IMPROVEMENTS IN AND RELATING TO APPARATUS TO BE USED IN TELEPHONIC SYSTEMS FOR PUTTING ANY OF THE INSTRUMENTS CONNECTED WITH A CENTRAL STATION INTO COMMUNICATION WITH EACH OTHER
Year: 1883

page_text: LETTERS 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 TO BE USED IN TELEPHONIC
SYSTEMS FOR PUTTING ANY OF THE INSTRUMENTS CONNECTED WITH A CENTRAL
STATION INTO COMMUNICATION WITH EACH OTHER " communicated to him
from abroad by H. T Cedergren and L. M Ericsson both of Stockholm in the
Kingdom of Sweden
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 20th October 1883. .
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN AND RELATING TO APPARATUS
TO BE USED IN TELEPHONIC SYSTEMS FOR PUTTING ANY OF THE INSTRUMENTS
CONNECTED WITH A CENTRAL STATION INTO COMMUNICATION WITH EACH OTHER
"
[a communication to him from abroad by H. T Cedergren and L. M Ericsson both
of Stockholm in the Kingdom of Sweden]
This invention relates to telephonic apparatus.
The object of the said invention is to enable any of a number of telephonic
instruments in a circuit or any instrument of the telephonic system not situated
within the same circuit to be put by means of a single conducting wire in direct
communication with the central station.
According to the said invention I provide one or more instruments at the
central station for the purpose of causing electric impulses, and one connecting
instrument within each circuit.
The apparatus for causing electric impulses is enclosed in a box and a cylindrical
case placed on the top of the said box. An upright shaft is provided the lower
.

page_text: extremity of which is in a suitable frame, the upper extremity passing through
the said frame and a dial, above the latter of which it has a crank or handle. On
the said shaft is secured a toothed wheel and a second wheel, the circumference of
which is provided with steps at certain interspaces and of certain length. Besides
the said wheels there are movably mounted on the shaft two connected wheels,
that is to say, a ratchet wheel in which catches a pawl secured to the second wheel
and a third toothed wheel. The said toothed wheel gears with a pinion on a
second shaft from which the motion is by means of gearing transferred to a third
shaft, to which are secured two wings acting to retard the motion of the apparatus.
Around the first shaft is secured a spring-box the spring of which tends to turn
the shaft in a certain direction. The communicator consists of a lever arm
provided with a knob and projecting from a fourth shaft supported at both ends.
At the sides of the said lever arm project two contact pieces which, by a spiral
spring are pressed upwards against the contact screws. The said contact pieces
are insulated from the fourth shaft and are brought into conducting connexion
with the electrodes of a battery.
Two levers are provided having contact pieces which, when the levers are turned
outwards, are brought into contact with adjustable contact screws. The said
two levers which are drawn inwards against a central support of springs are
placed one at the side of and a little lower than the second wheel and the other
at the opposite side of the first toothed wheel. One of the said levers has a hook
which by means of a spiral spring is pressed against a pin. In the same manner
the hook of the second lever is arranged. An elastic arm on which is a projection
retains the crank or handle when wanted and prevents it from turning round.
When the said elastic arm is pressed backwards the crank is disengaged so that
the first shaft is turned round under the action of the spiral spring. The
hook on the first arm will then glide up a plane in the circumference of the second
wheel, which plane is greater than the others, and by the said hook encountering
a pin it cannot be turned but brings, on the contrary, the said first lever outwards
so that one of the contact pieces comes in contact with a screw and thus closes the
circuit so that a current will pass along the line and last as long as the hook is
passing the plane. At the terminus of the line the current passes into the earth
after having passed through the coupling apparatus. From the earth contact the
circuit is completed through a contact piece and from this to the zinc electrode of
the battery. When the central shaft is revolving a pawl catches in the teeth of
the ratchet wheel and puts thus the third shaft in motion, which causes the wings
to lessen the speed of the movable parts, so that a certain length of time elapses
before the hook has glided across the plane. This plane is greater than those on
the second wheel as in beginning a current of greater duration is required in order
to overcome the momentum of the movable parts. When the plane has got below
the hook causing the latter to fall into the next following slot, the contact is
interrupted and, in lieu of this, a tooth of the first toothed wheel moves forward
passing beneath the hook of the second lever whereby the latter is pushed outwards,
so that another bow or contact spring comes into contact with a screw whereby
the conductor is connected with the earth with the view of discharging the
secondary current. The next impulsion is emitted in the line, when the hook has
glided upon the next plane of the second wheel. By this apparatus currents at
certain intervals and of certain duration are consequently caused by the hook of
the first lever alternately rising on the plane of the second wheel and falling into
the slots, and after each impulse a discharge can take place by the hook at the end
of the second lever moving onto the teeth of the first toothed wheel. Meanwhile
the crank has moved on the dial which is divided into as many divisions (in
which numbers are marked) as the second wheel contains planes. The box
enclosing the apparatus is at the top edge provided with a number of movable
books (one for each number). In order to cause a certain number of impulses on
the line it is only necessary to adjust the hook corresponding with the figure in
the division, when the crank, after having been disengaged from a retaining arm,

page_text: turns, until it stops against the erected hook. The crank is brought back to its
original position by manual power, in which case the pawl slides over the teeth of
the ratchet wheel, so that the train of gear wheels will not be brought into motion.
The spiral spring is relieved when the crank is turned back. The hooks of the
levers are then turned in the opposite direction but will only strain their spiral
springs and thus effect no displacement of the said levers from which it follows,
that no contacts are obtained.
.
In order to cause in the line a current in an opposite direction by means of this
apparatus it is only necessary to depress a communicator when the contact pieces
are brought into contact with pieces placed beneath them. The connecting
apparatus is enclosed in a box and consists of a dial, in the front of which moves
a hand secured on a shaft acted upon by a spiral spring, which tends to keep the
hand pressed against a pin on the dial. The circumference of the dial is divided
into as many divisions as the circuit contains telephonic apparatuses. Behind the
dial is secured on the said shaft a ratchet wheel, in which a hook at the end of a
link bar catches. This link-bar is connected with one arm of an angular lever
pivoted at its point, and the second arm of which forms the armature of an electro-
magnet of about 80 Siemens' units resistance. A lever is provided which at one
end is pivoted and at the other end lies against the ratchet wheel and serves as a
pawl thereof. This lever is suitably connected with the armature of a second.
electromagnet also of about 80 S. U. resistance: The dial is at its surface provided
with a number of contacts, with which the hand by means of a slight spring
secured at its under side comes in contact when the hand is turned in different
positions, and which contacts are put in electrical connection with the instruments
in the circuit. The apparatus comprises further a system of magnetic needles,
composed of three magnets, which in their longitudinal direction can be encircled
by a current passing from the first named apparatus at the central station and
through a bobbin surrounding the central magnet. The upper magnet has at the
top a small wheel or roller which, when the magnets are deviating to one or other
side come in contact with and raise one end of two levers, the other end of which
will then fall and come in contact with one of the contact pieces. A magnet is
arranged to fix the position of rest of the magnetic needles.
The crank having been disengaged in the apparatus at the central station a
current will be caused, as hereinbefore described which enters the connecting
apparatus through the line wire, passing round the magnets and to the hand it.
further passes to a pin and from this to the earth after having previously passed
through a bobbin of about 600 S: U. resistance. The magnetic needles deviate then
in one direction and raise a lever which then causes contact with a tongue, whereby a
shunt is obtained, so that the greater part of the current in lieu of passing through
the resistance coil to the earth, passes through one of the electro-magnets a lever
and the magnetic needle and thence to the earth. On this occasion the said magnet
attracts its armature whereby the link-bar turns the ratchet wheel and its shaft so
that the hand on the dial comes into contact with the next point of contact on the
dial. A bar prevents the hand from being returned by the spring. The next
following discharge of the current through the apparatus at the central station
causes one of the electro magnets to drop its armature. The next impulsion
arrives through the line, before the magnetic needle has had time to interrupt the
contact and then the operation just now described is repeated, whereby the hand
is brought over to the next contact. Thus it continues until the crank of the
apparatus at the central station stops against the erected hook. When the current
arrives at the connecting apparatus, a small portion of it can no doubt pass from
the contact at the dial to the signal bell of that telephonic apparatus within the
circuit which corresponds with this contact, but the conducting wire of this causes
a resistance of about 100 S. U. and the armature of the bells can moreover be
adjusted. Thus it will be evident that a person can from the central station, by
means of the said apparatus put himself or other subscribers in direct connection
with any telephone within the circuit. Suppose for instance that, an apparatus

page_text: has been put in connexion with the central station. When then the usual bell
signal is given, the current passes through the line and round the magnet which
by reason of the impulses rapidly succeeding each other in opposite direction is not
able to effect any contact. Consequently the current goes to the hand and
through this over to the bell of the apparatus which then is brought in operation,
and thence to the earth The subscriber called on by this signal can then speak
with the caller. When the conversation is finished and the final signal given the
communicator on the central station apparatus is depressed, when a current is
passed in an opposite direction This makes then the magnet deviate in the
opposite direction and brings the needle to another contact. The current then
passes through the other electro magnet and the needle to the earth, thereby the
armature will be attracted which in its order lifts a rack so that this disengages
the link-bar when the shaft with its hand is brought back into its former position
by means of the spiral spring. When the hand lies against a pin the central
station can be called upon from any apparatus within the circuit, if only a knob at
the apparatus be depressed, when the current passes from the battery of the said
apparatus through the wire, to the hand and from hence round the magnet to the
central station
When any apparatus within the circuit is coupled together, with the central
station this cannot be called upon from any other apparatus neither can the
conversation be listened to, because the hand is then resting on a certain point of
contact on the dial and the wire consequently put out of connection with the line.
This is made evident to the caller by the circumstance that no current passes the
bell apparatus of his telephone which consequently cannot ring
In a modification of this invention the magnetic needle is substituted by an
armature pivotted between the poles of a magnet.. This armature is surrounded
by the wire arriving from the line, which wire thence proceeds to the hand. Thé
pivoted armature is provided with a bar the lower extremity of which supports
a weight, tending to keep the bar vertical. When a current passes the armature
this turns in consequence of the influence of the magnet whereby one of the
contact springs attached to the top of the bar comes in contact with two points
whereby the current from the line in one case passes the electro magnet and the
bar and thence to the earth or through the other electro magnet and the bar to the
earth and creates then the same effects as the corresponding parts of the apparatus
In lieu of the armature a polarized relay with its armature might also be used in
order to effect contact in one or the other direction.
It is evident that the above described connecting apparatus would work if the
apparatus placed at the central station were. to be substituted by a common
communicator or any otherwise constructed apparatus, provided a certain number
of currents of certain duration and at certain intervals could thereby be passed to
the coupling apparatus and likewise a current in opposite direction and that a
discharge of the line could take place after each current
A modification of the coupling apparatus may be arranged so, that the contacts
of the dial are arranged in a straight line in lieu of in a circle and so that abové
these contacts moves a plate, or such like which is brought to and from thereby so
that the working magnets act upon a rack. Where the line between the central
station and the coupling apparatus is long, the electro magnets can be substituted-
by relays. The current in the coupling apparatus when no telephonic apparatus
is connected with the line is conducted to the earth and if required is provided
with a resistance of about 600 S. U in lieu of being conducted to the earth.

page_text: a, b indicate two levers having contact springs c, d, which, when the said levers
are moved outwards, are brought into-contact with the adjustable contact
screws e, f. The levers a, b are normally held in contact with the support or
piece by the springs h. The lever a is arranged at one side of, and slightly lower
than, the wheel I; and the lever 6 is arranged at one side of, and slightly lower
than, the wheel H.. The lever a is provided with a pivotted catch i which is held,
by means of a spiral spring k, against a pin ; and another pivotted catch m is
arranged in a similar manner upon the lever b.
n indicates a flexible arm having a projection n' which retains the crank or
handle F when necessary, and prevents the same from turning. When the said
flexible arm n is pressed backwards, the crank is disengaged so that the shaft C is
turned by the spiral. spring..in the box. G. The projection marked o on the
periphery of the wheel I will then come into contact with the catch i on the lever a
As the catch is held by the pin l'and cannot, therefore, be turned on its pivot by
the said projection, the lever a is moved outwards thereby, so that the contact-
spring is brought into contact with the screw e and closes or completes the
circuit in which the said screw is included.. A current is thus caused to pass into
the line, as long as the projection o remains in contact with the catch i. The
current passes from the post or terminal "C" to the contact piece U, thence through
the contact. screw Z and the wire to the contact piece e and through the spring c
into the metal of the apparatus from. which it passes to line through the post or
terminal "L" At the other end of the line the current-passes to earth through the
connecting or coupling apparatus hereinafter described. From the earth the circuit
is completed through the post or terminal." J "the contact screw A, the contact
piece V and the post or terminal "Z" of the battery..
:
i.
When the shaft O is revolving in the direction of the arrow Figure 4, the
pawl Lengages, with the teeth of the ratchet-wheel K and, by means of the
gearing hereinbefore described, rotates the shaft Q and with it the vanes R, which
retard the speed of the moving parts, so that a certain length of time must elapse
before the projection o has moved out of contact with the catch i; this projection
is longer than the other projections on the wheel I, as a current of longer duration
than usual is required when starting the apparatus, in order to overcome the inertia
of the moving parts.. When the projection o has passed the catch i and permitted
the latter to fall into the space next the said projection, the contact at e is
interrupted. At the same time a tooth or projection on the wheel H comes into
contact withe the catch m on the lever b, and pushes the said lever outwards so
that the spring & comes into contact with the screw f. By this means the
conductor is connected with the earth. The next impulse is emitted to the line
when the next projection to the one o on the wheel I comes into contact with the
catch Currents at certain intervals and of certain duration are thus emitted to
line by the contact of the catch'i with the projections on the wheel I, and after
each impulse a discharge takes place by the catch m on the lever b coming into
contact with the projections on the wheel H. The wheels H, I are turned by the
crank F the latter moving over the dial (Figure 2) which is divided into as many
parts as there are projections on the wheel I.
The cylindrical portion B of the box or case A is provided at the top edge with
a number of movable or adjustable hooks p (one for each division of the dial). In
order to emit any desired number of impulses to line it is only necessary to adjust
the hook corresponding to the said number on the dial, that is to say, to raise the
said hook, as shewn on the right hand side of Figure 1. The crank F after having
been disengaged from the retaining arm n, turns until it stops against the adjusted
or raised hook p. The crank is brought back to its original position by hand, the
pawl L sliding over the teeth of the ratchet-wheel K, so that the train of gear-
wheels will not be put in motion. The spiral spring in the box G is rewound
when the crank is thus turned back. The levers a and.b are not moved when the
crank is turned back, because the spring catches i, m yield and permit the projec-
tions on the wheels H, I to pass them without operating, the said levers. It

page_text: follows, therefore, that no contacts are made at e and during the backward
movement of the crank.
•
In order to emit to line, a current in the opposite direction by means of this
apparatus, it is only necessary to depress the communicator or manipulator T,
when the contact pieces U, V will be brought into contact with the pieces 9, "
placed beneath them. The current then passes from the post or terminal “C”
through the contact pieces U and g to the post or terminal "J" and earth, the
circuit being completed through the post or terminal "L" the contact pieces r
and V to the post or terminal "Z."
The connecting or coupling apparatus is illustrated in Figures 5 to 8 and is
enclosed in a suitable box or case. It comprises a dial a" in the front of which
is arranged a hand or pointer a' secured to a shaft 6' acted upon by a spring b³,
which tends to keep the said hand or pointer pressed against a pin o¹ fixed to the
dial. The circumference of the dial is divided into as many parts as there are
telephonic instruments connected with the said coupling apparatus.
Behind the dial, on the shaft b¹, is secured a ratchet-wheel d¹ with which a hook
at the end of the link or rod e' engages. This link or rod is connected with one
arm of a bell-crank-lever f¹ pivotted at its angle to the frame of the apparatus ;
the other arm of this lever forms the armature of an electro-magnet g' of about
eighty (80) Siemens' units resistance.
h' indicates a lever pivotted at one end to the frame of the apparatus, and the
other end of which rests against the ratchet-wheel and acts as a pawl. This
lever is suitably connected with the armature of an electro-magnet k¹ of about
eighty (80) Siemens' units resistance..
.
'
The dial at its surface is provided with a number of contact points c³, with which
the hand or pointer a', when it is rotated, is adapted to make contact by means
of-a slight spring a secured to its under side; each contact being in electrical
connection with one of the telephonic instruments connected with the said coupling
apparatus
a
The apparatus further comprises a system of three magnetic needles or magnets
which can be encircled longitudinally by a current passing from the first named
apparatus at the central station through a bobbin or coil surrounding the central
magnet. The upper magnet bas at the top a small wheel or roller which, when
the magnets deviate to one or the other side, comes in contact with and raises one
end of one of the levers m³, n¹.. The other end of the said léver is thus depressed
and comes into contact with one of the contact pieces o¹, p¹.
gindicates a magnet so arranged as to determine the position of rest of the
astatic system of magnetic needles.
The crank having been disengaged in the apparatus at the central station, a
current will be emitted to line as hereinbefore. described, which current enters the
connecting or coupling apparatus, passing around the magnets ; it then passes to
the hand or pointer a, thence to the pin c¹ and from this pin to the earth through a
resistance coil s¹ of about 600 Siemens' units. The magnetic needles or magnets
then deviate in one direction and raise the lever n' which makes contact with the
tongue or piece p³, so that a shunt is obtained, and the greater part of the current,
in lieu of passing through the resistance coil a¹ to the earth, passes through the
electro-magnet g the contact piece p¹, the lever n¹ and the magnetic needle..or
magnet to the earth. The magnet g¹ then attracts its armature, and moves the
bell-crank-lever f¹ so that the link or rod e¹ turns the ratchet-wheel d and its
shaft b until the hand or pointer a¹ comes into contact with the next contact
point on the dial. The lever or pawl h¹ prevents the said hand or pointer from
being returned by the spring 6. The next succeeding discharge of the current
through the apparatus at the central station, causes the electro-magnet gl to
instantly release its armature. The next electrical impulse passes through the line
before the magnetic needle or magnet has had time to interrupt the contact
between o' and pl. The operation just above described is then repeated, whereby
the hand or pointer a¹ is brought over to the next contact point on the dial, and so

page_text: "
on until the crank, of the apparatus at the central station stops against the adjusted
hook. When the current arrives at the connecting or coupling apparatus, a small
portion of it can no doubt pass from the contact on the dial to the signal bell of
that telephonic apparatus within the circuit which corresponds with this contact
but as the conducting wire of the latter has a resistance of about one hundred (100)
Siemens' Units and as the armatures of the bells are adjustable, the latter can be
so arranged that, they will not be sounded by the short current that may pass
through them.c
:
It will thus be evident that a person can from the central station by means of
the instruments above described put himself or other subscribers in direct
connection or communication with any telephone connected with the coupling
apparatus. Assuming, for instance, that the apparatus marked 3 in Figure 8 has
been put in connection with the central station. Then, when the usual bell signal
is given, the current passes through the line "L" and around the magnet ¹ which,
by reason of the induction currents or electrical impulses rapidly succeeding each
other in opposite directions, will vibrate but cannot effect any contact. Conse-
quently the current passes to the hand or pointer a¹ and through the same to
the bell of the apparatus 3, (which is then brought into operation) and thence to
the earth. The subscriber called by this signal can then speak with the caller.
When the conversation is finished and the final signal given, the communicator
or manipulator on the central station apparatus is depressed, so that a current is
emitted in the opposite direction, thereby causing the magnet to deviate in the
opposite direction and bring the lever m¹ into contact with the point o¹. The
current then passes through the electro-magnet k¹ and the needle or magnet / to the
earth. The armature is, therefore, attracted, and lifts the lever or pawl h¹ so
that the link or rod e' is disengaged, and the shaft 6' with its hand or pointer a¹ is
brought back into its original position by means of the spring 6. When the hand
or pointer a¹ rests against the pin c¹ the central station can be called from any
instrument connected with the coupling apparatus by depressing a knob t¹ of the
said instrument when the current will pass from the battery of the said apparatus
through the wire u' indicated by full lines, to the hand or pointer and thence
around the magnet to the central station.
When any instrument connected with the coupling apparatus is connected with
the central station, the latter cannot be called from any other apparatus, neither
can the conversation be. listened to, because the hand or pointer a¹ is then resting
on a certain contact point on the dial and the wire u¹ is consequently out of
connection with the line "L" This is made evident to the caller by the
circumstance that no current passes through the bell apparatus of his telephone,
which consequently cannot ring.
According to. a modification of the said invention illustrated in Figure 9, an
armature s pivotted between the poles of a magnet t is substituted for the magnetic
needles above described. This armature is surrounded by the wire connected with
the line, which wire thence proceeds to the hand or pointer a¹. The said pivotted
armature is provided with a bar the lower extremity of which supports a weight
which tends to keep the said bȧr vertical. When a current passes through the
armature, the latter turns by reason of the action of the magnet, so that one of the
contact springs u attached to the top of the bar comes into contact with one of
the points o¹, p¹. The current from the line, therefore, in one case, passes through
the electro-magnet ¹ and the bar and thence to the earth, and, in the other case,
through the electro-magnet g' and the bar to the earth, and produces the same
effects as the corresponding parts of the apparatus illustrated in Figure 8. In lieu
of the armature 8, a polarized relay with its armature might be used in order to
effect contact in one or the other direction.
บ
It is evident that the above described connecting or coupling apparatus would
work if an ordinary communicator or manipulator or other suitable apparatus were
to be substituted for the apparatus employed at the central station, provided a
suitable number of currents of sufficient duration and at suitable intervals could

page_text: thereby be passed to the connecting apparatus and likewise a current in the
opposite direction, and that a discharge of the line could take place after each
current.
The connecting apparatus may be arranged so that the contact points on the
dial are arranged in a straight line instead of in a circle, and so that above these
contact points is a plate or the like, which is moved to and fro by the working
magnets g', acting upon a rack. Where the line between the central station
and the connecting apparatus is long, relays can be substituted for the electro-
magnets The conductor of the connecting apparatus, which, when no telephonic
apparatus is connected with the line, is connected with the earth, and which is
provided with a resistance of about six hundred (600) Siemens' Units, instead of
being conducted to the earth, may, if desired, be provided with a condenser capable
of absorbing sufficient electricity for causing the magnetic needle to deviate to the
position of contact.
By the above described improvements a number of telephonic instruments can
be connected by wires to the contact points c* of the connecting or coupling
apparatus, which thus forms a local telephone exchange capable of being operated
from the central station so as to put either of the said telephonic instruments in
communication with the said central station, or with a telephonic instrument
connected therewith.
It is preferable to dispense with the calling or signalling wire u¹ and to connect
each of the contact points c with the earth through one of the telephones, and
with the pin c. Each subscriber connected with the local exchange can then call
up the central exchange by means of a magneto-generator and requires no battery.
If desired, the apparatus can be so modified or arranged that any two of the
telephonic instruments in connection with the connecting or coupling apparatus or
local exchange can be put into connection with each other from the central station.
without the aid of an operator at the said local exchange.
For this purpose, in addition to a division on the dial of the coupling apparatus
or local exchange for each telephone in connection with the said apparatus, I
employ other divisions for the purpose of connecting any two of these telephones
with each other when the pointer rests on the said divisions. These divisions,
when five telephones are connected with the local exchange or coupling apparatus,
are marked respectively 1-2, 1-3, 1–4, 1-5, 2-3 2-4, 2-5, 3-4, 3-5
and 4-5, and, when the pointer is turned by means of electrical impulses from the
central station, so that it rests on either of the divisions so marked, then those two
telephones corresponding to the numbers on the said division are connected and all
other telephones connected with the local exchange are cut out of circuit.
Having thus fully described the said invention as communicated to me by
my foreign Correspondents and the manner of performing the same I wish it
understood that I claim ;-
•
First. The above described method of enabling any telephonic instrument,
connected with a local exchange or coupling apparatus as above described, to be
put in communication with the central station or exchange or with any telephonic
instrument connected therewith, by means of the said coupling apparatus and a
suitable instrument at the central station for operating the same and a single
conducting wire connecting the said instrument with the coupling apparatus.
Second. The above described method of enabling any two instruments connected
with a local exchange or coupling apparatus as above described, to be put in
communication with each other, by means of the said coupling apparatus and a
suitable instrument at the central station for operating the same and a single
conducting wire connecting the said instrument with the coupling apparatus.
Third. The above described instrument or apparatus for causing electrical
impulses to be transmitted through the line in either direction, in which apparatus.
I employ two wheels having projections on their peripheries. in combination with
two levers, substantially as described with reference to Figures 1 to 4 of the
drawings, for the purpose specified.

page_text: Fourth. The above described connecting or coupling apparatus serving as a local
exchange and arranged to be operated from the central station by means of electric
currents, substantially as described with reference to Figures 5 to 8 of the drawings,
for the purpose specified.
Fifth. The modification of the connecting or coupling. apparatus, wherein I
employ, instead of the astatic system of magnetic needles or the magnet with its
armature, a polarized relay having its armature adjusted or arranged to make the
necessary contacts, substantially as described.
Sixth. The modification of my invention wherein I dispense with the calling or
signalling wire and connect each of the contact points of the coupling apparatus
with the earth through one of the telephones, and with the pin c³, and employ a
magneto-generator instead of a battery, substantially as set forth.
In witness whereof I the said William Robert Lake, have hereunto set my band
and seal this Nineteenth day of April in the year of Our Lord One thousand
eight hundred and eighty four.
WH BORT LAKE
T.1