Improvements in Electric Arc Lamps.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, ALBERT COOPER SEIBOLD, of Mount Vernon, County of Westchester, and
State of New York, United States of America, do hereby declare the nature of this
invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My invention relates to improvements in electric are lamps, my object being to
effect considerable economy of carbons, and of labour in trimming.
For this purpose I make a negative electrode capable of being used in any are
lamp, without regard to the particular construction or operation of the lamp, this
negative electrode being composed in part of a body of metal of low resistance, and
in part of a body of carbon covered by metal whereby the air is wholly excluded
from contact with the carbon, which is kept cool by the body of metal sustaining
it, thus rendering it practically unconsumable.
This effects a great economy of carbons and also of labour by enabling the
trimmers to attend to a given number of lamps in about one half the time usually
occupied.
I provide also an inexpensive attachment whereby those portions of the carbon
electrode next the electric arc are kept at a temperature considerably below that to
which they are usually subjected, and thus I retard the consumption of carbon, or
reduce the quantity consumed in a given time, without materially affecting the
brilliancy of the light.
Fig. 1 of the accompanying drawings is a longitudinal section of a negative
electrode according to my invention, in its complete form ready for use.
Fig. 2 is an elevation of both electrodes as arranged in the lamp.
Fig. 3 shews the positive electrode in elevation and the negative electrode in
longitudinal section.
Fig. 4 is an elevation partly in section showing a modified form of negative
electrode.
Fig. 5 shews the same with the positive carbon in position for operation.
Fig. 6 shews another modified form of the negative electrode.
Fig. 7 is a central vertical section illustrating part of my invention applied to both
the electrodes of an are lamp.
Fig. 8 is a part section showing the mode of inserting the positive electrode.
Referring to Figs. 1 to 5, inclusive, 1 is the positive electrode being a carbon
pencil of the usual kind fed by the mechanisin ordinarily used for arc lamps. 2 is
the negative electrode which consists of a rod, or bar of diamagnetic metal,
having its end for about one inch coated with a thin layer of carbon 3.
coated end has a thin coating 4 of copper electrolytically deposited upon the carbon
layer 3.
This
When the lamp is ready for use, the point of the positive electrode 1, rests upon
the end of the negative electrode, but when put in circuit the carbon 1,
rises from the negative electrode, striking the arc, which burns a hole 5 through
the coating of copper 4, and the portion of carbon thus exposed becomes coated with
a crust 6, consisting of small particles of carbon deposited from the point of the
positive electrode 1.
While the current is maintained, the deposition of carbon particles continues, and
at the same time they are consumed, the crust 6 being thus constantly renewed and
consumed.
By constructing the negative electrode as describel, the metallic stem 2

page_text: acts as a conductor for the current, while the layer of carbon 3 acts as a carbon
_electrode.
The coating of copper 4, by excluding air from the carbon layer, effectually
prevents its combustion, if heated to redness by the arc. This however, is not
likely, since the resistance of the steni 2 is low, and being a good 'conductor of
heat it assists in maintaining the carbon layer 3 at a comparatively low temperature.
Great durability of the negative electrode results from the fact that the carbon
deposit 6 is constantly maintained, protecting that portion of the carbon layer 3,
under the opening 5, from the heat of the are, that the copper coating by excluding
air prevents combustion of the carbon, and that the metal stem 2 keeps the carbon
layer cool.
Similar results are attained by adopting the modified construction shewn in
Figs. 4, 5 and 6. In these figures indicates the negative carbon which is embedded
in a sheath 2 of diamagnetic metal, such as copper. I prefer to make the negative
carbon short, as shewn, its end projecting at 4 above or nearly level with the upper
end of the sheath 2, which serves to keep the carbon cool and to exclude the air, thus
quite preventing combustion of the carbon except of the nipple 4 which is continually
being renewed by deposit from the positive electrode. The carbon may be
inserted as shewn in Fig. 6, in a metal sheath 2 which may be open at the lower
end but is preferably closed. If it is to be left open the carbon should be
pressed or packed tightly into the sheath, to prevent access of air to the heated end.
In Figs. 7 and 8, 1 denotes the upper or positive carbon electrode, and 2 desig-
nates the lower or negative carbon. 3 is a metal casing or tubular holder in which
the carbon is free to slide in its upper end is fixed a short tube 4 of the same
diameter as the carbon, so that it can be held in the ordinary carbon holder.
To the tube 1 is attached insulated a bracket 5, upon which is pivotted a lever 6,
its lower end carrying a plate 7, which lies substantially at right angles to
the axis of the tube and has a hole 8 through it somewhat less in diameter
than the carbon 1 so that only the point of the carbon projects below the
plate 7.
The lever 6 is so arranged, being pressed by a spring if necessary, that it holds
the plate-7 in position to support the carbon. 9 is a short metallic tube which
constitutes a cap, or shield, for the negative carbon 2. Its upper end has an inwardly
projecting edge 10, which contracts the opening to a diameter less than that of the
carbon, so that the cap rests upon the upper end of the carbon.
In order to prevent the parts from being lost or mislaid they are connected by a
chain or cord 12. The operation of these parts is as follows —
The carbon holder 3 being fixed by inserting the tube 4, in the upper
carbon holder the lever 6 is moved so as to swing the plate 7 away from the
lower end of 3.
The carbon is then pushed up the tube, and the lever is moved back so
that the plate 7, supports the carbon with its end projecting a little through the
opening 8. A spiral spring 13, is arranged to press down the carbon.
on it.
The negative carbon 2, being placed in the lower carbon holder the cap 9 is placed
The attachments for the chain 12 are insulated from the tube 3 and from the
cap 9.
The points of both the carbons when the arc is formed become highly heated, but
those portions which are enclosed in the metal tube 3 and in the cap 9 are kept at a
comparatively low temperature and the rapidity of consumption of the carbons is
thereby considerably lessened.
As the negative carbon 2 is consumed, the tubular cap 9, gradually descends by
gravity, a portion of the carbon always projecting above the metal. The use of the
tube 3 allows several short pieces of carbon, to be arranged in it. These pieces
which are now usually thrown away as useless, may thus be used with a considerable
resulting economy.*

page_text: Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electric arc lamp, the use of a negative electrode composed of a metallic
bar or rod having its end covered by a layer of carbon, which is enclosed by a plating
of copper, substantially as described.
2. In an electric arc lamp, the use of a negative carbon enclosed within a metal
sheath with its end exposed, substantially as described.
3. In an arc lamp in combination with a tube enclosing the positive carbon
electrode, a lever having at its end a plate with a hole through it of less diameter
than the carbon, this plate usually sustaining the carbon, but moved aside to admit
the carbon, substantially as described.
4. In an arc lamp, the use of a metallic cap, having an inwardly turned
upper edge surrounding and resting on the upper end of the negative carbon,
substantially as specified.
Dated this 28th day of February 1891
ABEL & IMRAY,
Agents for the Applicant.