IMPROVEMENTS IN TELEGRAPHICTELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to Daniel, Sinclair of Glasgow in the County of Lanark,
Electrical Engineer for an Invention of IMPROVEMENTS IN TELEGRAPHIC
"
.
"
PROVISIONAL SPECIFICATION left by the said Daniel Sinclair at the Office
of the Commissioners of Patents on the 7th July 1883.
DANIEL SINCLAIR, of Glasgow in the County of Lanark Electrical Engineer
IMPROVEMENTS IN TELEGRAPHIC AND TELEPHONIC APPARATUS,"
The object of this Invention is to provide means in connection with telegraphic
and telephonic lines and exchanges whereby a branch exchange may be worked
automatically, that is to say, whereby the functions of the branch operator, of
placing in communication any subscriber on his branch with any other subscriber
on the system; may be performed from the central exchange, and the services of the
branch operator may be dispensed with.
For this purpose I fit in the branch exchange, as hereinafter described, certain
novel appliances through which a subscriber to the branch may call the central
exchange, and by means of which the attendant at the central exchange 'by
operating a suitable sending instrument may place that subscriber's wire in commu-
nication with that of any other subscriber on the same branch, or in communication
through the trunk wire, leading to the central exchange, with any subscriber's wire.
on another branch, or with any other subscriber's wire of the system.
The necessary appliances for the central exchange comprise a commutator or
step-by-step sending instrument such as is commonly employed in telegraphy for.
transmitting currents to the electro-magnet of a distant receiving instrument, such
commutator or current transmitter being provided with a handle moving over a
graduated dial or other indicator whereby any number of currents may be trans-
mitted over the trunk line or lines to the electro-magnet' of the instruments or
appliances which I provide at branch exchanges.
The appliances fitted at each branch exchange comprise a central and an outer
hollow spindle on one axis; but suitably insulated from each other, and so fitted
that they are free to be turned or rotated independently of each other. These
D
...

page_text: spindles pass through a dial plate and are each fitted with a pointer, the one being
fitted over and made of greater length than the other somewhat like the hands of
a watch. The spindles and with them the pointers are caused to turn to any
extent desired by means of ratchet wheels acted on by pawls which engage in and
turn the ratchets to the extent of one tooth or more by the action on the pawls of
electro-magnets to the armatures of which they are attached, and which are
operated as relays by the intermittent or step-by-step currents transmitted from
the central station. Each pointer can by this means be turned round and in its
circular path be brought into contact with any one of the number of studs or
contact points fitted in two circles (an inner and an outer) round the dial plate.
The number of studs in each series is the same, and corresponds with the number
of subscribers wires entering the branch exchange, the two series of studs being
normally maintained by light springs in the circuit of the branch subscribers wires
to earth through the usual indicators which are ranged round the dial plate, and
each series of studs being electrically connected to one of the spindles of the
instrument with which-one of the trunk wires to the central exchange is electrically
connected. The spindles carrying the pointers over the dial are each fitted with a
second pointer or arm below the dial, and the arms and pointers which correspond
with each other move together when operated from the central exchange. The
arm on the outer spindle corresponds to the longer pointer on the dial and is so
arranged that in turning it comes in contact with and is stopped by the indicator
drop of the subscriber who has last called. The end of the corresponding pointer
on the dial is by the same movement brought to rest under the spring, which forms
the branch terminal of that subscriber's wire, and the subscriber is then in direct
communication with the central exchange. The arm fitted on the inner spindle is
formed with a double wedge-shaped or curved cam piece, which when the arm is
turned by the operator at the central exchange is brought against and raises the
indicator drop which fell when the subscriber called. If the calling subscriber
wishes to be put, in communication with another subscriber on the same branch
exchange, the inner spindle may be further moved to bring the shorter pointer
over the stud corresponding with the number of the subscriber wanted, but other-
wise the function of the inner spindle is mainly to operate the arm by which the
indicator drops are raised.
'
The mode of operating the branch exchange is as follows. When a subscriber
on the branch exchange wishes to call any other subscriber on the system he turns
the handle on his instrument as usual and thereby sends a magneto current through
his wire to the terminal spring on the dial at the branch, thence through the
.stud to the indicator and to earth, the indicator drop being caused to fall in the
usual way. The indicator armature is by the same action brought into contact
with a stop or spring connected direct to earth, whereby the circuit of the trunk
line, which is connected from the dial spindle to each indicator armature, is closed
and the call bell or indicator at the central exchange is sounded. The operator at
the central exchange thereupon places the telephone to his ear, slowly turns the
handle of the commutator or current-sending instrument, and sends a series of
currents from a battery through the electro-magnet actuating the ratchet and pawl
devices which give the step-by-step movement to the spindle of the long pointer of
the dial instrument at the branch exchange. The pointer is thereby moved round
until it makes contact with the terminal spring of the calling subscriber's wire,.
and by an insulated slip fitted on the lower side of the pointer cuts out the
subscriber's branch indicator, and earth. The proper extent of movement of the
pointer is determined by the arm on the outer spindle (corresponding to the long
pointer) coming into contact with and being prevented from inoving further by
the indicator drop which falls in the path of that arm. The central exchange
operator being now in direct communication with the subscriber, returns the call
by a magneto-current, asks the subscriber's number, and the number of the
subscriber who may be wanted by the caller. If the subscriber wanted is on a
different branch or has a wire to the central exchange, the operator connects the
53.31.

page_text: two subscribers through the ordinary switch board arrangement, but if the
subscriber wanted is on the same branch exchange, the operator switches the com-
mutator on to the second trunk wire connecting it to the central spindle of the dial
instrument at the branch, and then sends the requisite number of currents through
the electro-magnet and relay to actuate the ratchet and pawl devices which move
round the central spindle and its pointer, and bring the pointer opposite to or over
and in contact with the stud corresponding to the number of the subscriber wanted.
The two subscribers will then be in communication with each other through their
own wires and the trunk wires, which are joined together at the central
exchange.
'
When the operator at the central exchange wishes to call any subscriber on a
branch system, he turns the commutator handle from zero to the number corre-
sponding to that of the subscriber he wants, transmits a corresponding number of
currents to the instrument at the branch exchange, and moves one of the pointers
into contact with the terminal of the subscribers wire. He then rings up the
subscriber in the ordinary way by transmitting a magneto current, the battery
current of the commutator not being adapted to ring the call bell. If a battery
current should be employed for ringing the subscriber a pole changer and polarised
relay of the ordinary description should be employed. :
In case the commutator handle or sending instrument should be made to send a
greater number of currents than the number of steps by which it is desired to
advance the long pointer, and undue strain should be brought on the parts of the
ratchet and pawl devices, or on the arm which is stopped by the indicator drop,
the battery current from the commutator is shunted through a wire connecting
the trunk wire and a spring on the side of the indicator drop against which the
spindle arm presses, so that the electro-magnet is short circuited and the ratchet
and pawl devices put out of action.
By employing a pole changer at the central exchange, and a polarised relay in
connection with the electro-magnets which operate the ratchet and pawl devices.at
the branch exchange, a single trunk wire may be used in sending the currents
which actuate either of the pointers. Thus by sending a positive current from the
central exchange the polarised relay will be so set as to actuate the electro-magnet
and connections of the one pointer; and by reversing the pole changer a negative
current will be sent, which will so change the polarised relay as to bring into action
the other electro-magnet and pointer. The arrangement last described is specially
applicable in connection with telegraph lines.
>

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Daniel Sinclair in the Patent Office on the 5th January 1884.
DANIEL SINCLAIR, of Glasgow, in the County of Lanark, Electrical Engineer
< IMPROVEMENTS IN TELEGRAPHIC AND TELEPHONIC APPARATUS"
The object of my said Invention is to provide means in connection with tele-
graphic and telephonic lines and exchanges whereby a branch exchange may be
worked automatically, that is to say, whereby the functions of the branchi
operator, of placing in communication any subscriber on his branch with any
other subscriber on the system, may be performed from the central exchange, and
the services of the branch operator may be dispensed with. For this purpose, I
fit in the branch exchange, as hereinafter described, certain novel appliances
through which a subscriber to the branch may call the central exchange, and by
means of, which the attendant at the central exchange by operating a suitable
sending instrument may place that subscriber's wire in communication with that
of any other subscriber on the same branch, or in communication through the
trunk wire, leading to the central exchange with any subscriber's wire on another
branch, or with any other subscribers wire of the system.
The necessary appliances for the central exchange comprise a commutator or
step-by-step sending instrument such as is commonly employed in telegraphy for.
transmitting currents to the electro-magnet of a distant receiving instrument such
commutator or current transmitter being provided with a handle moving over a
graduated dial or other indicator whereby any number of currents may be
transmitted over the trunk line or lines to the electro-magnet of the instruments
or appliances which I provide at branch exchanges.
A modification of the improved instrument or appliances which I place at each
branch exchange is illustrated in vertical section and plan by figures 1 and 2 of
the accompanying drawings..
These appliances comprise a central spindle A and an outer hollow spindle Bon
one axis, but suitably insulated from each other, and so fitted in bearings in a box.
or casing C that they are free to be turned or rotated independently of each other.
These spindles A, B pass through a partition or dial plate C¹, and are each fitted
with a pointer, the one a being fitted over the other b. The spindles A, B, and
with them the pointers a, b, are caused to turn to any extent desired by means of
ratchet wheels D, E acted on by pawls d, e, which engage in and turn the ratchets
to the extent of one tooth or more by the action on the pawls d, e, of electro
magnets F, G to whose armatures f, g, they are attached by rods or wires f¹, g¹;
and the electro-magnets are operated as relays by the intermittent or step-by-step
currents transmitted to them from the central station by the trunk wires H, H.
Each pointer a, b, can by this means be turned round and in its circular path be
brought into contact with any one of a number of springs or contact points i, j,
fitted in two circles (an upper and lower) round the spindles, each upper and lower
pair of springs being electrically connected to each other. The number of springs
in each series is the same, and corresponds with the number of subscriber's wires
entering the branch exchange, the two series of springs being normally maintained,
by fixed studs i, j, in the circuit of the branch subscribers' wires to earth through
the usual indicators K which are ranged round the dial plate C¹, and each series of
studs, being electrically connected thereby to one or other of the spindles A, B,
of the instrument with which the trunk wires to the central exchange are
electrically connected as by the wires H, H³, and springs h bearing on the
spindles A, B. The spindles A, B, carrying the pointers a, b, are each fitted with

page_text: a second pointer or arm a¹ b¹, and the arms and pointers (a, a' or b; b') which
correspond with each other move together when operated from the central exchange.
The arm a¹ on the outer spindle A corresponds to the pointer a, and is so arranged
that in turning it comes in contact with and stopped by the indicator drop K₁ of
the subscriber who has last called, and whose indicator drop will have fallen to the
position indicated on the right hand side of figure 1. The end of the corresponding
pointer a is by the same movement brought to rest under the spring i which forms
the brunch terminal of that subscriber's wire, and the subscriber whose wire I iš
connected to the spring is then in direct communication with the central exchange
through the pointer a, the spindle A, and the trunk wire H. The arm 6¹ fitted on
the spindle B is formed at the end with a wedge-shaped or curved cam piece,
which when the armb is turned by the action of operator at the central exchange,
is brought against and raises the indicator drop K which fell when the subscriber
called. If the calling subscriber wishes to be put in communication with another
subscriber on the same branch exchange, the spindle B may be further moved to
bring the pointer b in contact with the spring corresponding with the number of
the subscriber wanted, but otherwise the function of the spindle B is mainly to
operate the arin b¹ by which the indicator drops K' are raised.
An
The mode of operating the branch exchange is as follows:-When a subscriber
on the branch exchange wishes to call any other subscriber on the system he turns
the call hangle on his instrument as usual and thereby sends a magneto current
through his wire to the terminal spring i on the instrument at the branch, thence
through the stud 2 and wire J, to the indicator K and thence to earth by the
wire J', the indicator drop K¹ being thus caused to fall in the usual way.
insulated metallic plate on the indicator armature is, by the same action,
brought into contact with a stop or spring k² connected direct to earth, whereby
the circuit of the trunk line H (which is connected from the spindle A to each
plate on the indicature armature) is closed, and the call bell at. the central
exchange is sounded or an indicator placed there is dropped. The operator at the
central exchange thereupon places the telephone to his ear, slowly turns the handle
of the commutator or current sending instrument, and sends a series of currents
from a battery through the electro-magnet F actuating the ratchet and pawl
devices D, d, which give the step-by-step movement to the spindle A and pointer a;
of the instrument at the branch exchange. The pointer a is thereby moved round
until it makes contact with the terminal spring i of the calling subscriber's wire,
and the pointer at the same time raises the spring i out of contact with the stud i
and thereby cuts out the subscriber's branch indicator and earth.
The proper extent of movement of the pointer a is determined by the arm a¹ on
the spindle A coming into contact with aud being prevented from moving further
by the indicator drop K¹ which falls in the path of that arm. The central
exchange operator being now in direct communication with the subscriber, returns
the call by a magneto current, asks the subscriber's number and the number of
the subscriber who may be wanted by the caller.
If the subscriber wanted is on a different branch, or has a wire direct to the
central exchange, the operator connects the two subscribers through the ordinary
switch board arrangement; but if the subscriber wanted is on the same branch
exchange, the operator switches the commutator on to the second trunk wire H¹
connecting it to the spindle B of the instrument at the branch exchange, and thien
sends the requisite number of currents through the electro magnet G to actuate
the ratchet and pawl devices E, e, which move round the spindle B and its
pointer b and bring the pointer b opposite to and in contact with the spring j
corresponding to the number of the subscriber wanted.
The two subscribers will then be in communication with each other through
their own wires I, J, and the trunk wires H, H', which are joined together at the
central exchange.
When the operator at the central exchange wishes to call any subscriber on a
;

page_text: branch system, he turns the commutator handle from zero to the number corre-
sponding to that of the subscriber he wants, transmits a corresponding number of
currents to the electro-magnet For G of the instrument, at the branch exchange
and moves one of the pointers a, or b into contact with the terminal i of the
subscriber's wire I. He then rings up the subscriber in the ordinary way by
transmitting a magneto current, the battery current of the commutator not being
usually adapted to ring the call bell. If a battery current should be employed for
ringing the subscriber a pole changer and polarised relay of the ordinary description
should be employed.
-
In case the commutator handle or sending instrument should be made to send a
greater, number of currents than the number of steps by which it is desired to
advance the finding pointer b, and undue strain should be brought on the parts of
the ratchet and pawl devices, or on the arm 63 which is stopped by the indicator
drop K', the battery current from the commutator is shunted through a wire
connecting the trunk wire and a spring on the side of the indicator drop against
which the spindle armi presses, so that the electro magnet F or G is short circuited
and the ratchet and pawl devices put out of action.
The electro-magnets F, G may be operated direct from the central exchange by
currents of sufficient strength transmitted along separate wires or by employing a
relay for each electro-magnet and providing a local battery at the branch exchange.
A relay L is shown fitted in the casing of the instrument, but the electrical con-
nections of the instrument are arranged as when the electro-magnets are operated
direct from the central exchange.
For convenience of illustration only a few subscribers indicators are shown as
fitted round the moving spindles and pointers, the positions of the indicators
being shown by radial dotted lines. A greater or less number of subscribers than
the drawing represents may be connected to the instrument.
By employing a pole changer at the central exchange, and a polarised relay in
connection with the electro-magnets which operate the ratchet and pawl devices at
- the branch exchange, a single trunk wire may be used in sending the currents
which actuate either of the pointers. Thus by sending a positive current from the
central exchange the polarised relay will be so set as to actuate the electro-magnet
and connections of the one pointer, and, by reversing the pole changer a negative
current will be sent, which will so change the polarised relay as to bring into
action the other electro-magnet and pointer. The arrangement last described is
specially applicable in connection with telegraph lines.
Having now described the nature of my said Invention, and in what manner
the same is to be performed, I declare that what I claim is;—
First. The apparatus herein described whereby a telegraphic or telephonic
instrument connected to a branch office or exchange may be placed in electrical
communication with any other similar instrument on the telegraphic or telephonic
system by an operator in a central exchange, substantially as herein set forth.
Second. The arrangement of apparatus forming the branch exchange instrument
herein described and illustrated.
Third. The arrangement in a branch exchange instrument of an electro-magnet,
actuated by a current sending instrument at a central office, to operate a ratchet
and pawl, or similar device, and thereby move a pointer or pointers into contact
with the terminal of a subscribers wire and place the subscriber in communication
with the central office, substantially as herein set forth.
Fourth, The arrangement or combination in a branch exchange instrument, of
two electro-magnets and ratchet and pawl devices actuated from a central office,
and operating separate pointers to bring them into contact with the terminals of
any two subscribers wires on the branch exchange and place such subscribers into
communication, substantially as herein set forth.
Fifth. In a telegraphic or telephonic branch exchange instrument, the two
spindles (A, B,) actuated from the central exchange, and carrying, the one a finding

page_text: arm and the other a replacing arm, in combination with the subscribers indicators
whose drops fall into the path of the arms, substantially as and for the purpose
set forth.
In Witness Whereof, I the said Daniel Sinclair, have hereunto set my hand and
seal, this Fourth day of January, in the year of our Lord One thousand, eight
hundred and eighty four.
Witness
WALLACE FAIRWEATHER C.E.
Fel. Inst. Patent Agents
Glasgow
D. SINCLAIR (L.S.)