IMPROVEMENTS IN AND RELATING TO APPARATUS FOR PUTTING INSTRU- MENTS CONNECTED WITH A CENTRAL TELEPHONE STATION INTO COMMUNICATION WITH EACH OTHER
Year: 1883

page_text: ETTERS PATENT to William Robert Lake of the firm of Haseltine, Lake,
&C Patent Agents, Southampton Buildings, London for an Invention of
"IMPROVEMENTS IN AND RELATING TO APPARATUS FOR PUTTING INSTRU-
MENTS CONNECTED WITH A CENTRAL TELEPHONE STATION INTO COMMUNICATION
WITH EACH OTHER communicated to him from abroad by George A
Cardwell of the City and State of New York, United States of America
">
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 6th June 1883.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, & Co, Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN AND RELATING TO APPARATUS
FOR PUTTING INSTRUMENTS CONNECTED WITH A CENTRAL TELEPHONE STATION INTO
COMMUNICATION WITH EACH OTHER," [a communication to him from abroad by
George A Cardwell of the City and State of New York, United States of America]
This invention relates to telephonic apparatus and has for its object to provide
means whereby in a system of individual telephone lines, the several subscribers
themselves may at will, through the intervention of a central office, connect their
respective lines with the lines of others, and communicate with such other sub-
scribers, without the assistance of operators at the central office, and so that such
communicating lines may be private, and confined to two subscribers, or subject to
connection by others, as desired, at the time.
The installation of the said invention requires a line from each subscriber to the
central office or exchange, an earth or metallic return, means at the central office
under the control individually of the subscribers, for effecting the various com-
binations of lines, and devices at the subscribers stations for bringing about the
required operations.
The said invention consists essentially in the combination and arrangement of
the various electrical and mechanical devices hereinafter described.
In entering upon the description of this invention I will suppose that a main
[Prine d

page_text: or central office is already chosen, having individual lines radiating therefrom to
the various subscribers and for the sake of clearness I will narrow the number of
subscribers down to three, numbered accordingly.
According to the said invention each subscriber has at his station a telephonic
apparatus, comprising a transmitter, receiver, and magnetic "call"; he is also
provided with an indicator, having a dial, with numbers upon it, corresponding
to the various subscribers to the system, and an index hand, which normally points
to the number denoting the subscriber to whose station it belongs.
This index hand is rotated by a spring-pawl actuated by an electro-magnet, or
it may be operated by a dead-beat escapement. Every time a current passes
through the magnet the pawl draws the ratchet wheel around one space, and with
it the said index hand two such spaces corresponding to one of the three lines, so
that in the present instance the ratchet wheel has six spaces. A battery is inserted
in the circuit between the earth and a two point switch. The first point is the
terminal of the battery beyond the magnet and the second point is the end of the
local telephone circuit enclosing the " bell," the transmitter, and the receiver, the
other side of such circuit going to ground.
The switch lever is the terminal of the line leading to the central office which is
then normally grounded.
At the central office each subscriber has a separate device under bis sole control,
as to its movements, but as will be seen in some degree subject to a change of
conditions by the other subscribers. This central office device consists broadly of
a mechanical or secondary motor capable of rotating a wheel, or hand which
constitutes a part of the subscribers' line and effecting contact in turn with the
lines of the other subscribers.
For such motor I prefer simple clock work or a train of wheels actuated by a
spring. I do not limit myself to clock-work for a motor as it may be substituted
by any other which will fulfil the requirements.—Upon the shaft of the motor,
but insulated therefrom, I mount a contact wheel upon whose periphery are a
number of detents. Above the motor I place an electro-magnet, and under this,
a swinging armature which normally projects in the path of the said detents but
when the current energises the said magnet the armature is drawn up, releasing
the detent, and leaving the motor free to at once set the contact wheel in rotation,
which will continue until the swinging armature falls in front of a detent and
stops it.
Between the contact wheel and the motor I fix a stationary disc or ring of
insulating material and upon this I attach a plate which I call the normal ground
plate and other plates, all at a common distance from the centre, and electrically
connected.
Upon the contact wheel is an arm which bears upon all the said plates in
succession when the contact wheel rotates.
Each contact wheel has at one point on its periphery a contact arm, which
projects in a plane different from that of the detents. In the present case there
are three equidistent stopping places around the circumference of the contact wheel,
one for each subscriber, at each of these a set of contacts are placed as follows, so
as to be operated by the contact arm, of the individual contact wheels. The
contact device is mounted on an insulated base suitably arranged. A spring plate
projects in the path of the contact arm, so as to be pushed outward slightly when
the said arm is passing it. Attached to the said spring plate, but insulated
therefrom, and in a plane not in the path of the contact arm, is a contact piece; a
front contact is arranged in a fixed position and a back contact is also arranged in
a fixed position so that normally the said spring plate rests against the front
contact but when pushed out by the contact arm it closes on the back contact and
opens the front one.
will
A front fixed contact is placed also so that the contact piece closes on it normally
but opens when the spring plate moves outwardly. For the sake of brevity
call the group of contacts a "coupling switch"

page_text: Instead of the said contacts a coil resistance may be placed in a subscribers'
circuit for the purpose of breaking the ground contact of each subscribers' circuit
and admitting of a private communication between two members of the exchange;
and in conjunction with the said contact arm an insulated contact may be
electrically connected with the armature of a coil of a much greater resistance than
the magnet coils so that it makes contact with the back contact piece for the
purpose of not admitting any interference during a conversation between two
parties.
As stated there is at the central office a motor, a contact wheel, and an electro-
magnet for every subscriber, and around each of the contact wheels are arranged,
in the manner stated, as many "coupling switches as there are subscribers, less
one, the normal position of each contact wheel not requiring any at that point.
"
The several arms on the contact wheels in passing or resting upon one of the
said plates which is for the purpose, made to yield slightly, forces asunder spring
contacts behind the disc of moulding material the first contact being electrically
connected with one of the said plates and the other being connected directly to the
ground.
Each subscribers line enters the central office and goes directly to the electro-
magnet controlling the motor of his contact wheel, thence to the said contact wheel
whence the circuit is diverted variously, according to the position of the said wheel.
According to the system herein before described the releasing of the motor at the
central office is effected by the momentary. introduction of a current, but by a
slight modification it can be arranged so that the battery may hold the motor
in closed circuit and release it by momentarily opening of the circuit.
In case of one subscriber calling another, his arm on the contact wheel has
broken his normal ground circuit at one of the contact plates which may be called
the terminal of his line. Should another subscriber now wish to speak to him,
such other subscriber may get as far as the said plate in the insulating plate but
cannot get on his line. Hence it is necessary to give the latter a circuit, which I
do by giving him a ground connection. For the instant the first subscriber starts
from the normal position, and the arm leaves the plate, the latter springs outwardly
and establishes contact by its extension with the ground contact behind the
insulating plate. This affords a circuit for another subscriber to use for returning
to normal when he finds the required line engaged or isolated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
6th December 1883.
WILLIAM ROBERT LAKE of the firm of Haseltine Lake & Co. Patent Agents
Southampton Buildings London "IMPROVEMENTS IN AND RELATING TO APPARATUS
"
FOR PUTTING INSTRUMENTS CONNECTED WITH A CENTRAL TELEPHONE STATION INTO
COMMUNICATION WITH EACH OTHER a communication to me from abroad by
George A. Cardwell of the City and State of New York United States of America
This invention relates to telephonic apparatus, and has for its object to provide
means whereby, in a system of individual telephone lines, the several subscribers
themselves may, at will, through the intervention of a central office, connect their
respective lines with the lines of others, and communicate with such other
subscribers, without the assistance of operators at the central office, and so that
such communicating lines may be private, and confined to two subscribers, or
subject to connection by others, as desired at the time.
The installation of the said invention requires a line from each subscriber to the
central office or exchange, an earth or metallic return, means at the central office
under the control individually of the subscribers, for effecting the various
combinations of lines, and devices at the subscribers' stations for bringing about
the required operations.
The said invention consists essentially in the combination and arrangement of
the various electrical and mechanical devices hereinafter described
In entering upon the description of this invention I will suppose that a main or
central office is already chosen, having individual lines radiating therefrom to the
various subscribers, and for the sake of clearness I will narrow the number of
subscribers down to three.
In the accompanying drawing
Figure 1 is a diagrammatic view showing the arrangement of circuits and
apparatus for three subscribers.
Figure 2 is a side elevation of the central office device hereinafter described
and
Figure 3 is a view of a portion of the same drawn to an enlarged scale.
According to the said invention each subscriber has at his own office or station
telephonic apparatus, comprising a transmitter, a receiver, and magnetic "call";
he is also provided with an indicator having a dial with numbers upon it,
corresponding to the various subscribers to the system, and an index hand,
which normally points to the number denoting the subscriber to whose station
it belongs.
This hand A is rotated by a spring pawl B actuated by an electro-magnet C, or
it may be operated by a dead-beat escapement. Every time a current passes
through the magnet C, the pawl B draws the ratchet wheel D around one space
and with it the said hand; two of such spaces corresponding to one of the throe
lines, so that in the present instance the ratchet wheel D has six spaces.
A battery E is inserted in the circuit, between the earth G, and a two point
switch F, H. The point F is the terminal of the battery beyond the magnet C
and the point H is the terminal of the local telephone circuit enclosing the " call,"
the transmitter J, and the receiver K, the other end of such circuit going to
ground G as indicated.
The switch lever L is the terminal of the line leading to the central office and
there normally grounded.

page_text: At the central office each subscriber has a separate device under his sole control,
as to its movement, but as will be seen, in some degree subject to a change of
conditions by the other subscribers. This central office device consists broadly of
a mechanical or secondary motor capable of rotating a wheel, or hand, which
constitutes a part of the subscriber's line and effecting contact in turn with the
lines of the other subscribers: for such motor I prefer simple clock work or a train
of wheels actuated by a spring. I do not however limit myself to clock-work for
a motor as it may be substituted by any other mechanism which will fulfil tho
requirements.
In Figure 2 M indicates the motor, upon the shaft N of which, but insulated
therefrom, I mount the contact wheel A¹ upon whose periphery are a number of
detents g'. Above the motor M I place an electro-magnet C¹, and under this a
swinging armature D', which normally projects in the path of the said detents, but
when the current energizes the magnet C₁ the armature D¹ is drawn up, releasing
the detent, and leaving the notor M free to at once set the contact wheel A¹ in
rotation, which rotation will continue until the armature.D' falls in front of a.
detent g and stops it.
Between the contact wheel A¹ and the motor M, I fix a stationary disc or ring
of insulating material P, and upon this I attach a plate c' which I term the normal
ground plate, and other plates d', all at a common distance from the centre of the
contact wheel, and electrically connected. Upon the wheel A' is an arm o, which
bears upon all the plates c', d¹, d' in succession when the contact wheel A², rotates.
Each wheel A has, at one point on its periphery, a contact arm i¹ which projects
in a plane different from that of the detents g'. In the present case there are
three equidistant stopping places around the circumference of the wheel A', one for
each subscriber. At each of these stopping places a set of contacts are placed as
follows, so as to be operated by the contact arm i, of the individual wheels A¹.
The contacts are arranged on a suitable insulated base. A spring plate h¹ projects
into the path of the contact arm i so as to be pushed outward slightly when the
said arm is passing it. Attached to the said spring plate, but insulated therefrom,
and in a plane not in the path of the arm i¹ is a contact piece l'. A front contact
piece 8 is arranged in a fixed position, and a back contact t¹ is also arranged in a
fixed position; normally the said spring plate h³ rests against the contact &¹ but
when pushed out by the arm i¹ it makes contact at t¹ and breaks contact at s¹. A
front fixed contact piece m' is also placed so that the contact piece l¹ bears against
it normally and breaks contact there with when the spring plate h¹ moves outwardly.
For the sake of brevity I will call the group of contacts l, m, h', s, t, a "coupling
switch."
Instead of the said contacts m¹ l' and ' 8' (Figure 1) a resistance coil may be
placed in a subscriber's circuit for the purpose of breaking the ground contact of
such subscribers circuit and admitting of a private communication between two
members of the exchange.
In conjunction with the said contact arm (Figure 1) an insulated contact may
be electrically connected with the armature of a coil of much greater resistance than
the magnet coils C¹ so that it makes contact with the contact piece t, for the
purpose of not admitting any interference during a conversation between two
parties.
"
As stated there is at the central office a motor M, a contact wheel A¹, and an
electro-magnet C¹ for every subscriber. Around each of the contact wheels A' are
arranged in the manner stated as many "coupling switches as there are
subscribers, less one-the normal position of each contact wheel A' not requiring any
at that point.
The contact wheels A¹ belonging to the several subscribers are in the drawings
marked with their respective numbers, "one," "two," "three," and the "coupling
switches" in corresponding figures in order to simplify the description.
The electric circuits are arranged as follows. Broken or dotted lines indicating
ground circuits only. The contacts h' t' of switch 3 at contact wheel "One," are

page_text: severally connected by two wires running directly to the contacts t'h' of switch 1 at
wheel Three." The contacts hat switch 2 of wheel "one" are connected to
contacts of switch 1, at wheel "two." The contacts h' t' of switch 3, at wheel
"two" are connected to the contacts t¹ h' of switch 2 at wheel "three." These are
all circuit wires as distinguished from grounding wires
No 1's normal ground circuit starts from the plate c¹ of that wheel it thence
passes to contacts m¹ l' of switch 1 at wheel two and thence to contacts m¹ l' of
switch 1, at wheel "three" whence it goes directly to the general ground.
""
No 2's normal ground circuit passes from the plate c¹ of that wheel to contacts
m¹ of switch 2 at wheel "three" and thence to contacts m' l of switch 2, at
wheel " one whence it goes directly to ground. N° 3's normal ground circuit
passes from the plate c' of that wheel to contacts m¹ l' of switch 3, at wheel "two"
and thence to contacts m³ 11 of switch 3 at wheel "one," whence it goes directly to
ground
The contacts 8' at the switches around wheel "one," are directly connected to the
plates c¹, d', d' on the disc P of that wheel. The contacts 8¹ around the wheel
"two" are correspondingly connected to the plates c' d' d' belonging to wheel " two "
and the contacts s' around wheel "three," are correspondingly connected to the
plates c d d belonging to wheel "three.""
Each of the arms o on the contact wheels A' in passing or resting upon one of
the said plates c', which is made to yield slightly presses apart the spring contacts
el, behind the disc P see Figure 2. The contact e¹ is electrically connected with
the plate c' and the contact r¹ is connected directly to the ground in each instance.
Each subscriber's line enters the central office and is connected directly to the
electro-magnet C' controlling the motion of his contact wheel A¹ it thence passes to
the said contact wheel A¹ whence the circuit is diverted variously, according to the
position of the same.
Suppose now that all the contact wheels A' are in their normal position with
arms o resting upon their plates c' and the contacts e¹¹ separated and that N° 3
desires to communicate with N° 1; N° 3 first throws his two point switch lever L
on to the point F thus at once introducing the battery to his line. If he has a
ground connection as he should have at the central office, by reason of the arm o of
his wheel A' resting upon the plate c¹ from which ground is made as before stated
through the "coupling switches" 3, at wheels "one" and "two,” the fact that he
has a circuit is at once announced by the magnet C attracting the armature B
which actuates the ratchet wheel D by means of the spring pawl and throws the
hand around to 1, on the dial thus showing that his wheel at central office is about
to reach the coupling switch 1.
The instant the battery finds a closed circuit, through the central office as stated,
it energizes the electro magnet C¹ there, which attracts the armature D', lifting it
out of engagement, with the detent g¹, upon which the motor M, starts moving, and
the wheel A¹ rotates, as it moves the arm o passes off the plate c' and the circuit is
thus broken, whereupon the magnets C¹ and C release their armatures; but the
wheel A¹ continues to revolve, until stopped by the next detent g' engaging with
tho now released armature D¹. Subscriber N° 3 after momentarily closing his
lever L over the point F restored it to the point H just before the wheel A¹ stopped.
At the instant the detent g¹ stopped the wheel A its contact arm had reached
and operated the "coupling switch" 1, that is pushed out the contacts h¹ breaking
the contact between m³ l' and s¹ and hand making contact between h³ and t' as N° 1's
ground circuit passes through the contacts m³, l', this is broken. N° 3 has no
ground of his own at the central office, at this juncture, as his arm o does not rest
on any ground plate on the disc P, but he has now a ground through No 1's line, at
No 1's distant station, because his arm i¹ rests against the contact h¹ which is thus
closed on the contact t' from which a direct wire goes to contact of the "coupling
switch "3 at wheel "one" such contacts h¹ being closed on its front stop 8. From
the latter there could be two circuits the current might pass from the stop s³ of
switch 2 at wheel "one" to ground, by way of No 1's ground, but as stated this

page_text: bas been broken, the other circuit therefore has to be taken this goes from the
points of switch 3 up to plate c¹ of wheel "three," whence it goes to the arm o
which rests upon it, thence by way of magnet Cover No 1's line and to ground at
No 1's station N° 3 now operates his magneto call and rings up N° 1.
If the communication is not desired to be private no further operation is required
before conversation.
As all the points s¹ around N° 1's wheel at the central office are in circuit
with c and all points h¹ are closed thereon any other subscriber can get on the line
of No 1 in the same manner that N° 3 did.
"
"
But if such a possibility is to be prevented as soon as N° 1 has been called, he
throws his battery on to line and causes his wheel "one to rotate, till its arm i¹
makes contact with the point h¹ of switch 3, he then restores his lever L to point H,
and converses. The two positions now occupied by the respective circuiting
wheels " one and "three are clearly shown in Figure 1 upon examination of
which it will be found that the lines N° 1 and 3, thus connected are absolutely
isolated from, and inaccessible to all other subscribers. As under any circum-
stances when the subscribers battery is on his line, the continuity of that line
depends upon the contact of the arm o at the central office with either of tho
plates c¹, d¹, d¹, the battery indicating hand A, and the local dial is moved around
by a step-by-step movement effected by the battery circuit being alternately closed
and opened by means of the said arm o, and plates c¹ d¹, The various circuit
closing plates are set on the plate P at such intervals with reference to the
switches 1, 2, 3, that the arm o will leave the plate d' before the arm ¹ makes the
desired line.
According to the system herein before described the releasing of the moter at the
central office is effected by the momentary introduction of a current but by a
slight modification, it can be arranged so that the battery may hold the motor in
closed circuit and release it by momentarily opening the circuits.
In case of a subscriber calling another his arm o on the contact wheel A¹ has
broken his normal ground circuit at the plate c' which may be called the terminal
of his line. Should another subscriber now wish to speak to him such other
subscriber may get as far as the said plate c¹ in the plate P but cannot get on his
line. Hence it is necessary to give the latter a circuit which is accomplished by
giving him a ground connection. The instant the first subscriber starts from
normal position, and his arm o leaves the plates c' the latter springs outwardly and
establishes contact by its extension e¹ with the ground contact behind the
plate P as shown in Figure 2. This affords a circuit for another subscriber to use
for returning to normal when he finds the required line engaged or isolated.
Having thus fully described the said invention as communicated to me by my
foreign Correspondent and the manner of performing the same I wish it understood
that I claim :-
:―
First A telephone exchange system comprising two or more independent lines
each provided with a mechanical moter at a central office, a wheel or hand
operated by the said moter and forming a part of the said line, an electro magnet
in the said line capable of releasing and arresting the said mechanical moter at
certain determinate points and thus controlling the movement of the said wheel,
one or more contacts around the path of the said wheel or hand forming terminals
of the other line or lines, a battery, and means at the subscribers stations for
energizing the said electro magnet thereby releasing the said mechanical motor.
Second-In a telephone exchange system, a series of independent mechanical
motors each provided with a rotating contact piece capable of making successive
connection with the terminals of other independent lines set in its path, in
combination with means for electrically releasing and arresting the said motor from
the distant subscribers station, substantially as described.
Third: In a telephone exchange system, the combination of the wheel A¹ having
detents g, with the magnet C, the armature D¹, and a motor M capable of
mechanically rotating the said wheel, substantially as described.

page_text: Fourth In a telephone exchange system, the combination of the yielding
plate c', its back extension e' and ground stop, with the rotating arm. o forming
a movable terminal of the individual line, substantially as described
Fifth-The combination of the battery E, an electro magnetic indicator A, B,
C, D, the line to the central office, the rotating terminal o of the said line, and the
circuit closing plates d', substantially as described, whereby the movements of the
contact wheel at the central office are indicated to the subscriber..
Sixth-In a telephone exchange system, a rotating arm, in combination with a
yielding contact plate and a ground connection, the said arm forming a movable
terminal of an individual line and making a normal ground circuit for the
subscriber at the central office, and the said yielding contact plate forming with the
said ground connection a possible ground or return circuit for another subscriber,
substantially as described.
Seventh-In a telephone exchange system comprising a series of individual
lines centreing at a common office, a series of circuiting arms or wheels therein
each individually controlled through one of the said lines, means for controlling the
same, a series of switches in the path of each of the said wheels or arms, and a
ground connection for each line passing from its circuiting wheel through one
switch in each of the said series of switches, and arranged substantially as
described, so that the ground circuit of a given line is broken when any of the
circuiting arms impinges on the switch belonging to such given line.
Eighth-In a telephone exchange system, the coinbination of a series of
independently controlled circuiting wheels A¹ having arms , with a series of
coupling switches around each wheel arranged to be operated by the impact of the
arm, the said switches being arranged in pairs and connected substantially as
described, whereby any two of the wheels A¹ may be electrically connected,
substantially as set forth.
Ninth The combination of the rotating arm i¹ with the contact pieces l¹ m³ h³ s',
and h¹t when connected, substantially as specified.
Tenth-In a telephone exchange system comprising a series of individual lines
converging to a central office or exchange, and means for automatically connecting
the said lines from the subscribers distant station; the combination therewith of
devices, substantially as set forth, capable of automatically connecting two or more
of the said lines, to any other line, whereby any of the subscribers so connected can
engage in general conversation.
In witness whereof I the said William Robert Lake have hereunto set my hand
and seal this sixth day of December in the year of our Lord One thousand
eight hundred and eighty three.
TIM DORT TAKE
WN RODT
RODT LAKE
(IS)