PROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Charles Dubos at the Office of the
Commissioners of Patents on the 17th June 1878.
CHARLES DUBOS, of Paris, Boulevard de Strasbourg, No. 23, Electrician.
PROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
.
" IM-
Electric lamps or regulators, as they are called, usually contain complex mechanism
for the purpose of adjusting the carbon points or other inaterials employed to the
proper distance for the production of the luminous are so as to allow for variations
in the electric force and for the irregular consumption of the material.
My Invention relates to a method of constructing such lamps, whereby I avoid
the use of complex mechanism or clockwork by making the adjusting action result
from the balancing of two forces, gravity and attraction, depending on the electric
force passing through the instrument. For this purpose I mount one of the carbons
on a soft iron rod or tube, which is guided to slide through the middle of a coil that
is in the electric circuit. The weight of the slide tends to move it in the one
direction, and the attraction of the coil when an electric current passes through it
tends to move it in the opposite direction; or the slide may be overbalanced by an
adjustible weight, the coil being so arranged as to act on it in opposition to such
weight.
When the carbons are at suitable distance for the passage of the required amount
of electricity to produce the luminous are the weight and the attraction of the coil
acting on the slide are adjusted in equilibrium.
When the electric force varies, or when the distance of the carbons becomes
altered by their consumption, the one force overbalances the other, and the one
carbon is moved nearer to or farther from the other until equilibrium of the forces
is again attained.
When it is desired to keep the luminous are at or nearly at one focus, I mount
both carbons on slides, connecting them by a cord or chain passing over guide
pullies, so that when the one is moved, as above described, the other is also moved
towards or away from it.

page_text: In cases where the one carbon is more rapidly consumed than the other the cord
or chain from the one slide is wound over a pulley or barrel, on the axis of which is
fixed a smaller pulley or barrel taking the cord or chain of the other slide.
The apparatus acting as above described may be made in various forms.
According to one form, which I find convenient, it consists of a tubular framing
of lyre shape, that is to say, two tubes for some distance in their upper portions
parallel, and then curving outwards away from one another, and again approaching
in a circular curvature, and meeting below.
The lower carbon slide is mounted at the bottom, the upper slide works within a
coil fixed between the parallel upper parts of the tubes, and the two slides are con-
nected by cords passing over guide pullies and round the outward sweep of the
framing within the curved tubes.
The focus of the light is at or near the centre of the circular sweep, which can be
backed by a reflector.
•
The apparatus may also have the usual form of the electric lamp, the one carbon
slide being guided through a coil fixed in the lower casing, and the other slide behind
it, having a projecting arm to carry the upper carbon over the lower carbon. In
this case the slide of the lower carbon is overbalanced by that of the upper carbon,
and on the upper slide I find it convenient to place an adjustible weight, which may
be a cup or vessel containing small shot or other easily variable load.
According to another form of the apparatus I arrange both carbons in slides,
guided each through the middle of a coil at a small inclination to one another, so
that they converge towards the focus where the carbon points nearly meet. Both
slides are in this case counterbalanced by a single weight connected to them by cords
or chains passing over guide pullies.
To prevent the. fracture or irregular consumption of the carbons from causing
fusion of some of the metal fittings of the apparatus I apply to each of the carbons
an intercepter, consisting of a piece of non-conducting material pressed by a spring
against the carbon near its point.
Should the end of the carbon break off or be rapidly consumed so that the inter-
cepter is no longer supported by it the pressure of the spring causes it to advance
over the end of the carbon, and so stop the passage of electricity.