IMPROVED MEANS FOR OBTAINING LIGHT BY ELECTRICITY
Year: 1879

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of IMPROVED MEANS
FOR OBTAINING LIGHT BY ELECTRICITY." A communication from abroad by
the Firm of A. de Méritens and Company, of Paris, France.
Scaled the 29th August 1879, and dated the 12th June 1879.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 12th June 1879.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middle-
sex, Patent Agent. "IMPROVED MEANS FOR OBTAINING LIGHT BY ELECTRICITY."
[A communication from abroad by the Firm of A. de Méritens and Company, of
Paris, France.]
This Invention relates to a multiple carbon "burner" for the production of the
electric light. When the "burners" now in use (other than regulators), such as
the Jablochkoff, Jamin, or Wilde candles, are considered it will be observed that
whatever method is adopted to fix the arc at the points of the carbons it must
leap over at a single bound the distance which separates the two points, and con-
sequently owing to the interval necessary must be produced by a current of high
tension. The tension theoretically necessary must, however, be still further
augmented in practice, because all the methods hitherto adopted to prevent the
are becoming hidden necessarily amplify the fan like diffusion of the are.
In the Jablochkoff candle, represented in Figure 1 of the accompanying Draw-
ings, this amplification is due to the presence of the insulating material, which
never disappears mathematically at the same time as the carbons are consumed.
In the Jamin candle, represented in Figure 2, the amplification is due to the
attraction of the arc by the current, and which attraction naturally varies with the
variations of the current itself.
In the Wilde candle, shown in Figure 3, the amplification is due to the
separation of the movable carbon m from the fixed one by the action of the
regulator electro magnet, whose power varies with the current.
In the multiple carbon burner of this Invention the arc is not formed between
two, but between a number of electrodes, by deriving the principal current

page_text: through as many branches as there are conductors. This derivation is effected
under such conditions that the tension of each derivation is proportional to the
resistance of the are interposed in it. Take, for example, the case of a burner
with four carbons, represented in Figure 4, in which A, B, are the extreme pair,
and a, b, the intermediate pair of smaller diameter than the others; the current
is derived as shown, but by interposing a resistance a proportionate to the resist-
ance of the arc a, b, a small portion of the current is derived through a, a, and
the principal current passes through the carbons A, B. When an alternating
current is used it is better the system of carbons should be symmetrical, that is
to say, that their number should be even, as the positive side presently becomes
negative.
Figure 5 represents an example of a burner with five carbons, and Figure 6
one with eight. Here we have an arrangement of wires which gives in some sort
a series of little candles comprised beneath a principal arc, but it will be evident
the derivations may be so arranged as to cause the ares to cross each other.
The advantages obtained by this Invention are fixity, brillianey, duration, and
diminution of resistance. 1st. Fixity; each two adjacent conductors being
similarly influenced the are cannot rest on adjacent points. 2nd. Brilliancy; a
small mass being more readily raised to a white heat than a large one, there is
an advantage in carrying the current through finer and more numerous con-
ductors, the points being heated proportionately as much the ones as the others
produce the effect of a luminous band or series, and the brilliancy is thus greater
than with other burners. 3rd. Duration; the combustion of the carbons in the
are being due chiefly to mechanical action, if this action be distributed through
a greater number of points it is weakened at each individually, and thus the
same result is obtained as if the mass were augmented, without however any
loss in light and divisibility. 4th. Diminution of resistance; the resistance is
greatly diminished as the are meets with a conductor of the same nature as itself
during more than half its extent. Moreover, if the resistance becomes excessive
in the principal are the secondary arcs alone are maintained, and serve to relight
the extreme carbons when the cause of extinction has ceased to exist.
Generally in practice the resistances are formed of wires wound on a single
core, but they may be of any other kind.
The relighting automatically may be effected by causing the small carbons to
strike quickly against one another by mechanical means, and particularly by
a hammer actuated by the resistance coil, which is in that case furnished with
a soft iron core. The important influence of the derived currents is readily
noticed; before their introduction the intermediate carbons are at a dull red,
but as soon as they pass the points are brought to a reddish white, and the
principal arc has a remarkable degree of fixity.
The principle of deriving the principal current through intermediale carbons
involves many consequences: in particular may be mentioned the case of a
burner, shown in Figure 7, with equal carbons, in which the derivations may
be so calculated as to burn with a direct current.

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
11th December 1879.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middle-
sex, Patent Agent. IPROVED MEANS FOR OBTAINING LIGHT BY ELMTRICITY."
A communication from abroad by the Firm of A. de Méritens and Company, of
Paris, France.
This Invention relates to a multiple carbon burner" for the production of the
electric light. When the "burners" now in use (other than regulators) such as
the Jablochkoff, Jamin, or Wilde candles, are considered it will be observed that
whatever method is adopted to fix the are at the points of the carbons it must
leap over at a single bound the distance which separates the two points, and con-
sequently owing to the interval necessary must be produced by a current of high
tension. The tension theoretically necessary must however be still further
augmented in practice because all the methods hitherto adopted to prevent the
are becoming hidden necessarily amplify the fan like diffusion of the arc.
In the Jablochkoff candle, represented in Figure 1 of the accompanying Draw-
ings, this amplification is due to the presence of the insulating material, which
nover disappears mathematically at the same time as the carbons are consumed.
In the Jamin candle, represented in Figure 2, the amplification is due to the
attraction of the are by the current, which attraction naturally varies with the
variations of the current itself.
In the Wilde candle, shown in Figure 3, the amplification is due to the
separation of the movable carbon from the fixed one by the action of the
regulator electro magnet, whose power varies with the current.
In the multiple carbon burner of this Invention the arc is not formed between
two, but between a number of electrodes, by deriving the principal current
through as many branches as there are conductors. This derivation is effected
under such conditions that the tension of euch derivation is proportional to the
resistance of the arc interposed in it. Or instead of derivations of the principal
current I may use secondary currents produced by the inductive action of the
primary current. These induced currents may be merely those generated in the
intermediate carbons when perfectly insolated from one another and from the
outside carbons through which the current passes, the burner in that case working
without any other device than that necessary to send the current through the
two outside carbons.
Figure 4 represents a burner with four carbons, in which A, B, are the extreme
pair, and a, b, the intermediate pair of smaller diameter than the others; the
current is derived as shown, but by interposing a resistance proportionate to
tho resistance of the arc a, b, a small portion of the current is derived through a, a,
and the principal current passes through the carbons A, B. When an alter-
nating current is used it is better the system of carbons should be symmetrical,
that is to say, that their number should be even, as the positive side presently
becomes negative.
Figure 5 represents an example of a burner with five carbons, and Figure 6
one with eight. Here we have an arrangement of wires which gives in some sort
a series of little candles comprised beneath a principal are, but it will be evident
the derivations may be so arranged as to cause the arcs to cross each other.
Figure 8 represents a burner in which the currents for the intermediate carbons
are merely generated by the induction of the principal current in the neighbour-
ing extreme carbons.
The advantages obtained by this Invention are fixity, brilliancy, duration, and
diminution of resistance. 1st. Fixity; each two adjacent conductors being
similarly influenced, the are cannot rest on adjacent points. 2nd. Brilliancy; a
small mass being more readily raised to a white heat than a large one, there is

page_text: con-
an advantage in carrying the current through finer and more numerous
ductors, the points being heated proportionately, the ones as much as the others,
produce the effect of a luminous band or series, and the brilliancy is thus greater
than with other burners. 3rd. Duration; the combustion of the carbons in the
are being due chiefly to mechanical action, if this action be distributed through
a greater number of points it is weakened at each individually, and thus the
same result is obtained as if the mass were augmented, without however any
loss in light and divisibility. 4th. Diminution of resistance; the resistance is
greatly diminished as the arc meets with a conductor of the same nature as itself
during more than half its extent. Moreover, if the resistance becomes excessive
in the principal are the secondary ares alone are maintained, and serve to relight
the extreme carbons when the cause of extinction has ceased to exist. Generally
in practice the resistances are formed of wires wound on a single core,
but they
may be of any other kind.
The relighting automatically may be effected by causing the small carbons to
strike quickly against one another by mechanical means, and particularly by
a hammer actuated by the resistance coil, which is in that case furnished with
a soft iron core. The important influence of the derived currents is readily
noticed; before their introduction the intermediate carbons are at a dull red,
but as soon as they pass the points are brought to a reddish white, and the
principal arc has a remarkable degree of fixity.
The principle of deriving the principal current through intermediate carbons
involves many consequences; in particular may be mentioned the case of a
burner, shown in Figure 7, having equal carbons, in which the derivations may
be so calculated that a direct current may be passed through one carbon A, and
derived at the point of said carbon through two others b, B.
Having described the nature of the said Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be protected
by the herein before in part recited Letters Patent is,-
The herein described system of burner with multiple carbons for the produc-
tion of the electric light, in which the intermediate carbons are consumed by
currents derived from the principal current, or by secondary currents produced
by the induction of the principal current, and particularly secondary currents
induced in the insulated intermediate carbons themselves, as specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Eleventh day of December, in the year of our Lord
One thousand eight hundred and seventy nine.
A. M. CLARK. (L.S.)