Improvements in Telephony and in Apparatus therefor.
Year: 1890

page_text: Date of Application, 8th Apr., 1890
Complete Specification Left, 6th Jan., 1891-Accepted, 7th Mar.. 1891
PROVISIONAL SPECIFICATION.
Improvements in Telephony and in Apparatus therefor.
I, MILO GIFFORD KELLOGG, of 135, 47th Street, Chicago, Illinois, United
States, Electrical Engineer, do hereby declare the nature of this invention to be
as follows:-
"
My invention relates to the multiple switch board telephone exchange system.
It consists, first, in a system of testing the lines of the exchange by which they
test "busy
whether they are switched at any board or their line annunciators
indicate a call; and, secondly, to an organization of apparatus for connecting two
lines of a ground circuit or one wire telephone exchange system by the use of one
plug and cord, and for receiving the calls, answering the subscriber, calling,
connecting with and calling on the line wanted, receiving the disconnecting signals
and disconnecting the lines and placing them in condition to receive new calls and
connections. I believe that the apparatus and the work required of the operators
is less in this system than in other telephone exchange systems.
It frequently happens, in the multiple switch board system, that an operator
receives calls from several lines at practically the same moment and it requires
some little time before he connects his answering apparatus to a certain line and
answers its call; and in the meantime, another operator at another board, tests
the line and finding it to test "free" or not in use, switches the line with another
line asking connection with it. The subscriber is annoyed and confused by not
getting the connection he wishes, and the first operator is annoyed and confused
when he attempts to answer the call and does not know that the line has, since
the call was made, been brought into use at another board. By making the lines
test "busy
as soon as their annunciators indicate their calls, I obviate this source
of annoyance and confusion both to the subscribers and the operators.
"
This, the most important feature of my test system, is applicable to metallic
circuit telephone exchange systems, as well as to ground or single wire circuit
systems, and also to other systems of operation and testing than that herein
described.
Each line switch has a contact spring which is normally in contact with a
contact point or piece and separated from said point or piece when a switch plug
is inserted, and has a second contact piece which is normally insulated from the
other parts but is in connection with said contact point or piece when a plug is
inserted. Said parts are so related to each other and to the switch holes, and the
switch plugs are so constructed that when a plug is inserted into a switch, it
separates the contact spring from the contact point or piece, connects the spring
with the conductor of the cord belonging to the plug and connects said contact point
or piece with said second or normally insulated contact piece.
There are extension pieces to the points placed along the switch holes and contact
pieces are placed along the switch holes in front of the extension pieces and
extending to the front of the holes. The holes are square or rectilinear holes
adapted to receive the switch plugs and cause them to operate the switches as
described and these are ebonite pieces on which the switch parts are mounted and
through the front of which are the holes.
There are switch plugs, one for each line and connected to the line through the
conductor of its switch cord and two contact pieces for the plugs one connected to
the cord conductor and adapted to form connection with the switch spring, and the
other adapted to bridge or connect pieces of the switch when a plug is inserted.
There are also compound answering switches one for each line. These switches
are operated on in part by the switch plugs of their lines and in part by the
operators as will be described.

page_text: I will call these compound answering switches 1, 2, 3, 4, 5 and 6 are contacts of
which 2, 3 and 5 are springs and 1, 4 and 6 may be points and rigid. An angle
or bell crank piece suitably pivoted is provided with a knob at one end within
easy manipulation of the operators and a projection at the other end adapted to
engage with, and operate on the irregularly shaped ebonite piece fastened to
spring 3. When the plug is in the socket of its answering switch (the piece being
in its normal position as shown) spring 5 is forced by the plug out of contact
with 6, and spring 3 is forced into contact with 2. When the plug is removed,
spring 5 passes into contact with 6 and spring 3 passes from point 2 into contact
with 4.
When then (the plug being removed) the operator presses the knob to its
extreme other position the projection on the lever operating on spring 3, forces it
into contact with point 1, and when thereupon the operator releases the knob,
the pressure of the spring carries it away from point 1 and it is held by the
projection in contact with spring 2.
There are calling annunciators one for each line. These annunciators are located
at the boards where their line plugs and cords and compound answering switches
are located. These annunciators are a well known form of annunciators used in
telephone exchanges. Each has two contacts normally separate but brought into
contact by the annunciator drop on the drop falling and indicating a call; one of
the contact pieces is a spring operated upon by the drop on falling and pressed by
it into contact with the other contact, which is a point.
.
There are operator's telephone's calling generators or batteries and test batteries,
one of each being located at each board. The connections are as follows: the line
passes normally in succession through a spring and point passing in each case to the
spring first; it is there connected to the contact piece of its switch plug and to
contact spring 3 of its answering switch. Spring 2 of the answering switch is
connected through the magnet of the line annunciator to earth. Point 1 of the
answering switch is connected through the calling generator or battery to earth,
while point 4 is connected through the operator's telephone and test battery to
earth and spring 5 is connected to carth. All the contact pieces of the switches
of a line are connected together and to point 6 of its answering switch and one of
the contacts, of its line annunciator. The other contact of the annunciator is
connected to earth.
At
The operation of the system is as follows: a subscriber wishing a connection,
operates his line annunciator. The operator observing the indication withdraws
the line plug from its normal position in its answering switch and by so doing
disconnects the line from its ground connection through the annunciator and
connects the line to the ground through his telephone and test battery. This is
done by the opening of contacts 2 and 3 and the closing of contacts 3 and 4.
the same time all the contact pieces of the switches of the line are connected to
earth through the closing of the contacts 5 and 6. The operator then by con-
versation finds out what line is wanted, then tests the line wanted, as will hereafter
be described, and if he finds it does not test busy, he places the plug in the switch
of the line tested and moves the angle or bell crank piece of the answering switch
to its extreme position and releases it. When the operator puts the plugs in the
switch, the line is disconnected from its normal ground connection through its
annunciator, and the two lines are connected together. When the angle or bell
crank piece is in its extreme position the calling generator or battery, grounded
on one side, is connected on its other side to the circuit- of the two lines and will
send a current to both lines which will ring the bell of the line wanted and will
ring the bell of the calling subscriber if he has in the meantime replaced his
telephone on its switch. When the knob is released the angle or bell crank piece
takes a position so that the circuit of the two lines are grounded at the central office
through the annunciator of the calling subscriber, and. any disconnecting signal
sent by either subscriber. will be indicated on the annunciator. The annunciators
should preferably be of high resistance and of such construction: as to offer
considerable retardation to telephone currents.

page_text: When the operator desires to listen to the circuit of the two lines to determine
whether they are through conversation he merely replaces the movable piece
of the answering switch to its normal position, and his telephone grounded at one
end is connected on its other side to their circuit.
;
The test system is as follows: When a line annunciator indicates a call, or the
line is brought into use, either by the withdrawal of its switch plug from its normal
position; or by the introduction of a plug into one of its switches, the contact pieces
of the switches of the line are connected to the ground. In the first case the con-
nection is made by the closing of the contact points of the annunciator; in the
second case, by the closing of the contacts 5 and 6, caused by the withdrawal of
the plug and the third case, by the connection established between the contact
point and contact piece of the switch used, through the medium of the plug. When
the line annunciator does not indicate a call and the line is not switched, the contact
pieces of the line are open to the ground. The operator, on testing a line places
the tip of the switch plug of the calling line on the contact piece of the switch of
the tested line, and thereby through the answering switch and the contact made
connects his telephone and test battery grounded on to the other side of the contact
piece. If then the line is in use and the piece is also connected to the ground a
complete circuit is established and the operator will hear a sound or click in his
telephone. If the line is not in use or engaged, he will hear nothing. He will
therefore know on testing whether or not the line is free to be switched to.
By this system of testing a subscriber's line is reserved to his own use from the
very moment when he operates his calling generator or battery and the service of
the exchange will be more satisfactory to him and to the operators. This feature
of my invention is applicable to other systems of operations and of lines in ways
which will now be apparent to those skilled in the art.
The operations of making a connection are (1) To remove the line plug from
its answering switch. (2) To test with the same plug the line wanted. (3) To
insert the plug in the switch of the line wanted. (4) To move the angle or bell
crank piece of the answering switch to its limit of motion.
To disconnect the lines the operator merely removes the plug from the switch
and places it in its normal position and places the angle or bell crank piece in its
normal position.
Dated this 9th do of Anvil 1900
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in Telephony and in Apparatus therefor.
I, MILO GIFFORD KELLOGG, of 135, 47th Street, Chicago, Illinois, United
States, Electrical Engineer, 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 the multiple switch board telephone exchange system.
It consists, first, in a system of testing the lines of the exchange by which they
test busy whether they are switched at any board or their line annunciators
indicate a call; and, secondly, to an organization of apparatus for connecting two
lines of a ground circuit or one wire telephone exchange system by the use of one
plug and cord, and for receiving the calls, answering the subscriber calling,
connecting with and calling on the line wanted, receiving the disconnecting signals
and disconnecting the lines and placing them in condition to receive new calls and
connections. I believe that the apparatus and the work required of the operators
is less in this system than in other telephone exchange systems.
It frequently happens, in the multiple switch board system, that an operator
receives calls from several lines at practically the same moment and it requires

page_text: some little time before he connects his answering apparatus to a certain line and
answers its call; and in the meantime, another operator at another board, tests
the line and finding it to test "free" or not in use, switches the line with another
line asking connection with it. The subscriber is annoyed and confused by not
getting the connection he wishes, and the first operator is annoyed and confused
when he attempts to answer the call and does not know that the line has, since the
call was made, been brought into use at another board. By making the lines test
busy
as soon as their annunciators indicate their calls, I obviate this source of
annoyance and confusion both to the subscribers and the operators.
This, the most important feature of my test system, is applicable to metallic
circuit telephone exchange systems, as well as to ground or single wire circuit
systems, and also to other systems of operation and testing than that herein
described.
66
"
In the accompanying drawings illustrating my invention, A and A' are sectional
views of sections of two multiple switch boards to which the same lines connect.
Two lines and their line switches on the boards, their annunciators, their plugs with
cords, their compound answering switches, two operator's outfits, including their
telephones and calling generators or batteries, and the connections of the lines with
their switches, annunciators, plugs aud cords, and of the operators apparatus are
shown in the drawings.
Each line switch has a contact spring which is normally in contact with a
contact point or piece and is separated from said point or piece when a switch
plug is inserted and has a second contact piece which is normally insulated from
the other parts but is in connection with said contact point or piece when a plug is
inserted. Said parts are so related to each other and to the switch holes, and the
switch plugs are so constructed that when a plug is inserted into a switch, it
separates the contact spring from the contact point or piece, connects the
spring with the conductor of the cord belonging to the plug and connects said
contact point or piece with said second or normally insulated contact piece.
yg are the contact springs, while hh are contact points on which the springs
normally bear. extension pieces to the points placed along the switch holes.
and are contact pieces placed along the switch holes in front of the extension
pieces and extending to the front of the holes. The holes, marked 11 are square
or rectilinear holes adapted to receive the switch plugs and cause them to operate
the switches as described. ab are ebonite pieces on which the switch parts are
mounted and through the front of which are the holes ll.
D D are the switch plugs, one for each line and connected to the line through
the conductor of its switch cord. ss' are two contact pieces for the plugs, one s
connected to the cord conductor and adapted to form connection with the switch
spring, and the other s adapted to bridge or connect pieces j and h¹ of the switch
when a plug is inserted. BB' are compound answering switches one for each line.
These switches are operated on in part by the switch plugs of their lines and in
part by the operators, as will be described.
In these compound answering switches 1, 2, 3, 4, 5 and 6 are contacts of which
2, 3 and 5 are springs and 1, 4 and 6 may be points and rigid. m is a piece adapted
to support the parts and k furnishes a socket or support for the plug which belongs
to the line of the switch. n is an angle or bell crank piece suitably pivoted, and
with a knob marked o at one end within easy manipulation of the operators and
a projection marked p at the other end adapted to engage with, and operate on the
--irregularly shaped ebonite piece fastened to spring 3 as shown. When the plug
is in the socket of its answering switch (the piece n being in its normal position as
shown) spring 5 is forced by the plug out of contact with 6, and spring 3 is forced
into contact with 2. When the plug is removed, spring 5 passes into contact with 6
and spring 3 passes from point 2 into contact with 4. When then (the plug being
removed) the operator presses the knob o to its extreme other position (in the
direction shown by the arrow), the projection p operating on spring 3, forces it
into contact with point 1, and when thereupon the operator releases the knob, the

page_text: pressure or the spring carries it away from point I and it is held by the projection p
in contact with spring 2.
w and are calling annunciators, one for each line shown. These annunciators
are located at the boards where their line plugs and cords and compound answering
switches are located. These annunciators are a well known form of annunciators
used in telephone exchanges. Each has two contacts normally separate but brought
into contact by the annunciator drop on the drop falling and indicating a call;
one of the contact pieces u is a spring operated upon by the drop on falling
and pressed by it into contact with the other contact, which is a point and
marked v.
t, t, are operator's telephones. S, S are calling generators or batteries and
SS are test batteries, one of each being located at each board. G in each case
represents a ground connection. The connections are as follows: the line passes
normally in succession through the spring g and point h, its last of line switches on
the several boards, passing in each case to the spring first; it is there connected
to contact pieces of its switch plug and to contact spring 3 of its answering switch.
Spring 2 of the answering switch is connected through the magnet of the line
annunciator to earth. Point 1 of the answering switch is connected through the
calling generator or battery to earth, while point 4 is connected through the
operator's telephone and test battery to earth and spring 5 is connected to earth.
All the contact pieces jj of the switches of a line are connected together and to
point 6 of its answering switch and one of the contacts, say v, of its line annunciator.
The other contact u of the annunciator is connected to earth.
The operation of the system is as follows: A subscriber wishing a connection,
operates his line annunciator.
The operator, observing the indication, withdraws
the line plug from its normal position in its answering switch and by so doing
disconnects the line from its ground connection through the annunciator and
connects the line to the ground through his telephone and test battery. This is
done by the opening of contacts 2 and 3 and the closing of contacts 3 and 4. At
the same time all the contact pieces jj of the switches of the line are connected to
earth through the closing of the contacts 5 and 6. The operator then by conversation
finds out what line is wanted, then tests the line wanted, as will hereafter be
described, and if he finds it does not test busy, he places the plug in the switch
of the line tested and moves the angle or bell crank piece of the answering switch
to its extreme position in the direction indicated by the arrow, and releases it.
When the operator puts the plugs in the switch, the line is disconnected from its
normal ground connection through its annunciator, and the two lines are connected
together. When the angle or bell crank piece is in its extreme position in the
direction of the arrow as indicated, the calling generator or battery, grounded on
one side, is connected on its other side to the circuit of the two lines and will send
a current to both lines which will ring the bell of the line wanted and will ring the
bell of the calling subscriber if he has in the meantime replaced his telephone on
its switch. When the knob is released the angle or bell crank piece takes a position
so that the circuit of the two lines are grounded at the central office through the
annunciator of the calling subscriber, and any disconnecting signal sent by either
subscriber will be indicated on the annunciator. The annunciators should preferably
be of high resistance and of such construction as to offer considerable retardation
to telephone currents.
When the operator desires to listen to the circuit of the two lines to determine
whether they are through conversation he merely replaces the movable piece of the
answering switch to its normal position, and his telephone grounded at one end is
connected on its other side to their circuit.
Some of the switching operations herein described have been obtained in other
systems by the use of two switching devices for each line, one a plug switching
device in which the line plug is normally placed and which makes certain switching
connections when the plug is withdrawn from the switching device and the other
an operator's switching device with a movable, commutator piece to be operated by.

page_text: the operator to make other switching connections. By the use of a compound
answering switch for each line, on which both the plug and the operator operate to
make the required switching connections, the apparatus is simplified both as to the
number of parts and the circuit connections required.
The test system is as follows: When a line annunciator indicates a call, or the
line is brought into use, either by the withdrawal of its switch plug from its normal
position; or by the introduction of a plug into one of its switches, the contact
pieces of the switches of the line are connected to the ground. In the first case
the connection is made by the closing of the contact points of the annunciator; in
the second case, by the closing of the contacts and 6, caused by the withdrawal of
the plug; and the third case, by the connection established between h and j of the
switch used, through the medium of the pieces of the plug. When the line
annunciator does not indicate a call and the line is not switched, the contact
pieces of the line are open to the ground. The operator, on testing a line places
the tip of the switch plug of the calling line on the contact piece of the switch of
the tested line, and thereby through the answering switch and the contact made
connects his telephone and test battery grounded on to the other side of the contact
piece. If then the line is in use and the piece j is also connected to the ground, a
complete circuit is established and the operator will hear a sound or click in his
telephone. If the line is not in use or engaged, he will hear nothing. He will
therefore know on testing whether or not the line is free to be switched to.
.
By this system of testing, a subscriber's line is reserved to his own use from the
very moment when he operates his calling generator or battery and the service of
the exchange will be more satisfactory to him and to the operators. This feature
of my invention is applicable to other systems of operations and of lines in ways
which will now be apparent to those skilled in the art.
The operations of making a connection are: (1) To remove the line plug from
its answering switch; (2) To test with the same plug the line wanted, (3) To insert
the plug in the switch of the line wanted, (4) To move the angle or bell crank piece
of the answering switch to its limit of motion as indicated.
To disconnect the lines the operator merely removes the plug from the switch
and places it in its normal position and places the angle or bell crank piece in its
normal position as shown.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. In a telephone exchange system a normally open test wire for a line, normally
open to the ground, and contacts and connections by which said test wire is con-
nected with the ground while either the line is switched for use or the line
annunciator indicates a call, in combination, with a test receiving instrument
grounded at one side and connected at its other side to a plug or device adapted
to be brought for testing into connection with said normally open test wire, and a
battery in the test circuit established substantially as set forth.
2. In a telephone exchange system a normally open test wire for a line, normally
open to the ground and contacts and connections by which said test wire is con-
nected with the ground by the line annunciator, on its indicating a call, in combination
with a test receiving instrument grounded on one side and connected on- its other
side. to a plug or device-adapted to be brought for testing into connection with said
test wire, and a battery in the test circuit established when the line is tested and
the annunciator indicates a call, substantially as set forth.
3. In a telephone exchange system a telephone line, a test circuit therefor
normally open at two points, and contacts and connections by which said test circuit
is closed at one point while either the line is switched for use, or the line annunciator
indicates a call, in combination with a test receiving instrument and a test battery
in said test. circuit, and means for closing the test circuit at the other of said points
to test whether the line is free or not.

page_text: 4. In a telephone exchange system, a telephone line and a line switch having
two contact points normally in contact, one of which is connected to the line and
the other of which is connected to the ground, and a test contact piece normally
insulated from the rest, in combination with a switch plug adapted to be inserted
into said switch, said plug having two contact pieces and when inserted disconnecting
the switch contact points normally in contact and through one of its contact pieces
connecting the line contact point of the switch with another line and through its
other contact piece connecting the test contact piece with the ground contact point
of the switch substantially as set forth.
5. In a telephone exchange system, a telephone line and a switch plug connected.
to the line by a flexible conducting cord, in combination with a compound answering
switch with contact points by which when the plug is withdrawn from the compound
switch the normal ground connection of the line is removed and the line is grounded
through the operator's telephone and when the operator moves a commutator piece
of said compound switch, the contact which grounded the line through the telephone
is opened, substantially as set forth.
6. In a telephone exchange system, a telephone line and a switch plug connected
therewith in combination with a compound answering switch, with contact points by
which, when the plug is removed from the compound switch, the normal circuit of
the line is open at the central office, and the circuit of the line is directed through
the operator's telephone, and when the operator moves a commutator piece of said
switch the contact completing the line circuit through the telephone is open,
substantially as set forth.
7. In a telephone exchange system, a telephone line and a switch plug connected
to the line by a flexible conducting cord, in combination with a compound answering
switch for the line with contact points by which when the plug is withdrawn from
said answering switch the ground connection of the line through its annunciator is
automatically removed and the line grounded through the operator's telephone, and
a commutator piece for said compound answering switch by which the operator
may at will disconnect the line from the ground connection through his telephone
and re-establish the ground connection through the annunciator, substantially as
set forth.
8. In a telephone exchange system, two lines temporarily connected together for
conversation in combination with a compound switching device with contact points
by which the operator may at will ground their circuit through either the line
annunciator of one of the connected lines or through his telephone or through his
calling generator or battery, substantially as set forth.
9. In a telephone exchange system, two lines temporarily connected together for
conversation in combination with a switching device with contact points by which
the operator may at will ground their circuit through either the line annunciator
on which the call originated or through his telephone, substantially as set forth.
10. In a telephone exchange system, two telephone lines normally connected to
the ground through their two line annunciators, in combination with switching
apparatus by which an operator may connect the two lines together for conversation
with their circuit grounded through one of their annunciators, the other annunciator
being disconnected from their circuit, substantially as set forth.
11. In a telephone exchange system, a telephone line and a switch plug connected
to the line by a flexible conducting cord, in combination with a switching device
having two contact points, which being closed to each other on the withdrawal of
the plug from the switching device ground the line through the operator's telephone
and a commutator piece which on being moved by the operator separates said contact
points, substantially as set forth.
12. In a telephone exchange system two telephone lines temporarily connected
together in circuit for conversation, in combination with an annunciator at the
central office connected for clearing out purposes to the ground on one side and to
the circuit of said lines on the other side, substantially as set forth.
13. In a telephone exchange system two ground circuit lines temporarily connected

page_text: together in circuit for conversation, in combination with an annunciator at the
central office connected for clearing out purposes to the ground on one side and to
the circuit of said lines on the other side, and calling generators at the subscriber's
stations.
D 1
1
1000
CARPMAEL & Co.,
Agents for the Applicant.