Improvements in Telephone Central-station Apparatus.
Year: 1888

page_text: Date of Application (in United Kingdom) 12th Oct., 1888
Complete Specification Left, 12th Oct., 1888
Complete "pecification Accepted, 16th Nov., 1888
Đ
COMPLETE SPECIFICATION.
Improvements in Telephone Central-station Apparatus.
We, THEODORE NEWTON VAIL, of Boston, County of Suffolk, State of Massachusetts,
United States of America, Electrician, and JOHN ASHBY SEELY, of New York, County
of New York, State of New York. United States of America, Electrical Engineer, do
hereby declare the nature of our joint invention for TELEPHONE CENTRAL-STATION
APPARATUS, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
Our invention is an improvement in the arrangement of telephone apparatus,
whereby intercommunication between distant points is facilitated, while the space
occupied and the expense of erecting and maintaining such apparatus are reduced.
Our improvement consists in connecting every sub-station line of a group in
multiple arc with an operator's head telephone and in terminating every sub-station
line of a group in a flexible connecting-cord normally resting by force of a gravity or
equivalent take-up upon strips, conductors, or connections forming the terminals of said
operator's telephone. By this means no preliminary signal is necessary, the sub-
station merely removing his telephone and speaking into the transmitter his own
number or designation and the number or designation of the sub-station required.
The details and arrangement of such a sub-station, with certain novel and improved
features, we have described in another application, to which reference may be had,
No. 18779 of 1888.
The drawing illustrates a series of metallic circuits entering a central station,

page_text: passing through a series of multiple boards, and terminating in a group upon one of
these boards.
The circuit C Centers the first board, G³, passes through a spring jack j, forming
one of the aggregate number on that board, then through a similar jack on the second
board, G2, and terminates, let us suppose, in a group on that board in a flexible cord, m,
having a double-contact plug, p, q, the two insulated contacts at its base resting upon
continuous strips or contacts 100 and 101. These strips or pairs of strips form the
terminals of the opposite ends of line circuits, and also the terminals, respectively,
of a local circuit, 90, 91, containing a head telephone, T, and a transmitter, T', which
are continuously in position for use by the operator assigned to that particular group.
It is to be observed, therefore, that the operator's head telephone and all the sub-
station circuits of the group are connected in parallel circuit, and any order or request
telephonically transmitted by a sub-station will be heard by the operator assigned to
the group, who raises the plug pg and places it in the jack of the called-for circuit,
which jack constitutes one of the aggregate number on the same board. Each operator
has push-buttons for ringing in either direction and keys for looping a telephone into
a circuit after it has been removed from its normal position..
c indicates two separate push-buttons, a similar pair being assigned to each circuit
of a group. They consist of cylinders of insulating material, each having two bends
of conducting material, 7 and 9, 8 and 10. 15, 17, and 19 are three sections of con-
ducting material, as are also 14 16 18. These sections form a continuous conductor,
including the bands 9, 11, 10 and 12, when the buttons are in a normal position.
1 and 2, 3 and 4 are bars of conducting material, each forming the terminals of a
generator.
5 and 7, 6 and 8 are contacts for uniting the line and generator when the buttons
or either of them is depressed.
SS are springs for returning the buttons ce to their normal position. The metal
strip 21 furnishes a suitable bearing for the lower end of these buttons.
There is also a looping in apparatus for each circuit. This is designed for use when
the plug is lifted from its norinal contact and it is necessary or desirable to listen to
operations on the connected circuits. We provide electrical connections 40, 41 from the
telephone set T to two contacts 42, 43, and the sub-station circuit is electrically con-
nected to two contacts, 44 45, as shown, so that by depressing button d a telephone set
is connected to the circuit independently of the normal position of the apparatus and
without disturbing the two circuits connected together for conversation.
Y,
We will now describe the operation of receiving a call and connecting two sub-
stations. Our operator has the head telephone in position. This telephone is normally
connected with one hundred circuits, let us suppose. A call is heard, "200 on 900,"
the first being the number of the calling station, the second that of the station called
for. The operator immediately raises plug pq of the circuit 200, and, if circuit 900
is idle, places said plug in spring-jack 900. This breaks circuit 900 at points ¹¹¹ in
its jack, and the points p and of the two contact-plugs connect with points a and
respectively. The two metallic circuits now form one continuous metallic circuit
containing a clearing out annunciator at the central station only, being free from the
central-station telephone, because all behind the jack j of circuit 900 is cut off and
the plug of circuit 200 is lifted from its telephone-contact. The central station now
depresses the rear push-button to signal the called-for sub-station, circuit passing from
circuit 900 to plug p 9, thence via. elements 18, 12, 8, 4, B1, 3, 6, and 19. The
called-for station responds and the conversation is carried on, as is well understood.
Should the central-station operator desire to listen key d is depressed, connecting
42 with 55 and 43 with 44, circuit being from the transmitting-station to plug p 9,
thence via cord m to point 45, 42, 40, T T¹, 41, 43, and 44, to cord m.
When
conversation is concluded, the calling-station sends an impulse from a generator to
line, dropping the annunciator, and the parts are restored to their normal position by
the operator.
We have shown a spring-jack having a dust-guard, p; but this feature of improve-
ment we have described and claimed in another application, No. 14110 of 1888.

page_text: Having now particularly described and ascertained the nature of our said joint
invention and in what manner the same is to be performed, we declare that what we
claim is
1. The combination of a central station, a series of sub-stations, a series of metallic
circuits, one for each sub-station, connected in parallel at said central station, a tele-
phone instrument for each circuit at the sub-station, a receiving telephone at the-
central station in a local circuit having fixed electrical contacts, two separable contacts
for each metallic circuit, and a suitable device for separately connecting and discon-
necting the two terminals of each metallic circuit with the terminals of the local
circuit, substantially as hereinbefore described.
2. The combination of a series of sub-stations, a central station, a series of metallic
circuits, one for each sub-station, a telephone-instrument for each circuit at the sub-
station, a receiving telephone at the central station, a local circuit having fixed
electrical contacts in which the receiving telephone is permanently located, a flexible
cord forming the terminal of each circuit, and a double-contact switch-plug for each
cord having electrical contacts registering with the fixed contacts of the local circuit
and normally resting thereon, whereby all circuits are connected in parallel with the
receiving-telephone, and any circuit may be connected and disconnected therewith
independently, substantially as hereinbefore described.
Dated this 26th day of September 1888.
THEODORE NEWTON VAIL.
JOHN ASHBY SEELY.