Improvements in and connected with Telephonic Apparatus.
Year: 1893

page_text: Date of Application, 16th Dec., 1893-Accepted, 3rd Mar., 1894
COMPLETE SPECIFICATION.
Improvements in and connected with Telephonic Apparatus.
We, CLÉMENT BOXNARD, of 206, Rue de Vaugirard, Electrical Engineer, and
FRANCOIS AUGUSTE PIAT, of 10, Rue St. Martin, Doctor of Law, both in
Paris, in the Republic of France, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The object of the present invention is to dispense with the central station in
private telephonic systems, by enabling each of the subscribers in the system to be
placed in direct communication with any other without interfering with the
conversation being carried on by any subscribers who may be already in
communication.
In the accompanying drawing,-
Figure 1 is a front elevation of a subscriber's set of instruments in the improved
telephonic system.
Figure 2 is a plan of the same, and,
Figure 3 is a rear view the back being removed to show the internal mechanism.
Figure 4 is a diagrammatic view of the connections.
Figures 5 to 14 are views in detail of the principal parts.
Each set of subscribers instruments of which there may be any desired number
comprises a wooden box a screwed to a base a¹ and provided with as many
windows as there are stations with which the subscriber may desire to com-
municate. Beneath the windows, arranged in a horizontal line and corresponding
in number with the windows, are holes a², each of which will receive a connecting
plug (Figures 1, 2 and 8) and below and opposite each of these holes a' an
indicator plate a³ is fixed to the plate a.
Opposite each window », but inside the box a, an indicator & can be caused to
appear, as will be hereafter described.
The front of the box a forming a table, is furnished in addition with a special
indicator plate, which can be concealed by a falling screen ³ (Figure 14) with a
call push & with a hook c on the right hand side for hanging up the receiver t', with
a bells and with a microphone or transmitter r.
On the upper part of the box a are arranged the screws b, b', 63, 6, (corresponding
with the lines from the various stations with which the one under description is
connected,) the screws, y (connected respectively with the positive and negative
poles of the battery) and the screws and t, the former of which corresponds with
the special line of the station, and the latter with the return wire.
On the call push d inside the box a rest (see Figures 4, 5 and 6) two plates d²,
acting as springs the said plates being fixed by screws to the box a and provided
with contacts pressing upon two plates of metal ³, d similarly screwed to
the box a.
A plate e having spring contacts e¹ (Figure 6) is mounted on pivots e° (Figures 3
and 5) fixed to the box a and is provided at its lower end with a prolongation e³
(Figure 6) which presses upon the call push dowing to the action of the spring e³,
which is constantly tending to press back the plate e. When the push & is pressed
the plate e is caused to swing so that the springs e¹ come into contact with the
studs ƒ', ƒ³, ƒ³, ƒ'^ which are imbedded in a block g of ebonite, and correspond
severally with the screws g', g', g³, g', connected by conducting wires to the electro
magnets, (Figure 4).
The plate when it is pressed by the push d, comes into contact with another
plate of metal h. fixed on the box a. This plate is connected by a conducting

page_text: wire with another plate i (Figures 3, 7, 8) which is fixed to the box a upon a plate
of insulating material which prevents the plug f from coming into contact with it
when the said plug is inserted in the hole F. The plate i can come into contact
with one or other of two metallic plates or according as it is or is not pressed
upon by the plug f.
Each of the indicators is fixed on the end of a magnetized bar k
(Figures 3, 9, 10) which carries a kind of hook of copper acting as a counterpoise
and tending to keep it in a vertical position except when it is attracted by the
electro magnet k³. The bar is adapted to oscillate on a fixed axis A³
(Figures 9 and 10) and the said bark and electro magnet are placed upon a
copper support upon which presses a metallic plate connected by a conducting
wire to one of the screws, 6, 12, 3. The hook c, which supports the receiver t¹,
is fixed internally on the lower side of the box a through the intervention of a
spring plate and carries near its centre a block of ebonite traversed by a
a metallic pin c³, which presses (Figures 3, 11, 12) upon the three spring
plates m, m³, m³, fixed by screws to the box a and connected respectively by
conducting wires with the plate i¹ the plate d' and the screw t.
ma
A metallic plate n (Figures 3, 13, 14) fixed to the box a, supports an electro-
magnet and its armature ³, the said armature being subject to the action of a
spring plate n, the action of which is controlled by a screw . By means of an
arm no, secured to the armature, the latter is caused to act upon an end of a lever P
at the other end of which is a hook which retains the screen. The motion of this
arm n also causes the operation of the hanımer of the bells which latter is placed
at the lower left hand corner of the front of the apparatus.
The metallic support n has the conductor which conveys the current to the
electro-magnet n' connected to it, and it is also connected by a conducting wire to the
transmitting microphone r. The support of the vibrator screw n is connected by
another conducting wire to the plate d², and two metallic contacts u and u², against
which the shank of the hook e lies when the pin is in its highest position, are
connected, to the metallic plate m', and to the wire of the receiver t respectively.
In order to explain the mode of action of the system of telephone circuits
above described it is necessary to refer to the diagrammatic view (Figure 4)
in which the letters of reference used above are made to apply to the same parts.
In a state of rest, the plug of each station should be placed in the hole F.
If now, for instance, the subscriber at station No. 1. desires to open com-
munication with say station No. 2, the plug of station 1 is placed in that one
of the holes a which corresponds with station No. 2. the said plug coming into
contact with the plate k, and causing it to leave the support k*.
The push & being now depressed the current is sent into the line of the station
called up, into which it enters by the screw 4, passing into the electro-magnet n³,
operating the bells and causing the arm n³ to press upon the lever P disengages
the screen whereby the plate v³, which may have (for instance) the word
"ANSWER" upon it is uncovered. The person called up is thus informed by
the bell and by the signal, that someone desires to speak with him, if he is
out he is informed on his return by seeing the signal, which is uncovered.
In any case, he knows that someone is, or has been, desiring to speak with him,
but is so far ignorant as to the station from which the call came. He, in his
turn, presses the button d at his station, leaving the plug fin the hole F so that the
contacts are connected with the negative pole of the battery by the plug,
as may be easily seen by examining Figure 4, the said plug f making contact
between the plates i and . The current arriving at the block ġ will only be able
to pass (in spite of the fact that all the lines are in conuection at the moment) by
that stud therein which offers to it a closed circuit, formed by the insertion of the
plug at the calling station. The current reaching this station by its own line
corresponding with the screw 1, passes through the inagnet k³ of the station
called up, and attracts the corresponding magnetized bar which descends and
takes up a position opposite the window. which corresponds with the calling
む

page_text: station, thus indicating to the person called up with what station he is in com-
munication, he then introduces the plug finto that hole a² which corresponds to the
calling station and puts the receiver t to his ear, whereupon either person can speak
to the other, in short, the apparatus is ready for operation in the same way as any
of those at present in use.
If two stations are already in communication and a third station introduces its
plug into the hole a corresponding with one of them, the subscriber at station No. 3
by reason of induction listen to the conversation already proceeding. To obviate
this inconvenience I employ the following arrangement :-
When two stations are in communication the one with the other, a completely
closed circuit is formed, the current re-entering each station at 1 and passing
through the electro-magnet n' which attracts the armature n³, the result of which
is to open the circuit between n² and n leaving the electro-magnet, the current
passes to the transmitter r the receiver t', the plate u and from there to the
positive pole of the battery through which it passes to the plug f. If then at a
third station the plug is introduced into one of the holes a as has just been said,
the armaturen cannot be attracted, the electro-magnet n' being on an open circuit,
the induced current will thus at the third station take the course l, n', n², n², d², dª, u
and from the latter to the battery to reach the plug f, it will thus fail to pass
through the transmitting and receiving apparatus, which will be short-circuited.
The consequence of this arrangement is that in the telephonic system now under
description the conversations are absolutely secret. In cases where apparatus of
high resistance is used, it is preferable to employ a relay to work the bell and to
make the latter independent; in this case the necessary connections at each station
may be suitably modified.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
1. A telephonic system adapted for automatic intercommunications, without a
central station, cach station in which can call up auy other immediately, and can
communicate with it without interfering with the conversations of any other
stations which may be in communication with each other, each station comprising a
case furnished with windows corresponding respectively with the windows of the
other stations in the system, behind which windows may be exhibited signals
carried by magnetized bars, oscillating under the influence of the electric current
in magnets arranged for this purpose, with holes, connectors corresponding
severally with the other stations in the system and with a plug which can be
inserted in the hole corresponding to the station with which one wishes to com-
municate and with a call push, au electric bell, a transmitter, and a receiver, the
last named being hung on a hook when the station is at rest, in order that its weight
may keep down this hook which connects up contacts suitably disposed, and which
when the receiver is taken off rises and connects up other contacts, substantially as
described.
2. The arrangement of the case placed at each station, carrying the transmitter
and the receiver, and the binding screws for the line wires (which latter are equal
in number to that of the stations plus one return wire) the local battery and the
bell the latter being operated by an electro-maguet traversed by the current of the
special line of the station, substantially as described.
3. In the stations as described the following arrangements:-
(a.) An electro-magnet the armature of which is furnished with an arm which
can act, on the one hand on a hooked lever which holds in position a
moveable screen under which is an indicator plate, and on the other hand, on
the hammer of a bell.
(b.) A plate acted upon by a spring and oscillating on pivots when the call
push is depressed upon, so as to make contact with studs connected to
electro-magnets.

page_text: (c.) Electro-magnets in suitable number acting, when they are traversed by an
electric current, on magnetized bars provided at one end with indicator -
signals, and at the other end with counterpoises which tend to keep them in
a vertical position.
(d.) A plug which can be introduced into a hole corresponding to the state of
rest of the apparatus, or into other holes corresponding with the electro-
magnets previously mentioned in communication with the various stations.
4. The apparatus consisting of the parts combined and grouped, substantially in
e manner described and shewn in the accompanying drawings.
Dated the 16th day of December 1893.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.