IMPROVEMENTS IN TELEPHONE TRANSMITTERS
Year: 1881

page_text: LETTERS PATENT to Charles Mosely, of the City of Manchester, in the
County of Lancaster, for an Invention of "IMPROVEMENTS IN TELEPHONE
TRANSMITTERS."
PROVISIONAL SPECIFICATION left by the said Charles Mosely at the
Office of the Commissioners of Patents on the 4th March 1881.
CHARLES MOSELY, of the City of Manchester, in the County of Lancaster.
"IMPROVEMENTS IN TELEPHONE TRANSMITTERS."
My improvements relate to the construction of apparatus for transmitting sound
by the aid of electricity, and have for their object the reduction in the amount of
electrical resistance in the transmitter and the attainment of an increased intensity
of sound in the receiving instrument, and consist in the employment of precipitated
sulphide of copper in a loose form or consolidated by pressure.
When I employ the precipitated sulphide of copper in the loose form, I enclose
it within a cavity formed in a nonconducting material such as wood, one side of
which is closed by a diaphragm. The bottom of the cavity and the underside of
the diaphragm are placed in metallic connection respectively with the opposite poles
of a battery or other source of electricity. When I employ the sulphide of copper
in the consolidated state, I construct a microphone mounted or fitted on a wood or
other diaphragm. I also use the consolidated sulphide of copper in the shape of
buttons, blocks, discs, or balls so placed as to be influenced by the vibrations of the
diaphragm.
In all cases I make the metallic contacts by means of a conducting material
between which and the sulphide of copper no chemical reaction can take place
under ordinary circumstances, for which purpose I prefer platinum.

page_text: "
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Mosely in the Great Seal Patent Office on the 1st September
1881.
CHARLES MOSELEY, of the City of Manchester, in the County of Lancaster.
IMPROVEMENTS IN TELEPHONE TRANSMITTERS."
My improvements relate to the construction of apparatus for transmitting sound
by the aid of electricity, and have for their objects the reduction in the amount of
electrical resistance in the transmitter and the attainment of an increased intensity
of sound in the receiving telephone, and consist in the employment of that salt of
copper variously known as precipitated sulphide of copper, proto sulphide of copper,
and cupric sulphide, the chemical formula of which is Cu S. This substance I use
either in a compressed or in a pulverulent state.
In carrying out my Invention I cause the proto sulphide of copper to form part
of an electric circuit, and so place it that it may be influenced by the vibrations of
a diaphragm when the latter is set in motion by the action of sound waves. The
variations in the rapidity and amplitude of the vibrations of the diaphragm
produce corresponding variations in the conductivity of the proto sulphide of copper
and therefore in the undulations of the electric "current " in the circuit in which
it is inserted.
My Invention may be applied in various ways, but in order that it may be more
readily understood, I will proceed to describe, with reference to the accompanying
Drawings, some typical examples of the manner in which the same may be carried
into effect.
Figs. 1 and 2 of the accompanying Drawings shew in section and plan a method
of employing the proto sulphide of copper in the pulverulent form. A is a cavity
formed in a nonconducting material such as wood; B and C are two conductors of
electricity, such as platinum or other metal, carbon, or the compressed proto
sulphide of copper, which are attached to the wires D, E, communicating respectively
with the opposite poles of the battery; F. is the body of the transmitter; G. is an
open mouth piece, and H is the diaphragm. The cavity A is loosely filled with
the pulverulent proto sulphide of copper, which being then in contact with the
conductors B, C, forms part of the electric circuit.
In Figs. 3 and 5 and their respective side elevations, Figs. 4 and 6, compressed
proto sulphide of copper is employed for the blocks B, B, and the pencils C, C.
A, A, are the diaphragms upon which are mounted the blocks B, B, between which
the pencils C, C, are freely suspended. In Fig. 3 opposite blocks are connected
with the wires E, F. In Fig. 5 one of the blocks B' is mounted on the centre of
the diaphragm, the other blocks being arranged around it so that the pencils may
be suspended between the central block and the other blocks in radial directions.
One half the number of the outer blocks are in electrical contact by means of the
metal strip or other conductor D, D, and the other half by means of the
corresponding strip or conductor D¹, D', the outer blocks being thus divided into
two series, one of which is connected to the wire E and the other to the wire F,
communicating respectively with the opposite poles of the battery. The pencils may
have their ends reduced in diameter, and are inserted in recesses formed in the blocks.
Fig. 7 shews in section and Fig. 8 in plan another example in which the
compressed proto sulphide of copper is employed. A is a metallic diaphragm; Bis
a fine spring having at its extremity over the centre of the diaphragm the
platinum point C; D is a disc of compressed proto sulphide of copper carried
by a stronger spring E. The diaphragm A is mounted in a cast iron ring F which
carries also the regulating lever G, this lever being jointed by the spring. H to a

page_text: projection formed on the ring. At its free end the lever G is bent so as to form an
inclined plane I, at the other end it is bent towards the diaphragm at a right
angle. At the end of this bent portion of the lever are fixed the springs B, E,
which must be carefully insulated from each other. Acting upon the inclined
plane is a small screw, which upon being moved inwards depresses, the lever, and
on being withdrawn allows it to rise; by this means a greater or less amount of
pressure may be brought about between the disc of proto sulphide of copper D, the
platinum point C, and the diaphragm. The electric circuit is completed through
the wires L, M; the diaphragm is surrounded on its periphery by the india rubber
band O, and is retained in position by the clips P, R; one of them R being longer
than the other and pressing upon the diaphragm serves to restrain the amplitude
of its vibrations. The clip R is prevented from coming into metallic contact with
the diaphragm by means of a piece of india rubber tube S slipped over it, and its
pressure on the diaphragm is regulated by the screw T. The sound waves are
caused to act upon the opposite side of the diaphragm through a suitable mouth
piece.
Fig. 9 shows in plan another arrangement, which in some cases I prefer to
adopt. A is a diaphragm of thin pine or other material capable of being vibrated
by sound waves. On the back of this diaphragm I cement one or more shallow
boxes or cells B, B, B, formed of ebonite or other nonconducting material. These
boxes or cells are loosely filled with the pulverulent proto sulphide of copper. In
the interior of the boxes or cells and upon that side next to the diaphragm are
fixed contact pieces formed of strips of platinum foil or other conducter C, C, two
for each cell, with their edges a short distance asunder. To each of the strips of
foil are soldered wires D, D, which are connected respectively with opposite poles
of the battery; by this means the circuit is completed through the proto sulphide
of copper contained in the cells. Instead of employing the closed boxes or
cells B, B, B, I may use them with one side open, in which case the contact pieces
of platinum foil or its substitute are secured to the diaphragm itself and the
cells B, B, B, are closed by cementing the edges of their open sides to the diaphragm
in such a manner that each cell or box includes one pair of contacts.
In all cases I prefer to make the contacts with the proto sulphide of copper by
means of a conducting material, between which and the proto sulphide no chemical
reaction can occur under ordinary circumstances, for which purpose I prefer to use
platinum.
Having thus described and ascertained the nature of my said Invention
and described some of the methods of performing the same, I wish it to be
understood what I claim as my Invention is the use of the proto sulphide or
precipitated sulphide of copper in a compressed or in a pulverulent state in the
construction of telephonic transmitters for the purposes and in the manner,
substantially as herein described.
In witness whereof, I, the said Charles Moseley, have hereunto set my hand
and seal, this Twenty sixth day of August, in the year of our Lord One
thousand sight hundred and eighty one
CHARLES MOSELEY. (L.S.)