Improvements in Telephonic Systems and in Apparatus therefor.
Year: 1899

page_text: Date of Application, 8th Sept., 1899-Accepted, 4th Nov., 1899
COMPLETE SPECIFICATION.
Improvements in Telephonic Systems and in Apparatus therefor.
We, MAX BYNG, Electrical Engineer, and FRANCIS GEORGE BELL, Electrician,
both of Nos. 69-71-88-92, Queen Victoria Street, in the City and County
of London, 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:—
Our invention relates to certain improvements in telephonic systems, and in
apparatus therefor, and has especial reference to a "reply and call" system which
is a modification of an intercommunication system, and is used in cases in which
it is necessary for a central station to call to, or be called by, and to speak with
a number of substations. Heretofore the central station was provided with
annunciators and spring jack contacts, corresponding in number to the number
of substations, but according to our invention the central station is provided with
an ordinary switch, having as many "ways" or contacts as there are substations,
and each substation has a two way switch representing "reply" and "call"
respectively.
In order that our invention may be the better understood, we have appended
the accompanying six sheets of drawings in which Figure 1 Sheet 1 shows the
internal connections of a ten line instrument for a central station for a system
shown diagrammatically by Figure 2 Sheet 2. Figures and 2 upon the
same sheet show the top and bottom connections of the central A enlarged.
Figure 3 Sheet 1 is a front elevation of an improved two way substation switch,
dispensing with a ringing key. Figure 4 Sheet 3 shows the action of the
switch, and Figure 5 upon the same sheet illustrates diagrammatically the
internal connections of the instrument. Figure 6, Sheet 4 is a diagrammatic
view of the connections and wires of an alternative system upon the lines of the
foregoing, when such substations are used. Figure 7 Sheet 5 is the same arrange-
ment showing a method of coupling any of the substations together upon the
lines of Figure 6 Sheet 4, independently of the central instrument, but through
the medium thereof. Figure 8, Sheet 6 is a similar modification for a like pur-
pose upon the lines of Figure 2 Sheet 2. Wherever possible, similar letters of
reference are used to indicate corresponding parts throughout the several draw-
ings.
In carrying our invention into effect we use at the central station of the
system an instrument shown in detail by Figure 1 Sheet 1, and by A Figure 2
Sheet 2, and Figure 8 Sheet 6, and in this case the only difference between the
central and substation instruments is in that the former has a switch with as
many contacts as there are lines or substations, and each of the latter have a
two way switch, corresponding to "call" and "reply," and are connected as
shown by the diagram Figure 2, Sheet 2.
The method of operation is as follows:-In order that the switch S may be
left in any position upon the central instrument (Figure 1 Sheet 1,) and a call
be received, the connections are arranged so that the line selector controls the
speaking circuit" and ringing key K only. The bell magnet b is always

page_text: connected to the home line H L, and is only thrown out of circuit by lifting the
receiver from the switch hook h. If the circuit be traced from H L terminal,
it will be seen that when the receiver is on the hook h a current passing
along the line would pass to g and thence through the spring contact f to the
hook hand so to the terminal Z E. (Zinc-earth). Therefore this circuit is
always available wherever the switch arm S may be placed, but it must also be
noted that when a call is received the switch arm S must be moved to the extreme
left stud, connected directly to the H L terminal, for reply. And when the
ringing key K is depressed, it directly connects the terminal C with the switch
arm S, completing the ringing circuit through which line the plate it rests upon
may represent.
"
If the operator at the central station A Figure 2 Sheet 2, wishes to call either
of the substations B, C, D, E, F, he places the line selector or switch arm S
upon the plate corresponding thereto, and presses the ringing key K. And if
the central receives a call from either of the substations, the switch arm S must
be placed on the first contact plate (extreme left) for reply, before replying to
the call. And at each substation when it is desired to call the central, the
switch S must be placed on "call" and the ringing key K pressed. When
receiving a call," the switch S must be placed on reply "before replying.
If it be desired to connect any two substations together so that they may
have communication independently of the central station, an addition is made to
the arrangement before described, which is shown by Figure 8, Sheet 6, in which
a connection box Z with sockets is coupled to the lines, and a double plug P P¹
connected by a flexible conductor arranged to connect either of such stations
according to directions sent from a substation to the central station A, and there
controlled.
An improvement on the instruments hereinbefore described in connection
with the reply and call" system is shown in detail by Figures 3, Sheet 1, and
Figures 4 and 5 Sheet 3. Here, instead of a two way switch S at the substations,
and a ringing key K in connection therewith we provide two push buttons p
projecting from the containing case A (Figure 3 Sheet 1). One of these push
buttons is marked "call" and the other "reply" as shown. Thus, if it is
required for a substation to call up the central station, the "call" button is
pressed, and if said substation receives a call from the central, the "reply" button
is pressed in reply, which simplifies the operation. When compared with the
turning of the switch, and also pressing the ringing key, especially in the case
of people at substations that are not expert in such manipulation. Also the instru-
ments are much neater and more compact. The construction of the device may
be described as follows; that is to say;
Referring to Figures 3 and 4, we mount upon a pivot p within a case A,
a Tshaped switch bar or lever M, which may make contact with either of two
contact strips or spring plates w w¹. Two springs C C are fixed on the interior
of the case A, and are so placed that either may be pushed forward by push
buttons which are arranged to pass through the case A and project there-
from. When Pis pressed the arm $ of the T switch lever M is raised by the
spring C being pressed against it, and the contact arm of M is forced into contact
with the plate or spring w¹, and when P1 is pressed, C is in a like manner
pressed against S and by raising it forces M into contact with w. When the
push buttons are released the springs C C cause them to regain their normal
position leaving M in the contact position in which it was last placed. Upon
the spring C is fixed an insulating plate a and a contact point c arranged so
that when Pis pressed the arm S of M does not make electrical contact with C
but when Pis pressed, the first portion of the corresponding movement of S is
by pressure upon a, but the pressure upon P being continued, the last part of
the movement is made by the direct contact of the point c. C is connected
through d to a source of current, so that when e makes contact with S, said
current is connected to M. Thus the first part of the movement of S, due to

page_text: pressure upon P throws M over towards from its prior contact with w, and
the continuation of the pressure upon P, and consequently upon C pushes M
completely into contact with w¹, and thus connects the " call" line with the
current. When P is released from the pressure of the hand C regains its normal
position, and when P¹ is pressed, C¹ not being connected to a source of current,
does not directly connect the current to M, but simply throws M over to the
contact plate or spring w corresponding to the reply circuit. But we may in
some instances arrange an electrical circuit upon C similar to that upon C.
Figure 5, Sheet 3, illustrates diagrammatically the internal connections of the
instrument herein before described, and in which is the reply" line and
u the "call" line, M the switch, P the "call" button and 1" the "reply" button,
A is a
C the battery contact spring, C₁ the push spring as before referred to.
section of part of the containing case B is the battery, S the call bell or buzzer,
I induction coil, X switch of telephone, which may be of the hand micro-tele-
phone type with a switch in the handle, or the ordinary type of wall instrument
in which the switch is actuated by hanging the receiver upon a hook, as referred
to in describing Figures 12 and 8, and R is the receiver and T the transmitter.
We may use at the central station any form or type of telephone or line selector.
Figure 6 Sheet 4 shows a system diagrammatically set forth in which the
substations 1, 2, 3, 4, 5, 6, are according to the device and arrangement herein-
before described with reference to Figures 3 4, and 5, and the central station
instrument is in accordance with the Specification of Letters Patent granted to
us, No. 16877 A.D. 1898. Now, in Figure 5 and the description thereof, we
have shown that if the ringing key of the central station be depressed, the current
is sent from u to the bell coils S, to terminal plate r, thence to contact g of
telephone switch, and to lever X and to terminal Z E which is connected to the
return wire of the system. In "reply" the substation operator presses 1"¹, and
takes up the telephone, causing X to break the circuit at X with q, and make
contact with o o, when it is open to speak. The circuit is now as follows;
that is to say is connected to contact w, lever M, the secondary winding of
the induction coil I, receiver R switch contact o, switch lever X and terminal Z E.
The local microphone circuit commences at m of the battery B, thence to ter-
minal M, C, primary winding of induction coil I (the secondary and primary
windings being indicated by thin and thick wires respectively) to the trans-
mitter T, contact o¹ of the switch switch lever X, and thence to terminal Z E and
the zinc terminal of the battery B. If, instead of receiving a call any substation
wishes to call up the central the push P is pressed, throwing the arm M. into
contact with u, and at the same time connecting the battery B through C
to M, w¹ and w¹, and so to the central through the bell, completing the circuit
by the return wire. With reference to Figure 5 the six substation circuits may
be followed as shown by the diagram Figure 6 Sheet 4.
So far as described the system only allows of calling or speaking to the central
station from any of the substations, but by the addition of a plug or switch
board Z (similar to that herein before described with reference to Figure 8,
Sheet 6) fitted at the central station, and shown by Figure 7 Sheet 5 of the
appended drawings, each substation may be put into direct communication with
another by the action of the operator at the central. The method of operation
would be as follows;-
We will presume that substation No. 1 (Figure 7) calls the central and intimates
a wish to speak to No. 3, and after the call, presses the reply button on the local
instrument. The operator at the central then turns the line selector to No. 3,
presses the ringing key, and waits for No. 3 to reply. The plug switch is pro-
vided with a flexible conductor carrying two plugs p, p¹. When No. 3 replies,
the operator at central states that No. 1 desires to communicate, and then inserts
one plug in No. 1 and the other in No. 3, listening meanwhile at his receiver
to assure himself of actual communication, which when established, enables him
to hang up his téléphone, and leave the two stations 1 and 3 in communication.

page_text: 66
The chief advantage of this system according to our invention is in that no
ring off" is required, since the next time the substations Nos. 1 and 3 are using
the telephone, the simple fact of pressing the "call" push would disconnect them
from each other, even if the plugs 2 2 were left in situ at the central according
to the last position thereof. Further, the operator can, from the central station
ascertain whether the substations Nos. 1 and 3 have finished, by listening through
his receiver, having the switch or selector on Nos. 1 or 3. And the central
station may at the same time be in communication with any other of the sub-
stations, whilst two are in communication with each other, as aforesaid. It is
open for the operator at the central station to plug any two substations together
by the board Z together by the board Z and plugs p p¹ before calling the sub-
station requiring such communication.
The addition of such a plug board, or like connector between substation ter-
minals is a distinct feature of our said invention and is illustrated in both cases
by Figure 7 Sheet 5 and Figure 8 Sheet 6 of the drawings.
Having now particularly described and ascertained the nature of our said
invention, we declare that what we claim is :.
First. In a telephonic system with "call" and "reply" circuits connecting
substations with a central station, the construction and employment of a two
way switch actuated by two push buttons in either direction substantially as
herein described and shown by the appended drawings, with especial reference to
Figures 3, Sheet 1, 4 and 5 Sheet 3, and Figure 6 Sheet 4.
Second. In a telephonic system with "call" and "reply" circuits connecting
substations with a central station, the combination of a two way switch actuated
by push buttons so that the movement that alters the position of the switch connects
a source of current temporarily or permanently to the circuit with which the
switch arm is then brought into contact, substantially as herein described and
shown by the appended drawings.
Third. The combination of connections and instruments constituting the
telephonic system shown by Figures 3, 4 and 5 and the diagram Figure 6 of the
appended drawings, substantially as described and set forth.
Fourth. In a telephonic system with "call" and "reply" circuits connecting
substations with a central station, the use of a plug board Z with connecting
plugs or equivalents zz for connecting any two substations together substantially
as herein described with especial reference to Figures 4-5-6-and 7 of the
appended drawings.
Fifth. In a telephonic system with "call" and "reply" circuits the employ-
ment of a plug or switch board for connecting two substations together from the
central; in cases where an ordinary two way switch is used for "call" and
reply" with especial reference to Figure 2 Sheet 2 and Figure 8 Sheet 6 sub-
stantially as and for the purposes herein described.
Sixth. In a telephonic system with "call" and "reply" circuits the method
of, and means for ensuring that the central station circuit in a condition of rest
does not offer a "shunt" or branch circuit to the speaking circuit, when the
switch arm is resting upon the contact plate of either substations whilst com-
municating as shown by Figure 7 Sheet 5 and Figure S Sheet 6; substantially
as herein described.
Dated this 20th dow of 1000
FREDK, WALKER.
73, St. Stephens Road, Upton Park, London, E.,
Agent for the Applicants.