IMPROVED METHODS OF AND APPARATUS FOR FACILITATING TELEPHONIC COMMUNICATION
Year: 1879

page_text: "
LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for the Invention of
IMPROVED METHODS OF AND APPARATUS FOR FACILITATING TELEPHONIC
COMMUNICATION." A communication from abroad by Michael Daniel
Connolly, Lawyer, of Philadelphia, Pennsylvania, Thomas Anthony Connolly,
Lawyer, of Washington, District of Columbia, and Thomas Joseph MoTighe,
Patent Agent, of Pittsburgh, Pennsylvania, all in the United States of
Amavinn
Sealed the 28th May 1880, and dated the 13th December 1879.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 13th December 1879.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVED METHODS OF AND APPARATUS FOR
FACILITATING TELEPHONIC COMMUNICATION." [A communication from abroad by
Michael Daniel Connolly, Lawyer, of Philadelphia, Pennsylvania, Thomas Anthony
Connolly, Lawyer, of Washington, District of Columbia, and Thomas Joseph
MoTighe, Patent Agent, of Pittsburgh, Pennsylvania, all in the United States of
America.]
This Invention has for its object to provide an "automatic telephone exchange"
or series of independent lines having means of electrical communication with each
other, and combined with mechanism controlled from the different stations and
adapted to automatically establish communication between any disengaged pair at
any and all times, while securing individual privacy between each pair, each
station being in communication with a main or principal station, through which
connections are automatically established between any two of the individual
stations.
In practising the said Invention I employ electricity and electro-magnetism,
whereby all the operations of the central office are rendered automatic. Any
member may communicate with any other member whose line is unoccupied. At
the same time he can isolate his own and the line he desires to communicate with
from all others. He is enabled to signal the member to be communicated with and

page_text: receive the answering signal, and while these two are using their lines all the
other members can be using their lines, two and two, without in any manner
interfering line with line.
Each station comprises the usual battery, a telephone, a call-bell, a reversing key,
a compound switch, and a dial instrument. The latter produces breaks in the
electric current, the number of which are indicated on the dial by a pointer, and
causes the central office mechanism pertaining to the given line to operate and
establish the connection of the two lines; then the current is reversed, and brings
into action mechanism at the central station, which isolates the connected lines and
rings the bell at the station to be called. At the station thus signalling "main"
is then switched to the bell; the signalled station now shunts his battery into main
line and rings the bell of signalling station; both now switch to their respective
telephones cutting out bells, and if necessary batteries from main line, whon
conversation may be carried on. When done talking the two parties restore the
devices to their normal condition, so that others may communicate with either.
"
The devices employed at the local stations are as follows, that is to say:-The
main line enters through a switch adapted to bring into circuit severally the dial
instrument, the call-bell, and the telephone and the local battery. The dial instru-
ment is an ordinary rheotome having a dial, on which are the numbers or letters
of the different stations in the system. A pointer is fixed to a break-wheel, whose
toothed periphery makes and breaks the circuit by striking a spring or finger, both
these devices being in the circuit, so that when the pointer is at, say 4, it means
that 4 breaks have been made in the circuit. Any form of rheotome adapted to
the use required may be employed. One of the wires from the rheotome leads to
the local battery, whose other pole leads to earth. In a branch line is a call-bell
mechanism. The wires from the local battery are controlled by a reversing key,
whose office is to change the direction of the electric current. The switch is formed
with an insulated branch having a conducting bar. When the switch is thrown to
the right the bar closes the circuit of the tiansmitter and the receiver is thrown
in by the switch proper. Two or more switches instead of one may be used.
The devices employed at the central office are as follows, that is to say:-On an
axis superimposed or side by side are as many ratchet-wheels as there are stations,
one ratchet and its appurtenant parts belonging to each station and under its
individual control. The ratchet has teeth corresponding in number with those of
the rheotome at the local station, and is turned on its axis by means of a dog or
equivalent device actuated by the armature of an electro-magnet in the main
circuit. The movements of the ratchet and pointer are exactly determined by the
current-impulses given at the local station by the rheotome. Concentric with the
axis is a conducting plate, in contact with which in a slide having longitudinal
movement on a pointer, and having a hook on its outer end. After passing through
the ratchet moving electric-magnet the current traverses another electro-magnet
whose armature is polarized so as to be thrown to one side or the other, according
as the current is normal or roversed. When in normal position the armature
contacts with a terminal of a contact plate, and when reversed it breaks that
contact. From the armature a wire descends to earth. From the magnet the
current proceeds normally to earth; thus a temporary circuit is secured for the
manipulation of the other devices, so that the operation of the rheotome at the local
station will always effect the step-by-step movement of the pointer at the central
office. Each of the stations has at the central office its own exclusive electro-
magnets, ratchet pointer, and plate. There is a series of bars hung or otherwise
suitably arranged outside the plates and parallel with the axis. Each bar reaches
over the whole series of plates. As many hooks project from a bar as there are
ratchets and pointers, that is to say, one for each circuit entering the central office,
and these hooks normally stand in such position that a hook of a slide on the pointer
will pass through and in electrical contact with another hook when the pointer is
rotated. The bar is connected to one of the terminals of an electro-magnet having
a polarized armature so connected to the bar that when the normal current passes

page_text: the bar is moved towards the axis, and when the current is reversed the bar is
drawn radially outward. From that magnet the current passes to the line of the
local station to which that particular bar belongs.
The operation of the rheotome at one station causes the pointer belonging to
that station at the central office to pass around till its hook makes a contact with
the bar belonging to the other station. I now reverse the current and at once
effect very remarkable results. The armature being thrown out of contact with
the plate cuts out the ground at the central office from the line under treatment,
the current now passes through this plate to the aforesaid slide through the con-
tacting hooks to the bar, thence to the other local station, returning by earth. At
the moment of reversal the magnet changes polarity, and its armature causes the
bar to move outward, so that all the hooks of the bar are now out of the path of
the hooks on all the other pointers, one of the hooks and the slide following the
bar, and thus preserving the contact so secured. Hence the line thus established
is isolated, and the pointer belonging to no other local station can obtain a contact
with that line; but while privacy is thus secured between the two stations
mentioned any other two can obtain a circuit in the same way. The ultimate
result is that on one exchange all the members may be talking at once, two and
two, and no one will get the messages intended for some one else. A further
result of the reversal of the current the ringing of the call-bell at the distant
station.
In cutting out the local battery the current leaves the line, and the electro-
magnet operating the ratchet at central office releases its armature. Now when
the other station switches its battery into main line to answer the call the direction
will be such as will not move the polarized armatures of the central office, but in
order to avoid the disconnection which would occur by this reverse current
attracting the ratchet armature I may make the surface of the contacting hooks
wide enough to permit the single attraction and stop of the pointer without
breaking the contact of the hooks, or I may cause the polarized armature to move
a stop against the ratchet armature; or provision may be made for temporarily
cutting one or both magnets of the coupled lines out of the circuit.
The above apparatus isolates the bar of the station called, but it is also advisable
to isolate the bar of the station calling. To effect this result I run a branch line
from the line of the station calling to a suitable terminal; another line is run from
the conducting bar of that station to the operative electro-magnet, which moves
said bar. An insulated strip or spring plug is fixed on the pointer belonging to
the same station, and so arranged that when the pointer is at an initial point or
zero on the plate the strip will be in contact with the two terminals, and thus
complete the circuit from the bar through the electro-magnet to the branch-line till
it meets the main line of the station it belongs to. When that station operates its
rheotome its pointer at the central office moves from the initial point or zero, and
the branch circuit is broken thereby. Now if any other than the station called
wishes to get on the line of the station calling there is nothing to prevent it
operating its pointer till contact is made with the bar of the first station calling,
but when that point is reached it cannot obtain a circuit at all with the line
belonging to said bar, and hence cannot interrupt or hear the conversation taking
place between the two already in circuit.
In a modified arrangement the special magnet for controlling the temporary
ground is dispensed with. The circuits are made from the contact bars through
the bar shifting magnets, and thence through their armatures, which are insulated
from said bars. The temporary ground of an operating line is through its contact
plate by way of its pointer hook or tappet, which normally is in contact
therewith.
The normal position of the armature of the shifting magnet is such as to run
circuit to each, and the hook or tappet on the pointer is so constructed that in
passing a normally situated bar it will be lifted or moved so as to divert the
current of the operating line to earth through the armature. If the current be

page_text: then reversed the circuit will be diverted by the movement of the armature to a
terminal of the line to which said bar belongs. The reversed current will simul-
taneously or virtually so effect a corresponding movement in the contact bar and
armature of the operating line.
The said Invention is not confined to the mechanical arrangements herein set
forth, as the principle of employing an apparatus by which the work at the central
office is done by an automatic machine operated directly from the local stations by
electro-magnetism; also the principle of employing a series of independent stations
having means of electrical communication with each other, and combined with
mechanism controlled from the different stations and adapted to automatically
establish communication between any disengaged pair at any and all times may be
applied in many ways.
In some cases the current-reversing arrangement may be dispensed with by
using two lines running from the main to the sub or central office, with a switch
at the former; after circuit is obtained the central ground may be cut.
To accommodato a larger number of lines the ratchet at the central station may
have an endless band passing over it and over a sprocket-wheel placed far enough
away to permit the required number of bars to be arranged across its path. This
band may have an arm projecting from it like the pointer, and a plate in contact
therewith, shaped so that the slide on the pointer would always be in contact with
it. All other devices would not be substantially changed.

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 12th June
1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, "IMPROVED METHODS OF AND APPARATUS FOR
FACILITATING TELEPHONIC COMMUNICATION." A communication from abroad by
Michael Daniel Connolly, Lawyer, of Philadelphia, Pennsylvania, Thomas Anthony
Connolly, Lawyer, of Washington, District of Columbia, and Thomas Joseph
McTighe, Patent Agent, of Pittsburgh, Pennsylvania, all in the United States of
America.
"
This Invention has for its object to provide what may be termed an "automatic
telephone exchange or series of independent lines having means of electrical
communication with each other, and combined with mechanisin controlled from the
different stations and adapted to automatically establish communication between
any disengaged pair at any and all times while securing individual privacy between
each pair, each station being in communication with a main or principal station
through which connections are antomatically established between any two of the
individual stations.
In practising the said Invention I employ electricity and electro-magnetism
whereby all the operations of the central office are rendered automatic. Any
member may communicate with any other member whose line is unoccupied. At
the same time he can isolate his own and the line he desires to communicate with
from all others. He is enabled to signal the member to be communicated with
and receive the answering signal, and while these two are using their lines all the
other members can be using their lines two and two without any interference of
one line with another
Each station comprises the usual battery, a telephone, a call bell, a reversing key,
a compound switch, and a dial instrument. The latter produces breaks in the
electric current, the number of the said breaks being indicated on the dial by a
pointer, and causes the central office mechanism pertaining to the given line to
operate and establish the connection of the two lines. Then the current is reversed
and brings into action mechanism at the central station which isolates the connected
lines and rings the bell at the station to be called. At the station thus signalling main
is then switched to the bell. The person at the signalled station now shunts his
battery into the main line and rings the bell at the signalling station. Both persons
now switch to their respective telephones, cutting out the bells and if necessary the
batteries from main line, when conversation may be carried on. When they cease
talking the two parties restore the devices to their normal condition so that other
persons may communicate with either.
DESCRIPTION OF THE DRAWINGS.

page_text: Figure 10 is a diagram of a modified and simplified construction and arrangement
of the central office mechanism and circuits.
Figure 11 is a detail view in section illustrating a special form of pointer hook
suitable for the mechanism shewn in Figure 10.
Figures 12 and 13 represent a modification of the said Invention hereinafter
described.
Like letters indicate the same parts throughout the Drawings.
The apparatus employed at the local stations is as follows, that is to say : —
The main line enters through a switch A. adapted to bring into circuit severally
the dial instrument A', the call-bell, the telephone, and the local battery A". The
dial instrument is an ordinary rheotome having a dial on which are the numbers
or letters of the different stations in the system. A pointer a is fixed to a break
wheel a¹ whose toothed periphery makes and breaks the circuit by striking a spring
or finger a", both of these devices are in the circuit so that when the pointer is at,
say 4, it means that 4 breaks have been made in the circuit. Any form of rheotome
adapted to the use required may be employed. One of the wires from the rheotome
leads to the local battery whose other pole leads to earth. In a branch line is the
call-bell mechanism. The wires from the local battery are controlled by a reversing
key C, whose office is to change the direction of the electric current. The switch
is formed with an insulated branch c¹ having a conducting bar a. When the
switch is thrown to the right the bar a' closes the circuit of the transmitter and
the receiver is thrown in by the switch proper. Two or more switches instead of
one may be used.
The apparatus employed at the central office is as follows, that is to say :-
On an axis E superimposed or side by side are as many ratchet-whoels E as there
are stations, one ratchet and its appurtenant parts belonging to each station and under
its individual control. The ratchet wheel has teeth corresponding in number with
those of the rheotome at the local station, and is turned on its axis by means of a dog
or equivalent device actuated by the armature of an electro-magnet F in the main
circuit. The movements of the ratchet wheel and pointer are exactly determined by
the current-impulses given at the local station by the rheotome. Concentric with the
axis is a conducting plate G, in contact with which is a slide e having longitudinal
movement on the pointer E", and having a hook e' on its outer end. After passing
through the ratchet moving electro-magnet F the current traverses another electro-
magnet H whose armature h is polarized so as to be thrown to one side or the other,
according as the current is normal or reversed. When in its normal position the
armature contacts with a terminal of the contact plate G, and when reversed it
breaks that contact. From the armature h a wire descends to earth. From the
magnet H the current proceeds normally to earth. Thus a temporary circuit is
secured for the manipulation of the other devices, so that the operation of the
rheotome at the local station will always effect the step-by-step movement of the
pointer at the central office. Each of the stations has at the central office its own
exclusive electro-magnets, ratchet, pointer, and plate. I, I, are a series of bars
hung or otherwise suitably arranged outside the plates G and parallel with the
axis. Each bar reaches over the whole series of plates G. As many hooks ¿¹
project from the bar I as there are ratchets and pointers, that is to say, one for each
circuit entering the central office; and these hooks normally stand in such a
position that the hook e¹ of the slide e on the pointer Ell will pass through and in
electrical contact with the hook i when the pointer is rotated. The bar I is
connected to one of the terminals of an electro-magnet K having a polarized
armature so connected to the bar I that when the normal current passes, the bar is
moved toward the axis E, and when the current is reversed the bar is drawn
radially outward. From the magnet K. the current passes to the line of the local
station to which that particular bar belongs.
As above stated, the operation of the rheotome at one station causes the pointer
belonging to that station at the central office to pass around till its hook makes a
contact with the bar I belonging to the other station. I now reverse the current

page_text: and at once effect very remarkable results; the armature being thrown out of
contact with the plate G cuts out the ground at the central office from the line
under treatment. The current now passes through the plate G to the slide s
through the contacting hooks e¹ and to the bar I, thence to the other local station
returning by earth. At the moment of reversal the magnet K changes polarity and
its armature & causes the bar I to move outward, so that all the hooks of the bars I
are now out of the path of the hooks on all the other pointers, the hook e¹ and the
slide e following the bar I, and thus preserving the contact so secured. Hence, the
line thus established is isolated, and the pointer belonging to no other local station
can obtain a contact with that line; but while privacy is thus secured between
the two stations mentioned, any other two can obtain a circuit in the same way.
The ultimate result is that on one exchange all the members may be talking at
once, two and two, and no one will get the messages intended for some one else.
A further result of the reversal of the current is the ringing of the call bell at the
distant station.
In cutting out the local battery the current leaves the line, and the electro-inagnet
operating the ratchet wheel at the central office releases its armature. Now when
the other station switches its battery into main line to answer the call, the direction
will be such as will not move the polarized armatures of the central office; but in
order to avoid the disconnection which would occur by this reverse current
attracting the ratchet armature I may make the surface of the contacting books
wide enough to permit the singlo attraction and stoppage of the pointer without
breaking the contact of the hooks; or I may cause the armature / to move a stop
against the ratchet armature, or provision may be made for temporarily cutting one
or both magnets of the coupled lines out of the circuit.
The above apparatus isolates the bar of the station called, but it is also advisable
to isolate the bar of the station calling. To effect this result I run a branch line
from the line of the station calling to a suitable terminal x; another line y is run
from the conducting bar of that station to the operative electro-magnet which
moves said bar. An insulated strip Z or spring plug is fixed on the pointer
belonging to the same station, and so arranged that when the pointer is at an initial
point or zero on the plate the strip Z will be in contact with the terminals x and y,
and thus complete the circuit from the bar through the electro magnet to the
branch line till it meets the main line of the station it belongs to. When that
station operates its rheotome its pointer at the central office moves from the initial
point or zero and the branch circuit is broken thereby. Now if a person at any
other than the station called wishes to get on the line of the station calling, there is
nothing to prevent him operating his pointer till contact is made with the bar of
the first station calling, but when that point is reached he cannot obtain a circuit
at all with the line belonging to said bar, and hence cannot interrupt or hear the
conversation taking place between the two already in circuit.
To sum up, the operations required are as follows:-To call another station the
operator switches on his battery, moves his index till it indicates the station
desired, reverses his key and then switches in the call-bell. When the answering
signal is received he switches in the telephone. When he ceases talking he switches
in the battery, places his reversing key back to its normal position, thus restoring
the polarised armatures at the central office, and then moves his index around to
zero, and leaves the switch on the call-bell.
At the station called, when the bell rings, the operator switches in his battery
with its direction conforming to that required to preserve the armatures at the
central office in the positions set by the station calling; this at once rings the
bell of the station calling, after which he switches in his telephone. When he
ceases talking, he simply switches back to the bell.
In the operations of the exchange it may happen sometimes that connection will
be sought through one line with another, the contact bar of which is shifted for the
accommodation of another line. If then the line seeking the non-obtainable
circuit should throw out its temporary ground by reversing the current, it would

page_text: "
be necessary to obtain some circuit in response to the operation so that the parts
might be restored to their normal position. The contact bars are accordingly
provided with supplementary hooks or contact parts which communicate with the
"ground," and which are so situated that when a bar is shifted outward said
contact parts will be met by the pointer hooks of the lines seeking non obtainable
circuits, and will give such lines new temporary "grounds." Again, should any
line seek contact with one whose pointer has left "home," it would be enabled to
shift the bar of such line, provided a circuit were obtainable, and hence another
temporary "ground" is desirable. This is provided by running a branch from one
of the bar shifting magnets of the line sought to "ground" through a pair of
spring or other equivalent contacts r, r, which are separated by an insulating
tongue S on the pointer when the latter is "home."
In the modified and greatly simplified arrangement of my improved apparatus
illustrated in Figure 10, and which may be employed in lieu of and perhaps as
preferable to the one already described, the special magnet for controlling the
temporary ground is dispensed with. The circuits are made from the contact bars
through the bar shifting magnets, and thence through their armatures which are
insulated from said bars. The temporary ground of an operating line is through
its contact plate by way of its pointer hook or tappet which normally is in contact
therewith.
B5
The normal position of the armature of the shifting magnet is such as to run
circuit to each, and the hook or tappet on the pointer is so constructed, that in
passing a normally situated bar it will be lifted or moved so as to divert the
current of the operating line to earth through the armature. If the current be then
reversed, the circuit will be diverted by the movement of the armature to a
terminal m' of the line to which said bar belongs. The reversed current will
simultaneously or virtually so effect a corresponding movement in the contact bar
and armature of the operating line. In the modification of the apparatus illustrated
in Figures 12 and 13, I dispense with the ground magnets and provide for cutting
out the ratchet inagnets so as to prevent the pointer from being moved out of
engagement with the contact bar on reversing the current. In these Figures A5, B5,
are two rings, the ring A being in circuit with the ground, and the other ring
in circuit with the main line. The circuit of the operating line is first through the
magnet C³, thence to the sliding contact spring &³, the collar c³, and through the
conductor d³ on the pointer to the terminal e at the end of the pointer. When
operations commence the circuit is made to ground through the ring Aº. Whenever
the pointer hook a³ passes one of the contact bar hooks do, the former is slightly
moved so as to divert the current from the ring A* to the hook d³, thence to the
magnets f, f, thence through the armature g to the ground terminal ho. This
enables the contact bar to be shifted by reversing the current. If now the pointer
coincides with the contact bar of the proper line and the current is reversed, the
hook (or contact bar) d³ is moved outwardly, and the circuit made by the terminal
with the ring B of the line sought. At the same time the pointer hook is
brought in contact with the ring B by the small spring n², Figure 13, and the
ratchet magnet is cut out of the circuit.
Though I have specifically described apparatus at the central office capable of
effecting the objects sought, I wish it to be distinctly understood that I do not
confine myself to the mechanical arrangements herein set forth, as the principle of
employing an apparatus by which the work at the central office is done by an
automatic machine operated directly from the local stations by electro-magnetism,
and also the principle of employing a series of independent stations, having means
of electrical communication with each other, and combined with mechanism
controlled from the different stations, and adapted to automatically establish
communication between any disengaged pair at any and all times may be applied
in many ways. The said Invention as above set forth contains many features
which simpler conditions would not require. One such condition is fulfilled by the
diagram, Figure 8, where M represents, say, the main office of a manufactory,

page_text: having a line running to some particular point whence other shorter lines divergo
to various departments of the works. The main office M is practically the same as
one local station in the system first herein described. N, N₁, N", are the short
lines terminating in a disc O, over which travels a pointer P as before described.
The main office index is rotated to bring the main line around to the proper point,
whereupon the ground is cut out and the circuit completed as before. This done,
the other sub-lines are necessarily isolated. In this case the current revorsing
arrangement may be dispensed with by using two lines running from the main to
the sub or central office with a switch at the former; after the circuit is obtained
the central ground may be cut.
To accommodate a larger number of lines the ratchet wheel at the central station
may have an endless band passing over it and over a sprocket-wheel placed far
enough away to permit the required number of bars to be arranged across its path.
This band may have an arm projecting from it like the pointer, and a plate in
contact therewith shaped so that the slide on the pointer would always be in contact
with it. The other devices would not be substantially changed.
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 under-
stood that I claim,―
First. An automatic telephone exchange or series of independent lines having
means for electrical communication with each other, and combined with mechanism
controlled from the different stations, and adapted to automatically establish com-
munication between any disengaged pair at any and all times while securing
individual privacy between each pair.
Second. An automatic telephone exchange comprising a series of three or more
converging independent lines and a central connecting apparatus, so constructed
and arranged that any member of the exchange may, while others are engaged, and
from his own individual station, place himself in direct cominunication with any
disengaged member of the exchange.
Third. A coupling or connecting instrument for converging telephone lines,
operated automatically by currents controlled from distant stations, and provided
with devices whereby any two independent lines may be directly coupled or
connected to the exclusion of all others from the same circuit, while permitting the
establishment of separate circuits between the lines so excluded.
Fourth. An electro-automatic central apparatus for telephone exchanges provided
with a step-by-step action or progressive movement for establishing the coincidence
of selected lines and a shifting conductor, by which coinciding lines may be isolated
or rendered independent of others in the exchange, and means for permitting the
free inter-communication of the latter.
Fifth. A series of independent telephonic lines converging to a central office or
intermediate station, in combination with connecting mechanism located at the
point of convergence, and capable of being automatically so manipulated through
such lines that any one of said lines may at all times at will be placed in electric
circuit with any other disengaged circuit of the series.
Sixth. A series of independent telephonic lines converging to a central office or
intermediate station, in combination with connecting mechanism located at the
point of convergence, and capable of being automatically so manipulated through
such lines that all or any nuinber of said lines may be placed in electrical circuit
pairs at the same time.
in
Seventh. In a telephonic exchange system consisting of a number of circuits
converging from distant stations to a central office, an instrument located in the
central office and containing electro-mechanical devices placed respectively in anid
converging circuits, and adapted to connect any or all of said circuits in mutual
contact in pairs simultaneously, and suitable means at each of the stations for
putting said electro-mechanical devices in operation.
Eighth. The method of perfecting inter-connection of independent lines in a
system of telephonic circuits in which each line is dependent upon a single circuit

page_text: by the operations of the normal and reversed currents from local batteries, the
normal current being employed to bring the two lines into contact, and the reversed
current to isolate the circuit so established from all others of the system.
Ninth. The method of restoring the normal relations of two connected lines in a
system of telephonic circuits which have been electrically connected by reversing
the current, consisting in restoring the current to its normal direction, and thus
causing the electro-mechanical connecting devices to resume their original position,
whereby the connection is severed, and the two lines are brought to their normal
condition.
Tenth. In a system of independent telephonic circuits converging to a central
office, the method of securing privacy between any two communicating stations
with reference to all other lines, consisting in removing or disconnecting, by means
of an electrical current controlled at either of said stations, any or all of the devices
through which any other station could communicate therewith.
Eleventh. In a system of telephonic circuits converging to a central office, a 1
movable electro magnetic switching device forming the terminal of a given line, in
combination with a series of conductors respectively forming the terminals of the
other lines of said system, a step-by-step action to effect coincidence of lines, a make
and break mechanism at the distant station of the given line, and an electric
generator, whereby the successive pulsations produced in the given line effect the 5
progressive contact of said switching device with the other terminals.
Twelfth. In a device for establishing intercommunication between separate and
independent lines of a system of telephonic circuits, the combination with a
travelling pointer whose movements are responsive to the intermissions of a
distantly controlled rheostome, and which forms a medium of communication
between a given line and a line selected from the others of the system, of a
conductor in constant contact with said pointer, the "ground," and an automatic
switch which alternately shunts the current of the operative lino directly to earth,
and through said conductor to the line brought into connection therewith.
In witness whereof, I, the said William Robert Lake, have hereunto set my a
hand and seal, this Twelfth day of June, in the year of our Lord One
thousand eight hundred and eighty.
DAR
TAD