Improvements in Telephone Exchange signaling App
Year: 1888

page_text: Date of Application (in United Kingdom), 1st Oct., 1888
Complete Specification Left, 1st Oct., 1888
Complete Specification Accepted, 5th Feb., 1889
Improvements in Telephone Exchange signaling Appare
We, THEODORE NEWTON VAIL, of 190 Walnut Avenue Boston, County of Suffolk,
State of Massachusetts, United States of America, Electrician, and JOHN ASHBY SEELY,
of 18 Cortlandt Street New York, County of New York, State of New York, United
States of America, Electrical Engineer, do hereby declare the nature of our said
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 is an improvement in the arrangement of apparatus for telephonic
signaling between sub-station and central station.
In our improved arrangement of telephone exchange apparatus we avoid the
necessity for the use of special indicating devices to receive calls or requests from
sub-stations, and we only use an annunciator for clearing out purposes.
Our improvement consists in connecting every sub-station line of a group with an
operator's head telephone at a central station, and in terminating every sub station
line of a group in a flexible connecting cord normally resting by force of a gravity
take-up upon conductors or connections forming the terminals of an operator's head
telephone. By this means no preliminary signal is necessary, the sub-station merely
holding his telephone and speaking into the transmitter his own number or designation
and the number or designation of the sub-station required. At the sub-station we
provide means for including a generator of electricity yielding a steady current in
the circuit. This is to be done immediately after speaking or announcing the
correspondent desired, and the call being received at the central station the operator
lifts the jack plug forming the terminal of the calling line preparatory to placing it in
the jack of the called for station's line. The act of lifting the plug temporarily breaks

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the circuit, and the armature of the bell magnet at the sub-station drops off, sounding
one or more strokes, signifying to the sub-station that the call is received and acted
upon that is, it operates as a return signal to the request. }
The accompanying drawing illustrates our invention.
1 is a subscriber's circuit, here shown as à metallic circuit uniting central station, A,
and sub-station B. At A there is a multiple-board arrangement. G, G¹, G are
three spring jacks on three separate boards, through each and all of which the wire 1
passes. This circuit L belongs to a group assigned to board G2, let us suppose. It
terminates in a flexible cord, c, and jack-plug P, held in position by a gravity
take-up, w. The two conductors forming opposite sides of the metallic circuit
terminate in electrical contacts 20 21 on the base of the plug.
22 and 23 are electrical contacts forming the terminals of a local circuit containing
an operator's head telephone set, T. These contacts are in such a position that
contacts 20 21 of the plug rest thereon when the plug is in its normal position, as
shown, so that the circuit 1 normally includes an operator's telephone-set.
In
At the sub-station B, there is a telephone-set T, consisting of a hand-telephone, a
contact varying transmitter with its local battery, and the well known arrangement of
gravity switch for changing the main line circuit from the bell branch to the telephone
branch, and vice versa, and for making and breaking the transmitter local circuit.
addition it is furnished. with a tumbler-lever, i, and special battery connection 17 for
connecting battery to line when the gravity-switch is moving in one direction only to
operate as a "ring-off" signal, this arrangement and apparatus being described and
claimed in another application for Letters Patent filed by us No. 13779 of 1888.
At the sub station there is also a supplementary switch-arm, a, normally closing
contacts 12 13 in the telephone branch and 14. 15.in the circuit of the, local battery.
Lever a carries electrical connections 8 in two insulated sections, one of which, (the
lower) is electrically connected to arın a, the other, 9, is insulated from arm a.
10 is a fixed electrical contact or strip of metal which, when a is depressed, unites
contacts 8 and 9.
The described apparatus operates as follows: Telephone T at the central station is
continuously in audible distance with respect to the operator: The sub-station lifts
his telephone and vocally announces his own number and that of the desired station.
He then immediately depresses lever a. This throws the local battery of the sub-
station in to the main line, circuit being viú, 1, local battery, 14, 9, 10,.8, a, to, 11,
through the plug and telephone at the central station. The circuit is closed and
armature of bell () is attracted. The operator at the central station has heard the call,
: however, and immediately lifts, plug P preparatory to placing it in the called-for-line
jack, but this act breaks the circuit, 1,, 1', temporarily, the armature of bell. C falls off,
striking the gong, and this indicates to the sub-station that his call was received and
acted upon. He then allows the spring retracted arm' a to resume its normal position
and carries on a conversation with the distant station. When through his com-
munication, the act of restoring the telephone temporarily connects and 17, thus
again including the local battery in the main line. This drops the annunciator n and'
the central station operator restores the normal conditions. There is provided at the
central station devices for ringing in either' direction through the batteries 6 b¹,
and there is a looping-in device, L:
We do not herein claim the arrangement of apparatus shown and described' at the
central station, nor that shown and described at the sub-station; as such arrangements
form the subject matter of other applications filed by us respectively numbered 13778
and 13779 of 1888.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The combination of a central: station and a sub-station united by an. electrical
conductor at the central station, a circuit-changing device' consisting of a switch-plug
normally forming part of said circuit at the sub-station, a gravity-switch, a telephone

page_text: branch, a bell branch, a generator of electricity, and a switch for including said
generator in the main circuit, consisting of a pivoted arm operating a line contact,
and a contact connected to said generator, whereby a change in the normal position of
said switch at the sub-station and of said apparatus at the central station produces a
signal irrespective of the position of the gravity-switch, substantially as hereinbefore
described.
2. The combination of a central station, and a sub-station, an electrical conductor
uniting said stations, telephone instruments in said circuit at both stations, a flexible
conductor at the central station normally resting upon a section of conductor to
complete said circuit, a generator of electricity at the sub-station, and a switch for
including said generator in the circuit, all arranged substantially as hereinbefore
described, whereby a change in the normal position of the flexible cord sounds a
signal at the sub-station.
"
3. The combination of two telephone-stations, an electrical conductor uniting said
stations, a fragment of said conductor containing an electro-magnetic indicating
instrument at each station, a device at one station-say the first-for connecting and
disconnecting said fragment with respect to the main circuit, a generator of electricity,
and a device for connecting and disconnecting said generator with respect to said
conductor at the second station, all arranged and operating substantially as herein-
before described, whereby a variation in connection of the line-fragment at the first
station changes the circuit of the generator and sounds a signal at the second
station.
11000