Year: 1887

page_text: Date of Application, 23rd Dec., 1887
Complete Specification Left, 22nd Sept., 1888
Complete Specification Accepted, 26th Oct., 1888
We, DAVID JOHNSTON SMITH, Secretary of the National Telephone Company, and
DANIEL SINCLAIR, Electrical Engineer, both of Royal Exchange Buildings, in the
City of Glasgow, do hereby declare the nature of this Invention to be as follows:-
In working telephonic exchanges, connection between subscribers is, under the
ordinary practice, made by means of a wire cord, having in its circuit a ring off
indicator, and provided at each end with a plug which is inserted in a jack forming
a terminal for each subscribers line, the wire cord cutting out of circuit the
indicators of the two lines which it serves to join. Our invention has for its object
to lessen the time required for making connections between subscribers by providing
means in connection with each line for directly joining up to any other line of an
exchange system without the use of the separate wire cords and plugs whilst obviating
the necessity for employing ring off indicators, and to enable the exchange operator
to ring up or call the subscriber wanted in the operation of making connection to
his line.
In carrying out our invention a connecting wire cord with a single plug is per-
manently attached to each line let into the switch boards in the exchange and when
one subscriber is to be connected to another the operator inserts the plug constituting
the terminal of the one subscribers line into the jack in the other subscribers line,
thereby also cutting the second subscribers indicator and earth out of the line to
which connection has been made, whilst leaving in circuit the indicator of the line
whose terminal plug has been used.
The several lines are so arranged and fitted up that they first reach the line jack,
or if in the multiple system the jacks, from which they pass through the indicators
to the cords and thence to the plugs; and the plugs are placed normally in contact
with earth terminals so that when at rest any current coming in from the line is
conveyed direct to earth; whilst in the act of lifting a plug to make connection from
one subscriber to another the earth is cut off and the line insulated.
In this way by
the single movement required for inserting a plug into a jack connection is made and
completed by the operator.

page_text: In connection with each exchange operator's telephone a cord provided with a
plug is fitted whereby on the insertion of the said plug into the jack in the line of
any subscriber who may call up the exchange the operator is enabled to answer the
call and in conjunction with the cord, which is connected to the battery or magneto
which provides the ringing current, is fitted a switch by means of which the operator
can at pleasure direct a ringing current through the line or place the exchange
telephone in circuit for speaking.
This switch is by preference fitted on or in proximity to the plug so that the
operator may in the act of making connection send a ringing current into the line;
but it may be fitted on the table in the usual way, or both in the plug and on the
table so that the operator in ringing may use the switch most conveniently situated
for the time being.
In conjunction with the switch board arrangements above described we may employ
automatic ring-off signalling devices such as are described in the Specification filed
under an application for Patent No. 13637 of 1887 the indicators described in said
Specification being used in substitution for the ordinary indicators and a switch
provided at the plug of each line whereby when the plug is removed a spring or other
device brings into circuit a battery current to serve the purpose described in the said
Specification. Or the ring-off arrangements described in the Specification filed under
an application for Patent No. 12844 of 1884 may be used in conjunction with the
present invention for the like purpose.
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page_text: We, DAVID JOHNSTON SMITH, Secretary of the National Telephone Company and
DANIEL SINCLAIR, Electrical Engineer both of Royal Exchange Buildings, in the
City of Glasgow, 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 :-
In working telephonic exchanges connection between subscribers is under the ordinary
practice made by means of a wire cord having in its circuit a ring off indicator and pro-
vided at each end with a plug which is inserted in a jack forming a terminal for each
subscriber's line the wire cord cutting out of circuit the indicators of the two linos
which it serves to join. Our invention has for its object to lessen the time required
for making connections between subscribers by providing means in connection with
each line for directly joining up to any other line of an exchange system without the
use of the separate wire cords and plugs whilst obviating the necessity for employing
ring off indicators, and to enable the exchange operator to ring up or call the
subscriber wanted in the operation of making connection to his line.
In the accompanying sheet of drawings figure 1 is a diagrammatic representation
of a telephonic switch board showing our invention applied thereto. L', L², L³,
represent three subscriber's lines led into the exchange. JI, J, J³, are the jacks,
13, 12, 13, the indicators C, C2, C3, the wire cords, P1, P2, P3, the terminal plugs and
T the operators table. A connecting wire cord with a single plug is permanently attached
to each line led in to the switch board in the exchange, and when one subscriber as
for example Number 1 is to be connected to another e.g., Number 2 the operator
inserts the plug P¹ constituting the terminal of Number 1 subscriber's line into the
jack J in the line of subscriber Number 2 thereby also cutting the second subscriber's
indicator I and earth out of the line to which connection has been made, whilst
leaving in circuit the indicator I' of the line whose terminal plug P' has been used.
The several lines are so arranged and fitted up that they first reach the line jack
(or if in the multiple system the jacks) from which they pass through the indicators to
the cords and thence to the plugs; and the plugs are placed normally in contact with
earth terminals at t on the table T so that when at rest any current coming in from
the line is conveyed direct to earth; whilst in the act of lifting a plug to make con-
nection from one subscriber to another the earth is cut off and the line insulated. In
this way by the single movement required for inserting a plug into a jack connection
is made and completed by the operator.
In connection with each exchange operator's telephone O, as represented at figure 2,
a cord provided with a plug P is fitted whereby on the insertion of the said plug
into the jack in the line of any subscriber who may call up the exchange the operator
is enabled to answer the call; and in conjunction with the cord C* which is connected
as shown to the battery or magneto M which provides the ringing current, is fitted a
switch S by means of which the operator can at pleasure direct a ringing current
through the line or place the exchange telephone in circuit for speaking.

page_text: This switch is by preference fitted on or in proximity to the plug so that the operator
may in the act of making connection by pressing on the switch send a ringing current
from the magneto M into the line; but it may be fitted on the table in the usual way
or, as shown at figure 3, both in the plug at S₁ and on the table at S so that the
operator in ringing may use the switch most conveniently situated for the time being.
This switch (S) and the connections to the magneto may also be applied to the
plugs (P1, P2, P3, etc.) on the table T.
In conjunction with the switch board arrangements above described we may employ
automatic ring-off signalling devices such as are described in the Specification filed
under an application for Patent Number 12844 of 1884.
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 arrangements of telephonic switch-board apparatus herein before described
with reference to the accompanying drawings whereby connection between two
subscribers may be made at the exchange by the use of a single cord and subscribers
may be called by the exchange operator in the act of making connection.
2. In telephonic switchboard apparatus a plug provided with a switch and con-
nections to a magneto or battery whereby a subscriber may be rung up in the act of
inserting the plug into the jack constituting the switch board terminal of that
subscriber's line substantially as described.
Dated this Twenty-first day of September 1888.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow,
Agents.