Improvements in Telephone Switchboard Apparatus.
Year: 1892

page_text: Date of Application, 26th Sept., 1892
Complete Specification Left, 26th June, 1893-Accepted, 29th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Telephone Switchboard Apparatus.
1, JOHN EDWARD KINGSBURY, of 79 Coleman Street in the City of London,
Manager, (a communication to me from abroad by The Western Electric Company
of Chicago, Illinois, United States of America) do hereby declare the nature of
this invention to be as follows:-
My invention relates to apparatus for switchboards of telephone exchanges,
more particularly, to that class of telephone switchboards in which the spring
jacks of line terminals and the annunciator of a line are connected permanently
therewith. Its object is to simplify the construction and to increase the durability
and reliability of the apparatus of such switchboards.
Heretofore in certain multiple switchboard systems the spring jacks upon the
different switchboards have been connected in parallel with the line, the annunciator
has been permanently connected in a bridge between the different sides of the line
circuit, and a separate normally open local circuit has been provided having
terminals upon each of the spring jacks adapted to be crossed together when a
connection is made with the line, and including a separate electro magnet or coil
upon the individual annunciator of the same line adapted to prevent the operation
of the individual annunciator when said coil is energized.
My invention relates specifically to the construction of the annunciator and to
apparatus of the above class of multiple switchboards, and is illustrated in the
accompanying drawings.
Figure 1, Sheet 1, is a diagram illustrative of the circuits of two telephone
lines of multiple switch board system in connection with my self restoring
annunciators.
Figure 2, Sheet 2 is a plan view from above of one of my self restoring
annunciators, portion of the supporting plate and of the shell surrounding the
front, or restoring electro magnet coil, being broken away to show the insulation of
the connections with the wire of the coil of said magnet.
Figure 3 is a view of the same from below.
Figure 4 is a detailed longitudinal sectional view of the same, the armature
forming the drop and the curtain operated thereby being in position to indicate
a call.
Figure 5 is a rear view.
Like parts are indicated by similar letters of reference throughout the different
figures.
The armature a is provided with the hook b, which extends forward and normally
engages with the drop e pivotted at d to hold said drop c in the position shown
most clearly in Figure 2. The main operating electromagnet is secured to the
supporting plate e as best shown in Figure 4, and directly opposite thereto is
secured the restoring electro magnet. The core of the restoring magnet is
preferably extended so as to project into the recess or opening 9 provided in the
drop e, in order that the drop c, which is of soft iron to act as an armature,
may have a considerable range of movement within the influence of the said
core f.
g
Figures indicating the number of the annunciator are provided upon the face of
the drop c.
The ends of the coil of the restoring magnet are brought out as shown most
clearly in Figure 2, through insulating bushings inserted through the shell of said
magnet. The rods kk insulated from the plate e, as shown in Figure 2, are
connected with these wires ii. These rods kk extend back to the rear of the

page_text: annunciator through bushings of insulating material provided in the frame 1, which
frame carries also the pivots of the armature a. Thus all the connections with
the annunciator may be made at the rear thereof. The contact piece m upon the
lower side of the drop may be connected with any circuit, as for example circuit n,
which it may be desired to ground. When the annunciator drop c is released and
falls to the position shown in Figure 4, the spring o under the same is forced against
the contact m as shown. This spring o being connected with the main frame of
the annunciator will serve as a ground connection for the contact m, as shown in
Figures 2 and 4. It will be observed that the latch or hook passes forward
through a notch provided in the plate e, and between the different halves of the
support p upon which the apron is hung. The annunciator as a whole is made thus
compact, and it will be understood that several will be mounted side by side quite
near together upon a single strip e.
When my annunciator is used in telephone exchange systems the coil g of the
operating electro magnet will be included in the circuit of the telephone line, while
the coil of the restoring electro magnet will be included in a circuit containing
battery, which circuit will be automatically closed when connection is made with
the line to which the annunciator belongs, and thus current being closed through
said coil r, the drop c will be attracted and thus automatically restored. That is to
say, the subscriber will send current through the coil q of the operating electro-
magnet, thus operating armature a and the latch or armature lever carried
thereby the shutter c, which is normally held by said latch, is thus released and
the apron thrown up to the position shown in Figure 4. The operator at the board
where the annunciator is placed, seeing the signal, answers the call. by inserting a
plug into the switch of the line containing the annunciator at her board; and the
circuits are so arranged that the act of plugging into this switch closes circuit
through the coil r of the restoring electro magnet, and thus the said magnet is
excited and the drop e is immediately restored.
I do not limit my invention to any particular circuit or systems of circuits, but
for the purpose of illustrating the utility of my invention when applied to telephone
exchange systems will briefly describe the circuits of Figure 1.
The telephone line s extends in metallic circuit from subscriber's station 1 to the
series of switches s¹s on different switch boards, and thence through the coil g of
the operating magnet of my individual annunciator. The test circuit or wire 83
connects from the front or insulated portions of switches s's through the coil r of
the restoring electro magnet battery to ground. The circuit of the subscriber of
station 2 may be precisely the same as that of station 1. The subscriber on
operating his generator sends current through coil q and so operates the annunciator.
The operator seeing the signal inserts plug t into switch s. Now, it will he
observed that the inner portion of the ring of this switch is provided with a ground
connection and that the metallic sleeve upon the shank of the plug serves as a
medium of electrical connection between the two parts of the ring or tube of the
switch; thus, when the plug t is inserted, the shorter spring of the switch is closed
to the tip which is connected as shewn with the tip strand of the pair of cords,
while the longer spring is connected to the insulated sleeve near the tip, which
insulated sleeve is connected with the sleeve strand of the cords.
Figure 6, Sheet 3, is a plan view of a strip or plate carrying 20 spring jacks.
Figure 7 is a front elevation of the same strip.
Figure 8 is a rear elevation thereof.
Figure 9 shows the same strip of spring jacks in a view from below, some of the
springs and other parts being shown removed from their places in the strip and
disposed above the strip of spring jacks.
Figure 10 is a transverse sectional view of the strip taken on the centre of one
of the spring jacks.
Figure 11 is a longitudinal section of a portion of the strip of spring jacks, the
section being made on the line 6-6 of Figure 1.
Figure 12 is a similar section on the line 7-7 of Figure 1..

page_text: Figure 13 is a perspective view of the metallic contact portions of one spring
jack arranged in their proper relative positions.
Figure 14 is a section of a small portion of the strip of spring jacks taken on
the line 9-9 of Figure 2, showing the method of leading the insulated connecting
strip from one of the contact pieces at the front of the jack to the rear of the
strip for connection.
Figure 15, Sheet 4, is a longitudinal central section of a connecting plug for use
with my improved spring jacks.
Figure 16 is a side elevation of the same.
Figure 17 is a diagram showing the connecting apparatus at the exchange, and
the spring jacks and annunciators of two telephone lines which extend to sub-
stations, whereat the apparatus is also shown.
Referring to Figure 6, Sheet 3, a is a strip or plate of hard rubber or other
suitable insulating material having projections at its opposite extremities by which
to secure it in place in the switchboard. In this strip a a are milled transverse
grooves a¹ a extending nearly across the strip, upon the upper side, and similar
grooves a² a² upon its lower side, as is best shown in Figures 9 and 11. Perfora-
tions are drilled from the front of the strip of spring jacks, one perforation to each
pair of grooves, having its axis centrally located and parallel with respect to the
grooves. A small portion of the insulating material is removed from between the
grooves so as to leave a rectangular opening a through the strip connecting
the two grooves at those ends which are nearer the front of the jack. In the
grooves a upon the under surface of the rubber strip a are mounted springs band c.
These are most clearly shown in Figures 9 and 10.
The bolt is insulated from the
The spring is the longer of the two so that its curved extremity is presented
close to the end of the perforation through the front portion of the strip a.
The
springs are insulated from each other by a strip or tongue d of hard rubber or
other suitable insulating material placed between them, thin and flexible enough so
as not to impede the flexion of the two springs. In the upper groove, a², is mounted
another spring similar to spring band of equal length. The three springs b, c,
and are firmly secured to the strip a by a bolt e passing through the different
springs and the body of strip a, having a head el bearing upon the spring and a
nut e screwed down upon the springs and c.
springs b and c by suitable rubber washers and bushings in the usual way.
In the perforations a³ in the front of the strip are inserted short tubes f of
metal, which are secured therein by any suitable means. The metal tube or
thimble is provided with a shoulder which bears against a corresponding ledge in
the perforation a³, so as to prevent the tube f from being thrust backward towards
the rear of the jack. The thimble f is provided with an extension f' connected
with it, designed to afford electrical connection to the strip from the rear of the
jack. This strip f¹ extends through an oblique duct 2, shown in dotted lines in
Figure 9 and thence through a transverse slot or saw cut at in the strip a to the
rear of the strip. In assembling the strip of spring jacks, the thimble f is placed
over a suitable mandril, and the extension f is inserted into the oblique duct; the
thimble is then forced into the perforation in the strip a by pressure upon
the mandril, the somewhat flexible extension f" following the oblique duct into the
transverse saw cut and thence to the rear of the jack.
In front of the thimbles f in the perforations a³ are placed additional rings or
very short tubes of metal g. These are forced into place against other ledges in
the perforation a³ and are secured in place by suitable means. The ring g is also
provided with an extension g' designed to project to the rear of the strip of spring
jacks for connection thereat. This extension g' may be a thin wire if desired. The
wire g' is led through another duct g² in the front portion of the strip a into a saw
cut a³, thence to the rear of the strip, where for the circuit herein shown, it is
connected with the spring , preferably by being soldered thereto.
Referring now to Sheet 4, I will describe the connecting plug designed for use
with this spring jack, shown in Figures 15 and 16. This plug is constructed

page_text: similarly to the two part or "double" plug in ordinary use and hence need not be
described in great detail. It consists of a tip h secured to the end of a rod which
extends along the axis of the plug and terminates in a block ² of metal, provided
with a binding screw adapted to receive one strand of a two part cord to make
connection therewith. The central rod and block 2 are surrounded by suitable
insulation. Concentric with the rod and block is a sleeve of suitable size for
insertion into the thimble of the spring jack and of such length that when the
plug is fully inserted, the end of the sleeve will be flush with the inner end of the
thimble. The sleeve is, however, not sufficiently large to touch the ring g when
the plug is fully inserted into the spring jack in order that the insulation between the
thimble and the ring g may be maintained. A continuation of the sleeve * forms
the tubular body of the plug. On the inside of the tube is provided another binding
screw adapted to receive and retain the other strand of the connecting cord.
A shell of insulating material surrounds the metallic body for a portion of its
length to prevent the deterioration of insulation by handling. Between the tip /
of the plug and the forward end of the sleeve is placed an insulated ring h
slipped on over the insulation and properly secured in place. It is this additional
ring upon the plug that forms the novel feature of the plug. The plug is so
constructed that the tip / projects sufficiently far into the spring jack to enter under
and make contact with the shorter spring cof the jack; the ring h' is so placed as
to enter between the springs and when the plug is fully inserted into the jack
and thus to cross them together; the sleeve makes electrical contact with the
thimble of the jack. The different contact pieces of the spring jack are shown
bearing upon their corresponding contact pieces of the plug in Figure 16.
Referring now to Figure 17 I will describe the circuits therein depicted in
detail and will trace the various operations involved in establishing connection
between two telephone lines by means of the system shown.
The apparatus at the substation is of the usual character. That at station 1
for example, comprises a calling generator i and signal bell in a branch from one
side of the line circuit, a telephone receiver and transmitter 3 in another
branch from the same side of the line circuit and a telephone hook switch i* con-
nected with the other side ¹ of the line circuit and adapted to connect the telephone
apparatus or the signalling apparatus alternately into the line circuit. The line k k¹
extends to the exchange whereat the different sides of the circuit are connected
with the thimbles f and the shorter line springs e respectively of two spring
jacks, one upon each of two sections m m¹ of multiple switch board. An indi-
vidual annunciator n is placed near the spring jack upon the section m' of
switchboard.
The operating coil n' of the annunciator is permanently connected in a bridge
or cross connection between the different sides kk' of the line circuit. The springs b
of all the spring jacks are connected directly to earth: the springs 6 of the
different spring jacks of one line are connected together and by a branch through
the restoring coil n of the annunciator n of the same line and a battery o to earth.
The apparatus at substation 2, and the spring jacks annunciator and circuit
connections thereof at the exchange are of similar character; the spring jacks 13
are placed one upon each of the sections m and m¹ of switchboard. The individual
annunciator n of the line is however placed upon a section m of switchboard near
the jack of the same line so as to be under the care of another attending operator.
Two pairs of connecting plugs and other accessory appliances are shown
complete, one at each section of switchboard. The plugs p p are of construction
shown in Figures 15 and 16 and described in connection therewith. The like
contact pieces of the two plugs of the pair are connected together by flexible
conductors qql and other circuit connections. Included in circuit between the two
plugs are two calling keys r and 7, each adapted to disconnect both contact pieces
of one of the plugs from those of the other and to connect them to wires & ¹
which form the terminals of the calling generator t. A listening key u is provided,
having contact points or anvils connected with the different sides q' of the cord

page_text: circuit and having its contact springs u¹ and u² connected with the terminals of the
telephone ; thus when the plunger of the listening key u is allowed to rise, as
shown in the upper cord circuit, the telephone w is connected in a bridge or branch
connection between the different sides of the cord circuit. A branch is connected
in the middle of the telephone coil to earth for testing purposes, in the well known
manner. An additional spring u³ is provided upon the listening key, insulated
from the other parts of the key but adapted to be raised when the plunger is
depressed so as to be separated from a contact anvil connected to earth.
A clearing out annunciator a similar in construction to the individual annunciators
is provided in connection with each cord circuit, having its operating coil per-
manently connected in another bridge between the different sides of the cord
circuit. The restoring coil a² is connected in a normally open local circuit
including the contact spring ³ and its anvil u' and a source of electricity. By
this device the clearing out annunciator a is automatically reset or restored to its
normal position whenever the telephone of the operator is brought into the
circuit.
I will now briefly describe the operation of establishing connection between two
subscribers' lines.
Suppose for example that subscriber at station 1 desires to communicate with a
subscriber at station 2. His switch hook being in its lowest position he rotates his
calling generator thus sending signalling current over the circuit kk' to the
exchange where the current finds circuit through the operating coil n' of the
individual annunciator thereat. The armature of magnet n' is attracted,
releasing the shutter of the annunciator and indicating the signal to the operator
attending at board m'. The operator then inserts one plug p of a pair into the
spring jack of that line at her board; the line circuit is thus extended through
the contact pieces c and f of the spring jack to the corresponding contact pieces h
and of the plug thence through the conductors g' of the cord circuit to the
listening key u belonging to that cord circuit. This key being in its normal
position, that shown in the upper cord circuit, the circuit is continued from
conductors 9 and through the contact points of the listening key to the
operator's telephone w whereby she is enabled to communicate with the subscriber
at station 1.
When the plug p was inserted into the spring jack, the plug besides connecting
the line contacts of the spring jack with the corresponding contact pieces of the
plug, at the same time crossed together the two local springs b and through the
ring upon the plug, thereby completing the local circuit including the battery o
and the restoring coil n² of the individual annunciator. The electro-magnet n² was
thereby energised, attracting the shutter of the annunciator and restoring the same
to its normal position, in which position it is retained as long as the plug remains
inserted in the spring jack.
Having received the order from subscriber at station 1, say for connection with
subscriber at station 2, the operator at board m' proceeds to test the line called for
to determine whether it is already in use or not. This she does by the well known
process of applying the tip of the remaining plug p of the pair to the test ring g
of the spring jack at her board belonging to that line. The plug p³ of the upper
pair of cords at board m is shown in position of making such a test of the spring
jack of line to station 2.
In the normal or idle condition of the line circuit, the test ring is electrified
to a difference of potential from the earth by the battery o, which finds circuit
through the restoring coil of the individual annunciator of the line to the different
test rings thereof. If, when the line is in that condition, the tip of a plug as 3 be
applied to the test ring, the circuit will be completed from the test ring touched, to
the operator's telephone, thence through one half of the telephone coil to earth;
and at each application of the tip of the plug to the test ring, a click will he
produced in the operator's telephone set indicating to her the idle condition of the
line.
When however the line is put into use by inserting a plug into a spring jack

page_text: thereof, the springs are crossed together directly, whereby the test rings are
connected directly to earth through a short circuit, and thereafter possess no
difference of potential from the earth; hence no response will be produced in the
telephone when the test plug is applied to the spring jack.
Assume that the operator at board m', having tested line to station 2, found the
line to be unoccupied; she then inserts the plug p' with which she has been
making the test into the spring jack of that line, whereby the two substations
are joined into a continuous loop circuit including the line circuits of both
substations, the contact pieces of the spring jacks at which the connections are
made corresponding contact pieces of the connecting plugs, and the conductors q q
of the cord circuit. The subscribers are thus enabled to communicate with each
other.
When they have finished their conversation one of them as for example sub-
scriber at station 1, may send a clearing out signal or signal for disconnection to
the exchange by replacing his telephone upon the switch hook and again rotating
his generator i. A portion of the current thus sent over the lines k k finds circuit
through the individual annunciator n as before but fails to operate the same because
the shutter of the annunciator is retained in its normal position by the continued
energization of the magnet ². Another portion of the current finds circuit
through the contact pieces of the plug to the cord circuit and thence through the
operating coil of the clearing out annunciator x. The operator at board m³ had
previously disconnected her telephone from the line circuit after having found the
subscribers in communication, and hence the clearing out annunciator is free to
respond to the signal for disconnection, its magnet 22 being unenergized; the
operator who made the connection is thus notified that the subscribers have com-
pleted their conversation. Whenever she introduces her telephone set into that
cord' circuit again, as to answer a call, by allowing the plunger of the listening
key to rise, the local circuit containing the restoring coil of the clearing-out
annunciator is closed and the clearing-out annunciator is reset.
Dated this 26th day of September 1892.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Telephone Switchboard Apparatus.
I, JOHN EDWARD KINGSBURY, of 79 Coleman Street, in the City of London,
Manager, (a communication to me from abroad by The Western Electric Company
of Chicago, Illinois, United States of America) 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 :-
My invention relates to apparatus for switchboards of telephone exchanges,
more particularly to that class of telephone switchboards in which the spring jacks
of line terminals and the annunciator of a line are connected permanently there-
with. Its object is to simplify the construction and to increase the durability and
reliability of the apparatus of such switchboards.
Heretofore in certain multiple switchboard systems the spring jacks upon the
different switchboards have been connected in parallel with the line, the annunciator
has been permanently connected in a bridge between the different sides of the line
circuit, and a separate normally open local circuit has been provided having
terminals upon each of the spring jacks adapted to be crossed together when a
connection is made with the line, and including a separate electro magnet or coil
upon the individual annunciator of the same line adapted to prevent the operation
of the individual annunciator when said coil is energized.
My invention relates specifically to the construction of the annunciator and to

page_text: apparatus of the above class of multiple switchboards, and is illustrated in the
accompanying drawings.
Figure 1, Sheet 1, is a diagram illustrative of the circuits of two telephone lines
of multiple switch board system in connection with my self restoring annunciators.
Figure 2, Sheet 2 is a plan view from above of one of my self restoring
annunciators, portion of the supporting plate and of the shell surrounding the
front, or restoring electro magnet coil, being broken away to shew the insulation of
the connections with the wire of the coil of said magnet..
Figure 3 is a view of the same from below.
Figure 4 is a detailed longitudinal sectional view of the same, the armature
forming the drop and the curtain operated thereby being in position to indicate
a call.
Figure 5 is a rear view.
Like parts are indicated by similar letters of reference throughout the different
figures.
The armature a is provided with the hook, which extends forward and normally
engages with the drop c pivotted at d to hold said drop e in the position shown
most clearly in Figure 2. The main operating electro magnet is secured to the
supporting plate e, as best shewn in Figure 4, and directly opposite thereto is
secured the restoring electro magnet. The core of the restoring magnet is
extended so as to project into the recess or opening y provided in the drop c, in
order that the drop c, which is of soft iron to act as an armature, may have a
considerable range of movement within the influence of the said core f.
Figures indicating the number of the annunciator are provided upon the face of
the drop c.
The ends of the coil of the restoring magnet are brought out as shown most
clearly in Figure 2, through insulating bushings inserted through the shell of said
magnet. The rods kk insulated from the plate e, as shown in Figure 2, are
connected with these wires i i. These rods k k extend back to the rear of the
annunciator through bushings of insulating material provided in the frame l, which
frame carries also the pivots of the armature a. Thus all the connections with
the annunciator may be made at the rear thereof. The contact piece m upon the
lower side of the drop may be connected with any circuit, as for example circuit n,
which it may be desired to ground. When the annunciator drop c is released and
falls to the position shown in Figure 4, the spring o under the same is forced against
the contact m as shown. This spring being connected with the main frame of
the annunciator will serve as a ground connection for the contact m, as shewn in
Figures 3 and 4. It will be observed that the latch or hook passes forward
through a notch provided in the plate e, and between the different halves of the
support p upon which the apron is hung. The annunciator as a whole is made thus
compact, and it will be understood that several will be mounted side by side quite
near together upon a single strip e.
When my annunciator is used in telephone exchange systems the coil 7 of the
operating electro magnet will be included in the circuit of the telephone line,
while the coil r of the restoring electro magnet will be included in a circuit
containing battery, which circuit will be automatically closed when connection is
made with the line to which the annunciator belongs, and thus current being closed
through said coil r, the drop c will be attracted and thus automatically restored.
That is to say, the subscriber will send current through the coil 9 of the operating
electro-magnet, thus operating armature a and the latch or armature lever carried
thereby the shutter c, which is normally held by said latch, is thus released and
the apron thrown up to the position shown in Figure 4. The operator at the board
where the annunciator is placed, seeing the signal, answers the call by inserting a
plug into the switch of the line containing the annunciator at her board; and the
circuits are so arranged that the act of plugging into this switch closes circuit
through the coil r of the restoring electro magnet, and thus the said magnet is
excited and the drop c is immediately restored.

page_text: I do not limit my invention to any particular circuit or systems of circuits, but
for the purpose of illustrating the utility of my invention when applied to telephone
exchange systems I will briefly describe the circuits of Figure 1.
The telephone lines extends in metallic circuit from subscriber's station 1 to the
series of switches s¹s on different switch boards, and thence through the coil q of
the operating magnet of my individual annunciator. The test circuit or wire s
connects from the front or insulated portions of switches s¹² through the coil r of
the restoring electro magnet battery to ground. The circuit of the subscriber of
station 2 may be precisely the same as that of station 1. The subscriber on
operating his generator sends current through coil 9 and so operates the annunciator.
The operator seeing the signal inserts plug t into switch s. Now, it will be
observed that the inner portion of the ring of this switch is provided with a ground
connection and that the metallic sleeve upon the shank of the plug serves as a
medium of electrical connection between the two parts of the ring or tube of the
switch-thus, when the plug t is inserted, the shorter spring of the switch is closed
to the tip which is connected as shewn with the tip strand of the pair of cords,
while the longer spring is connected to the insulated sleeve near the tip, which
insulated sleeve is connected with the sleeve strand of the cords.
Figure 6, Sheet 3, is a plan view of a strip or plate carrying 20 spring jacks.
Figure 7 is a front elevation of the same strip.
Figure 8 is a rear elevation thereof.
Figure 9 shows the same strip of spring-jacks in a view from below some of the
springs and other parts being shown removed from their places in the strip and
disposed above the strip of spring jacks.
Figure 10 is a transverse sectional view of the strip taken on the centre of one
of the spring jacks.
Figure 11 is a longitudinal section of a portion of the strip of spring jacks, the
section being made on the line 6-6 of Figure 6.
Figure 12 is a similar section on the line 7-7 of Figure 6.
Figure 13 is a perspective view of the metallic contact portions of one spring
jack arranged in their proper relative positions.
Figure 14 is a section of a small portion of the strip of spring jacks taken on the
line 9-9 of Figure 7, showing the method of leading the insulated connecting strip
from one of the contact pieces at the front of the jack to the rear of the strip for
connection.
•
Figure 15, Sheet 4, is a longitudinal central section of a connecting plug for use
with my improved spring jacks.
Figure 16 is a side elevation of the same.
Figure 17 is a diagram showing the connecting apparatus at the exchange, and
the spring jacks and annunciators of two telephone lines which extend to sub-
stations, whereat the apparatus is also shown.
Referring to Figure 6, Sheet 3, a is a strip or plate of hard rubber or other
suitable insulating material having projections at its opposite extremities by which
to secure it in place in the switchboard. In this strip a a are milled transverse
grooves a¹ a¹ extending nearly across the strip, upon the upper side, and similar
grooves a² a² upon its lower side, as is best shewn in Figures 9 and 11. Perfora-
tions are drilled from the front of the strip of spring jacks, one perforation to each
pair of grooves, having its axis centrally located and parallel with respect to the
grooves. A small portion of the insulating material is removed from between
the grooves so as to leave a rectangular opening a through the strip connecting the
two grooves at those ends which are nearer the front of the jack. In the grooves a¹
upon the upper surface of the rubber strip a are mounted springs b and c. These
are most clearly shown in Figures 9 and 10.
The
The spring is the longer of the two so that its curved extremity is presented
close to the end of the perforation through the front portion of the strip a.
springs are insulated from each other by a strip or tongue d of hard rubber or other
suitable insulating material placed between them, thin and flexible enough so as not

page_text: to impede the flexion of the two springs. In the lower groove a², is mounted
another spring 6 similar to spring band of equal length. The three springs b, c
and 6' are firmly secured to the strip a by a bolt e passing through the different
springs and the body of strip a, having a head e¹ bearing upon the spring band a
nut screwed down upon the springs b and c. The bolt is insulated from the
springs and c by suitable rubber washers and bushings in the usual way.
In the perforations a³ in the front of the strip are inserted short tubes f of metal,
which are secured therein by any suitable means or in place of these short tubes or
thimbles spring contacts might be used. The metal tube or thimble f is provided
with a shoulder which bears against a corresponding ledge in the perforation a³, so
as to prevent the tube f from being thrust backward towards the rear of the jack.
The thimble fis provided with an extension" connected with it, designed to afford
electrical connection to the strip from the rear of the jack. This strip f¹ extends
through an oblique duct f2, shown in dotted lines in Figure 9 and thence through a
transverse slot or saw cut a in the strip a to the rear of the strip. In assembling
the strip of spring jacks, the thimble is placed over a suitable mandril, and the
extension is inserted into the oblique duct, the thimble f is then forced into the
perforation in the strip a by pressure upon the mandril, the somewhat flexible
extension following the oblique duct into the transverse saw cut and thence to
the rear of the jack.
In front of the thimbles fin the perforations a³ are placed additional rings or
very short tubes of metal g. These are forced into place against other ledges in
the perforation a³ and are secured in place by suitable means. The ring g is also
provided with an extension g' designed to project to the rear of the strip of spring
jacks for connection thereat. This extension g' may be a thin wire if desired. The
wire is led through another duct g² in the front portion of the strip a into a saw
cut a³, thence to the rear of the strip, where for the circuit herein shown, it is
connected with the spring b', preferably by being soldered thereto.
Referring now to Sheet 4, I will describe the connecting plug designed for use
with this spring jack. shown in Figures 15 and 16. This plug is constructed
similarly to the two part or "double" plug in ordinary use and hence need not be
described in great detail. It consists of a tip secured to the end of a rod ' which
extends along the axis of the plug and terminates in a block 2 of metal, provided
with a binding screw 3 adapted to receive one strand of a two part cord to make
connection therewith. The central rod h¹ and block 2 are surrounded by suitable
insulation. Concentric with the rod and block is a sleeve of suitable size for
insertion into the thimble f of the spring jack and of such length that when the plug
is fully inserted, the end of the sleeve will be flush with the inner end of the
thimble. The sleeve is, however, not sufficiently large to touch the ring g when the
plug is fully inserted into the spring jack in order that the insulation between
the thimble and the ring g may be maintained. A continuation of the sleeve /
forms the tubular body of the plug. On the inside of the tube is provided another
binding screw adapted to receive and retain the other strand of the connecting
cord. A shell h of insulating material surrounds the metallic body h* for a portion
of its length to prevent the deterioration of insulation by handling. Between the
tip of the plug and the forward end of the sleeve is placed an insulated ring h
slipped on over the insulation and properly secured in place. It is this additional
ring ' upon the plug that forms the novel feature of the plug. The plug is so con-
structed that the tip h projects sufficiently far into the spring jack to enter under
and make contact with the shorter spring c of the jack; the ring h' is so placed as to
enter between the springs 6 and when the plug is fully inserted into the jack and
thus to cross them together; the sleeve h makes electrical contact with the
thimble of the jack. The different contact pieces of the spring jack are shown
bearing upon their corresponding contact pieces of the plug in Figure 16.
Referring now to Figure 17 I will describe the circuits therein depicted in detail
and will trace the various operations involved in establishing connection between
two telephone lines by means of the system shown.
R

page_text: The apparatus at the substation is of the usual character. That at station 1 for
example comprises a calling generator i and signal bell in a branch from one
side of the line circuit, a telephone receiver and transmitter in another
branch from the same side of the line circuit and a telephone hook switch i* con-
nected with the other side k¹ of the line circuit and adapted to connect the telephone
apparatus or the signalling apparatus alternately into the line circuit. The line k k'
extends to the exchange whereat the different sides of the circuit are connected
with the thimbles f and the shorter line springs c respectively of two spring
jacks, one upon each of two sectious m m¹ of multiple switch board. An indi-
vidual annunciator n is placed near the spring jack upon the section m³ of
switchboard.
The operating coil n¹ of the annunciator is permanently connected in a bridge
or cross connection between the different sides k k of the line circuit. The
springs 6 of all the spring jacks are connected directly to earth; the springs b¹ of
the different spring jacks of one line are connected together and by a branch
through the restoring coil n² of the annunciator n of the same line and a
battery o to earth.
The apparatus at substation 2, and the spring jacks annunciator and circuit
connections thereof at the exchange are of similar character; the spring
jacks are placed one upon each of the sections m and m¹ of switchboard. The
individual annunciator n³ of the line is however placed upon a section m of switch-
board near the jack 12 of the same line so as to be under the care of another
attending operator.
Two pairs of connecting plugs and other accessory appliances are shown complete,
one at each section of switchboard. The plugs p p are of construction shown in
Figures 15 and 16 and described in connection therewith. The like contact pieces of
the two plugs of the pair are connected together by flexible conductors q q' and other
circuit connections. Included in circuit between the two plugs are two calling
keys r and r, each adapted to disconnect both contact pieces of one of the plugs
from those of the other and to connect them to wires s s which form the terminals
of the calling generator t. A listening key u is provided, having contact points or
anvils connected with the different sides q q' of the cord circuit and having its
contact springs u¹ and u² connected with the terminals of the telephone w; thus
when the plunger of the listening key u is allowed to rise, as shown in the upper
cord circuit, the telephone w is connected in a bridge or branch connection between
the different sides of the cord circuit. A branch is connected in the middle of the
telephone coil to earth for testing purposes, in the well known manner.
An
additional spring u³ is provided upon the listening key, insulated from the other
parts of the key but adapted to be raised when the plunger is depressed so as to
be separated from a contact anvil u* connected to earth.
A clearing out annunciator x similar in construction to the individual annunciators
is provided in connection with each cord circuit having its operating coil per-
manently connected in another bridge between the different sides of the cord
circuit. The restoring coil is connected in a normally open local circuit
including the contact spring us and its anvil u' and a source of electricity. By
this device the clearing out annunciator is automatically reset or restored to its
normal position whenever the telephone of the operator is brought into the circuit.
I will now briefly describe the operation of establishing connection between two
subscribers' lines.
Suppose for example that subscriber at station 1 desires to communicate with a
subscriber at station 2. His switch hook being in its lowest position he rotates his
calling generator thus sending signalling current over the circuit k k', to the
exchange where the current finds circuit through the operating coil n' of the
individual annunciator n thereat. The armature of magnet n' is attracted, releasing
the shutter of the annunciator and indicating the signal to the operator attending
at board m'. The operator then inserts one plug p of a pair into the spring jack /
of that line at her board; the line circuit is thus extended through the contact

page_text: pieces c and of the spring jack to the corresponding contact pieces h and h* of
the plug thence through the conductors q q' of the cord circuit to the listening
key u belonging to that cord circuit. This key being in its normal position, that
shown in the upper cord circuit, the circuit is continued from conductors
and g¹
through the contact points of the listening key to the operator's telephone w
whereby she is enabled to communicate with the subscriber at station 1.
9
When the plug was inserted into the spring jack, the plug besides connecting
the line contacts of the spring jack with the corresponding contact pieces of the
plug, at same time crossed together the two local springs band b' through the
ring upon the plug thereby completing the local circuit including the battery o
and the restoring coil n of the individual annunciator. The electro-magnet was
thereby energised, attracting the shutter of the annunciator and restoring the
same to its normal position, in which position it is retained as long as the plug
remains inserted in the spring jack.
Having received the order from subscriber at station 1, say for connection with
subscriber at station 2, the operator at board m' proceeds to the line called for
to determine whether it is already in use or not. This she does by the well
known process of applying the tip of the remaining plug pl of the pair to the
test ring g of the spring jack at her board belonging to that line. The plug p³ of
the upper pair of cords at board m is shown in position of making such a test of
the spring jack 12 of line to station 2.
In the normal or idle condition of the line circuit, the test ring 9 is electrified to
a difference of potential from the earth by the battery o, which finds circuit through
the restoring coil of the individual annunciator of the line to the different test
rings thereof. If, when the line is in that condition, the tip of a plug as p³ be
applied to the test ring, the circuit will be completed from the test ring touched,
to the operator's telephone, thence through one half of the telephone coil g to
earth; and at each application of the tip of the plug to the test ring, a click will
be produced in the operator's telephone set indicating to her the idle condition of
the line. When however the line is put into use by inserting a plug into a spring
jack thereof, the springs bb are crossed together directly, whereby the test rings
are connected directly to earth through a short circuit, and thereafter possess no
difference of potential from the earth; hence no response will be produced in the
telephone when the test plug is applied to the spring jack.
Assume that the operator at board m', having tested line to station 2, found the
line to be unoccupied, she then inserts the plug p' with which she has been making
the test into the spring jack 13 of that line, whereby the two substations are joined
into a continuous loop circuit including the line circuits of both substations, the
contact pieces of the spring jacks at which the connections are made, corre-
sponding contact pieces of the connecting plugs, and the conductors 971 of the
cord circuit. The subscribers are thus enabled to cominunicate with each other.
When they have finished their conversation one of them as for example subscriber
at station 1, may send a clearing out signal or signal for disconnection to the
exchange by replacing his telephone upon the switch hook and again rotating his
generator i. A portion of the current thus sent over the lines k k¹ finds circuit through
the individual annunciator n as before but fails to operate the same because the
shutter of the annunciator is retained in its normal position by the continued
energization of the magnet n². Another portion of the current finds circuit through
the contact pieces of the plug to the cord circuit and thence through the operating
coil of the clearing out annunciator x. The operator at board m² had previously
disconnected her telephone from the line circuit after having found the subscribers
in communication, and hence the clearing out annunciator x is free to respond to the
signal for disconnection, its magnet 22 being unenergized; the operator who male
the connection is thus notified that the subscribers have completed their conversation.
Whenever she introduces her telephone set into that cord circuit again, as to answer
a call, by allowing the plunger of the listening key to rise, the local circuit

page_text: :
containing the restoring coil of the clearing-out annunciator is closed and the
clearnig out annunciator is reset.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. The combination, with the operating magnet and the restoring magnet mounted
end to end, of the rods kk, with which the ends of the coils of the restoring magnet
are connected, said ends of the wire of the coils being insulated from the shell, and
the rods being carried back to the rear of the annunciator, substantially as and for
the purpose specified.
2. The combination, with the iron gravity drop normally held by the hooked
lever of the operating maguet, of said lever, the retaining magnet having its pole
piece extended, and the drop being provided with a recess corresponding to said
extended pole, substantially as specified.
3. The combination, with the iron gravity drop and the operating electro magnetic
device for releasing the same, of the contact closing spring closed by the drop when
I the drop is released, and the magnet with its pole presented to said drop for
restoring the drop and thereby permitting the circuit closing spring to open,
substantially as specified.
4. The combination in an annunciator, with the tubular electro magnetic devices,
of the plate upon which they are mounted, the ends of the wire of the coils of one
magnet being carried out through insulating bushings in the shell thereof, said ends
being extended by insulated rods through said plate to the rear of the annunciator,
substantially as described.
5. The combination, with the tubular electro magnets placed end to end, of the
armature lever or hook extending over both the said magnets, the shells of said
magnets being provided with a groove for said lever to permit the same to lie close
thereto, substantially as shown and described.
6. The combination with a spring jack having an insulated thimble or equivalent
contact spring and three insulated contact springs, two of said springs being of equal
length, of a connecting plug in said jack having three insulated contact pieces, one
of which makes contact with the thimble or equivalent contact spring of the jack,
another of which makes contact with both of said springs of equal length, and the
remaining contact piece of which makes contact with the remaining spring, substan-
tially as specified.
7. The combination with a connecting plug, of a tip terminating a stem having
means for connecting a flexible cord thereto, a sleeve concentric with said stem but
insulated therefrom, also having means for connecting a conductor thereto, and an
insulated ring in front of said sleeve, substantially as specified.
8. The combination of the tip / terminating the stem h¹, the sleeve * concentric
with said stem, the insulating sleeve surrounding said stem h¹, and the ring h² on
said insulating sleeve, substantially as described.
9. In a spring jack, the combination with a thimble or tube or equivalent contact
spring, of a test ring located in front of said tube and insulated from it, substantially
as described.
10. In a spring jack, the combination with a tube or thimble or equivalent contact
spring, of a narrow test ring in front of said thimble or equivalent contact spring,
and insulated therefrom, the opening of said test ring being larger than the opening
in said tube, substantially as described.
11. The spring jack having thimble for equivalent contact spring, and the spring
contacts bb and c, in combination with the plug having tip h, making contact with
spring c, sleeve making contact with thimble for equivalent contact spring, and
ring making contact with both springs band 6.
12. The spring jack having test ring y, thimble for equivalent contact spring,
and spring contacts 66' and c, in combination with the plug having tip making
contact with spring c, the sleeve / making contact with thimble for equivalent

page_text: contact spring, and the ring h' making contact with both springs 6 and b', as
described.
13. The combination with the block a of insulating material of the thimble for
equivalent contact spring, test ring 9, and spring contacts b b and c mounted
thereon, substantially as described.
14. The combination with the block a of insulating material formed with the
grooves a¹ and a³, and the cylindrical apertures a³ therein and the rectangular
perforations a therethrough, of the test rings y and the thimbles for equivalent
contact springs in said apertures, the springs b and c in said grooves a', and the
springs in said grooves a², substantially as described.
15. The block a of insulating material, formed with the grooves a' and a², the
cylindrical apertures a³, and the saw cuts a' and a³, and the ducts g² and f² leading
from different points in said apertures a³ into the saw cuts a³ and a respectively, in
combination with the springs b¹ mounted in the grooves a², the springs b and c
mounted in the grooves a', the test rings g in front of said perforations a³ having the
extensions g' extending through the ducts g² and saw cuts a³, and the thimbles f
or equivalent contact springs, in another portion of said apertures a³, having
extensions f¹ extending through ducts f' and saw cuts a* to the rear of the spring
jacks, substantially as described.
16. The combination with the contact spring 61, of the test ring g electrically
connected therewith, substantially as specified.
Dated this 23rd day of Juno 1802
J. E. KINGSBURY.