IMPROVEMENTS IN INCANDESCENT ELECTRIC LAMPS AND IN THE PREPARATION OF CARBONS FOR THE SAME دو
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by David Graham and Harry John
Smith at the Office of the Commissioners of Patents on the 22nd March
1882.
DAVID GRAHAM, Electrical Engineer and HARRY JOHN SMITH Ph.D. Chemist
both of Glasgow in the County of Lanark North Britain "IMPROVEMENTS IN
INCANDESCENT ELECTRIC LAMPS AND IN THE PREPARATION OF CARBONS FOR THE
SAME
دو
This Invention, which relates to incandescent electric lamps, has especial reference
to improvements in the construction or formation of carbon or other filaments or
plates for the same, whereby the electric current is transmitted with great regularity,
and an equal light is maintained.
In the ordinary construction of incandescent lamps, the current flows directly
from one pole to the other, and from end to end of an arched, looped, or wave-formed
carbon filament, and great difficulty being experienced in making the carbons to
have equal electrical resistance, the same current cannot readily be made to produce
an equal amount of light in each of a number of lamps of the same kind. To.
overcome this difficulty the filament is, according to this Invention, made in the
form of an endless band, strip, or plate of carbon or other suitable material, of
circular, oval, rectangular or other convenient shape, and the two poles are connected
at points which may be equi-distant, or nearly so, from each other, so that the current
flows round the circumference or perimeter of the filament or plate. The filaments
or plates when so constructed are much less liable, than those of the ordinary form,
to break or shiver when under incandescence.
These endless filaments or plates may be formed in a number of different ways.
In one modification the filament cut in the form of a circular or oval band or
ribbon of parchment, parchment paper, or other suitable material, and carbonised.
The conducting wires are connected to the filament at opposite sides by any ordinary
connection, it being preferred to pass the wires through eyes or holes in the band
or ribbon, and connect them to washers of platinum or other conductor held by
binding screws or other attachment; and two or more ring bands or strips may be
fitted within each other in an open globular form.

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In a modified arrangement, the carbon is made in the form of a disc, or of a plate
which may be rectangular, or of any convenient shape, and this disc or plate is
either pressed out, or formed by the superposition of layers of carbonised parchment
or other suitable material, in such a manner as to have a very thin annular or other
shaped portion left between the central and outer portions which are comparatively
thick. A metallic conducting piece is fitted in the centre of the plate, and the outer
edge or rim is fitted and held by plates or clamps of conducting material. One of
the conducting wires is connected to the outer holding plates or clamps, and the
other wire, leading from the central clamp or plate, may be led through a non-
conducting guide or eye on the outer plates, to prevent vibration of the carbon or
other material; and when the current is transmitted through the carbon plate, the
thinner annular or other shaped portion will be rendered incandescent. Should the
plate become cracked, the current will not be stopped, but a regular degree of
incandescence will be maintained.
Carbon plates of this construction may be perforated, or they may be cut in the
form of spoked wheels, and the plates may be so formed as to produce, when under
incandescence, highly ornamental effects.
The filaments or plates forming the carbons may be prepared by any ordinary
process, but by a further improvement of our Invention, these filaments or plates
are cut out of parchment, or parchment paper, or other substance which may be
saturated with paraffin or other hydrocarbon, and whose surface is coated or brushed
over with graphite or other similar material. The cut filaments or plates are pressed
between sheets of paper or other thin glazed sheets of material containing a
hydrocarbon, and are then carbonised by heat, the carbon of the hydrocarbon in the
sheets being deposited on the cut filaments or plates.
When the "carbon" plates are formed in layers as hereinbefore described, the
parchment paper, or other material from which the carbons are made, is cut in the
form of washers which are cemented or joined together by a mixture of pitch or
other similar substance containing carbon, with Benzol or other solvent; and when
the plates thus formed are carbonised, the Benzol or spirit is volatilised, while the
carbon of the pitch or other material unites the layers into a solid plate.
The filaments or plates when being carbonised are secured and pressed between
metal plates within a close vessel, the requisite pressure being maintained equally
during the carbonising process by means of weights resting either directly over the
upper metal plate, or on rods passing from it out through the close vessel.
The opening door through which the plates are inserted and withdrawn from
the vessel in which the carbonising process takes place, may be formed of a metallic
shelf covered at the joints with graphite or powdered char.