IMPROVEMENTS IN PRODUCING THE ELECTRIC LIGHT
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
PRODUCING THE ELECTRIC LIGHT." A communication from abroad by Charles
Ludovic Pilleux, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 13th February 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN PRODUCING THE ELECTRIC LIGHT." [A com-
munication from abroad by Charles Ludovic Pilleux, of Paris, France.]
This Invention relates to improvements in electric lighting, and consists in the
interposition between two ordinary rheophores of one or inore carbons, whereby
(according to their number and distanco apart) either a single luminous arc is
formed by the juxtaposition of two sparks, or two luminous points united by a
voltaic arc extending between the points of the carbons placed between the
rheophores, but without traversing the entire length of said carbons.
In order that the Invention may be more readily understood I have illustrated
it in the accompanying Drawings, Figures 1, 2, 3, 4, and 5 of which show different
arrangements. A, A', are two-rheophores; E is the carbon rod introduced in the
voltaic arc.
Referring to Figure 1 it will be seen that the end of the carbon E bridges over
the small interval which separates the two rheophores and is in constant contact
with both, and descends as fast as it is consumed. The current produces a spark
at the point of contact 6 and another at point c, the interval between the two
sparks being equal to the diameter of carbon E, which is regulated according to
the tension of the current so that the two sparks shall combine and form what
I may term a solid voltaic arc, which constitutes the essential feature of the
Invention.
In applying the Invention the mass of the body to be heated is always
proportionate to the energy of the current. Thus, if, for example, it is desired to
obtain a powerful light with 50 Bunsen elements a carbon of a certain size is
employed, which is raised to about 3000°, but if two elements only are used, instead
of the same sized carbon, which would be barely reddened, I use one so much

page_text: smaller that it will still be raised to 3000° by the weak current. Thus an infinitely
weak current should heat an infinitely small particle of carbon, a mere geometrical
point so to speak; but as the light in this case would be of an infinitely short
duration, owing to the consumption of the carbon (even in a vacuum) the end of a
carbon rod of infinitely small diameter is employed, forming a reserve, so to speak,
of luminous points, the rod descending as it is consumed in order to maintain the
light. In this manner the light may be divided to an almost infinite extent.
The Invention may be carried out in various ways, and the arrangements shown
in Figures 1, 2, 3, are sufficiently clear without further description.
In the arrangement shown in Figure 4, which differs slightly from the former, a
solid voltaic arc is still obtained if the two rheophores A, A, are placed so close
together that the heating of the two contact points b, c, with the carbon produces
only a single spark. With 4 Bunsen elements, for example, and a carbon not
exceeding 1 millimetre in diameter a voltaic arc will be produced if the rheophores
be only half a millimetre from each other, but if they are three-fourths of a
millimetre apart a spark would only be produced at 6 and the remainder of the
carbon be simply reddened. In this latter case the current would traverse a portion
of the carbon rod, which then serves as a rheophore, and the solid luminous arc of
this Invention would not be produced.
In Figure 5 is represented an arrangement for producing large lights. A, A¹, are
the rheophores and E, E', the carbon, which is double, as shown. Each carbon is
in contact with a rheophore at b and c respectively, and they rest upon stops F, G,
made of some infusible material, such as magnesium or zirconium. In this manner a
true voltaic arc is formed between the two carbons E, E', having this distinguishing
feature, that the ends only of the carbons inserted in said arc are traversed by the
current.
The carbon or carbons employed may theoretically be of indefinite length since
they are not traversed by the current, and either vegetable, mineral, or artificial
carbon may be used. The rheophores may be made of platinum, iridium, or of
osmium (provided, in the latter case, that no free oxygen is present in the
surrounding medium or atmosphere), or of other infusible conducting material.
The light may be produced either in the open air or in a medium or atmosphere
of rarefied air, or of a gas, or in vacuo, according to the kind of carbon employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 12th
August 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN PRODUCING THE ELECTRIC LIGHT." A com-
munication from abroad by Charles Ludovic Pilleux, of Paris, France.
This Invention relates to improvements in electric lighting, and consists in the
introduction into the voltaic are by interposition between two metallic conductors
or rheophores of the extremity or extremities of one or more carbons, whereby
(according to the number and distance apart of the said carbons) either a single
luminous are is formed by the juxtaposition of two sparks or two luminous points
united by a voltaic arc extending between the points of the carbons without the
current traversing the entire length of said carbons.
In order that the Invention may be more readily understood I have illustrated
it in the accompanying Drawings, Figures 1, 2, 3, 4, and 5 of which show different
arrangements. A, A', are two conductors or rheophores, and E is the carbon rod
whose extremity is introduced in the voltaic arc.
Referring to Figure 1 it will be seen that the end of the carbon E bridges over
the small interval which separates the two rheophores, and is in constant contact
with both of them and descends or is fed up as fast as it is consumed. The current
produces a spark at the point of contact 6 and another at the other point of
contact c. The interval between the two sparks is equal to the diameter of
carbon E, which is regulated according to the tension of the current, so that the
two sparks shall combine and form what may be termed a solid voltaic arc, which
constitutes the essential feature of the Invention.
In applying the Invention the mass of the body to be heated is always
proportionate to the energy of the current. Thus, if, for example, it is desired to
obtain a powerful light with 50 Bunsen elements a carbon of a certain size is
employed, which is raised to about 3000°, but if two elements only are employed I
use, instead of the same sized carbon (which would be barely reddened), one so
much smaller that it will still be raised to 3000° by the weak current.
With an
infinitely weak current an infinitely small particle of carbon should be used, a mere
geometrical point, so to speak; but as the light in this case would be of an infinitely
short duration, owing to the consumption of the carbon (even in a vacuum), I
substitute the end of a carbon rod of infinitely small diameter, which forms a
reserve, so to speak, of luminous points, the rod descending or being fed up to the
rheophores as fast as it is consumed in order to maintain the light. In this manner
the divisibility of the electric light may be carried to an almost infinite extent.
The Invention may be carried out in various ways and the arrangements shown
in Figures 1, 2, 3, are sufficiently clear without further description. In the
arrangement shown in Figure 4, which differs slightly from the former, a solid
voltaic arc is still obtained if the two rheophores A, A', are placed close enough
together so that the heating of the two contact points b, c, with the carbon produces
only a single spark. With four Bunsen elements, for example, and a carbon not
exceeding one millimetre in diameter a voltaic arc will be produced if the rheophores
be only half a millimetre from each other, but if they are three-fourths of a milli-
metre apart a spark only would be produced at b, the remainder of the carbon
being simply reddened. In this latter case the current would traverse a portion of
the carbon rod, which then serves as a rheophore, and the solid luminous arc of
this Invention would not be produced.
In Figure 5 is represented an arrangement for producing large lights. A, A¹, are
the rheophores and E, E', the carbon, which is double, as shown. Each carbon is
in contact with a rheophore at b and c respectively, and they rest upon stops F, G,

page_text: made of some infusible material, such as magnesia or zirconium. In this manner a
true voltaic arc is formed in the interval between the two carbons E, E', having
this distinguishing feature, that the ends only of the carbons inserted in said arc
are traversed by the current. This arrangement may in practice be modified, as
shown in Figure 6. The two conductors terminate in claw shaped electrodes H, H',
which touch the cone formed by the combustion of the carbon, thereby enabling
the magnesia stops F, G, used in Figure 5 to be dispensed with. To obtain an
automatic relighting the two carbons E, E', are contained in iron sheaths F, and
fed up by spiral springs G as fast as they are consumed, and the tubular sheaths F
are so mounted as to be capable of adjustment nearer or farther apart. The
conductors A, A!, are wound around these sheaths, the one being wound in a
right handed and the other in a left handed helix. By this arrangement the
carbons (which touch one another when not influenced by the current) are caused
to mutually repel one another immediately the current passes, and the arc is thus
established between them.
The carbon or carbons employed may theoretically be of indefinite length since
they are not traversed by the current, and either vegetable, mineral, or artificial
carbon may be used. The conductors or rheophores may be made of platinum,
iridium, or of osmium (provided, in the latter case, that no free oxygen is present
in the surrounding medium or atmosphere), or of other infusible conducting
material.
The light may be produced either in the open air or in a medium or atmosphere
of rarefied air, or of a gas, or in vacuo, according to the kind of carbon employed.
Having described the nature of the said Invention and the manner of performing
the same, 1 declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,-
1st. In an electric lamp the introduction of the end or ends of one or more
carbon rods into the interval separating the conductors of the current so as,
according to the number and distance apart of these carbons, to obtain either a
simple luminous are formed by the juxtaposition of two sparks or two luminous
points united by a voltaic arc extending between the points of the carbons located
between the conductors, without the current traversing the carbons lengthwise,
substantially as and for the purpose herein specified.
2nd. In an electric lamp the combination with the two conductors A, A', of the
two carbon rods E, E³, interposed between the said conductors, and resting on :
infusible stops F, G, as and for the purpose herein specified, and represented in
Figure 5.
3rd. The combination of two conductors wound in opposite directions upon two
iron sheaths and terminated by claw shaped electrodes H, H', which bear against
the conical ends of the carbons E, E', which are contained within the sheaths and
fed up by springs, the whole operating as and for the purpose described in reference
to Figure 6.
In witness whereof, I, the said Alexander. Melville Clark, have hereunto set
my hand and seal, this Eleventh day of August, in the year of our Lord