IMPROVEMENTS IN TELEPHONIC AND TELE- GRAPHIC APPARATUS
Year: 1881

page_text: LETTERS PATENT to Thomas Anthony Connolly, of Washington, District of
Columbia, United States of America, now of 8, Southampton Buildings,
London, for an Invention of "IMPROVEMENTS IN TELEPHONIC AND TELE-
GRAPHIC APPARATUS.”
PROVISIONAL SPECIFICATION left by the said Thomas Anthony Connolly
at the Office of the Commissioners of Patents on the 6th August 1881. .
THOMAS ANTHONY CONNOLLY, of Washington, District of Columbia, United
States of America, now of 8, Southampton Buildings, London. 'IMPROVEMENTS
IN TELEPHONIC AND TELEGRAPHIC APPARATUS."
"E
The chief object of my Invention is to provide means whereby, in a telephonic
exchange, the operations of the central office will be rendered automatic, so that
the subscribers or members of the exchange may individually effect the requisite
connection and disconnection of the lines, thereby avoiding the necessity of calling
the central office and having the service performed by manual labour, as is
now customary. The said Invention is also partly applicable for telegraphic
purposes.
A telephone exchange based on my system and embodying my Invention
comprises & central machine or apparatus operated or controlled by electro-
magnetism, a series of subscribers' or members' stations provided with devices for
effecting such operation or control of the central machine, and lines or conductors
leading from the members' stations to the central machine for the transmission.
of the currents from the said stations to the central machine, and for the inter-
communication of stations connected through the said central machine.
The subscribers' stations are-also provided with telephonic apparatus and suitable
devices for receiving and sending signals.
I will first proceed to describe the central apparatus. This consists of a machine
of upright cylindrical form resting on a base, in which are fitted the binding posts
for the various conveying wires. The main frame of the machine consists chiefly
of uprights and a cap. To these uprights are attached electro-magnets having
pivotted armatures, to which are connected escapements or ratchet and pawl
devices for converting the notion of the armatures into intermittent rotary
[Price 81

page_text: motion of a suitable ratchet wheel or rack. The electro magnets are energized
from a main battery or generator located at the central office of the exchange.
Normally the circuits of the said magnets are open. The closing of the circuits
is effected by means of relays in the normal circuits of the subscribers' or members'
lines. These relays are responsive to the impulses transmitted from the subscribers'
stations, hence each pulsation of an armature is in keeping or correspondence with
that of its relay. These relays are polarized, and preferably of the form known as
"Siemens"" polarized relays, and are adapted to close the circuit of the magnets
when the current which energizes the said relay is passing in one direction. The
current in the reverse direction may be utilized for signalling purposes without
effecting any operation of the central machine. The magnets and their ratchet
appliances are employed to effect the rotation of rings or wheels, one of which is
allotted to each lino. In addition to a ring, each line possesses a "contact bar" or
frame. These frames are pivoted either inside or outside the ring or outside of
the wheel. They are arranged at regular intervals around the rings and are
parallel with the axis thereof.
6:
Each bar traverses the whole series of rings, so that all the rings have a like
relation to each and every frame. A connection of any two lines is effected
through the ring of the operating or calling line and the contact bar or frame of
the called line. For this purpose each ring is furnished with a coupling or
connecting device, which in the arrangement under consideration consists of a
tripper or toggle lever, which as a ring rotates comes in contact with the
several frames, and rotates, turns, or moves the same on their shafts or bearings.
At the same time the tripper or toggle, which is normally tangential or inclined
with reference to the periphery of the ring, assumes a different position, that is to
say, it straightens out, and if then the movement of the ring is discontinued, the
tripper and frame remain in their conjointly assumed positions.
The object of moving the frame as stated is to isolate it, so that when engaged
by a line no other line can obtain connection with it. For this purpose the
conditions are such that in its normal position the outer head or end of the
tripper does not project sufficiently far beyond the ring or wheel to touch the
frame or contact bar when moved or turned by an engaged tripper or toggle.
A line when not in use, or when employed in effecting connection with another,
completes its circuit to earth or to a common ground, or return through its tripper
or toggle. When engagement is made with a line, this ground or earth connection
is broken by the movement of the tripper under the toggle action of a frame or
contact bar, and the circuit is completed through the line in which the frame is
located.
More specifically each ring or wheel consists of two plates or rings of metal
separated by an insulating filling. The lower plate is in constant contact with the
frame of the central machine which communicates with earth or common ground,
or return either through supporting rollers if a hollow ring is used, or through a
central shaft if a wheel with spokes be the form.
If the ring form be used the lower plate may be formed with teeth on its
periphery to gear or engage with a pinion which is driven by the magnet and its
appurtenances, or the dog or pawl connected to the armature may engage directly
with the lower plate, which will then have its teeth suitably bevelled. The same
plan of operations may be adopted if a wheel be substituted for a ring; but in
this case it is preferable to operate the wheel from the magnet. through a ratchet
wheel on the central shaft secured to the main wheel. It is not however necessary
for the purposes of this Invention that the form of the wheel or ring, or the
mechanism for imparting motion to the same should be of any particular nature.
Various contrivances adapted to the purpose will suggest themselves to a skilful
constructor, and are within the compass of my Invention.
The tripper or toggle lever consists of a tinger pivotted to the upper plate of
the ring or wheel, and formed with a shoulder abutting against a stop which limits
its movement in one direction, and against which the tripper is held in

page_text: impingement when not engaging with a contact frame by an easily yielding
spring. A spring tail piece or continuation of the tripper or toggle. impinges
against a bent metal pin, stud, or block, rising from the lower plate of the wheel or
ring, and travels thereon during a portion of the movement of the tripper on its
pivot. Thus the operating line, which leads into the upper plate, and thence to
the tripper or toggle, makes ground through the said pin, stud, or block, until in
engaging with a contact frame, such ground connection or contact is broken by the
tail piece leaving the same, when the circuit is diverted into the contact frame, to
be thence led to the line thereof. As above stated the tripper or toggle lics
normally in an oblique or tangential position. Its outer end is formed with a
slight concavity or recess, by which a contact frame in its path is caught and beld
in effecting and maintaining engagement therewith. As the tripper passes each
unoccupied contact frame, momentary engagement and conjoint movement ensue,
and the diversion of circuit from central ground to line of engaged frame follows.
Circuit or contact is made with the ring from the line thereof by means of a brush
or rubber in the path of the same line, insulated from the main frame. A wire
leading from the said brush connects with a binding post or cup to which is led a
return wire from the relay of the same line, the main line wire from a station
leads to connections in the central machine, which will hereinafter be described,
thence to the relay, and from the relay by the return wire to the binding post.
This circuitous path is provided in order that the relay of a called or passive line
may be cut out so as to reduce resistance, but principally to prevent such relay
from being operated by the current of the operating line. The cutting out is
effected by the following means, that is to say, the contact frames consist each of a
pivoted metal bar or shaft, journalled in insulated bearings at the top and bottom
of the machine. Radial metallic arms support and secure a slender rod, which is
the contact bar proper or the medium of engagement with a tripper or toggle.
Attached to the pivoted shaft near its lower end is a metal arm or brush, or
preferably two connected brushes insulated from the shaft, and bridging a pair of
insulated segments of metal, the inner one shorter than the outer one. The direct
line leads from its binding post to the outer or longer segment, and the circuit is
thence by the brush to the inner segment, and thence to the relay. There is
another metallic arm or contact spring attached to, but in circuit with the shaft,
and so arranged that when the frame is swung to its limit the said metallic arm
will come in contact with a pin rising from the outer segment, the brush at the
same time leaving the inner segment and breaking the connection of the two, thus
when a contact frame is engaged the circuit with its line is made directly from the
outer segment to the line without passing through the relay, the latter being in
the branch circuit connected permanently with the inner or shorter segment. It
has been explained that when a contact frame is swung out to its limit, and
engaged by a toggle or tripper, the toggle or tripper of another line will pass by
without contacting or obtaining engagement therewith, thus preventing disturbance
of the communication through the frame of the called line. Engagement however
with the frame of an operating line is not thus provided against, but such
provision is necessary to prevent the operating line from being broken. For this
purpose each contact frame is furnished with an arm supporting an antifriction
roller, which rides on the periphery of the insulated filling of the ring of the same
line. A cam recess in the said filling adjacent to the tripper receives the said
roller when the ring is home, but as the latter begins to move the wheel is pressed
outward to the periphery of the insulated filling. By this operation the contact
frane of the operating line is swung on its pivotal points sufficiently to avoid
contact of the passing trippers, but not far enough to break the circuit through
the segments. It is therefore only when a line is at home that its contact
frame can be caught. The term "home" is used to indicate the normal position
of the tripper, that is, when it coincides with the contact frame of the line to
which it belongs or pertains. A contact frame however is not to be pushed out
by its own line tripper, otherwise the tripper of another line could not engage it.

page_text: •
1
To avoid such a difficulty each contact bar is notched or recessed at a point
opposite or on the plane of its line tripper, so that when the latter is home it
projects into the notch or recess and does not touch the bar.
As will be seen the planes of the contact frames are oblique with reference to
the circumferential lines of the rings, but this arrangement is arbitrary and need
not be adhered to. The frames are normally maintained in proper relation to the
rings, and after being swung outward and released, are retracted by means of
springs suitably arranged. These springs also serve to keep the tripper and
contact rod, in close and reliable impingement.
I will now proceed to describe the local subscribing station apparatus. As has
been shewn the operations of the central line connecting apparatus are responsive
to electrical impulses sent over the lines from the local or subscriber's stations.
These impulses are produced by the intermittent closing of a normally open battery
circuit which correspondingly closes the relay at the central machine, and thus
bring into action the power whereby the mechanical switching operations are 1
performed. Each local or subscriber's station for this purpose is furnished with an
independent battery or generator which has one pole grounded or in connection
with a return common to all the lines. The local subscriber's station apparatus for
giving control of the central devices pertaining to a given line are for convenience
enclosed in a box or case to which are connected, if desired, the necessary devices
pertaining to the usual telephonic transmitter and receiver which need not be
particularly described.
From the battery the line and ground conductors lead to a reversing key which
is carried by a toothed disc or wheel, the teeth of which correspond in number
with the number of impulses necessary to effect a complete revolution at the
central machine of the carrier of a contacting finger or tripper. The said disc or
wheel is caused to rotate by suitable clock-work mechanism, and its teeth
successively pass a contact making spring or arm which completes or closes the
open line circuit and sends an impulse therethrough.
The toothed disc or wheel is covered by a dial upon which the several lines of
the exchange are indicated by suitable numbers or letters at regular intervals
completing the circle. Holes are bored through this dial in coincidence with the
said numbers or letters for the reception of a transferable pin or plug. A stud on
the disc or wheel comes in contact with this pin on open circuit and arrests the
movement of said wheel at any given number opposite the said pin, whereupon the
operations of the devices pertaining to the operating line at the central apparatus
cease, the operating line being then in coincidence. and circuit with the line at
whose number or letter the pin is placed.
To provide for a reversal of the current after such circuiting has been effected
the line and ground wires from the local station battery lead to the reversing key
through brushes touching insulated collars on the disc shaft, which collars com-
municate with the terminals or contact points of the reversing key. The latter has
⚫ an elongated arm which as the disc comes to a stop touches and bears against the
pin when the same is at any but its home position. Under such conditions the
direction of the current while the disc is rotating is such as will effect the operation
of the relay, but when the arm of the reversing key strikes the pin the direction of
the current is reversed. The hole for the reception of the pin when at home, that
is, at the number on the disc or dial of the station to which it belongs is out of the
circle of the other holes, hence when the disc arrives home the arm of the reversing
key does not strike the pin, so that no reversal takes place. The object of the
reversal is to provide for calling a distant station by an operating line without
operating the relay of the latter. This calling is performed under the reversed
current by means of a circuit-closing key or push in a branch or shunt line, which
is normally open and is only to be closed when the circuit-closing wheel is at rest
and the main circuit open. Now when a line is at "home" and its pin in a "home"
position, it is in a condition to be called, but at no other time is it in such
condition; then when a calling current is received the relay of the called line is

page_text: cut out, as previously explained, so that the calling current cannot affect it, as it
otherwise would, the direction being suited to such operation.
Now having been called a call is returned from a distant station by simply.
pressing the push button at the latter. The return call current is then in the
normal direction, that is to say, in the direction under which the called line relay
would operate were it in circuit, but it is in the reverse direction relatively to the
relay of the calling line, or in the same direction as the calling current of the latter,
and hence has no effect on the said relay. This automatic method of reversing the
current is desired so as to obviate the possibility of mistake in making and
returning calls, growing out of the necessity in calling up a line and returning a
call of having the currents in the same direction, notwithstanding the peculiar
relations of the two lines, the one operating and the other passive. But for such
automatic contrivance relieving the callers of the necessity of exercising selection
in manipulating their calls, it would be necessary to provide an independent
reversing key which the caller would have to shift after obtaining a line, while the
person called must leave it alone. In this case if the caller were to accidentally or
inadvertently omit such shifting he would operate his relay, while if the called
subscriber should shift his reversing key he would also operate the caller's relay,
and so destroy the conditions obtained at the central apparatus as well as the
unison of the local indicator and the central devices.
The calls are sounded upon bells or gongs having suitable electro-magnetic
sounders in circuit with the main line.
In describing the operations of the central and local stations I have referred to
batteries or generators, but I do not wish to be understood as limiting myself to
any specific generator, such as a voltaic battery, as I may employ magneto-electric
currents for all or any of the operations dependent upon an electric current.
In the foregoing description the central machine or apparatus has been described
as a means for facilitating telephonic intercommunication, but its application is not
necessarily limited to telephonic exchange. The machine is really a combination of
devices through which electrical circuits are determined and produced, and such
circuits may be used either for telephonic or telegraphic purposes. The only
requirement when the machine is used for telegraphic purposes is that the signals
shall be sent by currents running in one direction only, so that such signals shall
not affect the polarized relays.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Anthony Connolly in the Great Seal Patent Office on the
6th February 1882.
THOMAS ANTHONY CONNOLLY, of Washington, District of Columbia, United
States of America, now of 8, Southampton Buildings, London. "IMPROVEMENTS
IN TELEPHONIC AND TELEGRAPHIC APPARATUS.”
The chief object of my Invention is to provide means whereby in a telephonic
exchange the operations of the central office will be rendered automatic, so that
the subscribers or members of the exchange may individually effect the requisite
connection and disconnection of the lines, thereby avoiding the necessity for calling
the central office and having the service performed by manual labor as is now
customary.
The said Invention is also partly applicable for telegraphic purposes.
A telephone exchange based on my system and embodying this Invention
comprises a central machine or apparatus operated or controlled by electro-
magnetism, a series of subscribers' or members' stations provided with devices for
effecting such operation or control of the central machine and lines or conductors
leading from the members' stations to the central machine for the transmission of
the currents from the said stations to the said central machine, and for the inter-
communication of stations connected through the said central machine. The
subscribers' stations are also provided with telephonic apparatus and suitable
devices for receiving and sending signals.
I have devised a variety of electro-mechanical combinations for accomplishing
the object in view, all depending on the same substantial principle.
Some of these I have illustrated in the accompanying Drawings, in which
Figure 1 is a diagram illustrating the relation of the central office machine and
the subscribers' station devices to each other, in an automatic telephonic exchange
constructed in accordance with my Invention.
Figure 2 is a horizontal sectional view of the central office machine or switching
apparatus; and
Figure 3 is an elevation partly in section of the same.
Figure 4 is a plan or top view shewing the form of pawl and ratchet devices I
prefer to employ in the central office machine.
Figure 5 is a front elevation of a subscriber's station box, a portion of the same
being broken away to shew the internal arrangements.
Figure 6 is a diagram illustrating the circuits of the subscriber's station
box; and
Figure 7 is a similar view shewing more in detail the circuits in the said
subscriber's station box.
Like letters indicate the same parts throughout the Drawings.
I will first proceed to describe the central apparatus or machine illustrated in
Figures 1, 2, 3, and 4 of the Drawings. This apparatus or machine is of an upright
cylindrical form resting on a base A, in which are fitted the binding posts for the
various conveying wires. B designates the main frame of the machine consisting
chiefly of the uprights b and the cap b'; to these uprights are attached the electro-
magnets B' having pivoted armatures B', to which are connected escapements or
ratchet and pawl devices for converting the motion of the armatures into inter-
mittent rotary motion of a suitable ratchet wheel or rack. The electro magnets B¹
are energized from a main battery or generator located at the central office of the
exchange. Normally the circuits of the said magnets are open. The closing of

page_text: these circuits is effected by means of relays C in the normal circuits of the
subscribers' or members' lines; these relays are responsive to the impulses transmitted
from the subscribers' stations, hence each pulsation of an armature B³ is in keeping
or correspondence with that of its relay. These relays are polarized, and preferably
of the form known as "Siemens"" polarized relays, and are adapted to close the
circuit of the magnets B' when the current which energizes the said relay is
passing in one direction. The current in the reverse direction may be utilized for
signalling purposes without effecting any operation of the central machine. The
magnets B¹ and their ratchet appliances are employed to effect the rotation of the
rings or wheels D, one of which is allotted to each line. In addition to a ring each
line possesses a "contact bar" or frame D¹; these frames are pivoted either inside
or outside the ring, or outside of the wheel; they are arranged at regular intervals
around the rings, and are parallel with the axis thereof. Each bar traverses the
whole series of rings, so that all the rings have a similar relation to each and every
frame. A connection of any two lines is effected through the ring of the operating
or calling line and the contact bar or frame of the called line; for this purpose each
ring is furnished with a coupling or connecting device, which in the arrangement
under consideration and shewn in the Drawings consists of a "tripper" or toggle
lever c; this lever, which as a ring D rotates, comes in contact with the several
frames, and rotates, turns, or moves the same on their shafts or bearings; at the
same time the tripper or toggle, which is normally tangential or inclined with
reference to the periphery of the ring, assumes a different position, that is to say,
it straightens out, and if then the movement of the ring is discontinued the tripper
and frame remain in their conjointly assumed positions.
The object of moving the frame, as above stated, is to isolate it, so that when
engaged by a line no other line can obtain connection with it; for this purpose the
conditions are such that in its normal position the outer end or head of the tripper
does not project sufficiently far beyond the ring or wheel to touch the frame or
contact bar when moved or turned by an engaged tripper or toggle.
A line when not in use, or when employed in effecting connection with another,
completes its circuit to earth, or to a common ground or return through its tripper
or toggle. When engagement is made with a line this ground or earth connection
is broken by the movement of the tripper under the toggle action of a frame or
contact bar, and the circuit is completed through the line in which the frame is
located. Speaking more specifically each ring or wheel consists of two plates or
rings d, d, of metal separated by an insulating filling d³; the lower plate is in
constant contact with the frame of the central machine which communicates with
earth or common ground, or return either through supporting rollers if a hollow
ring is used, or through a central shaft d' if a wheel with spokes is employed. If
the ring form be used the lower plate may be formed with teeth on its periphery
to gear or engage with a pinion which is driven by the magnet B' and its appur-
tenances, or the dog or pawl connected to the armature may engage directly with
the lower plate which will then have its teeth suitably bevelled; the same plan of
operations may be adopted if a wheel be substituted for a ring. In this case however
it is preferable to operate the wheel from the magnet through a ratchet wheel on
the central shaft secured to the main wheel. It is not however necessary for the
purposes of this Invention that the form of the wheel or ring, or the mechanism for
imparting motion to the same, should be of any particular nature, various con-
trivances adapted to the purpose will suggest themselves to a skilful constructor,
and are within the scope of my Invention.
The tripper or toggle lever c consists of a finger pivoted to the upper plate of the
ring or wheel, and formed with a shoulder c¹ abutting against a stop c, which limits
its movement in one direction, and against which the tripper is held in impingement
when. not engaging with a contact frame by an easily yielding spring c³. A spring
tail piece or continuation of of the tripper or toggle impinges against a bent metal
pin, stud, or block e extending upward from the lower plate of the wheel or ring,
and travels thereon during a portion of the movement of the tripper on its pivot.

page_text: Thus the operating line which leads into the upper plate and thence to the tripper
or toggle makes ground through the said pin, stud, or block, until in engaging with
a contact frame such ground connection or contact is broken by the tail-piece
leaving the same, when the circuit is diverted into the contact frame to be thence
led to the line thereof. As above stated, the tripper or toggle lies normally in an
oblique or tangential position, as shewn; its outer end is formed with a slight
concavity or recoss, by which a contact frame in its path is caught and held in
effecting and maintaining engagement therewith. As the tripper passes each
unoccupied contact frame, momentary engagement and conjoint movement ensue,
and the diversion of the circuit from central ground to the line of the ongaged
frame follows. The circuit or contact is made with the ring from the line thereof
by means of a brush or rubber F in the path of the same line insulated from the
main frame. A wire leading from the said brush connects with a binding post or
cup f, to which is lead a return wire f¹ from the relay of the same line. The
main line wire G from a station leads to connections in the central machine, which
will hereinafter be described, thence to the relay, and from the relay by the return
wire to the binding post f. This circuitous path is provided in order that the
relay of a called or passive line may be cut out, so as to reduce resistance, but
principally to prevent such relay from being operated by the current of the
operating line. The cutting out is effected by the following means, that is to say,
the contact frames consist each of a pivoted metal bar or shaft H journalled in
insulated bearings at the top and bottom of the machine, radial metallic arms h, h²,
support and secure a slender rod h², which is the contact-bar proper, or the medium
of engagement with a tripper or toggle. Attached to the pivotted shaft H near
its lower end is a metal arm or brush h³, or preferably two connected brushes
insulated from the shaft and bridging a pair of insulated segments h* of metal, the
inner one shorter than the outer one. The direct line leads from its binding post
to the outer or longer segment, and the circuit is thence by the brush h³ to the
inner segment, and thence to the relay. H' is another metallic arm or contact
spring attached to but in circuit with the shaft H, and so arranged that when the
frame is swung to its limit the said metallic arm will come in contact with a pin i
rising from the outer segment, the brush H³ at the same time leaving the inner
segment and breaking the connection of the two. Thus when a contact frame is
engaged, the circuit with its line is made directly from the outer segment to the
line without passing through the relay, the latter being in the branch circuit
connected permanently with the inner or shorter segment. It has been explained
that when a contact frame is swung out to its limit and engaged by a toggle
or tripper, the toggle or tripper of another line will pass by without coming into
contact or obtaining engagement therewith, thus preventing disturbance of the
communication through the frame of the called line. Engagement however with
the frame of an operating line is not thus provided against, but such provision is
necessary to prevent the operating line from being broken. For this purpose each
contact frame is furnished with an arm K supporting an anti-friction roller k, which
rides on the periphery of the insulated filling of the ring of the same line. A cam
recess in the said filling adjacent to the tripper receives the said roller when the
ring is home, but as the latter begins to move the roller is pressed outward to the
periphery of the insulated filling. By this operation the contact frame of the
operating line is swung on its pivotal points sufficiently. to avoid contact of the
passing trippers, but not far enough to break the circuit C through the segments.
It is therefore only when a line is at home that its contact frame can be caught.
The term "home" is used to indicate the normal position of the tripper, that is to
say, the position it occupies when it coincides with the contact-frame of the line to
which it belongs or pertains. A contact frame however is not to be pushed out by
its own line tripper, otherwise the tripper of another line could not engage it. To
avoid such a difficulty each contact-bar is notched or recessed at a point opposite
or on the plane of its line tripper, so that when the latter is home it projects into
the notch or recess and does not touch the bar.

page_text: As will be seen the planes of the contact frames are oblique with reference to
the circumferential lines of the rings, but this arrangement is arbitrary and need
not be adhered to. The frames are normally maintained in proper relation to the
rings, and after being swung outward and released are retracted by means of
the springs L suitably arranged. These springs also serve to keep the tripper and
contact rods in close and reliable impingement.
I will now proceed to describe the local subscribing station apparatus illustrated
in Figures 1, 5, 6, and 7 of the Drawings. As, has been shewn, the operations of
the central line connecting apparatus are responsive to electrical impulses sent
over the lines from the local or subscribers' stations. These impulses are produced
by the intermittent closing of a normally open battery circuit which correspond-
ingly closes the relay at the central machine, and thus brings into action the
power whereby the mechanical switching operations are performed. Each local or
subscribers' station for this purpose is furnished with an independent battery or
generator which has one pole grounded or in connection with a return common
to all the lines. The local subscribers' station apparatus for giving control of the
central devices pertaining to a given line are for convenience enclosed in a box or
case P, to which are connected, if desired, the necessary devices pertaining to
the usual telephonic transmitter and receiver, which need not be particularly
described.
From the battery the line and ground conductors lead to a reversing key N,
which is carried by a toothed disc or wheel m³, whose teeth correspond in number
with the number of impulses necessary to effect a complete revolution at the
central machine of the carrior of a contact making finger or tripper. The said
disc or wheel is caused to rotate by suitable clockwork mechanisin (not shown in
the Drawings), and its teeth successively pass a contact making spring or arm M³
which completes or closes the open line circuit, and sends an impulse therethrough.
The disc or wheel m' is covered by a dial M², upon which the several lines of
the exchange are indicated by suitable numbers or letters at regular intervals
completing the circle. Holes are bored through this dial in coincidence with the
said numbers or letters for the reception of a transferable pin or plug m³. A
stud m' on the disc or wheel comes in contact with this pin on open circuit, and
arrests the movement of the said wheel at any given number opposite the said
pin, whereupon the operations of the devices pertaining to the operating line at the
central apparatus cease, the operating line being then in coincidence and circuit
with the line at whose number or letter the pin is placed.
To provide for a reversal of the current after such circuiting has been effected,
the line and ground wires from the local station battery lead to the reversing key
through brushes me touching insulated collars on the disc-shaft, which collars
communicate with the terminals or contact points of the reversing key. The
latter has an elongated arm m³, which, as the disc comes to a stop, touches and
bears against the pin when the same is at any but its home position. Under such-
conditions the direction of the current while the disc is rotating is such as will
effect the operation of the relay, but when the arm of the reversing key strikes the
pin the direction of the current is reversed. The hole for the reception of the pin-
when at home, that is, at the number on the disc or dial of the station to which it
belongs, is out of the circle of the other holes. Hence when the disc arrives home
the arm of the reversing key does not strike the pin, so that no reversal takes
place. The object of the reversal is to provide for calling a distant station by an
operating line without operating the relay of the latter. This calling is performed
under the reversed currents by means of a circuit closing key or push Q in a
branch or shunt line which is normally open and is only to be closed when the
circuit-closing wheel is at rest and the main circuit open at Q¹. Now when a line
is at "home" and a pin in a "home" position it is in a condition to be called, but
at no other time is it in such condition. Then when a calling current is received,
the relay of the called line is cut out, as previously explained, so that the calling

page_text: current cannot affect it as it otherwise would, the direction being suited to such
operation.
Now having been called, a call is returned from a distant station by simply
pressing the push button at the latter. The return call current is then in the
normal direction, that is to say, in the direction under which the called line relay
would operate were it in circuit, but it is in the reverse direction relatively to the
relay of the calling line, or in the same direction as the calling current of the latter
and hence has no effect on the said relay. This automatic method of reversing
the current is desirable, so as to obviate the possibility of mistake in making and
returning calls growing out of the necessity of calling up a line and returning a
call of having the currents in the same direction notwithstanding the peculiar
relations of the two lines, the one operating and the other passive. But for such
automatic contrivance relieving the callers of the necessity of exercising selection
in manipulating their calls, it would be necessary to provide an independent
reversing key which the caller would have to shift after obtaining a line while the
person called must leave it alone. In this case if the caller were to accidentally
or inadvertently omit such shifting he would operate his relay, while if the called
subscriber should shift his reversing key he would also operate the caller's relay,
and so destroy the conditions obtained at the central apparatus as well as the
unison of the local indicators and the central devices.
The calls are sounded upon bells or gongs having suitable electro-magnetic
sounders in circuit with the main lines.
In describing the operations of the central and local stations I have referred to
batteries or generators, but I wish it understood that I do not limit myself to any
specific generator, such as a voltaic battery, as I may employ magneto-electric
currents for all or any of the operations dependent upon an electric current.
In the foregoing description the central machine or apparatus has been described
as a means for facilitating telephonic intercommunication, but its application is
not necessarily limited to telephonic exchange. The machine is practically a
combination of devices through which electrical circuits are determined and
produced, and such circuits may be used either for telephonic or telegraphic
purposes. The only requirement when the machine is used for telegraphic purposes
is that the signals shall be sent by currents running in one direction only, so that
such signals shall not affect the polarized relays.
Having thus fully described my said Invention, and the manner of performing
the same, I wish it understood that I claim,―
First. In a telephone exchange adapted to automatically couple lines, and having
a series of normally disconnected lines grounded at the place of convergence and
in circuit with connecting mechanism, the combination with such mechanism of a
main battery or equivalent motor and suitable means for controlling the said
battery or motor through the said lines, and for effecting the necessary movements
of such connecting mechanism, substantially as above set forth.
Second. In an automatic telephone exchange comprising a series of lines or.
conductors leading to a central station and in circuit at such station with auto-
matic connecting mechanism, the combination with the same of generators at the
local stations or distant termini of the said lines for sending electric impulses over
the latter, and a main battery or motor at the central station operating responsively
to impulses sent over the said lines from the local batteries to produce the necessary
movements of the connecting mechanism for the automatic connection and dis-
connection of the said lines, as above set forth.
Third. In automatic telephonic exchange system, comprising a series of normally
disconnected lines converging to a central station, provided with mechanism for
automatically connecting the said lines, the said mechanism being moved by a
main battery or equivalent motor located at the central station, and controllable by
electric impulses sent from the local batteries located at the remote ends or at
distant points on the said lines and operating through the latter the combination

page_text: with the said lines, the central connecting mechanism, the main and local batteries
of relays located at the central station, and operated by the said local batteries to
throw on the main battery, and thereby effect the necessary movements of the
central mechanism for connecting and disconnecting the lines, as above set forth.
Fourth. In an automatic telephonic exchange system comprising a system of
independent lines converging to a central station, provided with connecting
mechanism, a inain battery for operating the said mechanism, relays for throwing
on the said battery, and local batteries for operating the said relays; the combi-
nation therewith of switches located in each line in the circuit between the local
batteries and the relays, and capable of being operated from other lines, whereby
one subscriber calling another may cut out the relay of the latter.
Fifth. The combination in a telephone exchange or electric line connecting
apparatus of a series of conductors normally grounded at a central or common
station, each of the said conductors having in circuit a relay, an engaging finger
sustained on a ring or traveller, a ground and line switch all in circuit, and a
movable section or contact bar normally out of circuit, but carrying the said switch,
whereby when a given line is worked for calling or connecting, its finger will be
carried into engagement with the contact bar of another line, the grounds of both
lines being thereby broken, the calling line through the movement of its finger, and
the other through the movement of its switch, the lines connected, and a through
circuit established over both, substantially as herein described.
Sixth. The combination in an automatic telephone exchange or line connecting
apparatus of a relay adapted to respond to currents sent over a line in circuit
therewith, a battery connected with the said relay so as to be thrown onto a
short independent line when the said relay is closed, an electro-magnet in circuit
with such battery, a "progressive" movement connected with the armature of the
said magnet, a wheel or traveller in circuit with the relay line, but arranged to be
moved by the said progressive movement, thereby when a working current is sent
over the said line through the said relay the battery is thrown onto the short line,
and the wheel or traveller caused to move and carry the finger along, substantially
as set forth.
Seventh. The combination in an automatic telephonic exchange or electric
line connecting apparatus of a series of relays or keys and switching devices
normally in circuit therewith, and arranged to operate, substantially as described;
whereby when two lines are connected through the medium of such connecting
apparatus, the relay of a sought or called line will be cut while the relay of the
calling line or seeking line will remain in circuit, substantially as above set forth.
Eighth. The combination with an automatic line connecting apparatus, the
switching or connecting devices and their operative mechanisin of relays constantly
in the path or circuit of the calling lines to provide for the restoration to normal
of said calling line.
Ninth. In a telephonic exchange apparatus a movable finger normally in circuit
with the ground at the central exchange or connecting device and forming a
portion of the circuit of a line leading from a distant station to such central device,
the said finger being mounted on a ring or carrier and adapted and designed when
its carrier is moved to come in contact with sections or bars forming parts of other
conductors or lines, and by such contact to break its normal ground and secure
circuit to ground at another distant station over the contacted line, substantially
as above set forth.
Tenth. In a telephonic exchange apparatus a movable conductor pertaining to a
given line and normally out of circuit in combination with suitable devices,
whereby the movement of the said conductor by a calling line breaks the normal
or central ground of its own line, and establishes circuit between the two lines,
substantially as above set forth.
Eleventh. In a telephonic exchange line connecting apparatus a relay in
combination with a switching device, which normally completes the circuit to
ground at the central device through the said relay, and which upon being duly

page_text: moved, substantially as described, cuts out such ground and leaves a line in
unbroken or continuous circuit with the calling line as specified.
Twelfth. In a telephonic line connecting apparatus a receiving conductor
arranged, substantially as described, so that it may be moved by the conducting
finger of any line and isolated thereby from possible contact of other conducting
fingers.
Thirteenth. In a telephonic apparatus a receiving conductor through which
circuit may be made from a calling to a called line, the conductor being.constructed
and arranged substantially as described, whereby when the line to which it
pertains is employed in seeking or effecting coincidence or connection with another
line, such conductor will be shifted beyond the reach of the other operating lines
or their travelling contact devices.
Fourteenth. In a telephonic exchange apparatus adapted for automatic circuiting
purposes the combination of the following elements, namely: A travelling circuiting
finger stud or contact device normally grounded in circuit with a telephonic line
mechanism for causing the said circuiting finger to travel, a relay to bring the said
mechanism into action, a switch between the. said finger, and a distant line terminal
for effecting the diversion of the circuit from ground through another line, and a
movable conductor coinciding with the same home or normal position of said
finger.
Fifteenth. In a telephonic or telegraphic line connecting apparatus the
combination with a series of parallel travellers carrying conducting fingers
normally grounding the respective lines leading thereto of a corresponding series
of receptive conductors traversing the said travellers at intervals, and adapted for
the engagement of the fingers, the said travellers and fingers and the receiving
conductors being so constructed and relatively arranged that any finger may
engage with any disengaged traversing conductor but that pertaining to its own
line, shift the same out of path of the other fingers, and switch the said receiving
conductor into circuit with its line and break the central ground of both lines.
Sixteenth. The combination in an automatic telephonic exchange of a series of
lines grounded at independent or local stations, and at a central exchange (or a
station common to all) batteries at each independent station, and at the central
station a switch or connecting mechanism at the central station actuated by the
said main battery, and operating responsive to currents sent from batteries at the
independent or local stations to cut out the grounds or any two lines (or of all the
lines in pairs) at the central station, and to restore the same, substantially as
above set forth.
Seventeenth. A local or subscriber's station apparatus adapted for use in
connection with an automatic central connecting or switching apparatus, comprising
means for transmitting electric impulses, to effect operations in the central
apparatus, a register, an electrical aların, and an automatic reversing switch, for
the purposes described.
In witness whereof, I, the said Thomas Anthony Connolly, have hereunto
set my hand and seal, this Thirty first day of August, in the year of
our Lord One thousand eight hundred and eighty one.