IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by John Sinclair Kelso at the Office of
the Commissioners of Patents on the 9th March 1883.
JOHN SINCLAIR KELSO, Junior, of the Town of Stamford, in the County of
Fairfield, and State of Connecticut, one of the United States of America, Electrical
Engineer, "IMPROVEMENTS IN ELECTRIC LAMPS"
My invention relates to improvements in the manufacture of that class of Electric
Lamps in which an electric current is caused to pass through and heat a carbon
fibre or filament forming part of the circuit, and which carbon fibre or filament is
enclosed in a glass tube or globe, from which the air is exhausted so as to form a
vacuum, or the tube or globe is filled with an artificial atmosphere.
My invention consists in arranging two or more carbon fibres or filaments or
their equivalents upon a support, either divided or insulated centrally.
The carbons or filaments are mounted in such manner that so long as the main
or first carbon remains perfect, that carbon alone shall become incandescent, but
immediately the said first or main carbon or filament breaks or fails, the current
shall be automatically and instantaneously caused to pass through and cause another
carbon, carbon fibre or filament to become incandescent.
Any number of carbons, carbon fibres or filaments may be brought into operation
in succession.
Carbons or carbon filaments arranged according to my invention may be
employed in any desired form or construction of incandescent lamps, and in any
known system of incandescent lighting by electricity.
In carrying out my invention I employ a main carbon or filament, and a
secondary carbon or filament or series thereof, of which there may be any desired
number adapted for consecutive operation as the prior carbons or filaments become
broken or fail. The opposite ends of the main carbon are supported in sockets or
clamps formed on or affixed to the opposite ends of a divided support, which is by
preference formed of bent wire arranged in two parts or sections, which are
supported respectively by wires formed by preference of platinum, and sealed or
otherwise supported in the globe or tube of the lamp. The main and supporting
wires are connected in the ordinary manner by means of other wires with an
electric apparatus. The opposite ends of the secondary carbon or filament are
supported in sockets or clamps formed on or affixed respectively to the inner ends
17077

page_text: of wires forming a divided support. The divided support in some cases I propose
to form of German Silver wire, a sufficient length of which is coiled up, in order to
form the divided sections, to insure that said sections shall have a greater resistance
to the passage of electricity when heated by the passage of a current of electricity
therethrough, than the resistance offered by the main carbon or filament, when
heated and rendered incandescent by the passage of the said current.
One end of the main carbon is mounted on a section in position such that there
shall be a direct line of current from the induction wires, directly across a half
support, and thence up through the main carbon and around the same when it will
cross the opposite section and be conducted away by the eduction wires, so long as
the main carbon remains perfect, but immediately the main carbon breaks, the
current no longer being able to pass the same it will be diverted and pass imme-
diately and automatically from the induction wires along the wire of the coil
forming the first section, and thence up and through the second carbon, thereby
rendering it incandescent. The current will then pass through the wire of the
coil forming the second section, and out by the eduction wires, as before.
The wires forming the sections of the divided support must be provided with an
insulated coating or covering, as will be understood.
Three or other number of carbons may be employed, mounted upon a support
formed in sections, each composed of a coil of wire, the coil of wire of the two end
sections being of a given resistance, while the intermediate sections should be
formed of a coil of wire of a length sufficient to offer a greater resistance to the two
end sections, by preference double that of the same, the object being to prevent
the current passing to and rendering another carbon incandescent until both the
first and second carbons have broken. This may be effected by drooping the coils
of the sections, or by coiling a greater quantity of wire into the sections, or by
reducing the diameter of the wire.
In arranging a series of carbons upon a divided support I prefer to arrange the
resistance of the carbon connected with the respective pairs of sections, in such a
manner that the said respective pairs of sections, when heated shall have a resistance
greater than the resistance of the preceding carbon. In proportion as the resistance
of the pairs of sections is increased the resistance of the carbons is decreased. This
is effected, by preference by increasing the diameter of the cross-section of the
carbon. This arrangement of the resistance of the carbons enables me to obtain a
uniform amount of light from the respective carbons.
The support for the carbons may be formed of a series of sections insulated one
from the other, the two end sections respectively, being connected together by a
bent wire or coil, while the other sections are connected by an elongated coil.
In fitting up a lamp according to my invention care must be taken to ascertain
by means of the galvanometer, the resistance of the direct or first carbous, and of
the successive carbons in relation to the resistance of the support by which they
are carried.