Improvements in Arc Taps
Year: 1895

page_text: Date of Application, 11th June, 1895-Accepted, 13th July, 1895
Arc Lamp.
1. SAMUEL PLEASANTS PARMLY, of Suite 1410 Marquette Building, City of
Chicago, County of Cook, State of Illinois, one of the United States of America,
Gentleman, do hereby declare the nature of my invention of Improvements in Arc
Taps, 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 arc lamps and has for its object to provide a double
service or long burning arc lamp with but a single pair of electrodes. It is
illustrated in the accompanying drawing wherein;
Fig. 1 is a side view of the lamp,
Figs. 2, 3, 4, 5, 6, 7 and 8, details and cross sections of various forms of the
carbon electrode used.
The groups here illustrated are each of them in the general form of an ellipse
in cross section or a plate having such a cross section as would constitute a form
having a width substantially one-half its length. The cross sectional area is
substantially equal to twice the cross sectional area of the ordinary round
carbons.
A is a case containing the operating mechanism of the lamp, B B are the side
bars, C the upper carbon rod to which the carbon D is attached, E the lower
carbon rod held in the carbon holder F. G is a carbon substantially elliptical
in cross section, H is a similar carbon with angular edges; J is a carbon right
angle in cross section; K is a carbon composed substantially of two round carbons
in contact or with a thin and relatively wide rib; L is a carbon diamond shaped in
cross section, and M is a carbon elliptical in cross section. The preferred form
of carbon is substantially that shown in Figures 1, 2 and 7, or in other words, a
carbon substantially elliptical in cross section and having a cross section whose
width is substantially one-half of its length with rounded or flattened ends. The
central transverse diameter may be extended or shortened, as for example, in the
two forms shown in Figures 5 and 6.
I have found by a long course of experiments that where a carbon formed
substantially as suggested is employed in a lamp and placed in opposition to a
smaller carbon that the tendency is to burn in something like the form indicated
in Figure 1 and also that both carbons or electrodes retain a continuously heated
end so that as the arc travels along the opposed edges, which it must do, there
is no occasion for it to attack cold material and hence it is possible to keep a
comparatively uniform are although the same travels back and forth across the
edge of the opposed electrode. A satisfactory arc is obtained without material
localization by a construction of electrodes in which the arc is permitted to travel
back and forth. The rounded edges of the carbon are not of course indispensable
as with the square cornered form shown in Figure 4 a somewhat similar result is
obtained but it is attended with some irregularity of the arc and also with greater
shadow and hence is not the preferred form. Any of these several forms of carbons
shown can be used either with a similar carbon above or below or with any other
form of carbon above or below. Many other forms of carbons could easily be
devised which would be in effect the same as those here illustrated.
Referring to Figure 8 N N are the round carbons, and P is the intermediate
conductor.

page_text: These several forms are not meant here to be illustrated in exact proportion
or relation but they should be so constructed that when used the arc is kept in
motion for the most part and to a very great degree avoid localization.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim, is :-
1. The combination of an electric arc lamp with the usual mechanism for
controlling the carbons with two carbon electrodes, each consisting of a bar or
pencil having a cross sectional area substantially twice the cross sectional area of
the ordinary round carbon designed for use with the same current and substan-
tially or for the most part in the form of a bar with a thickness and a width as
one to two.
2. An arc lamp provided with carbons of substantially the form and shape shown
Dated this 11th day of June 1895.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.