Improvements in and connected with Aro Lamps.
Year: 1895

page_text: Date of Application, 7th Jan., 1895
Complete Specification Left, 7th Oct., 1895-Accepted, 16th Nov., 1895
PROVISIONAL SPECIFICATION.
Improvements in and connected with Aro Lamps.
I, JOHN BRUNSWICK BARTON, of 46, Brown Street, in the City of Manchester
Engineer (a communication from abroad, by William Jandus, of Cleveland, State
of Ohio in the United States of America), do hereby declare the nature of this
invention to be as follows:-
The annexed drawings and the following description set forth in detail, one
mechanical form embodying the invention; such detail construction being but
one of various mechanical forms in which the principle of the invention may
be used.
I said annexed drawings:
Figure 1 represents an axial section of the lower portion of my improved
electric lamp.
A globe N, which forms the outer are inclosing chamber, has the edges of its
top opening clamped between two metallic washers n, with two interposed yielding
washers n'. The lower metallic washer rests upon a flange h³, projecting outward
from the neck of the negative electrode supporting frame, and a nut n² upon the
external screw-thread of said neck, serves to draw the washers together to clamp
the edge of the globe. The bottom opening of the globe is formed with an
outwardly flaring flange n³, against the under side of which a flange o, upon a
vieldingly supported cover O may bear. Said cover slides upon an insulating
handle L, secured upon the lower end of the negative electrode holder, and has a
coiled spring 2 bearing upward against it, to force the cover yieldingly against the
flared bottom opening of the globe. The negative electrode holder is formed with
an upwardly projecting flange, 13, which forms a seat for a circumferentially
grooved lower neck p of a globe P of substantially cylindrical outline. A set
screw, passes through the flange of the seat, and enters the groove in the neck,
thus securing the globe in its seat. The upper end of the globe, which forms the
inner are inclosing chamber, is formed into a peripherally grooved neck pl, over
which fits a downwardly projecting flauge q, of a cover Q, which fits inside the
neck. The cover is cup-shaped and has an opening in its bottom, which is partly
covered by a washer q', through which the positive carbon passes. The top of the
cup-shaped cover is covered by a disc q², secured in the rabbeted upper edge of the
cover. A tube 3 passes through the disc, and serves as a passage and guide for
the upper carbon. The upper edge of said tube, and the central opening of the
washer, are inwardly bevelled, so that the carbon will meet with no resistance
when passed through the tube and washer. A set screw g, passes through the
flanges of the cover and engages the groove in the neck of the globe, so as to retain
the cover in position.
The bottom of the outer arc-inclosing chamber is closed to have limited inlet and
free outlet by the yielding cover O, which does not fit sufficiently tight in the
flange of the globe to close the bottom opening absolutely air-tight, but will admit
of a very limited inlet into the outer chamber. The cover will, however, permit of
free outlet for the air or gases contained in the outer chamber, so that explosions of
the coutents of the chamber will be prevented-all expansion of the contents of the
chamber being accommodated by free outlet for such contents. The outwardly
flaring flange, around the bottom opening of the globe will serve as a water shed,

page_text: preventing water from entering the joint between the globe and the yielding. cover,
when the lamp is employed in the open air or wherever it may be exposed to rain,
snow or condensation of moisture upon the surface of the globe. The inner arc-
inclosing chamber is closed tight but not air-tight. The lower end of the globe
fits upon its seat in the upper end of the negative electrode support, and the upper
end is partly closed by the cover, the washer in' the cover, and the disc having the
central tube. When the arc is formed, the air within the inner are inclosing
chamber becomes rarified or expanded, and the heated surplus is discharged into
the outer chamber, where, by virtue of its great levity, it finds its level in the
uppermost portion of said chamber, displacing a corresponding volume of cold air
through the outwardly yielding closure in the hottom of the outer chamber. The
product of combustion of the carbon and oxygen in the inner arc-inclosing chamber
is O2 (carbon binoxide), which subsequently becomes 0 (carbon monoxide). This
gas, together with the highly expanded nitrogen of the decomposed air, protects
the carbon points from rapid combustion. Fluctuations of the current and potential
in the circuit will cause fluctuations in the temperature of the are and, consequently,
expansion and contraction of the heated contents of the inner arc-inclosing chamber,
and a consequent outflow and inflow of gases out of and into the same. As this
process continues, the outer chamber becomes filled with hot, chemically inert
gases, which seek a higher level on account of their levity, and exclude the heavier
cold air, which escapes through the outlet provided in the bottom of the outer
chamber by the outwardly yielding closure. Finally, these inert gases,-chiefly
nitrogen, surround the inner arc-inclosing chamber, so that subsequent readjust-
ment of pressure between the two arc-inclosing chambers takes place between these
chemically inert gases, to the more or less perfect exclusion of oxygen, which can
only gain access to the outer chamber by a very slow process of diffusion through a
very limited inlet. The incident fluctuations of current or potential in the circuit
cause expansion and contraction of the contents of the inner arc-inclosing chamber
and consequent outflow and inflow of gases out of and into said chambers. Such
disturbances tend to adjust themselves in the direction of the least resistance, which
in this lamp is at the top of the inner chamber, where the opening presents less
obstruction to fluctuations in the gaseous contents, on account of the passage for
the electrode, than at the bottom, where the globe rests flat upon its seat.
Consequently, the adjustment of the gaseous contents of chambers will principally
take place at the top of the chambers, where the more highly heated, and con-
sequently more inert gases are located, which are nearly, if not entirely free from
oxygen. It is evident that, without an outer globe which is substantially air-tight
and absolutely air-tight at its top, such freedom in the provision of vents for the
inner chamber could not exist without a rapid oxidation of the electrodes, inasmuch
as the heat of the are would in such case generate a circulation of air around the
arc, besides the fluctuations in the surrounding atmosphere caused by the fluctuations
in temperature, both of which conditions would cause the electrodes to be rapidly
consumed. Should the outer arc-inclosing chamber,-air-tight above the arc,-be
substituted by a chamber air-tight below the arc but communicating with the
surrounding atmosphere above the arc, the heated gases would have a tendency to
rise and be displaced by the heavier cold air, besides the inflow and outflow due to
disturbances in the temperature. If, to overcome this tendency, the feed opening
for the upper electrode is narrowed down sufficiently to prevent such circulation
and flow of air, then disturbances in the feeding of the electrode are bound to
arise, unless the electrodes are uniformly perfect in diameter and alignment. Such
conditions are entirely unattainable with carbons, and practically unattainable with
metallic carbon rods. While the exclusion of oxygen from the arc,-which is the
point desired to be attained-would be most completely attained in a completely
air-tight are inclosure, such condition is not successful for several practical reasons.
The expansion of the contained gases in a completely air-tight inclosure would be
liable to cause a rupture of the latter; air-tight fittings and bearings are difficult
to maintain, particularly under pressure, and an explosive gas is generated within
·

page_text: the arc inclosure which will endanger the structure when the arc is relighted, in a
completely air-tight inclosure. Vents have been provided for relieving dangerous
pressure, but such vents admit more or less oxygen to consume the carbons. The
particular advantage obtained by my improvement consists in the lengthening of
the life of the carbon in electric lamps. This feature enables me to use a tubular
carbon with a very thin wall, and at the same time to have such carbon last for a
much longer time than a solid carbon with an exposed arc.
Dated this 7th day of January 1895.
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for Applicant.
I, JOHN BRUNSWICK BARTON of 46, Brown Street in the City of Manchester
Engineer (a communication from abroad by William Jandus, of Cleveland, State
of Ohio in the United States of America), do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The drawing filed with the Provisional Specification and the following
description set forth in detail, one mechanical form embodying the invention, such
detail construction being but one of various forms in which the principle of the
invention may be used.
The drawing filed with the Provisional Specification represents an axial section
of the lower portion of a lamp constructed according to my invention.
A globe N, which forms the outer arc inclosing chamber, has the edges of its
top opening clamped. between two metallic washers. n, with two interposed yielding
washers n. The lower metallic washer rests upon a flange 2, projecting outward
from the neck of the negative electrode supporting frame, and a nut n² upon the
external screw-thread of said neck, serves to draw the washers together to clamp
the edge of the globe. The bottom opening of the globe is formed with an
outwardly flaring flange n³ against the under side of which a flange o upon a
yieldingly supported cover Omay bear. Said cover slides upon an insulating
handle L', secured upon the lower end of the negative electrode holder, and has
a coiled spring bearing upward against it, to force the cover yieldingly against
the flared bottom opening of the globe. The negative electrode holder is formed
with an upwardly projecting flange which forms a seat for a circumferentially
grooved lower neck of a globe P, of substantially cylindrical outline. A set
screw passes through the flange of the seat, and enters the groove in the neck,
thus securing the globe in its seat. The upper end of the globe, which forms the
inner arc-inclosing chamber, is formed into a peripherally grooved neck p², over
which fits a downwardly projecting flange 9 of a cover Q which fits inside the neck.
The cover is cup-shaped and has an opening in its bottom, which is partly covered
by a washer q, through which the positive carbon passes. The top of the cup-
shaped cover is covered by a dise q², secured in the rabbeted upper edge of the
cover. A tube 3 passes through the disc, and serves as a passage and guide for
the upper carbon. The upper edge of said tube, and the central opening of the
washer, are inwardly bevelled, so that the carbon will meet with no resistance
when passed through the tube and washer. A set screw q passes through the
flange of the cover and engages the groove in the neck of the globe, so as to retain
the cover in position.
The bottom of the outer arc-inclosing chamber is closed to have limited inlet and
free outlet by the yielding cover O, which does not fit sufficiently tight in the

page_text: flange of the globe to close the bottom opening absolutely air-tight, but will admit
of a very limited inlet' into the outer chamber. The cover will, however, permit
of free outlet for the air or gases contained in the outer chamber, so that explosions of
the contents of the chamber will be prevented, all expansion of the contents
of the chamber being accommodated by free outlet for such contents. The
outwardly flaring flange around the bottom opening of the globe will serve as a
water shed, preventing water from entering the joint between the globe and the
yielding cover, when the lamp is employed in the open air or wherever it may be
exposed to rain, snow or condensation of moisture upon the surface of the globe.
The inner arc-inclosing chamber is closed tight but not air-tight. The lower end
of the globe fits upon its seat in the upper end of the negative electrode support,
and the upper end is partly closed by the cover, the washer in the cover, and the
dise having the central tube. When the are is formed, the air within the inner
arc-inclosing chamber becomes rarified or expanded, and the heated surplus is
discharged into the cuter chamber, where, by virtue of its great levity, it finds its
level in the uppermost portion of said chamber, displacing a corresponding volume
of cold air through the outwardly yielding closure in the bottom of the outer
chamber. The product of combustion of the carbon and oxygen in the inner
arc-inclosing chamber is CO2 (carbon binoxide), which subsequently becomes CO
(carbon monoxide). This gas, together with the highly expanded nitrogen of the
decomposed air, protects the carbon points from rapid combustion. Fluctuations
of the current and potential in the circuit will cause fluctuations in the temperature
of the arc, and, consequently, expansion and contraction of the heated contents of
the inner arc-inclosing chamber, and a consequent outflow and inflow of gases out
of and into the same.
As this process continues, the outer chamber becomes filled
with hot, chemically inert gases, which seek a higher level on account of their
levity, and exclude the heavier cold air, which escapes through the outlet provided
in the bottom of the outer chamber by the outwardly yielding closure. Finally,
these inert gases, chiefly nitrogen-surround the inner arc-inclosing chamber, so
that subsequent readjustment of pressure between the two arc-inclosing chambers
takes place between these chemically inert gases, to the more or less perfect
exclusion of oxygen, which can only gain access to the outer chamber by a very
slow process of diffusion through a very limited inlet. The incident fluctuations
of current or potential in the circuit cause expansion and contraction of the contents
of the inner arc-inclosing chamber and consequent outflow and inflow of gases
out of and into said chambers. Such disturbances tend to adjust themselves in the
direction of the least resistance, which in this lamp is at the top of the inner
chamber, where the opening presents less obstruction to fluctuations in the gaseous
coutents, on account of the passage for the electrode, than at the bottom, where
the globe rests flat upon its seat. Consequently, the adjustment of the gaseous
contents of the chambers will principally take place at the top of the chambers,
where the more highly heated, and consequently more inert gases are located,
which are nearly if not entirely free from oxygen. It is evident that, without an
outer globe which is substantially air-tight and absolutely air-tight at its top, such
freedom in the provision of vents for the inner chamber could not exist without a
rapid oxidation of the electrodes, inasmuch as the beat of the arc would in such
case generate a circulation of air around the arc, besides the fluctuations in the
surrounding atmosphere caused by the fluctuations in temperature, both of which
conditions would cause the electrodes to be rapidly consumed. Should the outer
arc-inclosing chamber,-air-tight above the arc,-be substituted by a chamber
air-tight below the arc but communicating with the surrounding atmosphere above
the arc, the heated gases would have a tendency to rise and be displaced by the
heavier cold air, besides the inflow and outflow due to disturbances in the
temperature. If, to overcome this tendency, the feed opening for the upper
electrode is narrowed down sufficiently to prevent such circulation and flow of air,
then disturbances in the feeding of the electrode are bound to arise, unless the
electrodes are uniformly perfect in diameter and alignment. Such conditions are

page_text: entirely unattainable with carbons, and practically unattainable with metallic
carbon rods. While the exclusion of oxygen from the arc, which is the point
iesired to be attained,-would be most completely attained in a completely air-
tight are inclosure, such condition is not successful for several practical reasons.
The expansion of the contained gases in a completely air-tight inclosure would be
liable to cause a rupture of the latter; air-tight fittings and bearings are difficult
to maintain, particularly under pressure, and an explosive gas is generated within
the arc-inclosure which will endanger the structure when the arc is relighted, in
a completely air-tight inclosure. Vents have been provided for relieving dangerous
pressure, but such vents admit more or less oxygen to consume the carbons. The
particular advantage obtained by my improvement consists in the lengthening of
the life of the carbon in electric lamps. This feature enables me to use a tubular
carbon with a very thin wall, and at the same time to have such carbon last for
a much longer time than a solid carbon with an exposed arc.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manuer the same is to be performed, I declare that what I
claim is :-
1. In an arc lamp; prolonging the life of the carbons by enclosing the arc
within two or more chambers so arranged that the upper part of the outer chamber
is made air tight or nearly so while the lower part permits some communication
with the outer atmosphere and the inner chamber permits a limited communication
between its interior and the gaseous contents of the outer chamber or chambers;
the combination of the chambers being so devised as to surround the arc with inert
or non-oxidising gases and prevent or minimise the access of the oxygen of the
air to the carbons as herein set forth.
2. In an arc lamp; the combination of inner and outer chambers, the inner
chamber enclosing the arc being closed air tight or nearly so at its lower end and
having restricted communication at its upper end while the outer chamber is closed
air tight at its upper end and has some communication with the atmosphere at its
lower end, the combination being so devised in order to cause the inuer chamber
to discharge its contents into and take its supply of gases from the upper part of
the outer chamber where the hottest and most inert or non-oxidising gases
accumulate, for the purpose of prolonging the life of the carbons as herein set
forth.
3. An arc lamp; having, an outer chamber as N made air tight at the top but
opening freely outwards below by means of a valve as O which valve also allows a
limited air inlet; an inner chamber as P air tight or nearly so below but with a
loosely fitting cover as Q at the top through which the carbon is fed; and are
lamp mechanism as at A of any known kind, substantially as hereinbefore
described with reference to the accompanying drawings.
Dated this 5th det
1005
MARKS & CLERK,
18 Southampton Buildings, London, W.C., Agents.

page_text: Cate of Application, 7th Jan, 1895
Complete Specification Left, 7th Oct, 1895-Accepted, 7th Jan., 1896
A communication from abroad by WILLIAM JANDUS, of Cleveland, in the State
of Ohio, in the United States of America, Engineer.
I, JOHN BRUNSWICK BARTON, of 35 Seedley Road, Pendleton, Manchester,
in the County of Lancashire, Engineer, do hereby declare the nature of this
invention to be as follows:-
The annexed drawings and the following description set forth in detail, one
mechanical form embodying the invention; such detail construction being but
one of various mechanical forms in which the principle of the invention may
be used.
In said annexed drawings,
Figure I represents an axial section of the upper portion of my improved
electric lamp;
Figure 11, an axial section of the lower portion of said lamp ;
Figure III, a side elevation of the upper portion of the lamp, removed from its
casing, and illustrating the upper portion of the lamp in axial section, at right
angles to the section illustrated in Figure I, and illustrating parts of the magnet
body as broken away and removed;
Figure 1V, a detail view of the device for regulating the amount of resistance
in the main coil;
Figure V, a perspective detail view of the spring contact for the negative
conductor in the lamp;
.
Figure VI, a perspective view of the negative electrode supporting frame;
Figure VII, a top view of the rheostat for the negative electrode support;
Figure VIII, a side view of said rheostat ;
Figure IX, a top view of the switch ;
Figures X and XI, detail views, respectively of the carbons in an ordinary arc
lamp and in my lamp, illustrating the conditions of the arc in said two forms, and
Figure XII, a top plan view of the brush holder.
The lamp has an axial electrode containing tube, A, which extends about the
entire length of the upper portion of the lamp, and forms the main frame part of
the lamp structure, to which all other parts are secured or from which they are
supported. This tube is formed with a shoulder, a, against which the upper end
of the axial bore of a magnet body, B, bears. Said magnet body consists of an
upper annular portion, B, and a lower annular portion, B², connected by two or
more vertical wall portions, B³. The general outline of the maguet is thus
substantially cylindrical with more or less open walls. A tubular portion, B, is
securely jammed into the opening of the upper annular portion of the magnet, and
such part of this tubular portion as projects below the annular upper portion is
reduced and shaped to the form of a truncated cone. A tube, b, of non-magnetic
metal is secured around the upper end of the conical part of the tubular portion,
and into the opening of the lower annular portion of the magnet, to form an air-
tight annular chamber within the magnet body, such chamber being formed
between said tube b and the axial tube A, and decreasing in size towards its upper
end on account of the conical part of the magnet projecting down into it.
A substantially right-angled, stirrup-shaped yoke, B³, is formed upon the under

page_text: "
"
L
side of the lower annular portion of the magnet, and has a central opening, which
is concentric with the openings of the annular portions, registers with the axial
bore in the truncated conical tubular portion, is of the same size as said bore, and
fits snugly upon the axial carbon-containing tube A, whereby said tube is aligned
absolutely true in its axial relation to the magnet, and whereby the tubular
armature, which plays upon the axial tube and within the annular chamber of the
magnet, will be guided absolutely true in its movement and will not be liable to
bind within the chamber. A series coil, C, is placed within the walls of the
magnet body and around the tube b, which forms the outer wall of the annular
chamber in the magnet. The tubular armature D, is of such dimensions that it
will have a snug, but sliding fit upon the axial tube A and within the tube b, so
that the armature will have an air cushion to its up and down movements in the
annular magnet chamber. The axial bore of the armature has a truncated conical
recess, d, in its upper end, which recess corresponds with the truncated conica!
inner tubular portion of the magnet. The lower end of the tubular armature is
formed with longitudinal slots, d'. A flaring pan, d², is' secured to the lower end
of the armature and has radiating slots, d³, which register with the slots in the
armature, and with longitudinal slots, a', in the axial tube A. Clutch rings, d*,
have vertical and radial play in the slots of the tube, armature and pan, and are
retained in their respective slots by means of a ring, d³, which passes through said
clutch rings and is of a sufficient diameter to prevent the clutch rings from
dropping into the axial tube and become caught in the slots of the same, when the
electrode is withdrawn from the tube and the slots of the armature yet register
with the slots in the axial tube. The lower ends of the slots in the axial tube are
some distance above the yoke at the lower end of the magnet, so that the clutch
rings will be thrown outward in the pan, when the armature is entirely release
and drops down upon the yoke, whereby the clutch rings can offer no resistance to
the insertion of the electrode into the axial tube when the lamp is being trimmed.
The magnet is drawn up against the shoulder a upon the axial tube by means of a
nut, a², upon the lower screwthreaded end of said tube. One terminal, c, of the
series coil is connected to the positive conductor E, of the lamp, by being clamped
to a screw bolt, e, which passes through the upper annular portion of the magnet
and is insulated from the same, and which has said positive conductor secured to
its upper end. The other terminal, c¹, of the series coil is secured in contact with
the magnet by a screw, c³, which enters the upper annular portion of the magnet
and thereby causes the magnet to form a part of the conductor in the lamp. Said
binding screw c², also secures the upper end of a longitudinally slotted bar, e³, of
brass, copper, or similar good conducting material to the upper annular portion of
the magnet, and the lower end of said bar is secured to the lower portion of the
magnet. A slide, c, is movable upon the slotted bar, and a screw, e³, passes
through said slide. The point of said screw is pyramidal or otherwise formed with
edges or ridges, so as to form an insulator cutter which may cut away the insulation
from the outer windings of the series coil, and thus form a contact at the winding
against which it is brought to bear and from which it has cut the insulation,
thereby cutting out the portion of the outer winding of the coil above the screw,
and short-circuiting the current through the slotted bar to the magnet body. The
number of Ampere turns of the coil may thus be adjusted and regulated according
to the energy to be consumed in the lamp, and according to the pull which the
magnet is required to have. An annular disc, F, has a downwardly projecting
neck, f, at its central opening, and an internally screwthreaded cap, f, is formed
at the lower end of said neck. A nut, a³, fits upon the screwthreaded lower
portion of the axial tube, and supports the cap, neck and annular disc,-an
insulating washer, 12, being interposed between the nut and the under side of the
cap. A brush holder, G, is secured to the lower end of the axial electrode
containing tube. Said brush holder consists of an annular casing, G', the upper
internally rabeted edge, g, of which is internally screwthreaded to receive the
externally screwthreaded flange, gl, of a cover, G, which is formed with a central,

page_text: screwthreaded opening, which is screwed upon the lower end of the axial tube.
A brush support, g, in the shape of an annular disc, has its outer edge supported
upon the rabbet of tlie casing, and is secured upon said rabbet by the flange of the
cover. The outer edge of said annular disc and the edge of the central opening
have radiating and registering notches, g³ and 9, respectively, into which notches,
brush rings, g, have radiating support and play. As the radiating brushes may
project from all sides towards the central opening through the brush holder, and as
said brushes form parts of the positive conductor within the lamp,-being in contact
with the support and holder, which is in contact with the axial tube, which again is
in electrical contact with the magnet body,-the annular brushes may have current
feeding contact with the positive electrode, when the latter is inserted through the
brush holder and into the axial electrode containing tube. A negative electrode
supporting frame, H, (see Figure VI) has an externally screwthreaded neck,
at its upper end, which neck is screwed into the internally screwthreaded cap f¹,
(see Figure 1) of the negative conductor disc, F. Said disc is connected to the
negative conductor J, of the lamp, by a spring contact, j, adjustably secured upon
a rod, j', which is secured through and insulated from the lower annular portion of
the magnet.
The negative conductor passes through and is insulated from the
upper annular portion of the magnet, and is secured in contact with the upper end
of the rod . An insulating washer, F¹, is placed upon the upper side of the
negative conductor disc,-for a purpose which will be explained later, and said
washer is cut away at the point where the spring contact projects to bear against
the disc, as clearly illustrated in Figure V. A ring, H', is formed at the lower
end of the negative electrode supporting frame, concentric with the neck of said
frame and with the axis of the entire lamp structure. Said ring has a circular
interior shape, with notches, h', at points of its circular interior,-four equidistant
notches being illustrated in the drawing, and being illustrated as formed by outward
bulges of the ring. The negative electrode K, is secured in a negative electrode
holder, L, by means of a set screw, l, which enters the axial socket of said holder.
Said axial socket is intersected at its lower portion by a slot, l', of greater width
than the diameter of the socket, which slot gives access to the socket for the
purpose of adjusting the carbon in the socket and for the purpose of removing
the negative carbon from the same, if the carbon should become stuck in the
socket or burned down to the upper end of the socket, so that it cannot be removed
from the latter at the upper end of the same. A rheostat, M, has an axial sleeve, m,
in metallic contact with the electrode holder, and adjustably secured upon the
latter by means of a set screw, m¹ (see Figure Vill), passing through a collar, m³
at the lower end of the sleeve. The axial sleeve of the rheostat has a lateral
flange, m³, projecting outward from near its lower end. A cylindrical casing, m*,
of so much greater interior diameter than the exterior diameter of the sleeve, as
to leave an annular space between the casing and sleeve, has an inwardly projecting
flange, m, through which pass screws, me, which pass through, and are insulated
from the foot flange m³, of the inner sleeve. The two flanges are insulated from
each other by means of an insulating washer, m'. The cylindrical casing is formed
with short lugs, m³, and longer lugs, m³, at points corresponding to the notches in
the ring of the negative electrode supporting frame, so that the rheostat may be
inserted through the ring from below, with the short upper lugs moving upward
through the notches, whereupon the rheostat may be turned to bring the lugs to
bear against the upper and lower edge of the ring, at points between the notches,
thereby securing the rheostat and negative carbon holder in said ring. For the
purpose of preventing the rheostat from being turned so far around that the lugs.
will again be brought to register with the notches, the lugs are preferably connected
by vertical ribs, mo, one of which may strike a stop screw, 2, (see Figure VI)
upon one of the circular portions of the interior of the ring. The long lugs serve.
to prevent the rheostat from being pushed too far up through the ring. An
annular cylinder, M', of a compound containing carbon, is placed within the
aunular space between the casing and axial sleeve, and is insulated from the

page_text: surfaces of the same by insulating sleeves, m". The lower end of the resistance
cylinder M' is in contact with the inwardly projecting flange of the casing, and
the upper end of the cylinder is in contact, near the inner edge,. with a hub, m,
projecting downward from an annular disc,.m, screwed upon the upper end of the
axial sleeve. The hub of the annular disc is the only portion of the same, which
is in direct contact with the resistance cylinder, as an insulating washer, m,.is
interposed. A number of screws, m18,. however, pass through the annular disc and
the insulating washer, and one or more of said screws may be screwed down against.
the end of the resistance cylinder. As the outer casing of the rheostat is in
metallic contact with the negative electrode supporting frame, which forms a part
of the negative conductor of the lamp, and the lower portion of said casing is in
electrical contact with the lower end of the resistance cylinder, while the upper
end of said resistance cylinder is electrically connected to the negative electrode
holder, the current will pass through said holder, the axial sleeve and annular disc,
the resistance cylinder, the casing, and the electrode supporting frame, to. the
negative conductor, and the extent of electrical contact with the resistance
cylinder, and, consequently, the amount of resistance to the passage of the current
through the resistance cylinder, which forms the resistance element, may be
increased or decreased by placing a smaller or greater number of the contact
screws m, in contact with the resistance element.
By these means, the relative resistances of the arc and rheostat may be adjusted.
The positive carbon R, is secured in the end of a carbon sheath, R', said sheath
having a socket at one end, which is closed by a partition, r, in the sheath, so as to
prevent draught from passing upward through the tubular carbon. prefer to use a
tubular carbon, which has very thin walls, the cross-sectional area of the axial
bore of the carbon being greater than the cross-sectional area of the solid portion
of the carbon. A cap, A¹, is screwed upon the upper end of the axial tube A. of
the lamp structure, and a screw bolt, A³, passes through said cap and has its head
clamped between the upper end of the axial tube and the cap, by the latter,-being,
however, insulated from the axial tube and cap by insulating washers and packing, a'.
A ring, S, is clamped upon the axial tube by means of a nut, s, upon the threaded
upper portion of the tube, two metallic washers, s¹ and s, being respectively above
and below the ring, and insulating washers, s³, between the ring and metallic
washers. The nut forces the ring and washers towards the cap A', and thereby
clamps the ring. The ring is insulated from the axial tube by a sleeve, s', of
insulating material. The ring has an upwardly bent arm, s, projecting from its
edge, and has two downwardly bent arms, sands, (see Figure III), diametrically
opposite each other and at right angles to the upwardly bent arm. A doubled
spring, 8, is secured to the upwardly bent arm, and is insulated from the same by
an insulating plate, s. Two contact plates, T and T', are secured to the downwardly
bent arms and s, and are insulated from said arms by insulating plates, t and t¹.
The leads U and U', respectively the negative and positive lead, are respectively
connected to the downwardly bent arm and to the contact plate T. The
binding screw t2 which secures the negative lead, is inserted through the contact
plate T and the arms, insulated from the former and in contact with the latter,
and the positive lead is secured to the contact plate T¹, in direct contact with the
same, by a binding screw, t³. The positive conductor É, of the lamp, is connected
in contact with the contact plate T, by means of a binding screw, a, and the
negative conductor J, of the lamp, is connected in electric contact with the down-
wardly bent arm s', by a binding screw, x', inserted through and insulated from
the contact plate T', and in contact with the arm s. A contact bar, T2, i is pivoted
at its middle upon an insulating sleeve, a, and a switch lever, T, is pivoted above
said bar, the insulating sleeve being so stepped as to admit of said bar and lever
turning without one interfering with the movement of the other. The edge of the
central portion of the contact bar which is presented toward the doubled spring, is
formed with a segmental notch, t, extending from near one arm of the bar to a
point slightly beyond the middle of the distance between the two arms. The
:

page_text: switch lever is formed with a segmental slot, ts, opposite the handle portion of the
lever, and slightly shorter than the notch in the contact bar, with which notch it
registers and is concentric. A connecting arm, t, is pivoted at one end to the free
end of the doubled spring, and has a pin, t', projecting upward from its other end,
which pin projects into and slides in the slot in the switch lever. The end of the
arm slides in the notch of the contact bar, and may engage the shoulders at the
ends of said notch. The switch lever has a handle, t8, which is insulated from
the central portion of the lever, and which has a knob, t, for manipulating it. The
contact bar and switch lever are retained upon the insulated sleeve of the screw
bolt by a washer, 10, and insulating washer, t", held downward by a nut, t¹³, upon
the screw bolt. One arm of the contact bar is provided with a stop shoulder 13,
which may bear against the edge of the contact plate with which its end is in
contact; or both arins may be provided with such stop shoulders, the object of
the shoulder or shoulders being to stop the contact bar with its ends in electric
contact with the contact plates. The entire lamp structure above the globe is
The
inclosed in a casing which is supported by the parts of the lamp structure.
lower portion of said casing consists of a cylindrical casing, V, formed with
offsets, and v, at its upper and lower end. Said cylindrical casing V surrounds
the yoke of the magnet and the armature, and its offsets bear respectively against.
an insulating washer, b', upon the under side of the annular portion of the magnet,
and the insulating washer F1. A canopy, V₁, expands over the brush holder, and
bears against the top of the outer globe. A cylindrical casing, V2, surrounds the
magnet body, and rests with an offset, v2, upon an offset, v³, formed at the upper
edge of a flange, v, of the lower cylindrical casing, above the offset v, which bears
against the magnet. Said flange 4, is formed with ventilating openings, and the
upper portion of the upper cylindrical casing has ventilating openings, v, so that
the magnet and coil may be properly ventilated and thereby kept sufficiently cool.
A canopy, V, has an offset, v', with which it rests upon the upper edge of the upper
cylindrical casing. A cylindrical casing, V, is secured to the central opening of
this canopy and has a funnel shaped casing, V, secured to its upper end. A
canopy, V, is secured with its central opening upon the screw bolt, A2, and over-
hangs the upper edge of the funnel shaped casing, a space being formed between
the overhanging portion of the canopy and the upper portion of the funnel shaped
The
casing, in which the switch handle may have play, as illustrated in Figure 1.
canopy rests upon the nut 12, which secures the switch mechanisın, and has an
insulating washer, v8, placed against it from above. A small cap, V', fits upon the
bolt, against said washer, and an eye, V8, having a screwthreaded hole in its
periphery, is screwed upon the upper end of the bolt, securing said cap, washer and
canopy, and serving as a means for suspending the lamp.
In practice, the lamp is suspended by its eye, and the leads are inserted through
the upper canopy, and respectively connected to the transverse conductor formed
by. the ring S and its arms, and to the opposite contact plate of the switch, as
illustrated in Figure 11. The lamp is constructed to operate on a constant
potential circuit, and a number of lamps will, consequently, be connected to the
main conductors in multiple arc. When the lamp is not burning the circuit of the.
lamp is broken, as the connection between the leads through the lamp is interrupted.
by the contact bar of the switch being out of contact with the contact plates..
When the current is to be turned into the lamp, the switch handle is turned so as.
to bring the end of the segmental slot in the switch lever to bear against the pin
of the arm pivoted to the spring, and thereby force said spring open. The moment
said pin passes the central line between the fulcrum of the switch lever and the
end of the spring, the latter will force the end of the arm against the shoulder of
the segmental notch in the contact bar, throwing the latter over to engage the
contact piates, as illustrated in Figures III and IX,-the pin of the pivoted arm
sliding in the segmental slot of the switch lever, without moving the same. The
switch is opened by reversing the above-described movement, which will throw the
contact bar out of contact with the contact plates. When the circuit is closed in

page_text: the lamp by the switch being closed, the current will pass from the positive lead,
through the contact plate T₁, the contact bar and the opposite contact plate T, to
the positive conductor which is secured to said contact plate. The positive con-
-ductor conveys the current through the coil of the magnet, energizing the latter,
to the magnet body and axial tube A, which parts thus form a part of the conductor
in the lamp. The current passes through the axial tube to the brushes, which
convey the current to the positive electrode, passing between them. From the
positive electrode, the current forms the arc, or directly passes to the negative
electrode from which it passes through the holder for the same and through the
rheostat, the negative electrode support, the negative conductor disc F, the spring
contact, and the negative conductor, to the transverse conductor, S, which conveys
the current to the negative lead, across the top of the lamp. The arc is formed by
the magnet raising the armature and its clutches, whereby the positive electrode is
.raised. The ring a, which retains the clutch rings, is free to have vertical play
upon the armature, and may therefore move up and down with the clutch rings so
as to insure their correct horizontal alignment, and to control the rings that they
will all clamp the electrode at the same time. The resistance device of the rheostat
is formed from a compound of carbon and sonie refractory and non-conducting
material, such as fire clay; said material being finely comminuted and intimately
mixed, whereupon the tubular body is suitably moulded and subsequently dried
and baked. As carbon is non-volatile, and the rheostat is exposed to a high degree
of heat in the outer arc-inclosing chamber, I prefer to employ carbon as the
conducting material iu the resistance body; but, if the rheostat is less exposed to
heat, any other conductor, in a finely comminuted form, may be employed in place
of the carbon. The proportion of the conductor to the refractory non-conductor
may be varied according to the degree of resistance desired. The finely com-
minuted conductor, being imbedded throughout the refractory and non-conducting
.mass, will be protected against oxidation by said refractory and non-conducting
mass, as air will be mechanically included from the conducting particles by the
surrounding mass. The resistance body of the rheostat will, consequently, not be
affected by the heat to which it is exposed, being inclosed within the outer arc
inclosing chamber in a highly heated atmosphere. The rheostat is not liable to be
injured by accidental exposure to a current of excessive strength, as its structure
is such that it will not be affected by a high temperature caused by such excessive
.current. The entire lamp structure is supported from the axial electrode con-
taining tube and its screw bolt, the outer casing being also supported from said tube
through the lower cylindrical casing being clamped between the lower end of the
magnet and the negative conductor disc F, which, in its turn, is supported by the
nut upon the lower end of the axial tube. This entire construction renders
the lamp structure rigid and durable. The top of the outer arc inclosing chamber
is closed airtight, and no communication can take place with the interior of the
lamp structure, excepting through the brush box and the axial tube. The latter
is, however, closed airtight at its upper end, and closed at all other points excepting
at the slots through which the clutches project. The chamber surrounding the
clutches is closed airtight by the lower cylindrical casing and its washers, and any
communication which might be established through the spaces between the
armature and the axial tube and the magnet tube, is cut off by the airtight fit of
.said tube to the tubular portion and the upper annular portion of the magnet, and
by the airtight fit of the tubular portion of the magnet upon the axial tube.
In the are formed between two solid carbons, the arc is formed from the centre
of the end of the positive carbon, where a crater is formed by the more rapid
consumption of the carbon at the point of formation of the arc than at the sides.
The light given by a lamp employing solid carbons will consequently essentially
radiate from the arc and from the negative carbon, as the incandescent starting
point of the arc at the positive carbon will largely be hidden by the walls of
the crater there formed. Such walls cannot become incandescent on account of the
radiation of heat through the solid mass of the carbon, which thus keeps the

page_text: temperature of the surrounding walls of the crater, below the point of volatilisation:
of carbon. The only rays of light from the incandescent crater, which will be visible
and can serve in the illumination, are the rays which can project downward around
the point of. the negative carbon, which obstructs the more vertical rays.
When:
a tubular carbon is employed, the are will be formed from a point in the lower
edge of the wall of the tube, which point will become highly incandescent, as the
mass of the carbon is so slight that the heat of the arc cannot be as quickly
dissipated as in the case of a solid carbon. As the incandescent point of the
carbon will thus be upon the outside of the latter, the light produced by this lump,
employing the tubular carbon will be greater than in one employing a solid carbon.
The arc will travel around the annular lower edge of the carbon, but such travel.
of the arc and the point of incandescence will not affect the evenness of the light
to a perceptible degree, as the arc is long and the radiation of light is, conseque itly,.
not obstructed by the carbons as in a short are. For the purpose of illustrating
the difference between the illuminating actions of solid carbons in the ordinary
are lamp, and of a tubular positive carbon in my lamp, Figures X and XI
respectively illustrate the ends of such carbons with the lines of radiation indicated.
by dotted lines. For the purpose of diffusing any inequalities in the light of the
are formed from a tubular carbon, one or both globes may be of ground or
opalescent glass. Tubular carbons have heretofore been employed in arc lamps,
but such carbons have had comparatively thick walls, with a small axial bore, for
the same purpose as soft cored carbons have been employed, namely, for the
purpose of insuring the formation of the are as nearly axial to the carbon as.
possible. Such carbons, however, do not accomplish any different results from the
results of the ordinary solid carbons, as regards radiation of light, as the arc is in
both cases formed at the axis of the carbon. Tubular carbons with very thin walls.
cannot be advantageously used in the ordinary are lamp for the reason that they
would burn out in a short space of time in the open arc, and the light would be
unsteady in a low voltage lamp on account of the fluctuations in the arc of such
lamp. The long are in my lamp admits of the successful employment of the
tubular carbon, and the inclosing of the are admits of the long are being steadily
maintained and of the consumption of the thin walled carbon being retarded so is
to make such carbon considerably longer lived than a solid carbon in an open or
exposed arc. As a current of air, and later of other gases, would be liable to be
created through the tubular carbon, the socket portion of the carbon sheath, in
which the carbon is secured, is closed, so as to prevent the possibility of such
current. The carbon sheath and the washer in the cover for the inner arc-inclosing-
chamber serve as a cut-out for the lamp. When the positive carbon has been
cousumed to such an extent that the lower end of the carbon sheath reaches said
washer, the sheath will be stopped as the opening of the washer is of just sufficient.
size to pass the carbon while it stops the sheath. The arc will, consequently,
gradually increase in length, as the carbons are consumed, until the distance between.
the ends of the carbons becomes too great for the maintenance of the are, when
the latter will break, and the path for the current through the lamp will be
unobstructed. When the lamp is to be trimmed, the insulating handle is grasped
and the negative electrode holder with its rheostat is turned so as to bring the lugs.
upon the casing of the latter to register with the notches in the rheostat supporting
ring of the electrode supporting frame. The entire carbon holder, rheostat and
inner globe may then be removed, the ring of the supporting frame being of such
diameter that the inner globe will easily pass through it. The upper carbon and
sheath slips down with the globe, being supported in the tube upon the cover of
the same.
When the holder, rheostat and inner globe are detached, the interior of
the outer globe may be cleaned by inserting the hand with a cloth through the
bottom opening of the globe. The inner globe may be cleaned and a new carbon
inserted in the negative carbon holder. A new positive carbon may be inserted. in
the sheath and thereupon inserted from above, through the tube in the cover of the
inner globe. The carbon holder, rheostat and globe may now be..again inserted

page_text: into the outer globe, the carbon sheath and upper carbon being pushed up between
the brushes by the lower carbon. When the long lugs of the rheostat strike the
ring, the carbon holding structure may be turned and again locked in place. As
the vertical diameter of the outer globe may vary, the carbon holder is adjustably
secured in the rheostat,--the set screw m' providing such adjustability, so that
the carbon holder may be adjusted to bring the yielding cover to a proper fit in the
flaring flange of the globe, when the rheostat is in its proper secured position in
the ring of the carbon supporting frame. By the term "carbon holding structure,"
the entire detachable structure is meant, namely the carbon holder, cover and
rheostat.
,
"
Improvements in and connected with Electric Arc Lamps.
I, JOHN BRUNSWICK BARTON of 46, Brown Street, in the City of Manchester,
Engineer, (a communication from abroad by William Jandus, of Cleveland, State
of Ohio in the United States of America), do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The drawings filed with the Provisional Specification and the following description
set forth in detail, one mechanical form embodying the invention; such detail con-
struction being but one of various mechanical forms in which the principle of the
invention may be used.
Referring to the drawings filed with the Provisional Specification:
:-
Figure 1 represents an axial section of the upper portion of my improved electric
lamp;
Figure 2 an axial section of the lower portion of said lamp;
Figure 3 a side elevation of the upper portion of the lamp, removed from its
casing, and illustrating the upper portion of the lamp in axial section, at right
angles to the section illustrated in Figure 1, and illustrating parts of the magnet
body as broken away and removed;
Figure 4 a detail view of the device for regulating the amount of resistance in
the main coil;
Figure 5 a perspective detail view of the spring contact for the negative
conductor in the lamp ;
Figure 6 a perspective view of the negative electrode supporting frame;
Figure 7 a top view of the rheostat for the negative electrode support ;
Figure 8 a side view of said rheostat ;
Figure 9 a top view of the switch;
Figures 10 and 11 detail views, respectively, of the carbons in an ordinary arc
lamp and in my lamp, illustrating the conditions of the arc in said two forms, and
Figure 12 a top plan view of the brush holder.
The lamp has an axial electrode containing tube A which extends about the
entire length of the upper portion of the lamp, and forms the main frame part of
the lamp structure, to which all other parts are secured or from which they are
supported. This tube is formed with a shoulder, a, against which the upper end of the
axial bore of a magnet body B bears. Said magnet body consists of an upper annular
-portion B¹ and a lower annular portion B connected by two or more vertical wall

page_text: portions B³. The general outline of the magnet is thus substantially cylindrical
with more or less open walls. A tubular portion B is securely jammed into the
opening of the upper annular portion of the magnet, and that much of this tubular
portion as projects below the annular upper portion is reduced and formed truncate-
conical. A tube b of non-magnetic metal is secured around the upper end of the
conical part of the tubular portion, and into the opening of the lower annular
portion of the magnet, to form an air-tight annular chamber within the magnet
body such chamber being formed between said tube b and the axial tube A, and
decreasing in size towards its upper end on account of the conical part of the
magnet projecting down into it. A substantially right-angled, stirrup-shaped
yoke B is formed upon the under side of the lower annular portion of the magnet,
and has a central opening, which is concentric with the openings of the annular
portions, registers with the axial bore in the truncate-conical tubular portion, is of
the same size as said bore, and fits snugly upon the axial carbon-containing tube A,
whereby said tube is aligned absolutely true in its axial relation to the magnet, and
whereby the tubular armature, which plays upon the axial tube and within the
annular chamber of the magnet, will be guided absolutely true in its movement and
will not be liable to bind within the chamber. A series coil C is placed within the
walls of the magnet body and around the tube which forms the outer wall of the
annular chamber in the magnet. The tubular armature D is of such dimensions
that it will have a snug, but sliding fit upon the axial tube A and within the tube b,
so that the armature will have an air cushion to its up and down movements in the
annular magnet chamber. The axial bore of the armature has a truncate-conical
recess d in its upper end, which recess corresponds to the truncate-conical inner
tubular portion of the magnet. The lower end of the tubular armature is formed
with longitudinal slots d¹. A flaring pan d² is secured to the lower end of the
armature and has radiating slots d³ which register with the slots in the armature,
and with longitudinal slots, a', in the axial tube A. Clutch rings d have vertical
and radial play in the slots of the tube, armature and pan, and are retained in their
respective slots by means of a ring do which passes through said clutch rings and is
of a sufficient diameter to prevent the clutch rings from dropping into the axial
tube and become caught in the slots of the same, when the electrode is withdrawn
from the tube and the slots of the armature yet register with the slots in the axial:
tube. The lower ends of the slots in the axial tube are some distance above the :
yoke at the lower end of the magnet, so that the clutch rings will be thrown
outward in the pan, when the armature is entirely released and drops down upon
the yoke, whereby the clutch rings can offer no resistance to the insertion of the
electrode into the axial tube when the lamp is trimmed. The maguet is drawn up
against the shoulder a.upon the axial tube by means of a nut a³ upon the lower
screw-threaded end of said tube. One terminal c of the series coil is connected to
the positive conductor E of the lamp, by being clamped to a screw-bolt
which
passes through the upper annular portion of the magnet and is insulated from the
same, and which has said positive conductor secured to its upper end. The other
terminal c¹ of the series coil secured in contact with the magnet by a screw c³ which.
enters the upper annular portion of the magnet and thereby causes the magnet to
form a part of the conductor in the lamp. Said binding screw c² also secures the
upper end of a longitudinally slotted bar c³ of brass, copper, or similar good con-
ducting material, to the upper annular portion of the magnet, and the lower end of
said bar is secured to the lower portion of the magnet. A slide o is movable upon
the slotted bar, and a screw c passes through said slide. The point of said screw
is pyramidal or otherwise formed, with edges or ridges, so as to form an insulator
cutter which may cut away the insulation from the outer windings of the series coil,
and thus form a contact at the winding against which it is brought to bear and from
which it has cut the insulation, thereby cutting out the portion of the outer winding
of the coil above the screw, and short-circuiting the current through the slotted bar
to the magnet body. The number of ampère turns of the coil may thus be adjusted
and regulated according to the watt power to be consumed in the lamp, and
e,
R

page_text: according to the pull which the magnet is required to have. An annular disc F
has a downwardly projecting neck f, at its central opening, and an internally screw-
threaded cap is formed at the lower end of said neck. A nut a³ fits upon the
screw-threaded lower portion of the axial tube, and supports the cap, neck and
annular disc, an insulating washer f being interposed between the nut and the
under side of the cap. A brush holder G is secured to the lower end of the axial
electrode containing tube. Said brush holder consists of an annular casing G¹ the
upper internally rabbeted edge 9 of which is internally screw-threaded to receive
the externally screw-threaded flange al of a cover G which is formed with a
central, screw-threaded opening, which is screwed upon the lower end of the axial
tube. A brush support 92 in the shape of an annular disc has its outer edge supported
upon the rabbet of the casing, and is secured upon said rabbet by the flange of the
cover. The outer edge of said annular disc and the edge of the central opening
have radiating and registering notches g³ and g* respectively, into which notches,
brush rings 9 have radiating support and play. As the radiating brushes may
project from all sides towards the central opening through the brush holder, and as
said brushes form parts of the positive conductor within the lamp,-being in contact
with the support and holder, which is in contact with the axial tube, which again
is in electrical contact with the magnet body,-the annular brushes may have
current feeding contact with the positive electrode, when the latter is inserted
through the brush holder and into the axial electrode containing tube. A negative
electrode supporting frame H has an externally screw-threaded neck, h, at its upper
end, which neck is screwed into the internally screw-threaded cap f' of the negative
conductor disc F. Said disc is connected to the negative conductor J of the lamp
by a spring contact j, adjustably secured upon a rod j¹ which is secured through and
insulated from the lower annular portion of the magnet. The negative conductor
passes through and is insulated from the upper annular portion of the magnet, and
is secured in contact with the upper end of the rod j¹. An insulating washer F¹ is
placed upon the upper side of the negative conductor disc-for a purpose which will
be explained later and said washer is cut away at the point where the spring
contact projects to bear against the disc, as clearly illustrated in Figure 5. A
ring H, is formed at the lower end of the negative electrode supporting frame,
concentric with the neck of said frame and with the axis of the entire
lamp structure. Said ring has a circular interior shape, with notches h¹
at points of its circular interior,-four equidistant notches being illustrated in the
drawing, and being illustrated as formed by outward bulges of the ring. The
negative electrode K is secured in a negative electrode holder L by means of a set
screw which enters the axial socket of said holder. Said axial socket is inter-
sected at its lower portion by a slot of greater width than the diameter of the
socket, which slot gives access to the socket for the purpose of adjusting the carbon
in the socket and for the purpose of removing the negative carbon from the same, if
the carbon should become stuck in the, socket or burned down to the upper end
of the socket, so that it cannot be removed from the latter at the upper end of the
same. A rheostat M, has an axial sleeve m in metallic contact with the electrode
holder, and adjustably secured upon the latter by means of a set screw m¹ passing
through a collar m² at the lower end of the sleeve. The axial sleeve of the rheostat
has a lateral flange m³ projecting outward from near its lower end. A cylindrical
casing m² of so much greater interior diameter than the exterior diameter of the
sleeve, as to leave an annular space between the casing and sleeve, has an inwardly
projecting flange m' through which passes screws m which pass through and are
insulated from the foot flange m³ of the inner sleeve. The two flanges are insulated
from each other by means of an insulating washer m². The cylindrical casing is
formed with short lugs me and longer lugs me at points corresponding to the notches
in the ring of the negative electrode supporting frame, so that the rheostat may be
inserted through the ring from below, with the short upper lugs moving upward
through the notches, whereupon the rheostat may be turned to bring the lugs to
bear against the upper and lower edge of the ring, at points between the notches,
ச

page_text: thereby securing the rheostat and negative carbon holder in said ring. For the
purpose of preventing the rheostat from being turned so far around that the lugs
will again be brought to register with the notches, the lugs are preferably connected
by vertical ribs mo, one of which may strike a stop screw h³ upon one of the
circular portions of the interior of the ring. The long lugs serve to prevent the
rheostat from being pushed too far up through the ring. An annular cylinder M¹
of a compound containing carbon, is placed within the annular space between the
casing, and axial sleeve, and is insulated from the surfaces of the same by insulating
sleeves m. The lower end of the resistance cylinder M¹ is in contact with the
inwardly projecting flange of the casing, and the upper end of the cylinder is in
contact, near the inner edge, with a hub m2, projecting downward from an annular
disc mscrewed upon the upper end of the axial sleeve. The hub of the annular
disc is the only portion of the same which is in direct contact with the resistance
cylinder, as an insulating washer m", is interposed. A number of screws, m¹³,
however, pass through the annular disc and the insulating washer, and one or more
of said screws may be screwed down against the end of the resistance cylinder. As
the outer casing of the rheostat is in metallic contact with the negative electrode
supporting frame, which forms a part of the negative conductor of the lamp, and
the lower portion of said casing is in electrical contact with the lower end of the
resistance cylinder, while the upper end of said resistance cylinder is electrically
connected to the negative electrode holder, the current will pass through said
holder, the axial sleeve and annular disc, the resistance cylinder, the casing, and
the electrode supporting frame, to the negative conductor, and the extent of
electrical contact with the resistance cylinder, and consequently the amount of
resistance to the passage of the current through the resistance cylinder, which
forms the resistance element, may be increased or decreased by placing a smaller
or greater number of the contact screws m¹³ in contact with the resistance element.
By these means, the relative resistances of the arc and rheostat may be adjusted.
The positive carbon R, is secured in the end of a carbon sheath R¹, said sheath
having a socket at one end, which is closed by a partition r, in the sheath, so as to
prevent draught from passing upward through the tubular carbon. I prefer to use
a tubular carbon, which has very thin walls, the cross-sectional area of the axial
bore of the carbon being greater than the cross-sectional area of the solid portion
of the carbon. A cap A¹ is screwed upon the upper end of the axial tube A of
the lamp structure, and a screw bolt A³ passes through said cap and has its head
clamped between the upper end of the axial tube and the cap, by the latter,-
being, however, insulated from the axial tube and cap by insulating washers and
packing, a. A ring S is clamped upon the axial tube by means of a nut s upon
the threaded upper portion of the tube, two metallic washers, s' and s², being
respectively above and below the ring, and insulating washers, 3, between the ring
and metallic washers. The nut forces the ring and washers towards the cap A',
and thereby clamps the ring. The ring is insulated from the axial tube by a
sleeve, s, of insulating material. The ring has an upwardly bent arm, s³, pro-
jecting from its edge, and has two downwardly bent arms, s, and s, diametrically
opposite each other and at right angles to the upwardly bent arm. A doubled
spring, s, is secured to the upwardly bent arm, and is insulated from the same by
an insulating plate, s. Two contact plates, T and T', are secured to the
downwardly bent arms, s and s, and are insulated from said arms by insulating
plates, t and t¹. The leads u and u', respectively the negative and positive lead, are
respectively connected to the downwardly bent arms and to the contact plate T¹.
The binding screw 2 which secures the negative lead, is inserted through the
contact plate T and the arm se, insulated from the former and in contact with the
latter, and the positive lead is secured to the contact plate T, in direct contact
with the same, by a binding screw, t³. The positive conductor E, of the lamp, is
connected in contact with the contact plate T, by means of a binding screw,, and
the negative conductor J of the lamp, is connected in electric contact with the
downwardly bent arm s", by a binding screw, a¹, inserted through and insulated

page_text: from the contact plate T¹, and in contact with the arm s. A contact bar, T2, is
pivotted at its middle upon an insulating sleeve a³, and a switch lever T³, is pivotted
above said bar, the insulating sleeve being so stepped as to admit of said bar and
lever turning without one interfering with the movement of the other. The
edge of the central portion of the contact bar which presents toward the doubled
spring, is formed with a segmental notch t*, extending from near one arm of
the bar to a point slightly beyond the middle of the distance between the two
arms. The switch lever is formed with a segmental slot to, opposite the handle
portion of the lever, and slightly shorter than the notch in the contact bar, with
which notch it registers and is concentric. A connecting arm is pivotted at one
end to the free end of the doubled spring, and has a pin t' projecting upward from
its other end, which pin projects into and slides in the slot in the switch lever.
The end of the arm slides in the notch of the contact bar, and may engage the
shoulders at the ends of said notch. The switch lever has a handle t8 which is
insulated from the central portion of the lever, and which has a knob to for
manipulating it. The contact bar and switch lever are retained upon the insulated
sleeve of the screw bolt by a washer 10 and insulating washer ", held downward
by a nut 12, upon the screw bolt. One arm of the contact bar is provided with a
stop shoulder 13, which may bear against the edge of the contact plate with which
its end is in contact; or both arms may be provided with such stop shoulders,
the object of the shoulder or shoulders being to stop the contact bar with its ends
in electric contact with the contact plates. The entire lamp structure above the
globe is inclosed in a casing which is supported by the parts of the lamp structure.
The lower portion of said casing consists of a cylindrical casing V, formed with
offsets v and v', at its upper and lower end. Said cylindrical casing V surrounds
the yoke of the magnet and the armature, and its offsets bear respectively against
an insulating washer b', upon the under side of the annular portion of the magnet,
and the insulating washer F¹. A canopy V¹ expands over the brush holder, and
bears against the top of the outer globe. A cylindrical casing V2 surrounds the
magnet body, and rests with an offset v2 upon an offset v³, formed at the upper edge
of a flange of the lower cylindrical casing, above the offset v, which bears
against the magnet. Said flange is formed with ventilating openings, and the
upper portion of the upper cylindrical casing has ventilating openings, so that
the magnet and coil may be properly ventilated and thereby kept sufficiently cool.
A canopy V has an offset ' with which it rests upon the upper edge of the upper
cylindrical casing. A cylindrical casing V4, is secured to the central opening of
this canopy and has a funnel shaped casing V8, secured to its upper end. A
canopy V is secured with its central opening upon the screw bolt A³, and
overhangs the upper edge of the funnel shaped casing, a space being formed
between the overhanging portion of the canopy and the upper portion of the
funnel shaped casing, in which the switch handle may have play, as illustrated in
Figure 1. The canopy rests upon the nut 2, which secures the switch mechanism,
and has an insulating washer 8 placed against it from above. A small cap V' fits
upon the bolt, against said washer, and an eye, V³, having a screw-threaded hole
in its periphery, is screwed upon the upper end of the bolt, securing said cap,
washer and canopy, and serving as a means for suspending the lamp.
In practice, the lamp is suspended by its eye, and the leads are inserted through
the upper canopy, and respectively connected to the transverse conductor formed
by the ring S and its arms, and to the opposite contact plate of the switch, as
illustrated in Figure 3. The lamp is constructed to operate on a constant potential
circuit, and a number of lamps will, consequently, be connected to the main
conductors in multiple arc. When the lamp is not burning the circuit of the lamp
is broken, as the connection between the leads through the lamp is interrupted by
the contact bar of the switch being out of contact with the contact plates. When
the current is to be turned into the lamp, the switch handle is turned so as to
bring the end of the segmental slot in the switch lever to bear against the pin of
the arm pivotted to the spring, and thereby force said spring open. The moment

page_text: said pin passes the central line between the fulcrum of the switch lever and the
end of the spring, the latter will force the end of the arm against the shoulder of
the segmental notch in the contact bar, throwing the latter over to engage the
contact plates, as illustrated in Figures and 9, the pin of the pivotted arm
sliding in the segmental slot of the switch lever, without moving the same. The
switch is opened by reversing the above-described movement, which will throw the
contact bar out of contact with the contact plates. When the circuit is closed in
the lamp by the switch being closed, the current will pass from the positive lead,
through the contact plate T₁, the contact bar and the opposite contact plate T, to
the positive conductor which is secured to said contact plate. The positive
conductor conveys the current through the coil of the magnet, energizing the
latter, to the magnet body and axial tube A, which parts thus form a part of the
conductor in the lamp. The current passes through the axial tube to the brushes,
which convey the current to the positive electrode, passing between them. From
the positive electrode, the current forms the arc, or directly passes to the negative
electrode from which it passes through the holder for the same and through the
rheostat, the negative electrode support, the negative conductor disc F, the spring
contact, and the negative conductor, to the transverse conductor S, which conveys
the current to the negative lead, across the top of the lamp. The arc is formed
by the magnet raising the armature and its clutches, whereby the positive electrode
is raised. The ring do, which retains the clutch rings, is free to have vertical play
upon the armature, and may therefore move up and down with the clutch rings so as
to insure their correct horizontal alignment, and to control the rings that they will
all clamp the electrode at the same time. The resistance device of the rheostat is
formed from a compound of carbon and some refractory and non-conducting
material, such as fire clay; said material being finely comminuted and intimately
mixed, whereupon the tubular body is suitably moulded and subsequently dried
and baked. As carbon is non-volatile, and the rheostat is exposed to a high degree
of heat in the outer arc-inclosing chamber, I prefer to employ carbon as the
conducting material in the resistance body; but, if the rheostat is less exposed to
heat, any other conductor, in a finely comminuted form, may be employed in place
of the carbon. The proportion of the conductor to the refractory non-conductor
may be varied according to the degree of resistance desired. The finely com-
minuted conductor, being embedded throughout the refractory and non-conducting
mass, will be protected against oxidation by said refractory and non-conducting
mass, as air will be mechanically excluded from the conducting particles by
the surrounding mass. The resistance body of the rheostat will, consequently,
not be affected by the heat to which it is exposed by being inclosed within
the outer arc inclosing chamber in a highly heated atmosphere. The rheostat
is not liable to be injured by accidental exposure to a current of excessive strength,
as its structure is such that it will not be affected by a high temperature caused by
such excessive current. The entire lamp structure is supported from the axial
electrode containing tube and its screw bolt, the outer casing being also supported
from said tube through the lower cylindrical casing being clamped between the
lower end of the magnet and the negative conductor disc F, which, in its turn, is
supported by the nut upon the lower end of the axial tube. This entire con-
struction renders the lamp structure rigid and durable. The top of the outer arc
inclosing chamber is closed air-tight, and no communication can take place with the
interior of the lamp structure, excepting through the brush box and the axial tube.
The latter is, however, closed air-tight at its upper end, and closed at all other
points excepting at the slots through which the clutches project. The chamber
surrounding the clutches is closed air-tight by the lower cylindrical casing, and its
washers, and any communication which might be established through the spaces
between the armature and the axial tube and the magnet tube, is cut off by the
air-tight fit of said tube to the tubular portion and the upper annular portion of
the magnet, and by the air-tight fit of the tubular portion of the magnet upon the
axial tube.

page_text: In the arc formed between two solid carbons, the arc is formed from the centre
of the end of the positive carbon, where a crater is formed by the more rapid con-
sumption of the carbon at the point of formation of the arc than at the sides. The
light given by a lamp employing solid carbons will consequently essentially radiate
from the arc and from the negative carbon, as the incandescent starting point of
the arc at the positive carbon will largely be hidden by the walls of the crater
there formed. Such walls cannot become incandescent on account of the radiation
of heat through the solid mass of the carbon, which thus keeps the temperature of
the surrounding walls of the crater, below the point of volatilisation of carbon.
The only rays of light from the incandescent crater, which will be visible and can
serve in the illumination, are the rays which can project downward around the
point of the negative carbon, which obstructs the more vertical rays, thus forming
a hollow cone of undiffused light. When a tubular carbon is employed, the arc
will be formed from a point in the lower edge of the wall of the tube, which point
will become highly incandescent, as the mass of the carbon is so slight that the heat of
the are cannot be as quickly dissipated by radiation as in a solid carbon. As the
incandescent point of the carbon will thus be upon the outside of the latter,
the light produced by this lamp, employing the tubular carbon will possess greater
power than a solid carbon. The arc will travel around the annular lower edge of
the carbon, but such travel of the arc and the point of incandescence will not affect
the evenness of the light to a perceptible degree, as the arc is long and the
radiation of light is, consequently, not obstructed by the carbons as in a short arc.
For the purpose of illustrating the difference between the illuminating actions of
solid carbons in the ordinary are lamp, and of a tubular positive carbon in my lamp,
Figures 10 and 11 respectively illustrate the ends of such carbons with the lines of
radiation indicated by dotted lines. For the purpose of diffusing any inequalities
in the light of the are formed from a tubular carbon, one or both globes may be of
ground or opalescent glass. Tubular carbons have heretofore been employed in
arc lamps, but such carbons have had comparatively thick walls, with a small
axial bore, for the same purpose as soft cored carbons have been employed, namely,
for the purpose of insuring the formation of the arc as nearly axial to the carbon
as possible. Such carbons, however, do not accomplish any different results from
the results of the ordinary solid carbons, as regards radiation of light, as the arc is
in both cases formed at the axis of the carbons. Tubular carbon with very thin
walls cannot be advantageously used in the ordinary arc lamp for the reason that
they would burn out in a short space of time in the open arc, and the light would
be unsteady in a low voltage lamp on account of the fluctuations in the are of such
lamp. The long arc in my lamp admits of the successful employment of the
tubular carbon, and the enclosing of the arc as described in the Specifications to
my British Application for Patent No. 437A of 1895, admits of the long are being
steadily maintained and of the consumption of the thin walled carbon being
retarded so as to make such carbon considerably longer lived than a solid carbon in
an open or exposed arc. As a current of air, and later of other gases, would be
liable to be created through the tubular carbon, the socket portion of the carbon
sheath R', in which the carbon is secured, is closed, so as to prevent the possibility
of such current. When the lamp is to be trimmed, the insulating handle is
grasped and the negative electrode holder with its rheostat is turned so as to bring
the lugs upon the casing of the latter to register with the notches in the rheostat
supporting ring of the electrode supporting frame. The entire carbon holder, and
rheostat may then be removed. When the entire holder, and rheostat are
detached, the interior of the globe may be cleaned by inserting the hand with a
cloth through the bottom opening of the globe. The inner globe if such be
employed may be cleaned and a new carbon inserted in the negative carbon holder.
A new positive carbon may be also inserted. The entire carbon holder, and
rheostat may now be again inserted into the globe, the carbon sheath R' and upper
-carbon being pushed up between the brushes by the lower carbon. When the loug
lugs of the rheostat strike the ring, the carbon holding structure may be turned

page_text: and again locked in place. As the vertical diameter of the outer globes may vary,
the carbon holder is adjustably secured in the rheostat, the set screw m³ providing
such adjustability, so that the carbon holder may be adjusted to bring the
yielding cover to a proper fit in the flaring flange of the globe, when the rheostat is.
in its proper secured position in the ring of the carbon supporting frame. By the
term "carbon holding structure," the entire detachable structure is meant, viz. :-
the carbon holder, cover and rheostat.
Having now particularly described and ascertained the nature of my said inveu-
tion and in what manner the same is to be performed, I declare that what.
I claim is :-
:-
1. In an arc lamp; operating mechanism comprising an annular armature
surrounding a carbon, and an annular electro-magnet and coil or solenoid
surrounding the said armature, the armature being arranged to move easily in a
cylinder formed within the electro-magnet and coil or solenoid and the cylinder
being so closed as to form an air cushion and cause the armature to compress or
expand air to check too rapid movement, substantially as herein set forth.
2. In an arc lamp; operating mechanism as described with reference to Figure 1
of the drawings comprising an annular armature as D surrounding a carbon and an
annular electro-magnet as B2 and coil or solenoid as C surrounding the said
armature; the armature being arranged to move easily in a cylinder as 6 of non-
magnetic metal placed within the electro-magnet and coil or solenoid, the said
cylinder being closed at its upper end to form a dash pot there and cause the
armature to compress or expand air to check too rapid movement, substantially as.
and for the purposes herein before set forth.
3. In an arc lamp; the combination of an annular armature with clutch rings
as d Figure 1 operating in slots in the said armature and acting on inclined or
conical surfaces in a carrier forming part of or attached to the armature,
substantially as herein before set forth.
4. In an arc lamp; the arrangement whereby the magnet coil C Figure 1 is
removed from the influence of the heat of the arc as hereinbefore described.
5. In an arc lamp, the construction of a globe with an aperture for a valve.
formed with expanding or flaring edges as n³ Figure 2 to deflect water and prevent.
it from entering the lamp as hereinbefore described.
6. In an arc lamp; an interior rheostat as M Figure 2 placed inside the globe in
series with the lower terminal of the lamp circuit the said rheostat being composed
of a refractory and non-conducting substance such as fire clay and a finely com-
minuted conductor such as carbon in intimate mixture therewith, substantially as
set forth.
7. In an arc lamp; the detachable bayonet joint arrangement of the lower end.
of the negative electrode frame permitting the ready withdrawal of the negative.
carbon and the inner globe or chamber, substantially as and for the purposes.
hereinbefore described.
Doted this 7th October 1905
MARKS & CLERK,
18 Southampton Buildings, London, W.C., Agents.