IMPROVEMENTS IN PRODUCING LIGHT BY ELECTRICITY
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Isnc Louis Pulvermacher at the Office
of the Commissioners of Patents on the 19th October 1878.
ISAC LOUIS PULVERMACHER, of 194, Regent Street, in the County of Middlesex,
Electrician. "IMPROVEMENTS IN PRODUCING LIGHT BY ELECTRICITY."
My means of producing light by electricity for domestic and other lighting
purposes without the use of regulators and without noise, consists in inserting in
the circuit a vast number of very thin platinum wires at a very little distance from
each other, and in such a manner that they represent a bundle of wires nearly
similar to a brush composed of a number of platinum loops, the two ends of which
are set in a permanently good contact with a good conducting medium.
One method of carrying my Invention into effect is as follows:- Loops are formed
in a practical manner by winding a thin platinum wire over two wires of good
conduction and of larger diameter, kept apart at the distance of half the length that
it is intended to give to the loops. By this means a sort of band of a certain width
is formed in an analogous manner to my galvanic bands. I then solder the edges
of the platinum band to the stouter conducting wires which they surround. The
band may then be used in this state or folded longitudinally so as to bring the two
edges of the band parallel to each other, thus forming loops of the platinum wires.
In the fold or groove thus formed a strip of mica or other suitable insulating
substance is laid for preventing contact between one edge of the band and the other.
When one of the conducting wires is brought in contact at one of its ends with
one pole of an electro-generator, and the other conducting wire has one of its ends
in connection with the other pole, the current can only pass by circulating through
all the very thin platinum wires above referred to, which thereby become incan-
descent to a white heat and consequently luminous. It is well understood that the
quantity of electricity to be brought into play is to be graduated and adjusted in
proportion to the number of such platinum wires forming the luminous volume or
mass, in order on the one hand that no fusion of the platinum wire can take place,
and on the other hand that the total resistance in the external circuit created by
the insertion therein of all the platinum loops should approximate to the internal
resistance in the electro-generator,

page_text: In order to concentrate the whole into a small bulk and compact form, I roll it
either into a circular, convoluted, or spiral form when it has the approximate
appearance of a brush, in which state it may be inserted in a glass or other trans-
parent enclosure to prevent the cooling of the incandescent platinum loops by the
curront of air which their heat produces when unenclosed. By this means no
waste of heat can take place, and consequently the full intensity of the light is
conserved.
I may also form a vast number of platinum loops soldered to conducting wires
in the following manner:-
Through holes formed in a plate or strip of mica or any other suitable material I
pass thin platinum wires so as to form loops of the lengths intended. The mass of
loops thus have also in this case the appearance of a brush. The under portions of
the platinum wires visible on the back of the brush are set in united conduction
with a thicker wire which is provided during manufacture. The number of such
rows of loops are then brought in connection in alternate order, one half with one
pole and the other half with the other pole of the electro-generator, that is to say,
supposing there are 12 rows, the six even numbers will be in connection by one
conducting wire with one pole of the electro-generator, and the six odd numbers by
another conducting wire set in connection with the other pole.
The circuit thus established will cause the current to be distributed to the
number of platinum wire loops and render them incandescent in a similar manner
to that described above.
I sometimes coat or surround the loops with platinum black.
A further modification of the above consists in the use of platinum foil in lieu of
the thin platinum wire to be made incandescent to a white heat by the electric
current whereby the degree of heat causing fusion has no injurious effect.
I affix such platinum foil on a thin plate of mica or other suitable insulating
material capable of resisting heat by a suitable adhesive heat-resisting compound.
I provide the two edges with elongated clamps capable of good conduction and
pressing on the whole edge surface of the platinum foil, which clamps are in connec-
tion with the poles of the electro-generator.
The current supplied to these clamps must traverse the platinum foil, thereby
making it incandescent to a white heat, in a similar way to that described above
for the platinum wire. The platinum being supported by its backing will not easily
become disarranged, and will secure a lasting luminous sheet as long as a current of
sufficient intensity passes.
The shape and size of such illuminating plates depends upon the particular
purpose for which the light is intended.
A thin platinum coating on the insulating material may be secured if preferred
by a chemical process.
In the above-described methods of producing light the current is constantly con-
tinuous, but if it is intended to produce the luminous phenomena by multitudes of
sparks produced by an intermittent current I use these kinds of brushes as
electrodes, one of them being caused to rotate by a small magnetic engine, thereby
rubbing on the surface of the other electrode which is in a fixed position beneath.
In this case the loops need only to be short and the platinum wire hard drawn and
disseminated so far apart as would secure regular and distinct interruptions by the
rubbing of one electrode over the surface of the other.