Improvements in Telephone Switchboards.
Year: 1891

page_text: Date of Application, 10th July, 1891
Complete Specification Left. 11th Apr.. 1892-Accepted. 14th "May. 1892
PROVISIONAL SPECIFICATION.
Improvements in Telephone Switchboards.
1, JOHN EDWARD KINGSBURY, of 79 Coleman Street in the City of London,
Manager, do hereby declare the nature of this invention to be as follows:-
My invention relates to telephone switchboards in or through which there are
two or more wires and connecting points ou those wires for each subscriber.
It has for its objects the simplification of construction, the reduction of the
liability to derangement from dust or other foreign particles, and facilities for
remedying such derangements should they arise.
Heretofore telephone switchboards having two or more wires for each subscriber
have been constructed so that the lines are attached to springs or contacts,
commonly called slippers. springjacks, or shortly, "jacks,"
,"which have been placed
so that they form recesses in the fabric of the switchboard, and connections have
been made with them by means of a plug or plugs attached to a flexible cord or
cords, the plugs being adapted to fit into the recessed jacks. It will be understood
that dust and foreign substances are liable to settle in such recesses causing trouble
by deranging electrically or mechanically the action of the springs or equivalent
contact surfaces, and it is evident that this liability to derangement is increased
when the openings of the recesses are in the line of falling particles; as for oxample,
when the jacks are placed with the recesses opening upwards.
As it has been customary to call the various points of contacts of lines on the
switchboard spring jacks or simply "jacka " I will for convenience adopt the same
designation for the contact points or surfaces of my invention, though as the form
which I may prefer to use may contain for the line contacts no springs I will call
them simply "jacks." Similarly as the moveable device for making connections
has been called a "plug" I will adopt a similar designation for the device used for
the same purpose in my invention, though it will be understood that it is not
strictly speaking a plug, and that I prefer to use a device which is so constructed
as to afford spring connections between it and the jack.
In my invention I reverse the order hitherto in use and construct the jacks so
that they project from the main fabric of the switchboard,.and the plug by which
connection is effected, I construct so that it shall be hollow or otherwise adapted
to make the necessary contacts on the projecting points or surface. The jacks I
may. cover, or partially cover, with a board or strip having apertures for the
passage of the plug so that in the event of dust collecting in or upon the contacts
the cover may be easily removed and the jacks quickly cleaned.
In making connections between subscribers in telephone switchboards, it is of
great importance that the required operations shall be quickly performed, and this
result is more readily attained by the use of a circular plug making the necessary
connections with the jack in the direction of its length, so that when placed in
position by the operator, say in a line from the front to the rear, or from above to
below, no particular part of its circumference has to be selected; and whilst I may
arrange my projecting contacts in any way, it will be understood that if one contact
of the jack formed one part of a semicircle and the other contact the other part of
a semicircle, and the plug were similarly divided, it would be necessary that the
plug should be placed in a 'defined position with respect to its circumference in
order that the respective contacts should coincide. Similarly if the contacts were
separated and the plug constructed so that its two surfaces formed two sides of a
aquare, or any formation other than a circular one, it would be necessary to select
a particular position for the plug so that its contacts should coincide with the
contacts on the jack. Such selection of position on the part of the operator

page_text: involves delay, and I therefore preferably construct my jacks so that one contact
surface projects beyond the other contact surface or surfaces and inversely for
the respective contacts on the plug. Whilst. I do not restrict myself to any
particular form, I prefer, for the reasons above stated, and also by reason of the
facilities in manufacture that the two or more contacts of the jack shall together
form a circular projection, one formning the centre, the other or others being of
tubular formation around it, with suitable insulating materia! between them, and
of different lengths the plugs I preferably construct of hollow tubes, one within
the other or others, the length of each tube being arranged so that the tubes are
adapted to make contacts with the respective conducting surfaces of the jack and
each tube boing made of a nature to grasp or press upon its jack contact.
My invention may be used with any form of switchboard, but it is more
particularly adapted for use on those systems in which the subscribers lines through
the board remain unbroken; as, for instance, the system described in the Specifica-
tion of the Letters Patent No. 20,099 of 1890, granted to me (a communication
from abroad), or on the system known as the law or circuit wire system, iu which
the subscriber signals to the central office by a special calling wire, and has no
signalling device in connection with his line. Upon such systems contacts only
are necessary, but where work is required to be performed at the jack other than
the making of line contacts with the plug additional mechanism is necessary.
In the case of multiple switchboards more than one jack is furnished for each
line so that connection may be made to a line from two or more places on a switch-
board or series of switchboards, and it is necessary that provision should be made
by which operators may know whether the line required is cugaged or disengaged.
This is known as the test system, of which there are several. In some cases
the test circuit forms a part of the subscribers line, and my invention is particu-
larly adapted to be used with those systems, but where the test circuit is
required to be distinct from the subscriber's line, I provide a testing point for each
jack, these testing points being electrically connected for the series of jacks
belonging to one subscriber; and I also provide a contact for each jack which is
connected in common to a signal producing device, and I preferably complete the
test circuit in an engaged jack or break such circuit through or by means of the
plug thereby avoiding the use in the jacks of make and break contacts liable to
derangement from dust and foreign particles.
Dated this 10th day of July 1891.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Telephone Switchboards.
I, JOHN EDWARD KINGSBURY, of 79 Coleman Street, in the City of London,
Manager, do hereby declare the nature of this invention aud in what mauner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
-
My invention relates to telephone switchboards in or through which there are
two or more wires and connecting points on those wires for each subscriber.
It has for its objects the simplification of construction, the reduction of the
liability to derangement from dust or other foreign particles, and facilities for
remedying such derangements should they arise.
Heretofore telephone switchboards having two or more wires for each subscriber
have been constructed so that the lines are attached to springs or contacts,
commonly called slippers, springjacks, or shortly, "jacks," which have been placed
so that they form recesses in the fabric of the switchboard, and connections have
been made with them by means of a plug or plugs attached to a flexible cord or
cords, the plugs being adapted to fit into the recessed jacks. It will be understood'

page_text: that dust and foreign substances are liable to settle in such recesses causing trouble
by deranging electrically or mechanically the action of the springs or equivalent
contact surfaces, and it is evident that this liability to derangement is increased
when the openings of the recesses are in the line of falling particles; as for
example, when the jacks are placed with the recesses opening upwards.
As it has been customary to call the various points of contacts of lines on the
switchboard spring jacks or simply "jacks" I will for convenience adopt the
same designation for the contact points or surfaces of my invention, though as
the form which I may prefer to use may contain for the line contacts no springs I
will call them simply "jacks." Similarly as the moveable device for making con-
nections has been called a "plug" I will adopt a similar designation for the
device used for the same purpose in my invention, though it will be understood that
it is not strictly speaking a plug, and that I prefer to use a device which is so
constructed as to afford spring connections between it and the jack.
In my invention I reverse the order hitherto in use and construct the jacks 80
that they project from the main fabric of the switchboard, and the plug by which
connection is effected, I construct so that it shall be hollow or otherwise adapted to
make the necessary contacts on the projecting points or surface. The jacks I may
cover, or partially cover, with a board or strip having apertures for the passage of
the plug so that in the event of dust collecting in or upon the contacts the cover
may be easily removed and the jacks quickly cleaned.
In making connections between subscribers in telephone switchboards, it is of
great importance that the required operations shall be quickly performed, and
this result is more readily attained by the use of a circular plug making the
necessary connections with the jack in the direction of its length, so that when
placed in position by the operator, say in a line from the front to the rear, or
from above to below, no particular part of its circumferenco has to be selected;
and whilst I may arrange my projecting contacts in any way, it will be understood
that if one contact of the jack formed one part of a semicircle and the other
contact the other part of a semicircle, and the plug were similarly divided, it
would be necessary that the plug should be placed in a defined position with
respect to its circumference in order that the respective contacts should coincide.
Similarly if the contacts were separated and the plug constructed so that its two
surfaces formed two sides of a square, or any formation other than a circular one,
it would be necessary to select a particular position for the plug so that its contacts
should coincide with the contacts on the jack. Such selection of position on the
part of the operator involves delay, and I therefore preferably construct my jacks
so that one contact surface projects beyond the other contact surface or surfaces
and inversely for the respective contacts on the plug. Whilst I do not restrict
myself to any particular form, I prefer, for the reasons above stated, and also by
reason of the facilities in manufacture that the two or more contacts of the jack
shall together form a circular projection, one forming the centre, the other or others
being of tubular formation around it with suitable insulating material between
them, and of different lengths the pluga I preferably construct of hollow tubes,
one within the other or others, the length of each tube being arranged so that the
tubes are adapted to make contacts with the respective conducting surfaces of the
jack and each tube being made of a nature to grasp or press upon its jack contact.
My invention may be used with any form of switchboard, but it is more particularly
adapted for use on those systems in which the subscribers lines through the board
remain unbroken; as, for instance, the system described in the Specification of the
Letters Patent No. 20,099 of 1890, granted to me (a communication from abroad),
or on the system, known as the Law or circuit wire system, in which the-subscriber
signals to the central office by a special calling wire, and has no signalling device
in connection with his line. Upon such systems contacts only are necessary, but
where work is required to be performed at the jack other than the making of line
contacts with the plug additional mechanism is necessary.
In the case of multiple switchboards more than one jack is furnished for each

page_text: line so that connection may be made to a line from two or more places on a
switchboard or series of switchboards, and it is necessary that provision should
be made by which operators may know whether the line required is engaged or
disengaged. This is known as the test system, of which there are several. In
some cases the test circuit forins a part of the subscribers line, and my invention
is particularly adapted to be used with those systems, but where the test circuit is
required to be distinct from the subscriber's line, I provide a testing point for
each jack, these testing points being electrically connected for the series of jacks
belonging to one subscriber; and also provide a contact for each jack which is
connected in common to a signal producing device, and I preferably complete the
test circuit in an engaged jack or break such circuit through or by means of the
plug thereby avoiding the use in the jacks of make and break contacts liable to
derangement from dust and foreign particles.
My invention is illustrated in the accompanying drawings
:
Figure 1 represents three jacks and a plug adapted to be used with them,
aaa are the jacks. Referring to a b is one contact, is the other contact, e is
insulating material separating b from d, e is a strip of insulating material upon
which the jacks are mounted, is a moveable cover which it may be convenient to
use, but which is not a necessary part of the invention, g is the plug in which his
the outer sleeve or cover, i is one metallic surface adapted to make contact with d
of the jack and jis the other metallic surface adapted to make contact with b of
the jack. The electrical separation of the two metallic surfaces of the plug and
the connection with them of the flexible conductors may be made in the ordinary
way as shewn in the drawing.
Figures 2 shew the application of my invention where work is required to be
performed at the jack other than the making of line contacts, the plug being shewn
attached to the jack. is a metallic surface forming part of a circuit other than
the line circuits, is also a metallic surface both being applied to the jack, m is a
metallic surface, preferably in the form of a ring, applied to the plug and adapted,
when the plug is placed in the jack, to complete the electrical connection between k
and 1.
If used as a test circuit in a multiple switchboard, & would be in contact with a
similar part in each of the jacks attached to the same lines, whilst would be
connected in common to a signal producing device. But such circuits may be used
for other than test purposes.
My invention admits of modifications in construction which would readily suggest
themselves to those skilled in the art, and I therefore do not limit myself to the
precise details of construction illustrated and described herein.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed declare that what
I claim is :-
1. In a telephone switchboard having two or more wires and contact surfaces on
the jacks in connection with those wires for each subscriber, the formation of the
jacks as projections from a base.
2. In a telephone switchboard having two or more wires and contact surfaces on
the jacks in connection with those wires for each subscriber, the use of plugs which
are hollow or otherwise adapted to make contacts with projecting jacks.
3. In a telephone switchboard the use of projecting jacks having contacts for the
line circuits in combination with contacts for a circuit or circuits (other than the
line circuits) to be completed through the plug by which the line connections are
made.
4. In a telephone switchboard the use of plugs which are hollow or otherwise
adapted to make contacts with projecting jacks and adapted to close by a metallic
attachment a circuit or circuits other than the line circuits of such jacks.
5. In a telephone switchiboard having two or more wires and contact surfaces on
the jacks in connection with those wires for each subscriber, the use of jacks, each

page_text: formed with two concentric conductors insulated from one another and the central
one projecting beyond the outer one and plugs with concentric tubular conductors
insulated from one another and split or divided at their ends to make contacts with
the inner and outer conductors of the jacks.
6. In a telephone-switchboard having two or more wires and contact surfaces on
the jacks in connection with those wires for each subscriber, the construction of
the jacks and plugs substantially as hereinbefore described and illustrated in the
drawings annexed.
J. E. KINGSBURY.