Improvements in Apparatus for Telephone Exchanges.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Telephone Exchanges.
I, JOHN EDWARD KINGSBURY of 79 Coleman Street in the City and County 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:
This invention relates to multiple switch board systems of telephone exchange
and its objects are, first,. to reduce the amount. of wiring required between the
different boards:; and, second, to reduce the size of the switches so that a larger
number of lines may be brought within the reach of each operator.
The invention is particularly designed for use in connection with metallic circuit
telephone lines and consists in telephone lines each connected with a different spring
jack switch upon one of the switch boards, each line being. connected through an
induction coil or converter with metallic sockets on other boards, one for each line
on each of two or more other switch boards..
The invention consists also in apparatus for making the connections between trunk
lines and the spring jack switches upon the first switch board, together with certain
details of construction and combinations of parts hereinafter described.
:
In the drawings which are illustrative of the invention―
Figure 1 is a diagram showing two telephone lines, each connected with a different
double spring jack switch on the first board and each through the medium of a con-
verter with different metallic sockets on each of two other boards, each line being
provided with a different branch from one of the coils of its converter, which branches
extend each through a different individual annunciater to ground, operators' outfits
being provided at the boards containing the metallic sockets.
Figure 2 is a diagram, showing two subscribers' stations and lines extending to
the first board with apparatus for connecting said lines with a trunk line.
Like parts are indicated by similar letters of reference throughout the different
figures..
Referring now to Figure 1, subscribers station 1 is connected with the central
office by a telephone line a consisting of two branches or limbs a' a²; the circuit of
limb a may be traced through the spring and contact of spring jack switch band
thence through one winding of the converter 61 to the contact point of spring jack
switch 62 and thence to the spring of said switch 62, with which spring the other
branch or limb a² is connected, and thence over said limb a² back to station 1. The
coil of coverter which is included in the circuit. thus traced is provided with a
branch 63 which passes through the individual annunciator 6 of the line and
thence to ground. For a detail of the apparatus at station 1 see station 1,
Figure 2.
'
The telephone line c of subscriber's station 2 consists of two branches or
limbs cc, limb c¹ being connected through spring jack switch d and thence through
a coil of repeating coil d' and thence the circuit may be traced through the contact
and spring of spring jack switch d2 and thence to subscriber's station 2 over limb c
A branch d³ from the coil of. converter d' which includes circuit c extends as shown
through individual annunciator, d to ground..
It will be observed that the frames or test pieces of the spring jack switches b*b*
are electrically connected; also the frames of switches d d of line c. One coil of
converter is included in the circuit of line a and a coil of the converter d in the
circuit of line c; the individual annunciator 6 of line a is included in a wire 63.
connected preferably with the centre of the coil of converter 6 whic's is included
1

page_text: inne a. The individual annunciator d' of line c is in a similar manner included in
the branch d³ which extends to the centre of that coil of d¹ which is included in
circuit of line c.
The other coil of converter 6 includes a wire e which extends to socket e¹ upon
board 2 and to socket e2 upon board 3.
The second coil of converter d¹ is included in like manner in a wire f extending
from ground through said coil to a socket f¹ on board 2 and a corresponding
socket on board 3.
At board 2 I have shown an operator's outfit consisting of a pair of connecting
cords with terminal plugs g g', a cam lever switch g², a clearing out annunciator 9³
connected between the two contact springs of the switch, the telephone g* in a branch
extending from ground through said telephone to the telephone contacts of the
switch g², a pair of calling keys go ge included in circuit of said connecting cords
and a test plug g' included in a ground branch which ground branch includes one
coil of an induction coil 98, the other coil of said induction coil being in a bridge
across the telephone terminals; the test battery g is included in the cord connecting
with the plug g¹. Similar operator's apparatus is shewn at board 3.
Referring now to the apparatus of the subscriber at station 2, it will be seen that
when the telephone is hung upon the switch as shown, the bell h and generator /' will be
included in the circuit of wire c; that is to say, the side or limb c¹ is connected
through the bell h and the generator to the telephone switch and thence to the
lower contact /2 of the switch and thence through key h³ to limb c². On removing
the telephone from the switch the lower contact his opened and the telephone
contact his closed, thus looping the telephone into circuit.
.;
The individual annunciators of the local lines are preferably distributed on boards 2,
3, etc. which are provided with the simple metallic sockets. The local connections
will thus be made upon the boards 2, 3, and not upou the board 1 which contains the
double spring jack switches b², d'd; this first board 1 I reserve for making the
trunk or toll line connections and it may be placed, if desired, in a room by itself..
Thus in Figure 2 I have shown two subscriber's stations 1 and 2, connected with
board 1 and a toll line or trunk line operator's outfit.
long distance lines are connected with a separate board 4. It is evident, however,
We will suppose that the
that they might be provided with switches upon board 1 if desired. I have shewn
the metallic circuit long distance line i connected through spring jack switch,
annunciator and thence through the other spring jack switch of the pair. It is...
necessary to be able to connect any one of the long distance lines i with any one of
the local telephone lines a c.
:
The calls of the different local lines will be received by the operators at the different.
local boards 2, 3, in the usual manner. Any local operator receiving a call for an
extra territorial line (as toll lines and other lines not belonging to the local system
are sometimes called) will notify the operator at board 4 of the call, giving the
number of the subscriber calling and the number or name of the extra territorial:
line with which the calling subscriber has asked connection.
The connection between any local telephone line, as line a, and any extra territorial:
line, as line i, may be made by loop plugs connected a shown by flexible cords
when inserted respectively in switch device i 3 of line.i and the switch.device b b² of
line a.
In this manner a local line and an extra territorial line
together in metallic circuit without including in the circuit any unnecessary.
be looped
resistance.
may.
In large exchanges I preferably place an operator at each of the boards 4 and 1,5
each being provided with a telephone set so arranged that they can communicate with
one another as desired.
Thus at board 1 I have shown telephone set 2 and at board 4 telephone set. The
local telephone line k is connected with telephone set and extends thence to
terminals k¹, k² and k³ on the different boards 1, 2, 3.
The call from any, the local boards as 1 or 2 is repeated over line k to the operator

page_text: at board 4 listening at telephone 7. The operator at telephone by depressing the
pair of keys puts herself in communication with operator at board 1 listening at
telephone
.
The generator is connected with appropriate contacts of ringing keys 12, 13³. By
depressing current will be sent from generator over any line with which the
twin plug is connected. By depressing ringing key 13, that is, by forcing down the
piston thereof, the generator is brought into circuit with the cords connecting with
the different terminals of twin plugs. The operator at board 4 may thus ring
in either direction to signal over a long distance wire or over any local line with which
she may be connected.
:
Each of the operators at the local boards is provided with a test plug connected with
her telephone for determining whether any line wanted or called for is already con-
nected or in use; thus test plug m is provided at board 1, the circuit of which is
connected with telephone set ; test plug g' is provided at board 2 as before described
and a test plug m¹ is provided at board 3 connected with the operator's telephone m²
through a converter m³.
I will now describe the manner of connecting any two local lines together upon one
of the switch boards 2, 3. We will suppose that subscriber 2 wishes connection with
subscriber 1. He depresses key ³ (figure 1) and turns generator h¹, thus sending
current over limb c¹ through switch d to coil d¹ and thence over branch d³ through
individual annunciator d' on board 3 to ground. The operator at board 3 seeing
shutter d fall, immediately lifts plug m and inserts the same into socket f³ corre-
sponding to line c. The listening in switch me being thrown to the position shewn, the
telephone m³ will be brought into the circuit of wire f.
The circuit thus formed may be traced from ground near telephone m² through
said telephone, thence to the telephone contacts of listening in key m³, thence to the
springs of said listening in key resting upon said contacts and thence from the
spring me through test battery m' and calling key m³ to the cord of plug m; this
plug m being inserted in socket f the circuit may be traced over wire f through the
winding of converter d' included in the circuit of wire f to ground. In the meantime
the subscriber at station 2 has let go of key ³ and taken down his telephone;
contact his thus opened and the telephone contact and local contact at being
closed the telephone is brought into the circuit of wire c; the operator at board 3 and
the subscriber at station 2 are thus brought into telephonic communication. The
subscriber having given his order the operator first by means of plug m¹ tests the line
called for; if the line tested is busy a click will be heard in telephone m² when
plug m¹ is touched to the switch of the line tested; if, however, the line is free she
will hear no click.
We will assume that the line called for was line a and that the plug m¹ having
been applied to socket e no click was heard in the telephone, the operator thereupon
inserts the other plug m³ of the pair in socket e² and depressing key m¹ throws
current over wire e in the circuit of which is included one winding of the converter 6';
this in a manner well understood will induce a current in the metallic circuit a
connected in the other coil of the converter and thus the bell included in the circuit of
line a at station 1 (for detail see Figure 2) will be rung.
The subscriber at station 1 taking down his telephone will disconnect his bell and
bring his telephone into circuit. The two subscribers will then be in telephonic com-
munication, that is to say, the loop or metallic circuit c will include the telephone of
subscriber 2 and one winding of converter d. The metallic circuit or loop a will
include the telephone of subscriber 1 and a winding of converter 6¹. The wires ef
which include the other windings respectively of the converter will be connected
together by means of the plugs m' m' and the flexible cords connected therewith.
On throwing up the cam lever of key m³ the clearing out annunciator m¹¹ is
brought into the circuit of the cords. When the subscribers are through talking
either may clear out in the ordinary manner by hanging up his telephone and turning
his generator.
Supposing one of two lines connected upon board 3 should be called for at another

page_text: .
board as for example, board 2; it will be observed that the test battery m' is included
in the circuit of wires ef when two subscribers are connected as above described.
There will thus be battery current present at all the other sockets of the connected
lines upon other boards. The operator then at another board, as board 2, by simply
touching the tip of plug g' upon socket would get battery current through the coil
of converter g³ connnected with telephone g; thus a click would be heard in the
telephone and she would know that the line c was busy and would inform the one who
had asked for line c of the fact..
It should be observed that the wire fis branched to the frame of the double switch d d
upon the first board and the wire is branched to the frame of the double switch b b²;
thus plug m may be used for testing at board 1. The loop plug is at board 1 is
provided with two tips, each tip being insulated from a metallic sleeve upon the shank
of each of the two parts; these sleeves are connected with the test battery n; when,
therefore, twin plug is inserted in the switch device of any line the frame of said
switch device with which the sleeves come in contact will be connected with battery n.
Thus any line is made to test busy at all the boards when connection is made there-
with at any of the boards whether the connection be at the first board or at one of
the local boards. 2, 3, etc.
We will suppose now that subscriber 2 wishes connection with a long distance line
as line; he will call the same as if he desired a local connection. Throwing down
shutter d the operator will make connection as before described by means of plug m
and find out what is wanted; finding that it is a trunk line connection wanted the
operator will apply the other plug m³ to socket k³, thus bringing herself into com-
munication with the operator listening at telephone 7 of long distance board 4; she
will thereupon inform long distance operator that subscriber 2 wishes connection with '
long distance wire i; operator at board 4 will thereupon depress key / to connect with
telephone of operator at board and will tell operator at board 1 to make connection
with line c of subscriber 2; this she will do by inserting twin loop plug in double
switch d d of line c. Operator at board 4 will at the same time insert twin plug into
the switch. By means of calling 'key 12 current from generator may be sent over
the long distance wire and by means of key 3 current may be sent over the circuit
of subscriber 2. By means of listening key n¹ operator at board 4 may bridge
telephone between the cords n² n³.
One coil of the clearing out annunciator n* is included iu cord n² and the other
coil in cord n³; these coils being wound in opposite directions will act together upon
the armature. If a call is sent in over a long distance line, as line i the shutter
will be thrown down and the operator inserting twin plug in double switch i¹ and
throwing up the cam lever of listening key n¹ will bring telephone into circuit.
Having received the order she will operate key l and repeat the order to the operator
at board 1 and the operator at said board 1 will, after having found the line wanted.
is not in use, insert the twin plug corresponding to the one in use at board 4 into
.the double switch of the line wanted. The insertion of twin plug will cause
the line with which connection is thus. made to test busy at all other boards as
boards 2, 3.
The test plug m may be applied to socket k³ whenever operator at board 1 wishes to
connect with operator at board 4.
The repeating coils or converters 1 d¹ may consist each of two coils say, having a
resistance each of one hundred and sixty ohms.
It will be seen that any telephone line connected upon the first board is cut off
from the repeating coil and all the connections in the remaining boards of said line,.
thus connections with long distance lines are practically free from resistance; for
local connections, however, the small amount of resistance introduced into the circuit
by the repeating coils will not be harmful. The economy of my system when applied
to very large exchanges will be apparent since spring jack switches upon the local
boards are not required. The number of connections for each line upon the local
boards being greatly diminished the problem of cabling, that is, of disposing of the
wires at the rear of the boards, is made very simple.

page_text: The busy test which I have shown is found to be satisfactory; other.systems might,
however, be used with good results.
.It is apparent that the Invention admits of various other modifications which would
readily suggests themselves to those skilled in the art and I therefore do not limit
myself to the details of construction 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 I declare that what I
claim is :-
:
1. The combination with a telephone line connected with a switching device upon
the switch board of a telephone exchange, of a converter, one coil of said converter
being included in said telephone line, a branch from said coil extending to ground
and containing an individual annunciator upon one of two or more other switch boards
of the exchange, the other coil of said converter being included in a branch wire-
extending from ground through said other coil and having a connection or socket¨¨¨
upon each of said other local boards.
2. A metallic circuit extending from a subscribers station through a double spring
jack switch device and one coil of a converter between the two portions of said
switch device, a branch from said coil to ground through an individual annunciator
and a key and generator at the subscriber's station, whereby the limb of said metallic
circuit containing the generator may be closed to ground at the subscriber's station
and the annunciator operated on turning the generator, substantially as and for the
purpose specified.
3. A subscriber's apparatus consisting of a telephone, a telephone switch operated
thereby, a bell and: generator and a key for grounding the portion of the circuit con-
taining the generator and bell, said circuit extending in two branches or limbs to
the subscriber's station and including one coil of a converter, a branch from said coil
to ground through an individual annunciator upon one of two or more switch boards,
a. branch wire: connected with ground and passing through the other coil of said
converter and extending to a different socket or connection upon each of said switch
boards, whereby the subscriber may signal the central office and bring his telephone
into a metallic circuit including one of the coils of the converter, the voice currents
sent over said metallic circuit being induced upon the ground branch containing the
other coil, substantially as and for the purpose specified.
1.
4. A metallic circuit telephone line including a subscriber's outfit and a key for.
grounding one side or limb of said circuit to ground at the subscriber's station of a
converter at the central office having one coil included in said metallic circuit, a
branch from the centre of said coil through an annunciator to ground, whereby the
subscriber on operating his grounding key may complete a circuit from his station
through said annunciator, substantially as and for the purpose specified.
5. The combination with a telephone line connected in metallic circuit through a
bell at the subscriber's station and one coil of a converter at the central office, of: a
wire including the other coil of said converter and extending to a socket or connection
upon each of two or more switch boards, of a source of electricity and a connecting
device at each of the boards adapted to close said wire as a primary circuit, whereby
on sending currents through said coil as a primary corresponding currents will be
induced, upon the telephone line to ring the bell at the subscribers' station, substantially
as and for the purpose specified.
6. The combination with two telephone lines each looped through a coil of a
different converter at the central office, of the other coils of said converters connected
together in a closed circuit, whereby telephonic communication is established between
the subscribers, substantially as and for the purpose specified.
7. The combination with two metallic circuit telephone lines, each provided with a
double spring jack connecting device at the central office, of a pair of twin plugs and
flexible connecting cords between said plugs, whereby on inserting the plugs into said
double spring jack switches of the two lines the two lines are connected together and
..

page_text: the portions of the lines back of the spring jacks cut off, substantially as and for the
purpose specified.
8. The combination with a switch board provided with double spring jack switch
devices with which different telephone lines are connected, each telephone line being
provided with a different converter and including a coil thereof and each being
provided with a branch extending from said coil of its converter to ground through
an individual annunciator upon one of several local switch boards, a wire for each
telephone line including the other coil of the converter thereof and extending to a
different switch or socket on each of the local boards and to the insulated frame of the
double spring jack device of its line upon the first board, a subscriber's outfit upon
each of said telephone lines, an operator's apparatus at each of the local switch
boards, one or more long distance or extra-territorial lines and an operator's outfit at
the terminal of said long distance or extra-territorial line connected with an operator's
outfit at the board containing the double spring jack devices of the local lines,
whereby an operator at one of the local boards on receiving a call for an extra-
territorial line may notify the long distance operator thereof, whereupon the long
distance operator in conjunction with the operator at the first, board may connect the
local line with the extra-territorial line-in. metallic circuit and whereby the long
distance operator upon receiving a call for.connection with a local line may test said
local line and make connection therewith, substantially as and for the purpose
specified.
9. A metallic circuit telephone line provided with a double spring jack switch
device upon the first board and connected through the medium of a converter with
other local switch boards, of a long distance line provided also with a double spring
jack switch device and a pair of twin plugs and connecting cords, each cord including
a different coil of a clearing out annunciator wound oppositely whereby the long
distance line and the local line may be looped together, substantially as and for the
purpose specified.
10. The combination of a metallic circuit extending from a subscriber's station
through a double spring jack device and one coil of a converter between the two
portions of said switch device, a branch from said coil to ground through an
annunciator and a key, and generator at the subscriber's station, whereby said
metallic circuit may be connected to ground at the subscriber's station and the
annunciator operated by turning the generator substantially as and for the purpose
specified.
11. A telephone circuit consisting in the combination of two wires, each of said
wires being provided with a switching device upon the first. board and connecting
through the medium of a converter with the local switch. boards, of a long distance
line also provided with a switching device, and connecting cords and plugs, whereby
the long distance line and the local line may be connected together, substantially as
and for the purpose specified.
12. The combination with a telephone line passing through a switching device at
one section of a multiple board and through one coil of a converter, of a branch wire
extending through another coil of said converter to all of the sections of said multiple
board.
Dated thin 12th
1000