Improvements in Electric Arc Lamps.
Year: 1893

page_text: COMPLETE SPECIFICATION (AMENDED).
Improvements in Electric Arc Lamps.
I, LOUIS EMERSON HOWARD, of Plainfield, in the County of Union and State of New
York, United States of America, Gentleman 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 that is to say :-
This invention relates to electric arc lamps. Its object is to increase the life of
the carbons and, improve the quality of light, and-to-increase-the-efficiency-of-the
lamp-and-render-it-operative-with-a-lower-voltage:
am aware
In carrying out my invention I surround the arc with a transparent or translucent
heat resisting envelope tightly closed at all points below the arc, and provided with
means för permitting the egress of heated gases at the top, and make this envelope
sufficiently small in size. so-that-the-gases-surrounding the are-may-be-maintained
by-the-heat-thereof-in-a--luminous-or-incandescent-condition. In order to permit the
feed of the upper carbon, an opening is made in the envelope sufficiently close in fit
to just permit of the feed, and the arc is located near the top of the enclosing
envelope for the purpose of preventing a waste of the positive carbon and preventing
the ingress of air through the feed opening. It has heretofore been proposed to
enclose the arc in an air-tight envelope, but all such efforts have so far as
resulted in failure. If,-as-has-been-the-ease,--the-enclosing envelope-is--made-com-
paratively large-in-diameter, say, five inches or upwards, it--is--impossible--to
maintain--the-gases--in--a-luminous--or-incandescent condition, and--if the opening
through which the carbon feeds is made sufficiently large to admit of very free
transit of the carbon through it ingress of air is permitted which increases the
rapidity of consumption of the carbons; moreover, where the lamp is exposed to the
elements, rain or a draft of cold air striking the containing chamber when made of
glass is apt to shatter it. With my construction these difficulties are
I am enabled to make the transparent or translucent enclosing
envelope three inches or less in diameter, a size which will admit of main
taining--the--gases around the are incandescent or opalescent, resulting in an agree-
able light of large radiating area; and by making the feed opening a comparatively
close fit around the carbon and providing a valve or trap for the escape of heated
gases when the tension becomes sufficient to endanger the envelope, the life of the
carbon is prolonged to an extraordinary degree. A further incident of great
importance--which follows from the reduction-in size of the--enclosing-envelope is
that-the-lamp-will--operate--at-a-lower--voltage than other types-of-are-lamp,
result-probably due to an increased--degree--of--conductivity of-the-are-because--of
greater density of the hot gases.
overcome.
The several features of novelty of the invention will be more particularly
hereinafter described and will be definitely indicated in the claims appended to this
anecification.

page_text: In the accompanying drawings which illustrate the invention, Figure 1 represents
one form of an arc lamp constructed in accordance with my invention: Figs. 2 and 3
are detail views of the plug used at the top of the arc-enclosing envelope through
which the carbon is fed, and which is provided with means for permitting an egress
of the heated gases; Figs. 4 and 5 are horizontal and vertical cross-sections of a
modified construction of an arc-enclosing envelope, and Figs. 6 and 7 are detail views
of the hood or reflector used on the outer protecting globe, as shown in Fig. 1.
Where the lamp is exposed to the action of the elements an auxiliary globe A will
be provided around the arc-enclosing envelope to prevent rain or drafts from striking
its highly heated surface. The enclosed air and gases between the outer and inner
envelopes make the difference of temperature on the two sides of the arc-enclosing
envelope less and thus protect it. The feed-regulating mechanism which maintains
the are of a substantially uniform length irrespective of the gradual consumption of
the movable carbon may be of any suitable construction, and as it forms to part of
my present invention need not be specifically described.. Surrounding the arc is a
transparent or translucent envelope B preferably made of glass, and not to exceed
three inches, and preferably less, in horizontal diameter and of any desired length.
This chamber is preferably formed of substantially a bottle shape, having a neck at
the top, and is open at the bottom, though it may be formed in the shape of an open
cylinder and closes at the ends in a suitable manner, as illustrated in Fig. 5.
I will first describe the mode of construction illustrated in Figs. 1, 2 and 3 of the
drawings. At the bottom edge is formed by molding or otherwise a screw thread C,
and a metal cap D provided with a socket for the negative carbon E is provided with
a co-operating thread forming a close fit which when screwed upon the bottom of
the envelope B with an interposed washer of asbestos will form a gas-tight joint.
This cap may be spun from a metal capable of withstanding comparatively high tem-
perátures, such as copper or an alloy, and the socket is formed integral therewith
ör attached in any suitable manner so as to form a gas proof and heat resistant joint.
The arc is located near the top of the enclosing envelope, and the neck is provided
with a fire-proof plug F formed of asbestos pulp or any other suitable material into
which screws a metal glug G formed of two parts, as seen at g, gl, Fig. 2, between
which may be clamped a washer of soft heat-resisting material, such as asbestos, indi-
cated at 9. By this means a comparatively close fit may be formed around the
positive carbon H, the asbestos washer g² yielding sufficiently although a compara-
tively close fit to permit an easy feed of the positive carbon H. Through the body
of the plug G is formed an opening I over which rests a hinged metal valve J provided
with a limited stop K. With this construction the operation of the lamp will be as
follows:
Upon the closure of the circuit and the springing of the are the air in the enclosing
envelope B is robbed of its oxygen, and after a short time the-entire-body-of-the
gas chamber-B-becomes-highly-luminous, being filled--with--an-ineandescent-vapor
of carbon-which-results-in-e-light--emanating from--all--parts of the envelope
B, soft,-highly-luminous-and-steady. The heated gases by their expansive force and
tendency to rise effectually prevent the ingress of air through the narrow space
between the positive carbon and the metal plug, and since practically no air can
gain admission to the interior of the envelope a very slow consumption of the carbon
results. Such small particles of carbon as are carried through the arc or rendered
incandescent therein are deposited on the negative electrode and serve to build up
said electrode and maintain the arc substantially stationary in position, or in any
event at a point above the horizontal center of the envelope B and above the heavier
gases which collect at the bottom of the envelope, while a very slow destruction of
the positive electrode proceeds. In time a light deposit will be formed upon the inner
wall of the envelope B; but the heat-of the-enclosed-goses when this envelope--is--of
substantially-the-size specified is sufficient to maintain this deposit-in-an-incandes
cent-or-opalescent-cendition, adding-to-the-effectiveness-of-the-light-and-the rupidity
with-which-the-highly-luminous condition is effected. It is important that the plug G
surrounding the positive electrode should be metallic as it will then by reason of its high

page_text: conductivity maintain the tension of the thin film of gas around the carbon in the feed
opening and better prevent the ingress of the cold outside air. It is, moreover, impor-
tant that the metal should not come into direct contact with the glass enclosing envelope
B, when the latter is made of that material, in order to prevent fracture, and it is for
this reason that some heat non-conducting and fire-proof substance such as asbestos
is interposed. It is, moreover, important that the arc should be formed near the top
of the enclosing envelope since when so located it will localize the heat at the top
of the chamber and the better prevent the ingress of air by increasing the
tension of the enclosed gases at that point, thus conserving the life of the carbons ;
moreover, when so located by a short length of the positive carbon will be exposed
to the high heat of the are and surrounding gaseous envelope, thus lowering the
temperature of the external portion of the positive carbon and reducing the amount
of disintegration. Besides this, carbon when exposed to a high heat is subject to a
process of "over-carbonization" by which it becomes comparatively porous and its
resistance is increased. By exposing only a short section of the positive carbon such
over-carbonization is limited in extent, and the resistance of the lamp is therefore
lower than it would be if the arc were maintained lower in the enclosing envelope.
Another incident resulting from the location of the are near the top of the envelope
is the maintenance of steadiness and a maximum angle of illumination. I have
observed, moreover, that when so located there is less liability of the "bead" formed
on the negative electrode by the transit of carbon across the are to break off, and a
smoother surface of the negative carbon is presented to the are and a more equable
action of the lamp maintained. Accurate tests indicate that a lamp of my construc-
tion as herein before described will require only 25 or 30 volts for its operation, as
contrasted with 45 or 50 volts in other types of lamps. I attribute this result to the
dense body of conducting gas maintained in close relation to the arc by which its
resistance is materially lowered and the voltage necessary to maintain its action is
reduced. The small arc-enclosing envelope prevents dissipation of the gases and
maintains them at a greater density than would be possible with a large envelope.
Besides conserving-the-energy-in-the-manner-already-described-the-gases-glow-with
increased-brilliancy by-reason-of the-greater-density. In operating with my lamp
1 find that the best results obtained by using absolutely pure carbons,
and, I find that the negative carbon is increased in length or held above the
center of the envelope B, whereas the positive carbon is so slowly consumed that a
carbon of less than 12 inches in length will maintain the arc and its gaseous envelope
in continuous operation for more than 100 hours with a consumption of 270 watts, as
contrasted with a life of 7 hours and a consumption of 500 to 600 watts with other
forms of are lamps. I am aware that it has been proposed heretofore to operate an
arc lamp in an air-tight envelope, but when the envelopes are sealed an explosion of
the cylinder is liable to result, and when not sealed, a rapid consumption of carbons
will result and a smoking of -the enclosing envelope. Valves which rely for their
action upon accumulated pressure will interfere with a good action of the lamp and
make the light fluctuate in intensity and cause sputtering. In my lamp, however,
the enclosure, although practically tight against ingress of air, allows a steady outflow
of gases from the lamp. By means of my construction I provide as herein before
stated a light of large radiating surface which is far more desirable as a source of
illumination than one in which the light is emitted from a center of small surface
such as an ordinary arc. As herein before stated the arc enclosing envelope is
preferably surrounded by an auxiliary outer transparent or translucent envelope,
shown at A in Fig. 1, which may be supported upon a flanged collar at the lower part
of the lamp and secured in place by thumb screws or in any other suitable manner.
This globe is provided with a circular opening at the top which is covered with a
closely fitting conical reflecting hood L made in two separable parts I³, I², see Fig. 6,
so as to admit of convenient removal and replacement. These two parts are hinged
to each other at I³ and are also secured together at an opposite point by a spring
latch m which takes hold of a shoulder m³ but may be easily lifted and disengaged
therefrom. The hood L is fitted with non-conducting thimbles at O¹ and O³ through
are

page_text: "
which pass the descending portions of the supporting arms for the lamp and also with
an additional thimble 03 forming a fixed guide through which passes the positive
electrode H. The negative electrode may in some cases be formed of simply a small
piece or block of carbon, as indicated in Fig. 5 at E', supported in a solid rod of
metal E, Fig. ¿, having considerable mass and being a good conductor of heat. This
construction will maintain the negative electrode at a comparatively low temperature
and not only mitigate the amount of its disintegration by the heat of the arc, but
assist in the deposit of vaporized carbon, carried across the arc and redeposited on the
negative electrode. In the form of arc-enclosing envelope illustrated in Figs. 4 and 5
a simple cylinder open at both ends is formed of the transparent material. The
cylinder may, for example, be provided, as illustrated, with a lug or ridge formed
integral therewith, as indicated at x, which ridge may engage a thread or recess
formed in cape to constitute the top and bottom covers for the cylinder. These
covers may be formed of "vulcabeston or any other suitable non-conducting and
non-combustible material and the whole arc-enclosing chamber may be supported by
a metallic extension or rod extending upwardly from the lower part of the lamp
frame. The top, and bottom covers may be fitted air-tight by means of disks of
asbestos felt e, e¹. The upper end of the cylinder rises a short distance above the
upper end of the negative electrode and upon the top cap may be supported a hollow
cone N which may be conveniently formed of aluminium and will then serve as a
reflector to throw downwardly and outwardly the rays of light projected-upwardly
from the arc.
The top of this cone N may be provided with a metallic thimble or
plug P having an axial opening through which the positive electrode may freely pass.
The hollow cone is firmly supported in the top cap or cover of the cylinder in any
suitable manner which will form, an air-tight joint and if desired a flanged cone or
lining of reflecting metal may be provided inside the asbestos disk or washer which
will reflect downwardly all the rays of light emanating from the arc. This flanged
cone is indicated at Q in Fig. 5. With this construction the arc-enclosing envelope
may be rapidly assembled or taken apart by simply twisting the top and bottom caps
so as to disengage the threaded recesses formed therein from the projecting ridge
formed on the transparent cylinder. No valve is shown in the construction illustrated
in Fig. 5; although the valved opening will be preferably used, because yielding
more perfect results, the invention is practicable without it, the narrow opening
around the positive carbon between the latter and the metallic plug or thimble
permitting egress of heated gases.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I'declare that what I claim is :-
An-arc--lamp--having--the--electrodes--around-the-are--enclosed--in--a-small
transparent--or--translucent-envelope air tight-at-all points below-the--arc-and
provided-with-a-normally-closed-valve above the-are-whereby-the-envelope-is-filled
with-a-highly-luminous-gas-and-the-life-of the-electrodes-is-prolonged.
2. An-are-lamp-having-its--electrodes around the-are--enclosed--in-a-small
transparent-or-translucent envelope-so-arranged-as-to-maintain the-gases-luminous
in said-envelope-and-air tight against ingress of air-but- affording egress for the
heated gases developed by the-are.
3. An-are-lamp-having-its-electrodes-around-the-are-enclosed-in-a-transparent-or
translucent-envelope-air-tight-at-all-points below the-are-so-arranged us to maintain
the gases-luminone-in- said envelope, said-are-being- located near-the-top of the
envelope, means-for-preventing the ingress of air, and an outwardly opening valve
for permitting the discharge of guses.
4. An-are-lamp-having its ore-enclosed in a small transparent or translucent
envelope closed air tight below the arc, so arranged as to maintain the gases luminous
in said-envelope, a closely fitting-opening to permit feed-of-the-positive-carbon and
un-outwardly opening normally-closed valve in the top of the envelope-adjacent-te
the heated-gases.
An arc lamp, having its are enclosed in a transparent or translucent.envelope

page_text: provided with a metallic plug having a closely fitting opening to permit feed of the
positive carbon, and means for permitting escape of the gases produced by the arc.
2. 6. An arc lamp having its are enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, and provided with a plug at the top having
a closely fitting feed opening for the positive carbon.
3. 7. An arc lamp having its are enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a plug in the top of the envelope provided
with a closely fitting feed opening for the positive carbon, and a valved opening in
said plug.
4. 8. An are lamp having its are enclosed in a transparent or translucent envelope
enclosed air-tight at all points below the arc, a closely fitting opening in the top of
the envelope to permit feed of the positive carbon, and a heat non-conducting wall
between the wall of the envelope and the feed opening.
5. 9. An arc lamp having its arc enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a plug in the envelope above the arc
provided with a closely fitting feed opening for the positive carbon, and an outwardly
opening gravity valve normally closing a vent for the gases developed by the arc.
6. 10. An arc lamp having its arc enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a metallic plug in the top of the envelope
provided with a feed opening for the positive carbon, and an annular lining of yielding
fire-proof material such as asbestos producing a closely fitting wall around the carbon.
7. H. An arc lamp having its are enclosed in a glass envelope provided with a
closely fitting feed opening for the positive carbon at the top, and a gas-tight metallic
cap provided with a threaded rim engaging a thread on the bottom of the glass
envelope, said cap having a metallic socket for the negative carbon.
8. 12. An arc lamp having its are enclosed within a transparent or translucent
envelope, an auxiliary transparent or translucent envelope closed on all sides sur-
rounding said arc-enclosing envelope, and feed openings in the envelopes, whereby the
two sides of the arc-enclosing envelope are maintained at a comparatively uniform
temperature and fracture is avoided.
9. 13. In an electric arc lamp, the combination with the positive and negative
electrodes, of an enclosing cylindrical chamber or envelope of transparent material
surrounding the arc, an auxiliary enclosing transparent chamber closed on all sides,
and a conical reflector within the upper end of said chamber encircling the positive
'carbon,
10. 14. An arc lamp having its arc enclosed within a transparent or translucent
envelope provided with a reflecting cap at the top, said envelope being enclosed
in an auxiliary outer protective envelope also provided with a reflecting cap,
whereby all the rays of light thrown upwardly from the arc are utilized externally
of the lamp.
15. In-an-electric-are lamp, the combination with the movable-positive-electrode,
of-an-enclosing-globe, and a hood-closely-fitting the open top of said globe, and pro-
vided-with-a-metallic guide in open-communication with the atmosphere-through
which-said-movable-electrode-is-made-to-pass, for the purpose described.
11. 16. An arc lamp having its arc enclosed within a transparent or translucent
envelope provided with a separable top, an outer transparent or translucent envelope
for the purpose described, said outer envelope being closed on all sides, and being
provided with detachable cover.

page_text: Improvements in Electric Arc Lamps.
I, LOUIS EMERSON HOWARD, of Plainfield, in the County of Union and State of New
York, United States of America, Gentleman 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 that is to say:-
This invention relates to electric are lamps. Its object is to increase the life of
the carbons and, improve the quality of light, and-to-increase--the efficiency of the
lamp-and-render it operative-with-a-lower voltage.
In carrying out my invention I surround the arc with a transparent or translucent
heat resisting envelope tightly closed at all points below the arc, and provided with
means for permitting the egress of heated gases at the top, and make this envelope
sufficiently small in size so-that-the-gases-surrounding-the-are--may--be--maintained
by-the-heat-thereof-in-a-luminous-or-incandescent condition. In order to permit the
feed of the upper carbon, an opening is made in the envelope sufficiently close in fit
to just permit of the feed, and the arc is located near the top of the enclosing
envelope for the purpose of preventing a waste of the positive carbon and preventing
the ingress of air through the feed opening. It has heretofore been proposed to
enclose the arc in an air-tight envelope, but all such efforts have so far as I am aware
resulted in failure. If, as has-been-the-ease, the enclosing-envelope is made com-
paratively large--in-dinmeter,- Buy, five--inches--or--upwards, it--is--impossible--te
maintain-the-gases-in-a-luminous-or-incandescent-condition, and if the opening
through which the carbon feeds is made sufficiently large to admit of very free
transit of the carbon through it ingress of air is permitted which increases the
rapidity of consumption of the carbons; moreover, where the lamp is exposed to the
elements, rain or a draft of cold air striking the containing chamber when made of
glass is apt to shatter it.
With my
construction these difficulties are
overcome. I am enabled to make the transparent or translucent enclosing'
envelope three inches or less in diameter, e--size--which--will--admit-of-main-
taining-the-gases around-the-are-incandescent-or-opalescent, resulting in an agree-
able light of large radiating area; and by making the feed opening a comparatively
close fit around the carbon and providing a valve or trap for the escape of heated
gases when the tension becomes sufficient to endanger the envelope, the life of the
carbon is prolonged to an extraordinary degree. A further incident--of--great
importance-which-follows-from-the reduction-in-size-of-the--enclosing-envelope--is
that-the-lamp-will-operate-at-a lower voltage-than-other types of are lamps, a
result probably-due-to-an increased-degree-of-conductivity of the are--because-of
greater density-of-the-hot-gases:
The several features of novelty of the invention will be more particularly
hereinafter described and will be definitely indicated in the claims appended to this
specification

page_text: In the accompanying drawings which illustrate the invention, Figure 1 represents
one form of an are lamp constructed in accordance with my invention; Figs. 2 and 3
are detail views of the plug used at the top of the arc-enclosing envelope through
which the carbon is fed, and which is provided with means for permitting an egress
of the heated gases; Figs. 4 and 5 are horizontal and vertical cross-sections of a
modified construction of an arc-enclosing envelope, and Figs. 6 and 7 are detail views
of the hood or reflector used on the outer protecting globe, as shown in Fig. 1.
Where the lamp is exposed to the action of the elements an auxiliary globe A will
be provided around the arc-enclosing envelope to prevent rain or drafts from striking
its highly heated surface. The enclosed air and gases between the outer and inner
envelopes make the difference of temperature on the two sides of the arc-enclosing
envelope less and thus protect it. The feed-regulating mechanism which maintains
the arc of a substantially uniform length irrespective of the gradual consumption of
the movable carbon may be of any suitable construction, and as it forms no part of
my present invention need not be specifically described. Surrounding the arc is a
transparent or translucent envelope B preferably made of glass, and not to exceed
three inches, and preferably less, in horizontal diameter and of any desired length.
This chamber is preferably formed of substantially a bottle shape, having a neck at
the top, and is open at the bottom, though it may be formed in the shape of an open
cylinder and closes at the ends in a suitable manner, as illustrated in Fig. 5.
I will first describe the mode of construction illustrated in Figs. 1, 2 and 3 of the
drawings. At the bottom edge is formed by molding or otherwise a screw thread C,
and a metal cap D provided with a socket for the negative carbon E is provided with
a co-operating thread forming a close fit which when screwed upon the bottom of
the envelope B with an interposed washer of asbestos will form a gas-tight joint.
This cap may be spun from a metal capable of withstanding comparatively high tem-
peratures, such as copper or an alloy, and the socket is formed integral therewith
or attached in any suitable manner so as to form a gas proof and heat resistant joint.
The arc is located near the top of the enclosing envelope. and the neck is provided
with a fire-proof plug F formed of asbestos pulp or any other suitable material into
which screws a metal glug G formed of two parts, as seen at g, g', Fig. 2, between
which may be clamped a washer of soft heat-resisting material, such as asbestos, indi-
cated at . By this means a comparatively close fit may be formed around the
positive carbon H, the asbestos washer gå yielding sufficiently although a compara-
tively close fit to permit an easy feed of the positive carbon H. Through the body
of the plug G is formed an opening I over which rests a hinged metal valve J provided
with a limiting stop K. With this construction the operation of the lamp will be as
follows:
Upon the closure of the circuit and the springing of the are the air in the enclosing
envelope B is robbed of its oxygen; and-after-a-short-time-the-entire-body-of-the
gas-chamber-B-becomes-highly-luminous, being filled--with-an-incandescent vapor
of-carbon-which results in a light emanating from all parts of the envelope-
B, soft;-highly luminous-and steady. The heated gases by their expansive force and
tendency to rise effectually prevent the ingress of air through the narrow space
between the positive carbon and the metal plug, and since practically no air can
gain admission to the interior of the envelo pe a very slow consumption of the carbon
results. Such small particles of carbon as are carried through the arc or rendered
incandescent therein are deposited on the negative electrode and serve to build up
said electrode and maintain the arc substantially stationary in position, or in any
event at a point above the horizontal center of the envelope B and above the heavier
gases which collect at the bottom of the envelope, while a very slow destruction of
the positive electrode proceeds. In time a light deposit will be formned upon the inner
wall of the envelope B,-but-the-heat of the enclosed-gases-when-this-envelope-is-of
substantially the size-specified is sufficient-to-maintain-this-deposit-in-an-incandes-
eent-or-opalescent-condition,-adding to the effectiveness-of-the-light-and-the-rapidity
with-which-the-highly luminous condition is effected. It is important that the plug G
surrounding the positive electrode should be metallic as it will then by reason of its high

page_text: conductivity maintain the tension of the thin film of gas around the carbon in the feed
opening and better prevent the ingress of the cold outside air. It is, moreover, impor-
tant that the metal should not come into direct contact with the glass enclosing envelope
B, when the latter is made of that material, in order to prevent fracture, and it is for
this reason that some heat non-conducting and fire-proof substance such as asbestos
is interposed. It is, moreover, important that the arc should be formed near the top
of the enclosing envelope since when so located it will localize the heat at the top
of the chamber and the better prevent the ingress of air by increasing the
tension of the enclosed gases at that point, thus conserving the life of the carbons;
moreover, when so located by a short length of the positive carbon will be exposed
to the high heat of the are and surrounding gaseous envelope, thus lowering the
temperature of the external portion of the positive carbon and reducing the amouut
of disintegration. Besides this, carbon when exposed to a high heat is subject to a
process of over-carbonization" by which it becomes comparatively porous and its
resistance is increased. By exposing only a short section of the positive carbon such
over-carbonization is limited in extent and the resistance of the lamp is therefore
lower than it would be if the are were maintained lower in the enclosing envelope.
Another incident resulting from the location of the are near the top of the envelope
is the maintenance of steadiness and a maximum angle of illumination. I have
observed, moreover, that when so located there is less liability of the "bead" formed
on the negative electrode by the transit of carbon across the arc to break off, and a
smoother surface of the negative carbon is presented to the arc and a more equable
action of the lamp maintained. Accurate tests indicate that a lamp of my construc-.
tion as hereinbefore described will require only 25 or 30 volts for its operation, as
contrasted with 45 or 50 volts in other types of lamps. I attribute this result to the
dense body of conducting gas maintained in close relation to the arc by which its
resistance is materially lowered and the voltage necessary to maintain its action is
reduced. The small arc-enclosing envelope prevents dissipation of the gases and
maintains them at a greater density than would be possible with a large envelope.
Besides-eonserving-the-energy-in-the-manner--already described-the-gases-glow-with
inereased-brillianey-by-reason-of-the-greater-density. In operating with my lamp
I find that the best results are obtained by using absolutely pure carbons,
and, I find that the negative carbon is increased in length or held above the
center of the envelope B, whereas the positive carbon is so slowly consumed that a
carbon of less than 12 inches in length will maintain the arc and its gaseous envelope
in continuous operation for more than 100 hours with a consumption of 270 watts, as
contrasted with a life of 7 hours and a consumption of 500 to 600 watts with other
forms of arc lamps. I am aware that it has been proposed heretofore to operate an
arc lamp in an air-tight envelope, but when the envelopes are sealed an explosion of
the cylinder is liable to result, and when not sealed, a rapid consumption of carbons
will result and a smoking of the enclosing envelope. Valves which rely for their
action upon accumulated pressure will interfere with a good action of the lamp and
make the light fluctuate in intensity and cause sputtering. In my lamp, however,
the enclosure, although practically tight against ingress of air, allows a steady outflow
of gases from the lamp. By means of iny construction I provide as hereinbefore
stated a light of large radiating surface which is far more desirable as a source of
illumination than one in which the light is emitted from a center of small surface
such as an ordinary arc. As herein before stated the are enclosing envelope is
preferably surrounded by an auxiliary outer transparent or translucent envelope,
shown at A in Fig. 1, which may be supported upon a flanged collar at the lower part
of the lamp and secured in place by thumb screws or in any other suitable manner.
This globe is provided with a circular opening at the top which is covered with a
closely fitting conical reflecting hood L made in two separable parts 11, 12, see Fig. 6,
so as to admit of convenient removal and replacement. These two parts are hinged
to each other-at 13 and are also secured together at an opposite point by a spring
latch m which takes hold of a shoulder m² but may be easily lifted and disengaged
therefrom. The hood L is fitted with non-conducting thimbles at 01 and 02 through

page_text: which pass the descending portions of the supporting arms for the lamp and also with
an additional thimble 03 forming a fixed guide through which passes the positive
electrode H. The negative electrode may in some cases be formed of simply a small
piece or block of carbon, as indicated in Fig. 5 at E¹, supported in a solid rod of
metal E, Fig. 5, having considerable mass and being a good conductor of heat. This
construction will maintain the negative electrode at a comparatively low temperature
and not only mitigate the amount of its disintegration by the heat of the arc, but
assist in the deposit of vaporized carbon carried across the arc and redeposited on the
negative electrode. In the form of arc-enclosing envelope illustrated in Figs. 4 and 5
a simple cylinder open at both ends is formed of the transparent material. The
cylinder may, for example, be provided, as illustrated, with a lug or ridge formed
integral therewith, as indicated at a, which ridge may engage a thread or recess
formed in caps to constitute the top and bottom covers for the cylinder. These
covers may be formed of "vulcabeston" or any other suitable non-conducting and
non-combustible material and the whole arc-enclosing chamber may be supported by
a metallic extension or rod extending upwardly from the lower part of the lamp
frame. The top and bottom covers may be fitted air-tight by means of disks of
asbestos felt e, e¹. The upper end of the cylinder rises a abort distance above the
upper end of the negative electrode and upon the top cap may be supported a hollow
cone N which may be conveniently formed of aluminium and will then serve as a
reflector to throw downwardly and outwardly the rays of light projected upwardly
from the arc.
The top of this cone N may be provided with a metallic thimble or
plug P having an axial opening through which the positive electrode may freely pass.
The hollow cone is firmly supported in the top cap or cover of the cylinder in any
suitable manner which will form an air-tight joint and if desired a flanged cone or
lining of reflecting metal may be provided inside the asbestos disk or washer which
will reflect downwardly all the rays of light emanating from the arc. This flanged
cone is indicated at Q in Fig. 5. With this construction the arc-enclosing envelope
may be rapidly assembled or taken apart by simply twisting the top and bottom caps
so as to disengage the threaded recesses formed therein from the projecting ridge
formed on the transparent cylinder. No valve is shown in the construction illustrated
in Fig. 5; although the valved opening will be preferably used, because yielding
more perfect results, the invention is practicable without it, the narrow opening
around the positive carbon between the latter and the metallic plug or thimble
permitting egress of heated gases.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. An-are--lamp--having-the--electrodes-around--the-are-enclosed-in-a--small
transparent-or-translucent-envelope-air-tight-at-all--points--below-the-are--and
provided-with-a-normally-closed-valve-above-the-are-whereby-the-envelope-is--filled
with-a-highly-luminous-gas-and-the-life-of-the-electrodes-is-prolonged.
2. An-are-lamp--having-its--electrodes--around--the-are--enclosed--in--n--small
transparent-or-translucent-envelope-so-arranged-as-to-maintain the gases-luminous
in-said-envelope-and-air-tight against ingress of air but affording egress-for-the
heated-gases-developed-by-the-are.
3. An-are-lamp-baving its electrodes-around-the-are-enclosed-in-a transparent.or
translucent envelope-air-tight-at-all points below-the-are;-so-arranged as to maintain
the gases-luminous in said envelope, said are being located near-the-top-of-the
envelope, means-for-preventing-the-ingress-of-air, and-an-ontwardly-opening-valve
for-permitting-the-discharge of gases.
4. An are-lamp-having-its-are-enclosed in a small-transparent-or-translucent
envelope-closed-air-tight-below the are, so arranged as to maintain the gases-luminous
in-said-envelope-a-closely-fitting-opening-to permit feed-of-the-positive-carbon, and
adjacent-to
an-outwardly-opening-normally-closed-valve-in-the-top-of-the-envelope
the-heated-gases.
1. ǎ. An are lamp having its are enclosed in a transparent or translucent. envelope

page_text: provided with a metallic plug having a closely fitting opening to permit feed of the
positive carbon, and means for permitting escape of the gases produced by the arc.
2. 6. An arc lamp having its arc enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, and provided with a plug at the top having
a closely fitting feed opening for the positive carbon.
3. 7. An arc lamp having its are enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a plug in the top of the envelope provided
with a closely fitting feed opening for the positive carbon, and a valved opening in
said plug.
4. S. An arc lamp having its are enclosed in a transparent or translucent envelope
enclosed air-tight at all points below the arc, a closely fitting opening in the top of
the envelope to permit feed of the positive carbon, and a heat non-conducting wall
between the wall of the envelope and the feed opening.
5. 9. An are lamp having its arc enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a plug in the envelope above the arc
provided with a closely fitting feed opening for the positive carbon, and an outwardly
opening gravity valve normally closing a vent for the gases developed by the arc.
6. 10. An arc lamp having its arc enclosed in a transparent or translucent envelope
closed air-tight at all points below the arc, a metallic plug in the top of the envelope
provided with a feed opening for the positive carbon, and an annular lining of yielding
fire-proof material such as asbestos producing a closely fitting wall around the carbon.
7. H. An arc lamp having its arc enclosed in a glass envelope provided with a
closely fitting feed opening for the positive carbon at the top, and a gas-tight metallic
cap provided with a threaded rim engaging a thread on the bottom of the glass
envelope, said cap having a metallic socket for the negative carbon.
8. 12. An arc lamp having its arc enclosed within a transparent or translucent
envelope, an auxiliary transparent or translucent envelope closed on all sides sur-
rounding said arc-enclosing envelope, and feed openings in the envelopes, whereby the
two sides of the arc-enclosing envelope are maintained at a comparitively uniform
temperature and fracture is avoided.
9. 13. In an electric are lamp, the combination with the positive and negative
electrodes, of an enclosing cylindrical chamber or envelope of transparent material
surrounding the arc, an auxiliary enclosing transparent chamber closed on all sides,
and a conical reflector within the upper end of said chamber encircling the positive
carbon.
10. 14. An arc lamp having its are enclosed within a transparent or translucent
envelope provided with a reflecting cap at the top, said envelope being enclosed
in an auxiliary outer protective envelope also provided with a reflecting cap,
whereby all the rays of light thrown upwardly from the are are utilized externally
of the lamp.
15. In-an-electric-are-lamp, the-combination-with-the-movable-positive-electrode,
of-an-enelosing-globe;-and-a-hood-elosely fitting-the-open-top-of-said globe, and-pro-
vided-with-a-metallie-guide-in-open-communication with the--atmosphere--through
which-said-movable-electrode-is-made-to-pass;-for-the-purpose-described.
11. 16. An arc lamp having its are enclosed within a transparent or translucent
envelope provided with a separable top, an outer transparent or translucent envelope
for the purpose described, said outer envelope being closed on all sides, and being
provided with detachable cover.
1000