Year: 1888

page_text: Date of Application (in United Kingdom), 24th Sept., 1888
Complete Specification Left, 24th Sept., 1888
Complete Specification Accepted, 23rd Mar., 1889
We, THEODORE NEWTON VAIL, of 190 Walnut Street 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 switches, circuits, and
apparatus for use at a sub-station in a telephone-exchange.
The arrangement is designed for use in connection with our improved arrangement
of apparatus at a central station, described and claimed in another application for
Letters Patent, bearing even date herewith, No. 1377888.
We will assume that the central-station operator has a telephone continuously
within audible distance and reproducing or receiving telephonic communications from
a series of circuits, means for connecting any two circuits, means for ringing up,
means for listening in connected circuits, clearing-out annunciators, and all other
necessary appurtenances to a telephone central-station exchange, and that the sub-station
has the usual arrangement of gravity-switch, main-line brauches, hand-telephone, and
current-varying transmitter, with one or more cells of local battery, but no magneto-
generator.
It is our design that a subscriber on one circuit desiring to communicate with a
subscriber on a second circuit shall be connected by the central station upon request,
and for that purpose the subscriber shall proceed as follows: Removing the telephone
from its support upon the gravity-switch without preliminary ringing or signalling,

page_text: he speaks his own number or designation and the number or designation of the desired
correspondent. He immediately follows this by connecting a generator of electricity
giving a constant current into the line. This will energize his electro-magnetic bell,
bringing its armature into an attracted position. If the central station bas heard his call,
his circuit will be momentarily broken while the necessary connection is being made at
the central station, and the act of breaking circuit is rendered audible upon the sub-
station bell in the form of, say, one or two strokes. The generator is now removed
and the telephone may be again taken from its position of rest and conversation
carried on until finished. The gravity-switch is so improved by us that the act of
hanging up the telephone sends an impulse of electricity from a generator to the
central-station clearing-out annunciator; but the operation of removing the telephone
does not produce such an effect. The connection is now broken at the central station
by the operator, who has noticed the fall of the clearing-out annunciator-drop.
For the purpose of connecting a battery or generator to line after a call and before
a connection is made we provide a supplementary spring-retracted switch-arm, with
connections so arranged as to introduce a cell of battery into the line when the
normal position of said arm is varied, as by depressing it.
Our improved arrangement, then, while operating harmoniously with our improved
central-station apparatus, obviates the necessity for a magneto-bell, which is so
expensive and somewhat liable to disarrangement. At the same time the necessary
operations of a subscriber are simplified, enabling us to attain increased speed and
great expedition in securing the desired connection.
The accompanying drawings illustrate our invention.
Figure 1. shows the apparatus in its normal position. Fig. 2. shows the telephone
off the gravity-switch arm, the request having been transmitted, and the supple-
mentary arm depressed, awaiting a return-signal. Fig. 3. shows the telephone just
placed upon its hook and the arm in its descent closing contact to ring off
automatically.
Referring to Fig. 1. g, is the usual arrangement of gravity-switch applied to a
metallic circuit, L, L'. There is added an insulated contact, p, connected by a wire, 75,
to a point in the local circuit, 7. m, is a fixed bearing supporting the three-armed
lever, n, q, r, freely movable, but having the position of its centre of gravity varied
by the position of the arm, q. o, is a hook attached to arm, g, taking against the lever-
arm, r, when the switch-arm, g, ascends. This three-armed lever is what might be
called a "tumbler lever" and is electrically connected by wires 99 and 40 to a point
in the main circuit, L. When the telephone is lifted from the hook, o, engages
with r, and after carrying, r, a short distance so far changes its center of gravity that
it falls into the position shown in Fig. 2. no effective electrical contact being
established. When the telephone is hung upon arm, g, the descent of said arm, as
represented in Fig. 3, establishes contact between, p, and, r, thus temporarily
connecting battery, B, into the main line via elements L, 40, 99, m, r, p, 75, 80, i,
B, 101, to L, and the three armed lever falls into the normal position shown in Fig. 1.
It will thus be seen that a battery is connected to line only when the telephone is
hung up, as at the conclusion of a conversation.
The second improvement upon the ordinary and well-known arrangement at a sub-
station consists in the use of a supplementary switch-arm, by the operation of which
a generator may be connected to the main circuit for the purpose of signalling.
a,
is a spring-retracted pivoted lever.
1, is a conducting-plate fixed to an insulating-bushing upon the lever, a.
j, is a similarly placed un-insulated conducting-plate. k, is a fixed contact for
electrically uniting , and, . Conducting-strips, 5, and, 6, are the terminals of the
divided telephone branch, 50, 51. Conducting-strips, 7, and, 8, are the terminals of
the divided primary circuit, 80, 81, of the transmitter, t.
When the supplementary lever, a, is depressed, circuit passes via elements,
L, a, j, k, l, 7, 80, i, battery, B, 101 to L¹.
The operation of transmitting a call and communicating telephonically is as follows:
The apparatus being in its normal position, as shown in Fig. 1, telephone, T, is lifted

page_text: from its hook and the gravity-switch, g, changes circuit from the bell branch via
L, b, 40, 41, 4, 9, 100, L', as shown in Fig. 1. to the telephone branch via
elements, L, 50, 5, 3, 6, 51, T, 52, 1, 53, 2, 1, 100, L', as shown in Fig. 2, and tilts
the three armed lever, n, q, r, into the position there shown. Without preliminary
signalling, the required connection is vocally communicated, the telephone placed in
its normal position, and the lever, a, immediately depressed, circuit now being, as
shown in Fig. 2. via elements, I, b, u, j, k, 1, 7, 80, i, B, 101, to, L'. The bell-magnet
armature is attracted by the closed electrical circuit, but the operator at the central
station in responding to this request incidentally breaks this circuit in transferring
the calling-line into connection with the required line, and the bell-magnet armaturo
drops off during such break, thus indicating to the sub-station that the call was
received and acted upon. The sub-station then allows arm, a, to resume its normal
position, and, taking down the telephone, speaks into the transmitter, t, in the usual
manner.
After finishing the conversation, the telephone is restored to its position. Fig. 3,
shows the connection between, p, and, r, established by this operation. Circuit being
temporarily via elements, L, 40, 99, m, r, p, 75, 7, 80, i, B, 101, to L', the ringing off
drop at the central station falls and the said station returns the wires to their normal
position.
It is to be noticed that in case the central station operator does not receive and
respond to the first announcement of a required connection the operation of replacing
the telephone and depressing arm, a, has connected battery to line and the clearing-
out annunciator has been operated, so that in no case will the sub-station fail to
receive proper attention.
We may employ a separate battery for use in calling, instead of using the trans-
mitter battery for all requirements.
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, at a telephone station, of a switch or circuit changer consisting
of a pivoted arm connected with the main line, an electrical contact connected with a
main-line branch containing a telephone, a second electrical contact connected with a
main-line branch containing an electro-magnet for operating a call or signal, an
electrical contact connected to a generator of electricity, an electrical contact connected
to the main line, and means, substantially as hereinbefore described, for temporarily
connecting the two last-named contacts upon movement of the arm in one direction
only.
2. At a telephone-station, a switch or circuit changer consisting of a pivoted arm
forming a support for the telephone and capable of movement in two directions, a
retractor for producing one movement, the gravity of the telephone when placed
thereon producing the other movement, a main line connected to said arm, an
electrical contact connected to a main-line branch containing a telephone, and a
contact connected to a main-line branch containing an electro-magnetic signalling-
instrument, in combination with two additional contacts, one of which is connected to
the main line, the other to a generator of electricity, and a tumbler-lever temporarily
forming an electrical connection between the last-named contacts upon a movement
of the arm in one direction only substantially as herein before described.
3. At a telephone-station, a switch or circuit changer having a contact with the
main line, a contact with a telephone branch, and a contact with a bell branch,
combined with a second switch or circuit changer having two contacts, the first
connected to a generator of electricity and the second to the main circuit, whereby,
when the second switch is operated, the generator and main line are connected
during the process of calling and preliminary to conversation substantially as herein-
before described.
4. The combination, at a telephone-station, of a main line, a contact-varying
telephonic transmitter, a local-battery for said transmitter, an electrical connection

page_text: from one side of said battery to the main line, and a switch or circuit changer having
a fixed contact and a movable contact, and an electrical connection from one of said
points to the battery and from the other contact to the line, all arranged substantially
as hereinbefore described, whereby the operation of the switch includes the said
battery in the line for the purpose of signalling.
5. The combination, at a telephone sub-station, of a main line, a branch line
containing a bell or signalling-instrument, a second branch containing a contact-
varying telephone-transmitter, a local circuit therefor, means for connecting either of
said branches with the main line, a supplementary switch or circuit changer embracing
a pair of circuit-closing points in the local circuit, a pair of circuit-closing points in
the transmitter branch, and a movable arm normally in position to close both said
pairs of points, a battery-contact, and a main-line contact electrically united by the
operation of said switch substantially as hereinbefore described.
_ Dated this 4th day of September 1888.
THEODORE NEWTON VAIL.
JOHN ASHBY SEELY.