IMPROVEMENTS IN APPARATUS FOR TAKING-UP, SENDING, AND REPEATING VOICE SOUNDS BY ELECTRICITY TO AND FROM DISTANT STATIONS OR PLACES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Matthew Townsend Sale at the Office
of the Commissioners of Patents on the 5th December 1877.
MATTHEW TOWNSEND SALE, of Chatham, in the County of Kent, Captain, Royal
Engineers. "IMPROVEMENTS IN APPARATUS FOR TAKING-UP, SENDING, AND
REPEATING VOICE SOUNDS BY ELECTRICITY TO AND FROM DISTANT STATIONS OR
PLACES."
According to this Invention the voice acts as a regulator, and not as a source of
power, whereby the strength of vibration of a metal disc, and consequent loudness
of articulate speech at the receiving station, are not limited by the strength of voice
of the speaker at the sending station.
My apparatus consists essentially of a plate or membrane which vibrates to the
tones of the voice. This membrane or plate causes to be introduced into a voltaic
circuit a resistance which varies exactly as the plate or membrane vibrates. The
current flowing along the line being (the source being constant) exactly as the total
resistance of the circuit, it follows that the current passing at any point in the line
varies as the membrane or plate vibrates. Theso currents passing through the coils of a
suitable electro-magnet, permanent magnet with coils, or polarized electro-magnet,
excite in an armature which takes the form of a plate vibrations which correspond
with those of the membrane or plate of the sending station; but the vibrations of
the plate at the receiving station can be heightened at will by the introduction of
an increased battery power in the circuit. I effect this by means of an apparatus
one form of which is shown in the accompanying Drawings.
a, a, is a circular metallic plate held by the collar g, g, against the disc f,f, which
is perforated by the mouth-piece h. The plate a, a, is free to vibrate in a manner
similar to a drumhead, and carries at its centre a light stud b, which is covered
with platinum. A fine screw c, c, is so placed working in a rigid standard e, e,
that its platinum covered end can be brought into contact with the stud above
mentioned, or receded from it at will, the distance between the screw and the stud
being capable of fine adjustment. The metal standard e, e, in which the screw
works is connected with the terminal screw i to which the line wire is attached,
whilst the metallic plate a, a, and with it the stud b, are placed in connection with

page_text: the terminal screw ke, to which one pole of a battery is connected, the other pole of
which is to earth or return wire.
In order to work the instrument a drop of a fluid or semi-fluid substance, or a
flame such as to be an imperfect conductor, but to be as little as possible liable to
electrolytic action, is placed between the end of the screw c, c, and the stud b, and
the screw is made almost to touch the stud.
On speaking into the mouth-piece has the plate vibrates to the tones of the
voice, the distance between the end of the screw and the stud varies with each
vibration, and as the distance varies so does the resistance offered by the drop of
fluid substance between the contact points of b and c vary. With the varying
resistance a varying current passes along the line. This vibrating current is
received at the distant station on an electro-magnet, or permanent magnet coiled,
or on a polarized electro-magnet, and there operates by the varying attraction of a
thin iron plate or diaphragm placed in front of it.
Suitable provision is mado for keeping up the supply of the fluid or semi fluid
between the platinum points of the sending apparatus.
The apparatus above described is one particular case only of the application of
my Invention.
I claim for my Invention, that it differs from other articulating electrical
instruments, in that the vibrations due to the sound of the voice do not originate
the currents which flow along the line, but merely control the currents which are
generated by a voltaic battery, and which may be of any strength .As the strength
of the currents which pass along the line, so are the vibrations of the plate at the
receiving station.