IMPROVEMENTS IN AND CONNECTED WITH TELEPHONIC TRANSMITTING APPARATUS, SPECIALLY ADAPTED FOR PAN- TELEPHONES
Year: 1881

page_text: PROVISIONAL SPECIFICATION leſt by Ernest de Pass at the Office of the
Commissioners of Patents on the 19th November 1881. A communication
from abroad by Léon de Locht-Labye, of 17, Boulevard Saint Martin,
Paris, France.
ERNEST DE PASS, of the Office for British & Foreign Patents, 68, Flect Street,
in the City of London, Patent Agent. "IMPROVEMENTS IN AND CONNECTED
WITH TELEPHONIC TRANSMITTING APPARATUS, SPECIALLY ADAPTED FOR PAN-
TELEPHONES." A communication from abroad by Léon de Locht-Labyo, of
17, Boulevard Saint Martin, Paris, France.
This Invention relates to improvements in telephonic transmitting apparatus,
and specially in those known as pantelephones, and is characterized by the
employment, in combination with batteries or voltaic currents, of a sound receiving
plate of unpolished wood, cork, or other suitable material, which plato, while
offering a large surface, is of slight weight and freely swings about one of its
points of support, or preferably on the end of spring lovers, said plate carrying a
carbon contact piece, which bears against a stop or abutting piece of carbon or of
metal, such as silver or platinum.
The sound receiving plate or pantelephone is by preference fixed at the ends of
spring arms or rods, which have very great freedoin of movement, allowing the
plate to undergo extensive variations of position under the influence of very feeble
sounds produced by the human voice, whether such sounds be emitted at some
distance or by the ordinary speech under the conditions which are most convenient
for a regular telephonic service.
In order to carry the Invention into effect it was necessary to ascertain by
experiments the most suitable dimensions for a pantelephonic plate, and when
such plate is to be made of cork it has been found necessary to make it of about
80 by 55/ and from 3 to 6º in thickness, and to suspend this plate by flat
springs of steel, copper, brass, or German silver, and it is preferred to provide such
springs with alots and set screws, by means of which the length of the same may
be varied so as to alter the points of contact of the carbon (placed at the lower part
of the pantelephonic plate) with the platinum stop fixed at the end of a jointed or
hinged metallic finger.
One important feature of this Invention is that the movable pántelephonic plate

page_text: and the entire arrangement are placed within a case or box closed by means of a
cover of woven fabric, felt, or other non-vibrating material, which allows the
vibrations of the sound of the voice to pass without altering them.
In order to more fully describe the Invention I proceed to explain by way of
example only a telephonic station provided with this pantelephonic apparatus.
The station consists of the pantelephone or plate with call buttons, a call-bell, a
signalling device continuing to act after the call, a contact breaking switch acting
by the weight of the telephone, and an induction coil.
All these parts are fixed on the back plate of the box or case, which latter is
closed by a sheet of textile fabric stretched in a wooden frame.
The cork plate (of the dimensions above stated) is suspended from a support by
two small springs made of very flexible German silver; a small perfectly even
disc of carbon fitted in the lower part of the plate is connected by a wire passing
along the plate with the circuit and is in contact with a platinum stop fixed to the
end of a small metallic finger provided with a suitable joint or hinge at its other
end; the said finger may be caused to bear more or less heavily against the plate,
and to thus ensure contact of the surface of the carbon with the platinum stop
throughout the length of this latter.
The pantelephone is established in the electric circuit of a battery in such a
manner that the current passes as herein after described.
In this arrangement 8 terminals outside the box are employed, the two outside
ones receiving the ends of the telephone wires.
One of these terminals is connected with the positive pole of the voltaic battery
and serves for the bell calls; another terminal is connected with the positive pole
of the last element of this battery, which is the pantelephonic element.
The negative pole of the battery is connected to the return wire or to earth, and
corresponds with another of the terminals.
Another terminal receives the line wire.
The arrangement of apparatus is identical at the two corresponding stations.
The working of the currents for the calls and for conversation is as
follows:-
The pressure of the finger on the call button in the first station breaks contact
of a spring with its contact piece and establishes contact of the same with another
stop or contact piece.
The electric current flows in the first station through suitable connections, passes
through the line wire to the second station, into whose apparatus it enters by the
linc wire terminal arriving at the signal switch; the current thence passes into the
bobbins of the call bell, whence it flows through the arinature and the spring, and
is conducted to the return wire and rejoins the negative polo of the battery at the
first station.
The circuit being closed the bell rings in the second station, which is thus
called. As soon as the disengagement of the lover is effected by the current a
disc outside the box is uncovered. If the attendant is absent at the moment of
the call this sigual continuing apprises him on his return that telephonic communi-
cation with him is required.
The answer is sent like tho call, then tho correspondents unhook their
telephones and place them to their ears, and keep them applied during the
conversation.
They can then speak in a natural tone without fatigue and without necessarily
approaching the apparatus.
In most cases it is sufficient to hold one telephone only to the ear, but it
must be always the right hand one, which must be unhooked to work the switch
lever.
The switch lever is brought against a terminal within the box at the same time
as contact of a small spring with its stop or contact piece is established.
Every modification of the current effected by the varying resistance in the
microphonic contact arrangement causes an instantaneous current in the outer

page_text: coil of an induction bobbin, which current flows through the line and the telephones
at the two stations.
This telephonic current follows the line wire, passes through one telephone (the
right hand one) and on to the other (the left hand one), one of whose wires is
attached to the interior wire of the induction bobbin, the other end of said wire
being attached to a terminal (negative pole one).
This current thus flows to the receiving station, in which it takes the opposite
path, and the circuit is closed by the line wire.
At the end of the conversation the telephones are suspended on their hooks,
and the signal is raised at each station..
All the setting of regulating that is required consists in causing the joint or
hinge of the stop or abutting piece to work in such a manner that close contact is
produced between the carbon plate and the platinum stud, and in modifying (by
means of the inclination of the plate) the more or less heavy pressure on the stop.
This setting offers no difficulty, as there is more than a centimeter distance between
the extreme positions of the stop, which allows conversation to be carried on under
ordinary conditions.
"
Instead of suspending the pantelephonic plate it may be arranged in unstable
equilibrium by using variable arrangements.
For signalling, the following arrangement may also be used:-Tho circuit
through which the current flows is made to comprise the telephones of the two
corresponding stations, or simply the inductor wire of an induction bobbin, whose
induced coil in such case forms a part of the telephonic circuit. The induction
bobbin of the telephonic transmitter will answer very well for this purpose.
The most simple arrangement is that presented by the friction of a metallic
point connected with one part of the circuit against a rough metallic surface
connected with the other part of the circuit; this metallic surface may consist of a
fragment of a file or of a piece of wire gauzo with close meshes; it is arranged on
the bed plate of the telephonic station like the striking surface for matches.
By causing (by hand) a metal point to pass over the aforesaid roughened surfaco
the current from the battery is alternately opened and closed in the circuit.