IMPROVEMENTS IN TELEPHONE TRANCALLTTING ADDADA
Year: 1881

page_text: LETTERS PATENT to John Thomas Gent and Henry George Ellery, trading as
John T. Gent & Co., of Faraday Works, Leicester, in the County of
Leicester, Electricians, for an Invention of "IMPROVEMENTS IN TELEPHONE
TRANCALLTTING
ADDADA"
PROVISIONAL SPECIFICATION left by the said John Thomas Gent and
Henry George Ellery at the Office of the Commissioners of Patents on the
24th May 1881..
JOHN THOMAS GENT and HENRY GEORGE ELLERY, trading as John T. Gent &
Co., of Faraday Works, Leicester, in the County of Leicester, Electricians.
"IMPROVEMENTS IN TELEPHONE TRANSMITTING APPARATUS."
This Invention relates to improvements in telephone transmitting apparatus, and
has for its object a simple mode of increasing the sounds and rendering the
articulations more clear and distinct when used for communicating between distant
stations.
In carrying out our Invention we make use of a thin plate or diaphragm of
wood, which is attached to the outside cover of the case containing the apparatus,
and placed a short distance from the same, the cover having an opening in the
centre through which the sounds or messages are.received upon the diaphragmn.
We fix thin plates of carbon side by side across and attached to the diaphragm,
the plates being near each other but not in contact.
We also attach brackets carrying bars of metal, on which are loosely hung metal
arms, each arm carrying a plug of prepared carbon, these again resting on or
against the carbon plates. We prefer to use twelve to sixteen of these arms and
carbon plugs, arranged in series of three or four, so that a current of electricity to
traverse the whole must pass over successive sets. Each arm, either suspended in
a vertical or horizontal position, is provided with an adjustable weight on a screw
threaded arm, so that by moving the said weight nearer or further from the centre
of suspension the prepared carbon plugs will rest with greater or less weight
against the carbon plates attached to the diaphragm.

page_text: The object of using a row of carbon plates and suspended arms is that the whole
of the vibrations of the diaphragm may be utilized, and resulting in more powerful
undulatory currents passing to the coil. One end of the row of carbon plates is
attached to a battery, the other end of the row passing to the primary wire of an
induction coil (placed for convenience within the same case); then again setting
up secondary currents, which pass to the receiver at the distant station, which
receiver may be of any of the usual forms.
Or the secondary current before it reaches the receiver at the distant end may bo
made to pass through coils of wire attached to a magnet placed near the diaphragm,
so that a series of undulatory currents corresponding with those originally sent are
set up in the diaphragm and reproduced in the receiver, thereby augmenting the
force of the vibrations and emitting a louder sound.
Where ordinary receivers are employed we make use of a flexible tube to contain
the wires, and so preserve them from injury, thus obviating one of the objections to
the use of wire conductors between the case containing the apparatus and the
telephone receiver. Suitable forks are provided, in which the receivers at the ends
of the tubes are placed when not in use, the said forks also acting as switches for
detaching the battery and placing the bell in circuit in the ordinary way.
An ordinary electric bell and stud is fitted to the apparatus.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent fled by
the said John Thomas Gent and Henry George Ellery in the Great Seal
Patent Office on the 22nd November 1881.
JOHN THOMAS GENT and HENRY GEORGE ELLERY, trading as John T. Gent
and Co., of Faraday Works, Leicester, in the County of Leicester, Electricians.
"IMPROVEMENTS IN TELEPHONE TRANSMITTING APPARATUS."
This Invention relates to improvements in telephone transmitting apparatus,
and has for its object a simple mode of increasing the sounds and rendering the
articulations more clear and distinct when used for communicating between distant
stations.
In carrying out our Invention we make use of a thin plate or diaphragm of
wood, which is attached to the outside cover of the case containing the apparatus,
and placed a short distance from the same, the cover having an opening in the
centre, through which the sounds or messages are received upon the diaphragm.
We fix thin plates of carbon or other suitable material side by side, across, and
attached to the diaphragm, the plates being near each other but not in contact.
We also attach to the cover brackets carrying a rod or bar of metal, on which
are loosely hung metal arms, each arm carrying a plug of prepared carbon or other
suitable material, these again resting on or against the plates. Each arm, sus-
pended either in a vertical or horizontal position, may be provided with an
adjustable weight on a screw threaded arm, so that by moving the said weight
nearer or further from the centre of suspension the plugs will rest with greater or
less weight against the plates attached to the diaphragm. One end of the row of
plates is attached to a battery, the other end of the row being connected to the
primary wire of an induction coil.
Where ordinary receivers are employed we make use of a flexible tube to contain
the wires, and so preserve them from injury, thus obviating one of the objections
to the use of wire conductors between the case containing the apparatus and the
telephone receiver.
Suitable forks are provided, in which the receivers at the ends of the tubes are
placed when not in use, the said forks also acting as switches for detaching the
battery and placing the bell in circuit in the ordinary way.
An ordinary electric bell and stud is fitted to the apparatus.
But to make our Invention better understood we will now proceed to describe
the same by reference to the accompanying Drawing, in which Figure 1 is a back
elevation (the case being removed) of a "transmitter "
with our improvements
applied thereto; Figure 2 is a plan of Figure 1; and Figure 3 is a vertical section
of the same; Figures 4 and 5, front elevation and plan respectively of the complete
apparatus. Figures 1 to 3 are drawn full size, and Figures 4 and 5 half full size.
Similar letters in all the Figures represent similar parts.
a is the thin plate or diaphragm of wood attached to the outside cover b of the
case of the apparatus and at a short distance therefrom, as shewn; dis the opening
in the cover, the said parts being of ordinary construction.
e, e, c, are the thin plates of carbon or other suitable material placed side by side,
across, and attached to the diaphragm a; f, f, are the brackets carrying the metal
rod or bar g, on which rod loosely hang the metal arms h, h; i, i, are the plugs
of specially prepared carbon or other suitable material in the lower ends of the
arms h, the ends of the plugs i resting against the plates e. In the Drawing
twelve arms are shewn arranged in series, but this number may vary. We
prefer to use twelve to sixteen of these arms and plugs, which numbers we have
found to answer well in practice, and we arrange them in series of three or four

page_text: respectively, so that a current of electricity to traverse the whole must pass over
successive sets. Each arm h is provided with a threaded rod j for receiving an
adjustable weight k, to allow of varying the weight or pressure of the plugs i
against the plates e. In the Drawing the arms h are shewn as being suspended
vertically; they may however be placed horizontally, or a fixed weight may be
used in place of the adjustable one.
The object of using a row of plates and suspended arms is that the whole of the
vibrations of the diaphragm may be utilized, resulting in more powerful undulatory
currents passing to the coil.
is the wire connecting one end of the row of plates e to the battery, and m the
wire connecting the other end of the row of plates e to the primary wire of the
induction coil (placed for convenience in the saine case), there again setting up
secondary currents which pass to the receiver at the distant station, which receiver
may be of any of the usual forms.
Ŏr the secondary current before it reaches the receiver at the distant end may
be made to pass through coils of wire attached to a magnet placed near the
diaphragm, so that a series of undulatory currents corresponding with those
originally sent are set up in the diaphragm and reproduced in the receiver, thereby
augmenting the force of the vibrations, and emitting a louder sound.
In the views shewn in Figures 4 and 5, n, n, are ordinary receivers; o, the
flexible tubes we employ to protect the wires p, p, from injury; 9, 9, are the forks
in which the receivers are placed when not in use, such forks also acting as
switches; r is the ordinary electric bell, which "owever may be dispensed with.
Having thus described the nature of our said Invention, and the best means with
which we are acquainted for carrying the same into effect, we wish it to be under-
stood that what we claim is,―
Firstly. The manufacture and use of telephone transmitting apparatus, having
series of loosely hung metal arms carrying plugs of suitable material resting on
plates, also of suitable material, arranged and operating substantially as and for the
purpose hereinbefore described and represented in the accompanying Drawing.
Secondly. The method of protecting the wire conductors connecting the ordinary
telephone receivers with the case containing the apparatus by enclosing the said
conductors within flexible tubes, substantially as described and shewn.
In witness whereof, we, the said John Thomas Gent and Henry George
Ellery, have hereto set our hands and seals, this 22nd day of November,
in the year of our Lord One thousand eight hundred and eighty one.