IMPROVEMENTS IN ELECTRIC LAMPS, AND THE MANUFACTure thereof, AND IN SYSTEMS THEREOF
Year: 1881

page_text: LETTERS PATENT to Peter Jensen, of 33, Chancery Lane, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN ELECTRIC LAMPS, AND
THE MANUFACTure thereof, AND IN SYSTEMS THEREOF." A communication
from abroad by Thomas Alva Edison, of Menlo Park, in the State of New
Jersey, United States of America.
PROVISIONAL SPECIFICATION left by the said Peter Jensen at the Office
of the Commissioners of Patents on the 8th June 1881.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. " IMPROVE-
MENTS IN ELECTRIC LAMPS, AND THE MANUFACTURE THEREOF, AND IN SYSTEMS
THEREOF." (A communication from abroad by Thomas Alva Edison, of Menlo
Park, in the State of New Jersey, United States of America.)
This electric lamp consists essentially of an incandescing conductor of high
resistance, hermetrically sealed in a glass vacuum chamber.
Great difficulty had always been experienced in attempting to so seal a glass
vacuum chamber that danger of separation or opening of the parts should be
avoided and a stable vacuum maintained.
In fact the maintenance of a stable vacuum had been pronounced impossible by
many scientists.
In the Specification and Drawings of Letters Patent, No. 578, grauted
February 10th, 1880, there is shown and described a process of manufacture by
which this end may be attained.
The same end is the object of one portion of this Invention, this embodying
changes which result in increased economy of cost of manufacture.
Hitherto it has been usual to blow the glass enclosing chamber or bulb of the
lamp from glass tubing, requiring that the glass first be made into a tube, the
tube divided into proper lengths, and the bulbs then blown, an expensive and
wasteful process. In this instance the bulb or chamber is to be blown directly from
the pot glass. The blower takes upon his blowing rod a sufficient quantity and
blows the same into a bulb, giving it just sufficient motion to cause the bulb to

page_text: elongate, so that its outer extremity shall be, or about be, semi-circular, from which
the sides taper gradually and in straight or approximately straight or slightly
curved lines to the end of the blowing rod.
The bulb so formed is then broken away at the tapered end sufficiently to leave
an aperture large enough for the introduction into the globe of the carbon and its
supports.
Upon the semi-circular end of the globe a small opening is made, and a small
tube formed thereon, either by drawing out the material at that end or by attaching
thereto a separate piece of tubing to form the exhaust tube of the completed lamp
for attachment to the exhaust apparatus.
A small piece of tubing is taken and an enlargement is blown therein of a
diameter about equal to the aperture referred to as being made in the tapering or
conical end of the globe or bulb.
The leading in wires, i.c., the wires which pass into the lamp and are to connect
with the carbons, are then laid in this tube, one end is then brought to a welding
or nearly melting heat, and clamped down by suitable means upon the wires,
hermetically and firmly sealing thein in the glass of the tubo.
Another portion of this Invention has for its object to furnish means for clamping
these leading in wires to the incandescing conductora moro cheaply and roadily than
by the platinum clamps heretofore used.
The wires which preferably are used are each in three sections, a central bit of
platinum for sealing into the mass of the glass with copper extremities, one leading
away from the lamp, one leading into the lamp for receiving and supporting the
carbon.
This latter section may be cut from flat or sheet copper with an enlarged end, or
it may be formed of a bit of wire, one of whose ends is flattened out. This
enlarged flattened portion is wrapped around the enlarged ends of the carbon,
securing it and making electrical contact therewith. This union may if desired
be electro plated, as set forth in Specification of Letters Patent, dated February 23rd,
1881.
The carbon being secured to the leading in wires, and they sealed in the small
tube above referred to, the carbon is introduced into the globe, and the edge of the
opening in the globe and the cnlargement of the tube sealed together at a welding
heat.
The lamp is then attached to the exhaust or vacuum apparatus by the exhaust
tube referred to, and the air exhausted therefrom.
When the proper degree of exhaustion has been attained, the lamp is sealed by a
fusion and welding of the exhaust tube near to the body of the lamp or globe.
Another part of this Invention relates to the carbons used as the incandescing
conductors in lamps for giving light by electrical incandescence, and its object is to
render more stable these carbon filaments, to the end that the life of the lamps may
on the average be prolonged.
When carbon filaments are used for lighting by incandesence, a phenomenon is
found to which may be applied the terin "electrical carrying." This is an absolute
carrying or moving of the carbon itself from the negative to the positive end of
the carbon.
The amount of such carrying depends upon the resistance of the filaments, the
degree of incandescence, the electro motive force between the clamping electrodes,
and the state of the vacuuin.
While its amount may vary with varying conditions of these elements, it is the
great cause of the ultimate destruction of the carbons used in high vacua, and if its
degree and amount can be reduced a proportionate increase in the life of the carbons
is insured.
To this end this portion of the Invention consists generally, first, in arranging
the carbons in the lamps so that the strongest portion thereof; or the portion having
the least resistance, shall be at the negative clamp; and secondly, in constructing a
carbon having a greater mass of matter and less resistance at one terminal than at

page_text: the other, the matter gradually decreasing, and the resistance gradually increasing
from one to the other pole.
In constructing such a carbon it is made of its fullest width at the negative end,
whence it gradually tapers to the positive end. This construction gives a lower
resistance and a lower incandescence at the negative end, whence it gradually
tapers to the positive end.
This construction gives a lower resistance and a lower incandescence at the
negative end, so that the carrying from such negative end by electrical action is
materially reduced, while the total resistance, candle power, and economy of the
carbon may remain the same, its duration or useful period being lengthened
proportionately to the reduction of carrying.
In practice such carbons should be made so that the unit of incandescence at the
negative pole will be about 11 or 12 candle power, rising gradually to 18 at the
positive pole, the average of the carbon or its total lighting effect being about
16 candle power under normal conditions.
It is evident that instead of carbons being made tapering from one pole to the
other as described, that the same result may be produced by taking ordinary
carbons uniform in size throughout their length, and increasing the mass of matter
and conductivity of one side by a deposit of carbon thereon, or soaking certain
parts in a carbonizable solution, drying, and then re-carbonizing.
It often happens that carbons intended to be of uniform size throughout their
length are found to be defective upon one side, that spots or weak places there
appear.
Such may be utilized by placing them in a lamp, so that the defective side
becomes the positive end of the loop, the other or perfect side having less resistanco,
being made the negative side.
By so using such carbons, their life or duration will not be materially shortened,
as the inevitable carrying then proceeds from the perfect to the imperfect side.
By the above described processes and others employed in the manufacture of
carbon conductors for the incandescent electric lamps used in the system, and in
the production and retention of vacun in the enclosing globos thereof, both the
carbons and the vacun are made so nearly perfect that the carbons will withstand
the heat of incandescence without being consumed thereby for a very long period.
In the present state of the art, however, it is impossible to manufacture a carbon
which will not eventually be destroyed. When i carbon is destroyed, the sub-
stitution of a new lamp is an exceedingly simple and easy matter where the lamp
is used in an accessible position. Sometimes however they may be used in
comparatively inaccessible positions, or in positions where it would be difficult or
inconvenient to substitute a new lamp for one burnt out when the latter event
happens.
Therefore some means seems desirable by which, when a lamp gives out and the
current ceases to pass through it, the circuit will be instantly and automatically
completed through another lamp, so that the extinguishment of the light will
be only momentary. To accomplish this is the object of this portion of the
Invention.
Generally speaking, the arrangement is as follows:-A small electro magnet is
placed in the circuit of the lamp, being magnetized by the current passing through
its helix.
The magnet is provided with an aperture, which as long as current passes is held
closely to it, but if the lamp from any cause is extinguished and the current ceases
to pass, is withdrawn by a spring or weight and makes contact at other points,
closing the circuit of a second lamp and lighting it instantly.
Means may of course be provided so that three or any desired number of lamps
may be placed together, and lighted and used successively.
If a number of incandescent electric lamps be arranged as a series on one circuit,
the interruption of the circuit at any one lamp by breakage of the incandescing

page_text: portion or from other cause results in the extinguishment of all the lamps upon
that circuit.
An arrangement which would obviate this and preserve automatically when one
is injured the circuit to all the other lamps seems desirable.
To accomplish this a number of lamps are placed in shunts to the main circuit,
each being provided with a magnetically operated switch so arranged that if
current ceases to flow through a lamp the circuit will be completed around it to
the others, and on the lamp being replaced current will again flow through it.
These switches are made as armature lovers, limited in their play on one side by
back stops, and on the other side connected to the main conductor through a small
resistance.
A small branch circuit passes around the lever without including it, and contains
a small electro magnet.
If no current is on, the armature rests on its back stop and is not attracted by
the magnet; but when current passes the resistance causes a fraction thereof to pass
through the magnet, which then attracts the armature lever, breaks the main
circuit, and allows current to pass through the shunt circuit of the lamp.
But if the lamp breaks and the current ceases to pass, the magnet releases the
armature lever, which falls and completes the main circuit as before, while upon
remedy of the injury the circuit is again automatically restored.
In these lamps it may sometimes happen that the enclosing globes are blackened
to some extent by the deposition of carbon carried thereby, the phenomenon known
as electrical carrying."
"
A further object of this Invention is to obviate any ill effects from this causo, to
which end it consists in attaching to each lamp a short lamp presenting such a
polarity to the positive side of the carbon filament that it will attract the highly
electrified carbon vapor downwardly to the clamps instead of permitting it to be
deposited upon the glass, as would be the case under ordinary circumstances,
especially in high vacua.
In electric lamps made as aforesaid it is best that the "leading in" conductors
above mentioned be very small in section, possess a coefficient of expansion under
heat influence as near that of the glass as possible, and be able to stand the degree
of heat requisite to fuse the glass around it.
Platinum possesses theso qualities in a marked degree, henco it is used as the
conductor, passing through and sealed into the glass of the enclosing globe, and
thence leading to the carbon or incandescent material.
It however is one of the most expensive elements used in the construction of the
lamp, and any arrangement which tends to economy in its use seems very desirable.
The object of a further portion of this Invention therefore is to furnish an arrange-
ment by which a minimum of platinum only is used in the leading in conductors,
the remainder being of cheaper material.
To accomplish this each leading in conductor is made of three pieces, a central
one consisting of a bit of platinum as long as or a trifle longer than is to be the
contact of the enclosing glass with the leading in conductor, an inner terminal,
which is to rise from the platinum bit within the globe to the height at which it
is desired to support the carbon, and an outer terminal which may be of any desired
or convenient length, the terminals being of copper or any suitable low resistance
conductor, and fastened to the central platinum by soldering, or in any other
efficient method.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Jensen in the Great Seal Patent Office on the 8th December
1881.
"IMPROVE-
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex.
MENTS IN ELECTRIC LAMPS, AND THE MANUFACTURE THEREOF, AND IN SYSTEMS
THEREOF. A communication from abroad by Thomas Alva Edison, of Menlo
Park, in the State of New Jersey, United States of America.
This electric lamp consists essentially of an incandescing conductor of bigh
resistance, hermetically sealed in a glass vacuum chamber.
Great difficulty had always been experienced in attempting to so seal a glass
vacuum chamber that danger of separation or opening of the parts should be
avoided and a stable vacuum maintained.
In fact the maintenance of a stable vacuum had been pronounced impossible by
many scientists.
In British Letters Patent, No. 578, of February 10, 1880, there is shown and
described a process of manufacture by which this end may be attained.
The same end is the object of one portion of this Invention, this embodying
changes which result in increased economy of cost of manufacture.
Hitherto it has been usual to blow the glass enclosing chamber or bulb of the
lamp from glass tubing, requiring that the glass first be made into a tube, the tubo
divided into proper lengths, and the bulbs then blown, an expensive and wasteful
process. In this instance the bulb or chamber is to be blown directly from the pot
glass. The blower takes upon his blowing rod a sufficient quantity and blows the
same into a bulb, giving it just sufficient motion to cause the bulb to elongate, so
that its outer extremity shall be or about be semi circular, from which the sides
taper gradually and in straight or approximately straight or slightly curved lines
to the end of the blowing rod.
The bulb so formed is then broken away at the tapered end sufficiently to leave
an aperture large enough for the introduction into the globe of the carbon and its
supports.
Upon the semi-circular end of the globe a small opening is made, and a small
tube formed thereon, either by drawing out the material at that end or by attaching
thereto a separate picce of tubing to form the exhaust tube of the completed lamp
for attachment to the exhaust apparatus.
A small piece of tubing is taken, and an enlargment is blown therein of a
diameter about equal to the aperture referred to as being made in the tapering or
conical end of the globe or bulb.
The leading in wires, i.c., the wires which pass into the lamp and are to connect
with the carbons, are then laid in this tnbe; one end is then brought to a welding
or nearly melting heat, and clamped down by suitable means upon the wires
hermetically and firmly sealing them in the glass of the tube.
Another portion of this Invention has for its object to furnish ineans for clamping
these leading in wires to the incandescing conductors, more cheaply and readily
than by the platinum clamps heretofore used.
The wires which preferably are used are each in three sections, a central bit of
platinum for scaling into the mass of the glass, with copper extremities, one leading
away from the lamp, one leading into the lamp for receiving and supporting the
carbon.
This latter section may be cut from flat or sheet copper with an enlarged end, or
it may be formed of a bit of wire, one of whose ends is flattened out. This
enlarged flattened portion is wrapped around the enlarged ends of the carbon,

page_text: securing it and making electrical contact therewith. This union may if desired bo
electro plated.
The carbon being secured to the leading in wires, and they sealed in the small
tube referred to, the carbon is introduced into the globe, and the edge of the
opening in the globe and the enlargement of the tube sealed together at a welding
heat.
The lamp is then attached to the exhaust or vacuum apparatus by the exhaust
tube referred to, and the air exhausted therefrom.
When the proper degree of exhaustion has been attained the lamp is sealed by
a fusion and welding of the exhaust tube near to the body of the lamp or
globe.
This may be better understood perhaps by reference to the Drawings, in
which,―
Figure 1 shows the globe as blown and attached to the blowing rod.
Figure 2, the globe with its end blown off and the exhaust tube attached.
Figure 3, the supporting tube.
Figure 4, the lamp completed and sealed.
Figure 5, the lamp provided with means of attachment to a fixture.
Figure 6, a wire or blank for supporting the carbon.
The blowing rod B, indicated in broken lines, is dipped into the molten or pot
glass, and a sufficient quantity taken up thereon, which is then blown into the
shape shown in Figure 1. This shape is semi circular at its outer end, from whence
the sides taper in straight or nearly straight lines to the smaller end, and this shape
distinguishes the lamp thus made from any heretofore made.
The part a' is then cut or broken from the body A, leaving an aperture at a.
A is then heated at b and a tube 63 formed thereon, either by drawing out the
material at b, or by attaching thereto a separate piece of tubing.
A piece of tubing D is taken and an enlargement d formed thereon of about the
diameter or of a slightly larger diameter than <<.
In this tube are laid the leading in wires 1, 2; these wires are each formed of
three sections, a central one p of platinum, which is the portion to be in contact
with the glass, with outer sections e, c, of copper.
The end i of the tube is then brought to a welding heat and squeezed firmly
together, sealing the parts p, p, of 1, 2, firmly and hermetically therein.
The carbon C is then attached to the wires e, c.
One of these wires is shown in Figure 6; they may be cut of the shape there
shown from flat copper, but it is preferred to take a piece of wire e and flatten its
end to form the enlargement e¹, which enlargement is folded upon or wrapped
around the enlarged end of the carbon, making a firm and secure contact therewith
and support therefor. If desired this union may then be plated.
The tube and carbon being arranged in relation to each other, as shown in
Figure 3, the carbon is introduced within the body of A, and the edges a and d
brought together, at which point they are then sealed by a welding or fusion of
the glass itself.
The lamp is then attached by the exhaust tube 62 to the vacuum apparatus, and
when the proper degree of vacuum has been reached it is "sealed off" at b³, the
result being the lamp shown in Figure 4.
Means S for attaching the lamp to its support or fixture are then secured thereto,
and the lamp is ready for the market.
Another part of this Invention relates to the carbons used as the incandescing
conductors in lamps for giving light by electrical incandescence, and its object is to
render more stable these carbon filaments, to the end that the life of the lamps may
on the average be prolonged.
When carbon filaments are used for lighting by incandescence a phenomenon is
found, to which may be applied the term " electrical carrying." This is an absolute
carrying or moving of the carbon itself from the negative to the positive end of the
carbon.

page_text: The amount of such carrying depends upon the resistance of the filaments, tho
degree of incandescence, the electro motive force between the clamping electrodes,
and the state of the vacuum.
While its amount may vary with varying conditions of these elements it is tho
great cause of the ultimate destruction of the carbons used in high vacua, and if its
degree and amount can be reduced a proportionate increase in the life of the
carbons is assured.
To this end this portion of the Invention consists generally, first, in arranging
the carbons in the lamps so that the strongest portion thereof, or the portion
having the least resistance, shall be at the negative clamp; and, secondly, in
constructing a carbon having a greater mass of matter and less resistance at one
terminal than at the other, the matter gradually decreasing and the resistance
gradually increasing from one to the other polc.
In constructing such a carbon it is made of its fullest width at the negative end,
whence it gradually tapers to the positive end.
This construction gives a lower resistance and a lower incandescence at the
negative end, so that the carrying from such negative end by electrical action is
materially reduced, while the total resistance candle power and economy of the
carbon may remain the same, its duration or useful period being lengthened
proportionately to the reduction of carrying.
In practice such carbons should be made so that the unit of incandescence at the
negative pole will be about 11 or 12 candle power, rising gradually to 18 at the
positive pole, the average of the carbon or its total lighting effect being about 16
candle power under normal conditions.
It is evident that instead of carbons being made tapering from one pole to the
other, as described, the same result may be produced by taking ordinary carbons,
uniform in size throughout their length, and increasing the mass of matter and
conductivity of one side by a deposit of carbon thereon, or soaking certain parts in
a carbonizable solution, drying, and then recarbonizing.
It often happens that carbons intended to be of uniform size throughout their
length are found to be defective upon one side, that spots or weak places there
appear.
Such may be utilized by placing them in a lamp so that the defective side
becomes the positive end of the loop, the other or perfect side having less resistance
being made the negative side.
By so using such carbons their life or duration will not be materially shortened,
as the inevitable carrying then proceeds from the perfect to the imperfect side.
These points are illustrated in Figures 7 and 8 of the Drawings.
Figure 7 represents a carbon made especially to carry out this Invention, and
Figure 8, the same embodied in a lamp.
In this case the end N intended for the negative end of the loop is made wido
and tapers gradually to the positive end P.
By the above described processes employed in the manufacture of carbon
conductors for the incandescent electric lamps, and in the production and retention
of vacua in the enclosing globes thereof, both the carbons and the vacua are so
nearly perfect that the carbon will withstand the heat of incandescence without being
consumed thereby for a very long period. In the present state of the art however
it is impossible to manufacture a carbon which will not eventually be destroyed.
When a carbon is destroyed the substitution of a new lamp is an exceedingly
simple and easy matter where the lamp is used in an accessible position. Sometimes
however they may be used in comparatively inaccessible positions, or in positions
where it would be difficult or inconvenient to substitute a new lamp for one burnt
out, when the latter event happens.
Therefore some means seems desirable by which when a lamp gives out and the
current ceases to pass through it, the circuit will be instantly and automatically

page_text: completed through another lamp, so that the extinguishment of the light will be
only momentary. To accomplish this is the object of this part of the Invention.
Generally speaking the arrangement is as follows:-A small electro magnet is
placed in the circuit of the lamp, being inagnetized by the current passing through
its helix. The magnet is provided with an armature, which as long as current
passes, is held closely to it, but if the lamp from any cause is extinguished and
the current ceases to pass, is withdrawn by a spring or weight and makes contact
at other points, closing the circuit of a second lamp and lighting it instantly.
Means may of course be provided so that three or any desired number of lamps
may be placed together and lighted and used successively.
Figure 9 of the accompanying Drawing is a diagram showing the connections of
two lamps properly arranged, while
Figure 10 and 11 show different methods of placing three lamps in circuit.
A, B, (Figure 9) reprosent lamps, the lamp A being now in operation. It is
placed in a derived circuit 7, 8, from the main conductors 1, 2, its current passing
from the main conductor 1 to the wire 7 through the coils of the magnet M to the
lamp, and thence by wires 9, 8, back to the main conductor 2.
But if from the giving out of the carbon, or from any other cause, current ceases
to pass through the circuit 7, 8, to the lamp A, the core of ML becomes demagnetized,
and the armature lever N which works on a pivot is withdrawn by means of the
spring a and closes circuit through the contacts c, c', changing the direction of the
current through 7, 8, which now passes through the armature N and wire 5 to
the lamp B, and thence back to the main conductor by wires 6, 8. Instead of
using the spring a the end of the armature lever may be weighted so that the
action of gravity will withdraw it from the magnet when the current ceases to pass
tliercin.
The arrangement of the lamps C, D, is somewhat different. In this case each
lamp has a separate return wire to the main circuit. The current normally passes
through the wire 4 and magnet M' to the lamp C, thence through the wire 3 back
to the main circuit. But if current ceases to pass through the magnet the
armature N' is withdrawn by means of the spring at making contact at the point d
and closing a circuit 4, 10, through the lamp D.
In Figure 10 the lamp C¹ is in the derived circuit 11, 12, in which is included
the electro magnet G which is provided with the armature И having the spring S.
When current ceases to pass to C' the armature H is withdrawn from the magnet G,
touching the contact fand causing current to pass through the wire K, armature H,
and contact point to the magnet G' and lamp A', the armature H' (which has
previously been held down by the end of the armature H now being attracted by
the magnet C), thence by wire 13 to the main conductor 2, so that the lamp C¹
will be replaced by A'. Should this in turn give out, the lamp B' is thrown into
circuit by the withdrawal of the armature HI' from the magnet G₁ and its consequent
contact with f', so that a circuit 12, 14, is completed through the lamp B¹.
Another form of this Invention may be seen in Figure 11. Here a derived
circuit 15, 16, passes through the magnet and lamp C, and if the current
through this should cease the circuit 15, 17, including the magnet P and lamp B²,
is formed by the contact of the armature S with o. R is a metal strip rigidly
secured at one end and normally passing half way between the magnets P, P'; but
when the magnet P is in circuit it is drawn toward P and held against it. But
should the current cease to pass through the circuit 15, 17, and the magnet P lose
its attractive force, the spring R will fly back, making contact at h, completing the
circuit 15, 18, through the lamp A³, and energizing the magnet P', so that R will
be held against the magnet and therefore against the contact h.
It is evident that by these arrangements or modifications thereof any desired
number of lamps might be so placed that cach could be instantaneously replaced
when necessary by another.
If a number of incandescent electric lamps be arranged as a series on one circuit,

page_text: the interruption of the circuit at any one lamp by breakage of the incandescing
portion or from other cause results in the extinguishment of all the lamps upon
that circuit.
An arrangement which would obviate this and preserve automatically when one
is injured the circuit to all the other lamps seems desirable.
To accomplish this a number of lamps are placed in shunts to the main circuit,
each being provided with a magnetically operated switch, so arranged that if
current ceases to flow through a lamp the circuit will be completed around it to
the others, and on the lamp being replaced current will again flow through it.
These switches are made as armature levers, limited in their play on one side
by back stops, and on the other side connected to the main conductor through a
small resistance.
A small branch circuit passes around the lever without including it, and contains
a small electro magnet.
If no current is on, the armature rests on its back stop and is not attracted by
the magnet, but when current passes the resistance causes a fraction thereof to
pass through the magnet, which then attracts the armnature lever, breaks the main
circuit, and allows current to pass through the shunt circuit of the lamp.
But if the lamp breaks and the current ceases to pass, the magnet releases the
arinature lover, which falls and completes the main circuit as before, while upon
remedy of the injury the circuit is again automatically restored.
These arrangements are shown in Figure 12 of the Drawings, in which G is a
generator, here shown as a single machine of the dynamic type, but which may be
of any desired type, and of which any necessary number may be used. From it
leads the main or consumption circuit 1, 2, while a circuit 3 therefrom leads around
its field of force magnets. In this field circuit 3 are included a resistance R and
switch S, which may be operated automatically or by hand to vary the strength
of the field circuit and so regulate the generative force of G.
In a derived circuit 4 is an electro-dynamometer I for indicating the pressure or
electro motive force of the current.
5, 6, 7, 8, 9, 10, are branch circuits, each starting from and returning to one
of the main or supply conductors.
In 5, 7, 8, and 10, switches 8, 8, are shown interposed in the main conductors
between the points of departure and return of the branch circuits, and forming
when in use the main circuit between those points, so that, as shown in 8, when
closed, the lamp is short circuited, the main circuit being complete around it, while
when open, as in 5, 7, and 10, the main circuit is thrown through the lamps.
At 6 and 9 are shown the means for preserving the circuit complete to the
remaining lamps notwithstanding any injury to one.
In such case the switch is made as an armature lever l, limited in its play in one
direction by a back stop a in the main circuit. Upon the other side the lever is
connected to the main conductor through a small resistance r.
From a main conductor and upon the side where is the back stop a a branch o
Jeads, in which is included a magnet m of low resistance acting upon an armature
lever l.
Supposing now that no current be on, or that the circuit be broken, the position
of the parts will be as in 6, with resting on its back stop.
If now the line be closed or current sent therethrough, the resistance r will
cause a fraction thereof to be deflected through o and m, whereupon m is charged
and attracts l, lifting it from its back stop, breaking the shunt l, r, around the
lamp, and causing all the current to pass through the lamp circuit, as in g.
If now a lamp breaks so as to interrupt its circuit the magnet m releases 1,
which dropping completes the circuit 1, r, around the lamp, as in 6, while upon
remedy of the injury the circuit through the lamp is again automatically restored.
In these lamps it may sometimes happen that the enclosing globes are blackened

page_text: to some extent by the deposition of carbon carried there by the phenomenon
known as "electric carrying."
A further object of this Invention is to obviate any ill effects from this cause,
to which end it consists in attaching to each lamp a short magnet, presenting such
a polarity to the positive side of the carbon filament that it will attract the highly
electrified carbon vapor downwardly to the clamps instead of permitting it to be
deposited upon the glass, as would be the case under ordinary circumstances
especially in high vacun.
Figure 13 of the Drawings is a view of the lamp with a magnet attached.
G is a lamp consisting of an hermetically sealed exhausted glass globe, in which
the filament c is secured in clamps a, b. Upon its side in a suitable support is
fixed the magnet N, S, the upper end of which reaches to about the height of the
clamps. It is placed upon the positive side of the carbon.
This magnet may be a very weak one, as a very weak magnet will deflect a
stream of electrified carbon vapor.
The effect of this magnet is to attract the vapor to the clamps, so preventing its
deposition upon the glass.
In place of the magnet a coil of wire with a current passing through it may be
used, as its effect would be to deflect or attract the vapor in the same way.
In these clectric lamps it is best that the leading in conductors above men-
tioned, be of very small mass in section, possess a coefficient of expansion under
heat influence as near that of the glass as possible, and be able to stand the degree
of heat requisite to fuse the glass around them. Platinum possesses these qualities
in a marked degree, hence it is used as the conductor, passing through and scaled
into the glass of the enclosing globe, and thence leading to the carbon or incandescent
material.
It however is one of the most expensive elements used in the construction of
the lamp, and any arrangement which tends to economy in its use seems very
desirable.
.
The object of a further portion of this Invention therefore is to furnish an
arrangement by which a minimum of platinum only is used in the leading in
conductors, the remainder being of cheaper material.
To accomplish this each leading-in conductor is made of three pieces, a central
one consisting of a bit of platinum as long as or a mere trifle longer than is to be
the length of the contact of the enclosing glass with the leading in conductor; an
inner terminal which is to rise from the platinum bit within the globe to the
height at which it is desired to support the carbon; and an outer terminal, which
may be of any desired or convenient length, the terminals being of copper or any
suitable low resistance conductor, and fastened to the central platinum by soldering
or in any other efficient method.
This is illustrated in Figures 14, 15, 16, and 17 of the Drawings, in which
Figures 14 and 15 show such a leading in conductor, and Figures 16 and 17
supporting necks, each with two such conductors properly sealed in.
A piece of platinum b is taken, and to it are secured copper terminals a, c.
Two ways of sealing in the wires are shown, one represented in Figure 16,
wherein the wires are laid in the tube which is to form the support for the carbon
and globe, the glass heated and pressed together as at c. In the other case in
Figure 17 a small bulb i is blown, and the. wires passed through the top, and tho
glass sealed therearound. In Figure 16 the wires are in contact with the glass for
a greater distance than in Figure 17. The length of the platinum b should be
proportioned to this length of contact, being just about equal or slightly greater in
length than the contact. For instance, in Figure 14 the platinum bis slightly
larger than the length of the sealing portion e of Figure 16, while in Figuro 15 it
is much shorter, but bears the same relation to the sealing length as in the other
case.

page_text: Of the copper wires c is the inner terminal, and receives upon its free end the
carbon which is fastened thereto by clamps, by plating, or by wiring.
a is the outer terminal, and may be of any desired length.
By this construction the advantages of platinum as a leading-in conductor are
preserved, while a minimum of the expensive material is used.
What is claimed is,―
First. The enclosing globe of an incandescent lamp blown directly from molten
or "pot glass," substantially as set forth.
Second. The method of manufacturing electric lamps, substantially as set forth,
consisting in forming the enclosing globe or chamber directly from molten or pot
glass, forming separately the supporting tube or neck for the incandescing con-
ductor, scaling the leading-in-wires therein, and attaching the carbon or incandescent
conductor to the leading-in-wires, and then hermetically uniting the parts, prior to
the exhaustion of the lamp, substantially as herein described.
Third. A clamp for receiving and supporting an end of an incandescent
conductor, consisting of a body of metal with flattened end adapted to be folded
upon or wrapped around the end of the conductor, substantially as set forth.
Fourth. A leading-in-wire composed of a central platinum section for scaling
into the glass, an outer section, and an inner section, the latter having a clamping
device integral therewith, substantially as set forth.
Fifth. The improved method of arranging incandescing carbon conductors in
electric lamps, consisting in so arranging them that the mass of matter shall be
greater and the resistance shall be less at one end than at the other, substantially
as set forth.
Sixth. A carbon for an incandescing conductor for an electric lamp, having one
of its ends or portions of less resistance and greater mass of matter than the other,
substantially as set forth.
Seventh. A carbon for an incandescing conductor for an electric lamp tapering
from one end to the other.
Eighth. The method of utilizing defectivo or spotty carbons for incandescing
conductors in electric lamps, consisting in arranging thein in the lamps so that the
more perfect side is the negative portion, substantially as set forth.
Ninth. In an electric lighting system the combination with two or more multiple
arc circuits, cach containing an incandescent lamp, of means for automatically
transferring the current from one circuit upon its breakage to another, substantially
as set forth.
Tenth. The combination with a multiplo arc or derived circuit containing an
electric lamp, of means for closing automatically upon the breakage of the above
noted circuit another multiple arc or derived circuit containing a lamp, substantially
as set forth.
Eleventh. The combination with a multiple arc circuit containing a magnet, of a
second multiple arc circuit controlled by the armature lever of the magnet, so that
the current is automatically transferred from the first circuit upon its breakage to
the second circuit, substantially as set forth.
Twelfth. The combination with two electro magnets of a spring armature passing
between them, and so arranged that upon the demagnetization of one magnet thie
armature will fly back and complete a circuit through the other magnet, and be
held thereby, substantially as set forth.
Thirteenth. The combination of a main circuit containing incandescent electric
lamps, and a magnetically operated switch at each lamp, automatically closing or
breaking the shunt circuit, so as to cut in or out of circuit the lamp, substantially
as set forth.
Fourteenth. The combination with one main circuit of a series of incandescent
electric lamps, and automatically operated magnetic switches controlling the circuit
through the lamp, substantially as set forth.
Fifteenth. The combination with an incandescent electric lamp of means, as

page_text: described, for preventing the deposition of carbon upon the globe, substantially as
set forth.
Sixteenth. A leading-in-conductor formed of a central platinum piece with
terminals of other metal, substantially as set forth.
Seventeenth. The combination of a pieco of platinum sealed into the glass, and
terminals of other metal secured thereto, substantially as set forth.
In witness whereof, I, the said Peter Jensen, have hereunto set my hand
and seal, this Fifth day of December, in the year of our Lord One
thousand eight hundred and eighty one.