary
helix C conveying current through bared track c on said helix's exterior periphery
and thence through a shifting conductor U, T, S, to the electrode, the following
members attached to said conductor, to wit; a central armature or suction core the
positive electrode N and a coil d of higherr esistance than that of the normal arc
concentric with and exterior to the stationary helix and electrically connecting
said conductor with line beyond the arc so as to divert the overflow and so wound
as to be repelled by said stationary helix in proportion to the overflow energy as
and for the purposes set forth.
Eighth. In the described combination with stationary helix C having electrical
connection, above with the positive rheophore and below (through bared track c, on
its exterior periphery and shifting conductor U, T, S,) with the positive electrode,
the following members attached to and travelling with said electrode to wit; a
suction core interior to and attracted by said helix and a longitudinally guided
differential coil d, that surrounds said helix and has, at or near its mid-length,
slots 6' which receive the wheels U of said conductor, substantially as and for the
purposes set forth,
In witness whereof I the said Benjamin Joseph Barnard Mills have hereunto
set my hand and seal this eighth day of February in the year of our Lord
One thousand eight hundred and eighty three.