An Improved System of Automatic Telephone Exchange.
Year: 1897

page_text: Date of Application, 29th Oct., 1897
Complete Specification Left, 27th Aug., 1898-Accepted, 28th Jan., 1899
PROVISIONAL SPECIFICATION.
An Improved System of Automatic Telephone Exchange.
I, MAX MARGOWSKI, Chairman and Managing Director of The Automatic Tele-
phone Company, Limited, of 13 and 14, Abchurch Lane, in the City of London, "do
hereby declare the nature of this invention (a communication to me by Gustave
Seligmann-Lui, of 78, Rue Mozart, Paris, France, Gentleman), to be as follows:-
This invention relates to a system of automatic telephone exchange whereby to
enable the subscribers to put themselves into communication with each other as they
may require, without the assistance of operators at the exchange.
Except where the number of subscribers is very low, the mechanisms by the in-
strumentality of which the various operations incidental to the fulfilment of the
requirements of the service may be performed, must unavoidably be very complicated
and expensive. On the other hand it is to be observed that all the subscribers in
connection with the telephonic system do not require to enter into communication at
the same time, and experience shews that even in the centres of commercial activity
and at the busiest hours of the day, the number of subscribers speaking at the same
time is scarcely one-fifth of the total number.
For these reasons and in contradistinction to what has been proposed and described
in other patents, it has not been deemed expedient to assign to each subscriber's line
a complete set of apparatus, which would involve as many complete sets'as there are
subscribers' lines, and would necessitate the placing of all the lines of the system
under the control of each of these sets of apparatus and would thereby considerably
augment the cost. On the contrary the whole number of subscribers of this system
being divided into a certain number of groups, there is provided for the common use
of the subscribers of each group, a single complete set of apparatus of which each
may avail himself as he may require, this set of apparatus being moreover so arranged
as to permit of so many distinct communications being carried on simultaneously and
independently as may have been predetermined upon, according to the number of
subscribers comprised in each group and the usual amount of traffic in the locality,
provision being made to prevent an established communication being disturbed or
overheard by the intentional or unintentional operations of third parties.
With this object and without altering the existing system of line wires, the
telephonic system of this invention comprises the following mechanisms and groups
of mechanisın:-
(1). In addition to the usual transmitter, receiver, and bell, at the subscriber's end
there is provided a signal-composing and transmitting device or apparatus whereby
to enable the subscriber to prepare and transmit in required order of succession such
a combination of signals as will have for effect to establish the communication
required;
(2) At the point of convergence of the subscribers' lines there is provided :--
(a) at the terminal of each line one or several connectors having for function to
establish at will the connection of this line with one or several " steering" and pro-
pelling devices appertaining to the group to which the line under consideration
belongs

page_text: for the joint use of all the lines constituting a group and according as each
erminates in one or several connectors, one or several "steering" and propelling
es each comprising:
:-
1) steerers having for function to steer the signals, amongst the several
catchers operated by each "steering" and propelling device on the appro-
priate one for the establishment of the intended communication and to
leave that one alone in circuit ;
2) a double propelling relay whereby to bring to the required position the
catcher disengaged by means of the steerer.
ch such "steering" and propelling device is only occupied during the very short
necessary for disengaging the catcher and bringing it to the required position,
evice thereafter again becoming available for use by any other subscriber of the
group.
catch-boards in suitable number on each of which a certain number of lines
presented by appropriate contacts corresponding both to the wires proper to
line and to a special local service wire, the number of catch-boards and of lines
ch catch-board being calculated to make up the total number of subscribers'
and the various contacts corresponding to each line being repeated as many
as it is desired to put catchers in connection with the assemblage of lines
ring on each catch-board;
in front of each catch-board are a certain number of catchers or line-takers each
the control of a "steering" and propelling device corresponding to a different
of lines and each catcher being itself composed of :-
1) a certain number of groups of contact pieces capable of being put in current
connection with the contact pieces by which the lines and their service
wires are represented on the catch-boards, but not touching the same when
in normal position;
(2) various operating devices in connection with the double propelling relay and
by means of certain of which all the groups of contacts may be moved as a
whole until one of them comes opposite to the line sought for, whilst the
others put in current connection the group of contacts thus brought opposite
this line to the exclusion of all the others;
3) various accessory devices whereby as soon as the operation of connecting is
completed, the subscriber "calling" is, as the case may be, either put in
connection with the line of the subscriber with whom he wishes to
correspond, or is notified by a signal that this line is engaged.
a suitable number of coupling boards upon each of which appear-by appropriate
ct pieces the various lines appertaining to a same group as well as their service
the contacts corresponding to each line being repeated as many times as there
tchers provided for the joint use of the group of lines shewn on the board;
in front of the coupling boards are couplers each connected to one of the
ers appertaining to the group of lines appearing on the board and comprising:
1) a gripping device capable of normally retaining the coupler in its position
of rest, of releasing it, and of stopping it again in any one of the positions
which it is capable of assuming along the coupling board;
-
2) a certain number of groups of contact pieces adapted to be put in current
connection with the contact pieces representing on the board the
subscribers' lines and their service wires;
3) special appliances by which in each of the positions to which the coupler
may be moved along the coupling board, each of the said contact pieces is
in turn and to the exclusion of any other, introduced into the electric circuit
about to be completed.
a device whereby the subscriber "called" is "rung-up" as soon as that
riber's line has been reached and has been ascertained to be disengaged;
devices whereby every part of the mechanism is returned to normal position
n as it has ceased to be used:-viz.: the "steering" and propelling devices
on as the communication has been established or has been ascertained

page_text: to be temporarily impossible; the connecting devices (catchers and couplers as well
as their accessory parts) as soon as the communication is terminated or has been
ascertained to be impossible;
(k) devices whereby to prevent the communication established between
subscribers being overheard or disturbed by a third party.
two
Such being generally the nature of the installation the operations necessary for
establishing a given communication are performed in the following manner:-The
"calling" subscriber A composes on his signal-composing and transmitting device
the distinguishing number of the subscriber B to whom he wishes to speak, whereupon
he sends in corresponding order of succession the signals thus prepared, producing the
following effects: The connector connects A's line to the "steering" and propelling
mechanism, the steerer actuated steers the signals on the catcher suitable for effecting
the required communication, the propelling relay brings the catcher to the required
position and then puts in connection the proper group of contacts.
The subscriber A listens for the "engaged" signal and, whether he hears it or not,
sends the last signal whereby, if the line happens to be engaged, all the parts. are
returned to normal position. If the line is free, the coupler is placed on the contact
corresponding to the line of the "calling" subscriber A and thus completes the
circuit, at the same time that the "called" subscriber B is "rung up" and continues
to be so, so long as no answer is given. Subscriber B now coming, the
communication is established. Should the subscriber B delay too long to reply, or
when the conversation is terminated, subscriber A "rings off" and the whole of the
parts are returned to normal position.
The "steering" and propelling mechanism is not occupied during the preparation
or composition of the signals nor during the conversation, but only during the short
time occupied in sending the signals and there is therefore no inconvenience in
providing only one such mechanism for a whole group of lines.
On the other hand the connecting devices (catcher and coupler) which have been
employed for establishing communication remain stationary so long as the
communication is in progress. There are therefore several of them for each group
of lines.
In order that the subscriber may be able to control, according to requirements, the
movements of these various parts it is necessary that he should have at command
distinctive signals discriminated according to their destination. The most simple
and most certain method of obtaining distinctive signals is to use currents
Moreover in the
sometimes of positive and sometimes of negative direction.
case of metallic circuits these currents of different direction may be sent through
the one or the other wire or through both at once associated in series or in parallel
circuits. This may be done without difficulty if suitable batteries be located with
the subscriber; or if (these batteries being located at the exchange and being
permanently connected to earth and to the line wires) the operations of the subscriber
have for effect to cut out of, or throw into, circuit high resistances whereby according
as they are thrown in, or cut out, to practically annul, or to give passage with
predetermined strength to, such or such currents actuating such or such mechanism.
The one or other method may be employed with greater advantage according as a
greater or less number of varieties of distinctive signals are required. In either
case however these means would not enable a sufficient number of independently
distinctive signals to be obtained, and for this reason another method is to reserve
one of the kinds of signals thus produced for actuating one or more distributing
devices whose function is to put successively to line, at the proper moment, the various
mechanisms required for the manipulation proper, and then these mechanisms are
actuated by the other signals available, which have no action upon the distributors
themselves. In this way, if need be, two kinds of signals would suffice. The more
numerous varieties of signals which are obtainable on metallic circuits either with
batteries located at the subscriber's station or at the exchange, afford a more
convenient and more ready means of working. In any case, in order that the signal-
composing and transmitting device shall fulfil its function, that is to say enable

page_text: signals, of each kind to be sent in required number and order of succession, it is only
necessary that this apparatus should afford a means of arranging, in required number
and succession, contact pieces connected, as the case may be, to one or other pole of
the batteries, to earth and to the various resistances and of moving over those contacts
a metallic brush in contact with other metallic contact pieces connected to the line
at suitable points. This essential feature will be easily understood, whilst the
arrangement and details of construction may be varied at will according to
the mechanical parts employed for effecting the arbitrary grouping of the contacts or
the motion of the brush. There is also to be provided in the signal-composing and
transmitting device, and index or visual signal which is kept "to line" so long as the
signal-composing and transmitting device is itself at rest, and designed to keep
the subscriber constantly notified whether the manipulating device appropriated to the
joint use of the group to which he belongs is available for use or is already engaged.
To this end the index is so arranged as to assume one or other position according as
the "steering" and propelling devices assigned to its group are at rest or not, the
details of this arrangement depending on the conditions of the installation as to the
location of the batteries, the use of a single or double wire for the line, etc.
The connector is the device whereby the subscriber who desires to enter into
communication places his line temporarily in connection with the "steering" and
propelling mechanism appertaining to his group. As this mechanism, after having
fulfilled its function, must be at once rendered available for common use by others of
the group, and must therefore be disconnected from the line for which it had just been
used, it must have a double motion the first for effecting the connection at the will
of the subscriber and the other for effecting disconnection as soon as the manipulation
is completed, the disconnection being preferably effected without the intervention of
the subscriber who might be preoccupied with the communication he is about to
make. The function and construction of the connector will therefore be analogous
to those already employed in the working of "self-raising annunciator-drops," the
only difference being that its function is to establish or break contacts instead of
disclosing or masking a numeral. One of the circuits found in such annunciators will
therefore serve for the making of connection by the subscriber and is under command
of the line, whilst the other is completely local and serves to automatically break the
connection at the proper moment.
The mechanisin provided for use in common by the lines constituting a group
comprises as its essential elements, as above explained, a steerer and a double
propelling relay. The steerer first steers the signals on that one of the local circuits
of which the catcher will afterwards be actuated by the relay and therefore the
steerer and relay must operate in succession. As moreover the number of local
circuits and of catchers amongst which the steerer must pick out the proper one is
the greater, the greater the number of subscribers on the whole system, and as the
number or complexity of the steerer must increase with the complication of their
duty, it would not be possible to obtain a sufficient number of signals distinguished
from each other by their nature or variety to enable the successive working of the
parts to be effected by the successive use of distinctive signals. Such a method
might perhaps suffice, if the number of subscribers were small and the steerer simple;
but if, as would generally be the case, the number of subscribers is large, recourse
must be had to the second mode of controlling successive operations, namely by the
use of distributors. The 66
steering" and propelling mechanism will therefore
generally comprise a distributor whose function is to put successively to line
(according to requirements and to the signals sent by the signal-composing and
transmitting device) the various parts of the steerer and the double relay. This
distributor consists, like those employed in various telegraph systems, of two rows or
series each comprising a certain number of stationary insulated contact pieces, each
suitably connected with other parts of the mechanism, and the required connections
being established successively or simultaneously between corresponding contacts o
the two series by one or more metallic rubbers or brushes shifted along the rows by
the action of an electro-magnet energized exclusively by means of signals of a certain

page_text: predetermined kind emitted by the signal-composing and transmitting device and
insensible to all others. These contact pieces may be conveniently arranged in a
circular path either on a disc or on a cylinder so that the brushes meet them in
succession when rotated. When the distributor has completed the various connections
required it is at once returned to its normal position so as to be ready for use again,
this being brought about either by a return motion by which it is brought back to its
starting point, or without return motion, if in the case of a circular path the normal
position is situated immediately after the last working contact.
The function of the steerer is to steer the signals on the catcher appropriate for the
establishment of the communication wanted, exclusive of any other. These catchers
being preferably actuated by means of local circuits and currents, this result may be
obtained by two methods equivalent in their results although inverse as regards the
mode of operation; i.e., no catcher being to line at starting, the successive action of
the various parts of the steerer to have for effect to establish the connection of one
and one only of these catchers; or conversely all the catchers to be initially connected
to line and the steerer to have for effect to disconnect all except one of them. In the
first case the local circuit corresponding to each catcher is broken at a certain number
of points and each part of the steerer is a device capable of restoring for a
predetermined number of catchers the continuity of the circuit at one single point so
that only that one catcher will be put to line of which the circuit has been completed
at all those points by the combination of parts of steerer successively actuated or left
at rest. In the second case each part of the steerer is capable of breaking at one
point the circuit of various predetermined catchers, so that there will remain finally to
line only the one catcher of which the circuit has remained unbroken according
to the combination of parts successively operated or left at rest in the
steerer.
For the electrical forms above described for carrying these two methods into effect,
mechanical forms may be substituted; in which case the circuit of each catcher will
have only one break and the parts of steerer successively brought into operation have
each for effect to actuate mechanical stops preventing the closing of a certain number
of circuits, so that there ultimately remains to line only the one catcher for which
according to the combination of parts of steerer successively operated or left at rest,
no obstacle has prevented the closing of the circuit. To obtain this result it is
evident that it is only necessary to provide electro-magnets each in turn put to line
by the distributor so as to comply with the corresponding signals emitted by the
signal-composing and transmitting device, and of which the armature or a part
operated by the armature remains after the completion of the signal in the position
to which it has been brought by the signal, whether this armature itself fulfils the
electrical or mechanical functions above described or whether it acts in the manner of
a relay, so that the working will be entirely performed by local currents which are
stronger and capable of greater and more sustained efforts than could safely be
produced by line currents.
Lastly in addition to these steerers, which may be designated as direct acting,
recourse may be had for putting to line the catcher required in each case to the
exclusion of all others, to mechanisins similar to those employed in certain
telegraphic apparatus and of which the function is to effect, by the combination
of a certain number of successive signals, the impression of a given letter or
figure. Similarly, for present purposes, the combination of successive signals would
be utilized to effect the connection to line of a given catcher, the mechanism
of the combiner actuating in this case a connecting instead of a printing device.
But in this case as in the telegraphic apparatus referred to, it would be necessary
to take into account not only the nature of each signal but also of the moment
of its emission, and this obligation would deprive the subscriber of some freedom of
working. It is however obvious that the combination of several of the above
5 .described methods might be adopted.
Once the catcher to be employed has. been picked out by the steerer, the distributor
puts to line the propelling relay which is merely a double relay capable of sending

page_text: local currents through one or other of two circuits controlling the movement of the
catcher according as the relay is itself actuated by a line current of one or other
direction.
In front of
"
The catch boards present in horizontal files and vertical rows, contact pieces
corresponding to the subscribers' lines, each group of subscribers being represented by
a separate catch board. Assuming for instance that the contact pieces corresponding
to the various subscribers' lines of the group be arranged in a vertical row, the catch
board would be provided with as many similar vertical rows as there are groups of
subscribers; and the corresponding contact pieces of a same horizontal file would be
connected to one another so as to be in relation with the same subscriber's line. To
each subscriber's line correspond three distinct series of contact pieces, namely two
series of contacts connected respectively with the two wires or members forming the
circuit (these being reduced to one in the case of single-wire lines) and a third
connected to a local wire specially assigned to the service of this line.
each vertical row of contact pieces is placed a catcher or line taker, comprising parts
by which it can put itself in connection with the subscriber's lines and their service
lines. But if the catcher were provided with only one set of these parts, and if it
were necessary to shift it by a step-by-step motion so as to reach the "wanted
subscriber's line in a vertical row, this could possibly necessitate an excessive number
of electrical impulses to produce the required number of steps, or too small a number
of contact pieces in each vertical row which would involve an excessive number of
catch boards and catchers and therefore lead to greater complication and expense.
Two means of obviating this objection may be adopted. The first consists in
employing but one set of contact pieces as above mentioned but in providing two
mechanisms for imparting progressive movement thereto, the one mechanism
operating in such manner as to impart a rapid motion by large steps for the greater
part of the travel, the other then imparting slow motion so as to complete the travel
by separate small steps. Many known mechanical combinations are available for
obtaining this result, and for putting the two mechanisms successively into action, it
is only necessary that they should be put in connection the one after the other
with the propelling relay whether the one be operated through one of the two
circuits and the other through the other, or whether the one of the circuits of
the relay operates a sort of distributor by which the two mechanisms are in turn
put in connection with the other circuit of the relay.
The other method consists in mounting on the catcher in the direction of the
height of the catch board several groups or sets of contact pieces so that in order to
bring a contact piece on to any given line it is never necessary to traverse more than
a small fraction of the total height of the row. As however one contact piece comes
upon the required line, others come at the same time upon other lines, and therefore
the working of the apparatus is as follows:-One of the circuits of the double relay
actuates a small distributor whereby the other circuit of the relay is connected at
first to the step-by-step propelment mechanism by means of which the small interval
between the nearest contact piece and the line to be reached is traversed; and
afterwards various steering devices similar to those which have been already
described and by means of which all the contact pieces of the catcher are
rendered or left inactive except the one which has been brought opposite the
required line and which alone enters into connection therewith.
In both ways
the line of the subscriber wanted is put into electrical connection with the catcher
but this catcher is itself still insulated.
Each group or set of contact pieces of a catcher comprises three pieces, namely,
two for connection with the two wires constituting each subscriber's line, and a third
for connection with a service wire appertaining to each line. It is by means of
this third contact that the operations necessary for establishing communication will
now be conducted.
With this object the service wire to each line terminates, in front of the connector
of this line, in a contact piece normally insulated like the line itself but which is put
to earth immediately the connector falls. On the other hand matters are so arranged

page_text: hat by the operation of the connecting devices themselves there becomes connected
o the service wire of any line "engaged" one pole of a battery whose other pole is
o earth. Lastly, upon the catcher the contact pieces corresponding to the service
vires are connected to earth through an electro-magnet. If now by the operation of
he catcher the contact piece is brought upon an "engaged" line the armature of
the electro-magnet becomes attracted, and closing a local circuit, sends by induction
through the line of the subscriber "calling" a noise or audible signal denoting that
the subscriber wanted is engaged. If on the contrary the line is free, its service
wire is insulated and the electro-magnet is not energized, and the subscriber "calling"
who listens for the signal knows by its absence that the line of the subscriber
wanted is not engaged. He then sends a final signal by means of his signal-
composing and transmitting device whereby the distributor is caused to advance one
step.
The coupling boards are arranged in the same way. The couplers which stand in
front of the coupling boards are each connected to one of the catchers appertaining
to the group of lines represented upon the coupling board, so that when a
subscriber belonging to this group sets about "calling" by the means above described
and puts in motion the catcher suitable for attaining to any given line, this very
catcher is always connected with one of the couplers on the coupling board on which
This coupler
is represented the line of the "calling" subscriber in question.
comprises the following parts:
(1) A gripping device which retains it normally in a position of rest and which
only releases it when the service contact of the corresponding catcher is in connection
with a disengaged line;
(2) A series of contact pieces by which the coupler may be put in connection
with the various lines of the coupling board as it comes opposite to them;
(3) A steering device analogous to those previously described which renders active,
each in turn and successively, the various contact pieces which during the motion of
the coupler are all at one time opposite to different lines.
As above explained, by the fall of his connector at the moment of calling, the
calling" subscriber puts the service wire of his own line to earth; if then the
service contacts of the coupler are connected to one pole of a battery of which
the other pole is to earth, the armature of an electro-magnet include in the circuit
will be attracted at the moment when the coupler reaches the line of the subscriber
"calling"; and this movement being utilized to restore the engagement of the
gripping device with the coupler, the latter will be held stationary in the desired
position, and thenceforth a complete connection will be established, made up of
three sections as follows:-From the subscriber "calling" to the coupler, from the
coupler to the catcher, from the catcher to the subscriber called." Similarly the
movements of this electro-magnet, or of the one which is controlled by the service
wire of the catcher, combined with the last step made by the distributor when the
calling" subscriber (having ascertained that the line wanted is free or not) sends
the last signal as above mentioned, enable, as the case may be, all the parts to be
returned to normal position by means of local currents if the line is engaged, or if
< ringing current which
it is free, permit of sending through this line a
continues until the subscriber wanted comes to his instrument whereupon the
connection being complete from end to end of the circuit the required conditions for
establishing conversation are fulfilled.
"
33
When the conversation has terminated, an electro-magnet connected to the line in
the same way as clearing-out drops now used, receives the clearing-out signal and
transmits it for effecting the return to normal position, to the same local mechanisms
which, in the case of the line being engaged, are influenced through the service wire
of the catcher or the coupler as above explained.
It is evident that it is absolutely impossible for a subscriber "calling" to overhear
or disturb a conversation in course of being carried on between the subscriber
"wanted" and a third party, since the connection of his own line with that of the
subscriber "wanted" cannot be prepared unless the latter is free, and can only be

page_text: finally completed when the subscriber "called " comes to his instrument, as all
preliminary operations affect only local circuits without connection with the lines
themselves.
Assuming the lines and apparatus to be in good working order, the subscriber
"calling" may be momentarily prevented from getting the connection wanted,
owing to three causes :-
(1) The employment at the same instant by another subscriber of the same
group, of the steering and propelling mechanism of which he ought to make use.
It has already been explained that the appropriation, which is invariably for a very
short period, of this mechanism is immediately notified to all the subscribers of the
group by the index or visual signal of their signal-composing and transmitting
apparatus.
(2) The fact that at the same moment communication is already established
between the subscriber "wanted" and a third party. It has been explained how
the subscriber "calling" is notified of the fact by an audible " engaged " signal.
(3) The employment at the same moment, by another subscriber of the same
group, for communication with any other subscriber, of the catcher whereof he
himself should have made use to effect the communication wanted, the duration of
this impediment being co-terminous with the communication from which it arises.
In such a case it is indispensable that the "calling" subscriber should be notified
as in the two other cases; but there is no object, and there would in a certain sense
be some inconvenience, in providing for this particular impediment a special signal
different from that which is given in the preceding case, and it is therefore preferable
to have only one and the same audible signal to denote that communication cannot
be established, whatever may be the nature of the obstruction.
In order that the subscriber who may desire to make use of a catcher shall be
notified by the same "engaged" signal that this catcher has already been appro-
priated by another subscriber of the same group, it is only necessary that in the
position of the catcher which corresponds to "communication established" the
distributor of this catcher shall establish a local connection between parts by which
the audible signal is produced and the part by which the steering mechanisms
enter into connection with this catcher. Normally this connection is automatically
broken as soon as the catcher, having received all necessary impulses, is brought
to the position of "communication established" and therefore no noise is sent
through the line. But if another subscriber attempting to use the same catcher
has sent the necessary working signals, not only have these signals no result and
are powerless to disturb the established communication, since the distributor of the
catcher has quitted the position in which impulses can be received, but when this
subscriber having completed the sending of the working signals, listens before
sending the final signal as above described, the connection established by the dis-
tributor and that afforded with the distributor by the steering mechanism, send
through the line the audible signal signifying "communication wanted impossible
for the moment." The various requirements for practical working would thus
appear to be fulfilled.
2011
1
200-y
I MAX MARGOwski, Chairman and Managing Director of The Automatic 50
Telephone Company, Limited, of 13 and 14, Abchurch Lane, in the City of London,
do hereby declare the nature of this invention (a communication to me by Gustave

page_text: Seligmann-Lui, of 78, Rue Mozart, Paris, France, Gentleman) and in what manner
he same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention relates to a system for enabling telephonic subscribers to auto-
matically establish communication with each other without assistance.
In the accompanying drawings, Figure 1 (Sheet 1) is a diagram to illustrate in
elementary form the operation of the system of grouping the " junction apparatus
at the central station, and showing two of the subscribers' lines as connected for
conversation, none of the mechanism by which this connection is effected being
shown.
"
Figure 1 (Sheets 1, 1, 1) is a diagram illustrating certain of the successive
changes of electrical connection involved in the process of establishing con-
versational connection. Figure 2 (Sheets 2 and 3 combined) is a diagram
llustrating the connections and operation of the mechanisms at the central station,
by which cominunication is established between two subscribers. Figure 3 (Sheet 4)
and Figures 4 and 5 (Sheet 5) illustrate the subscriber's "signal-composing
Apparatus; Figure 6 (Sheet 6) is a diagram of the connections of the said apparatus ;
Figures 7, 7, and 78, (Sheet 7) are respectively an elevation, a vertical section, and
a top plan of an "electro-magnétic commutator"; Figure 8 (Sheet 7) is a plan view
of the "main or group selector," certain of the electro-magnets being omitted;
Figure 8, (Sheet 7) is an elevation of this "selector," certain only of the electro-
magnets being shewn; Figures 9, 10, 11 (Sheet 8) shew various electro-propelment
mechanisms; Figure 12 (Sheet 8) shews certain contact springs; Figure 13 (Sheet 8)
shews a front elevation of the "catcher-on board"; and Figure 13 is a cross-section
of the same; Figure 14 (Sheet 9) shews in (part sectional) elevation the traversing:
screw mechanism of a "catcher-on"; Figure 14 (Sheet 9) is a sectional plan of the
same; Figure 14B (Sheet 10) shews, on a larger scale, the two positions of the
traversing-screw escapement; Figure 15 (Sheet 11) is a plan view of the mechanism
of one of the sets of contact fingers"; Figure 154 (Sheet 11) shews the lower one
of a pair of stop plates (the corresponding upper plate being shewn in Figure,15)
for holding the "contact-fingers" retracted. Figure 15" (Sheet 11) shews in side
elevation, on a larger scale, one of the "contact-fingers" in the position of
electrical contact with the corresponding wire of the "catcher-on board"; Figure 16
(Sheet 11) is a plan of the mechanism which controls the "selector of contact
fingers"; and Figure 16 is an elevation thereof; Figure 17 (Sheet 12) is a plan
view of the releasing and return-to-rest nechanisms of the traversing-screw for the
"linker"; Figure 18 (Sheet 12) is a plan of the mechanism of one of the sets of
contact fingers" of the "linker"; Figure 19 (Sheet 12) shews in (part secțional)
side view, the "linker" mechanism and the mechanisin for returning the. "contact
fingers" to initial position.
"
In contradistinction to other automatic systems of telephonic exchange, my system
is based on the fact that, in practice, all the subscribers do not require to speak
at one time. The subscribers are accordingly divided into groups, the lines of the
subscribers of any one group converging to a central station (which may be
established for the accommodation of one or of any number of groups) where
selecting and manipulating"
there is provided for each group a single set of "
mechanisin for use in common by the subscribers of that group whereby to enable
each subscriber of any group to govern all the mechanical manipulations necessary
for establishing communication with any other subscriber of the same or any other
group; but such mechanism forms no part of the chain of organisms whereby the
two lines are coupled together for conversation; and therefore, as soon, as the
manipulations of said mechanism for such coupling are completed, the function of
the mechanisin ceases, and it becomes available for use by any other subscriber of the
same group, whilst the communication established between the two subscribers
remains undisturbed. To this end there is interposed between each subscriber's
line and the "selecting and manipulating" mechanism common to the whole group,
1

page_text: a connector
99
of which the function is to establish, between the line to which it
appertains, and the mechanism common to the group, a temporary electrical con-
nection which is automatically broken when the manipulations are completed.
The "selecting and manipulating" mechanism of each group controls",
" junction
appliances serving to establish communication proper between the lines of corre-
sponding subscribers; the number of "junction" appliances controlled by each
selecting and manipulating" mechanism, and their arrangement, being such that a
subscriber may reach any other subscriber of the same or any other group at will,
and that several subscribers of the same group may, simultaneously and independently,
talk with their respective correspondents.
Such being a general outline of the system, I will first define certain terms of
nomenclature of which frequent use will be made. I designate " electro-magnetic
commutator" any arrangement in which a single electro-magnet controls, by the
movements of its armature, the simultaneous making or breaking of several electrical
connections. I designate particularly as "distributor" the known type of commutator
in which the contact pieces to be connected are in pairs on the same radii of two
concentric circles, connection being established by a brush or equivalent device
mounted on a central spindle and rotated step-by-step through ratchet-and-pawl gear.
If several connections are to be made or broken at once, the circles would be divided
into several sectors in which the pairs of contacts to be simultaneously influenced
would occupy corresponding positions, the spindle carrying as many brushes insulated
from each other as there are sectors.
"
By distinct signals or currents are meant signals or current emissions presenting
relatively to each other such differences, that each influences, differently, the same
group of receptive apparatus. And by "distinct combinations" are meant combina-
tions of signals differing from each other in the nature, order, or number of the
constituent signals.
Lastly by the name of" selectors "I designate any combination of electrical and
mechanical devices whereby, in response to a predetermined combination of signals,
the continuity of a predetermined electric circuit is established; each "selector
controlling a certain number of electric circuits whereof the continuity of each is
completed, to the exclusion of all the other circuits, only in response to the emission
of the corresponding distinct combination of signals.
وو
Such "selectors
may be variously constructed and several kinds are herein
described, all based on the same principle, viz. :—
The establishment of the continuity of each of the electrical circuits to be con-
trolled by a "selector," depends on the suppression of a certain number of electrical
or mechanical "obstacles," each of the said "obstacles" being under the control of a
different part or "member" of the "selector"; each "member" of the "selector"
operating differently in response to the various "distinct signals" by which it may be
influenced and, as the case may be, thereby suppressing the "obstacle" in certain
circuits and leaving it in others; the several "members" of the "selector" being
presented each in turn to the action of the signals respectively addressed to them in
the operative combination. Thus to establish the continuity of a given circuit it is
necessary, by the emission of a predetermined combination of signals, to act succes-
sively on the various "members" of the "selector" so that each suppresses the
"obstacle" placed under its control in respect of the circuit in question; and
reciprocally, if such a combination of signals be sent, only the corresponding circuit
will be established in its continuity, to the exclusion of all the others.
The greater the number of "distinct signals" available for use, the more numerous
the resources for controlling the various movements of the "members" of the
"selector." The successive presentation of these "members
23 to the action of the
signals respectively intended for them, is by connecting these "members" to the line
whence the signals emanate, through the medium of the successive contact pieces
of a "distributor," in such manner that a "member" will be substituted for the
preceding one in the connection with the line, when the brush of the "distributor "
passes from one position to the next.

page_text: a
By junction device" is meant a pair of conjoined apparatus respectively designated
"catcher-on" and a "linker." By "catcher-on" is meant an apparatus used for
catching on to, or making connection with, the line of a subscriber "wanted." By
"linker" is meant an apparatus for completing the direct telephonic connection of
the line of the subscriber "wanted" with the line of the subscriber "calling," to the
exclusion of the mechanism used in effecting the connection.
This explanation given, I will pass on to the general description of the system.
The apparatus which it comprises are as follows:-
-
At each subscriber's station a "signal-composing device" for sending the signals
necessary for the establishment of any particular communication ;
At the central station to which converge the lines of the subscribers comprised in
a group, there is provided:
(a) At the extremity of each line a "connector" whereby this line may be
temporarily put in connection with the mechanisms for use in common by the
subscribers of that group;
*
..!
(b) Selecting and manipulating" mechanism (for use in common by all the
subscribers of a group, to enable them to actuate the " junction" devices by which
to effect the material connection of the lines) comprising the following elements:-
A main or group "selector" whereby the subscriber " calling" appropriates the
junction" device which is suited for effecting the intended communication;
66
A "manipulator" whereby the manipulating signals or currents are transmitted,
in the form of local currents, to the "junction" device so chosen ;
A "main distributor" whereby the various "members of the "selector" and
the "manipulator" are successively connected to the line in order to receive the
signals which are intended for them respectively;
"
"
"
',
Lastly, "return-to-rest devices whereby the "connector" of a line which has
made a $1 call," the "main 'distributor," and the "main selector are automatically
returned to their initial position, as soon as all the signals or operative currents
necessary for the required communication have been sent;
and linker-board"
(c) Two boards respectively designated "catcher-on board
upon which appear (in the form of wires or other suitable contact pieces), the two
wires of each of the lines of the group, and in addition thereto a local service-wire
is assigned to each line on each board, the "
on the two boards
service-wires
appertaining to the same line being quite distinct. In each board the line and the
* service contact wires or pieces appertaining to the same subscriber's line are
arranged side by side in a horizontal row and in regular order; whilst the contact
wire or pieces appertaining to different subscribers of the group are arranged above
one another in regular order, there heing, for instance, five superposed horizontal
rows at regular intervals and then a vacant space, then five more rows, and so on.
The "catcher-on board" is used when a line comprised in the group is called"";
the "linker-board" is used when a line comprised in the group is "calling";
(d) "Junction devices for the use of each group of subscribers, there being
duplicate, triplicate or more sets of such junction devices for each of the circuits
controlled by the "main selector" appertaining to this group, the purpose of such
duplication being hereafter explained in the detailed description of such "twin
apparatus. Each "junction" device is composed of two parts in electrical connection
with each other by suitable conductors, one of said parts termed the "catcher-on"
serving to make contact with the line of the required correspondent, the other part
called the "linker " serving for making contact with the line of the subscriber
"devices of the same
calling." All the "linkers" appertaining to the "junction
group are arranged side by side in front of the "linker-board" of this group, whereas
the "catchers-on "appertaining to this same group are distributed one in front of
each of the "catcher-on boards" corresponding to the various groups into which the
subscribers are divided. Consequently when a subscriber desires to call any other
subscriber, he will always find amongst the "junction" devices controlled by the
"main selector" and the "manipulator" of his group, a junction" device whereof
the "catcher-on" is in front of the "catcher-on board on which appears the line
66
"
$6
وو

page_text: ***
front of the "linker-board" on which appears the line of the subscriber "calling."
The desired communication will thus be established :-
(1st) When the "catcher-on" has made contact with the line of the subscriber
"wanted"; and
(2nd) When the "linker" has made contact with the line of the subscriber
$6 calling."
This conversation" position is illustrated in diagram Figure No. 1 in respect of
the line LL2 of a "calling" subscriber in Group I and the line L* L*2 of the
"called" subscriber in Group V.
To accelerate the finding of the subscriber "wanted" by the "catcher-on," the
latter is provided with a certain number of sets of contact fingers," of which that
set only is made use of which is most adjacent to the line "wanted," on the
"catcher-on board"; the other sets of "contact, fingers" being rendered (or left)
inactive by means of a special "selector" termed "contact-fingers-selector.". To
actuate in succession the various mechanisms which constitute the members of this
""selector" and those which bring into operative position the set of "contact fingers"
to be used, a
"distributor" is employed, termed "catcher-on distributor."
(e) "Return-to-rest" devices which enable the "catcher-on" and "linker," which
have been used for establishing a given communication, to be returned to their
initial position as soon as this communication has terminated.
It would not be possible to enter into a detailed description of the circuits and
mechanisms, without first choosing a particular type of telephonic line-wire system
and apparatus. According as the lines of the system have an earth return or
complete metallic circuit, and according as the location at each subscriber's station
of batteries capable of furnishing the operative currents or signals is, or is not,
permissible, the number of distinct signals available for use is different. Conse-
quently, upon the number of "distinct signals" available depends the arrangement
of the "signal-composing" device which should be capable of producing all the kinds
of "distinct signals" admissible by the type of line-wire system and arrangement of
batteries adopted; likewise the arrangement of the "selectors" by which the
diversity of these "distinct signals" is utilized. For precision of description a
specific example is necessary, but the modifications involved, if another example be
chosen, do not materially affect the system. I will therefore take as example a
two-wire system and suppose that the batteries furnishing the operative currents
or signals, and even the battery which serves for conversation, are (for each
group of subscribers,) 'concentrated at the central station to which the lines of the
group converge.
16
In a central battery system the manipulation by well known means, of high
resistances at the station of the subscriber calling," enables three sorts of "distinct
signals to be obtained; viz. :-current through one of the wires earthed without
resistance at the subscriber's station :-current through the other wire earthed without
resistance at the subscriber's station :-current through both wires connected in series
without any resistance being interposed between them and without being earthed at
the subscriber's station. It is only necessary that the battery by which the operative
currents or signals are to be furnished, be put to earth by its middle, at the central
station. I will also suppose for this preliminary explanation that the number of
subscribers on the telephonic system is not too high, so that a "main selector"
having two "members" will suffice, and I will afterwards shew how a greater number
of subscribers could be treated.
It is clear by these hypotheses that the "signal-composing" device could be
reduced to three keys which by suitable manipulation would enable any combination
formed of the three "distinct signals" above mentioned to be sent, each of these
signals being used as often as required and in any required place in the combination.
But, in order to prevent the formation and transmission of erroneous combinations
of signals due to human fallibility, recourse is preferably had to a "signal-composing"
device such as that shown in Figures 3, 4 and 5, and of which the communications

page_text: are shewn in Figure 6. It consists of front and back frames between which may be
traversed, in guides 162, 163, a double brush 164, 165. Upon the back are mounted
six vertically sliding racks numbered 1, 2, 3, 4, 5, 6, each capable of being raised by
a handle and of being retained in position of adjustment by locking pins carried by
a horizontal slide bar 150. Each rack carries a tablet bearing, on the upper half,
contact pieces, and on the lower half, (of which are inscribed) a series of numbers,
the height to which each rack is raised determining the nature and number of the
contact. pieces brought into the path x-y of the contact brush 164. The rack No. 4
alone differs from the others, in that it only carries two spring fingers 152 and 153
which, according to the height of adjustment, make contact respectively with the
two fixed contact pieces 154, 155, or with the two contact pieces 155, 156; it also
carries a sort of shutter 157 presenting two apertures arranged diagonally. The
front (of which Figure 4 shews the image as reflected in a mirror) comprises a
horizontal conductive strip 158 fixed at the level of the path x-y of the brush 165,
this strip 158 being interrupted by a gap opposite to the contact pieces 187, 188,
189, 190, and 191, 192, 193, 194, carried by the racks Nos. 5 and 6.
This front has
a horizontal slot 159 for the passage of the handle 160 of the double contact brush;
a second slot 161 for the handle of the sliding bar 150; and lastly, five windows
opposite the columns of figures of the racks Nos. 1, 2, 3, 5, and 6. The,, tablet of
rack No. 3 bears two contiguous columns of numerals, but, according as rack No. 4 is
adjusted, the one or other aperture of shutter 157 coincides with the one or other
half of the window in front of these two columns, so that the column opposite the
other half is masked. The double brush (Figure 5) whose movement is guided by
rails 162, 163, is drawn towards the right by a weight, and normally presses the
spring 166 (Figure 3) against the stud 167; when at the other end of its course it
presses similarly the spring 168 against the spring 169 and becomes engaged by a
detent 170 which retains it in that position. On the sliding kar 150 is a slide
block 171 to which the handle 162 is attached, and when the latter is operated, the
block alone moves at first, and by means of a stud, causes the spring contact 172 to
bear against contact 173 and the block afterwards meeting a stud 174, the sliding
bar 150 is moved also, whereby the locking pins 151 are disengaged from the racks
and the detent 170 from the contact brush.
By referring now to diagram Figure 6 (Sheet 6) it will be seen that the two line
wires L, 1, are connected, the one L' to the contact plate 155 and the other L² to
each of the two contact plates 154, 156; that conductive strips 181, 182, 183, are
connected to the spring finger 153, and that the comb-like pieces 184, 185, 186,
having limbs of unequal length are connected to the other spring finger 152; so that,
according as the rack No. 4 is drawn up more or less, the connection of the line
wires L, L, with the contact strips 181, 182, 183 and 184, 185, 186 are reversed.
On the other hand the small contact pieces 187, 188, 189, and 190 of the
rack No. 5 and the similar contacts 191, 192, 193, 194 of rack No. 6, and the
long contact piece 195 of the same rack, are connected without possibility of
reversal as follows:-188, 192, 195 to the line wire L'; 189, 193 to the line wire L*;
and 187, 190, 191, 194 to earth. The two parts of the strip 158 (shewn above the
diagram in Figure 6) are connected to earth. Normally the brush presses spring
contact 166 against stud 167 thereby earthing wire L' through the subscriber's
bell mechanism 199, the high resistance 196, and an indicator 197; as soon as
the brush is moved, this contact is broken and the wire L' is isolated; on reaching
the end of its course, when the brush carrier presses the spring 168 against 169
and when the subscriber's receiver is taken off the hook, the line wire L2 is put
to earth through the subscriber's conversation apparatus 198 the high resistance
196 and the indicator 197; lastly, of the two springs 172, 173, the latter is
permanently to earth and the former is connected to the contact-pieces 181,"
182, 183 in whose reversals of connection it participates. The vertical distances
separating from each other the contact pieces 187, 188, 189 and 190 of rack No. 5,
and the contacts 191, 192, 193, 194 of rack No. 6, are less than the width of
the brush, and the position of the contacts on the tablet is such that two of them

page_text: will always be presented together in the path x-y of the brush, which thus
establishes electrical communication between them on its passage.
196
The operation of the "signal-composing" device is as follows:-Normally, the line
wire L2 is isolated and the line wire L¹ is to earth through a resistance of from 1000
to 2000 ohms. As soon as the subscriber, after having adjusted the racks, begins to
move the brush 164, 165, the wire L¹ is also isolated. Then the following effects are
produced in succession:-
(1) A signal of invariable kind is sent, the wire L' being put to earth when the
brush passes over the contacts 195 and 158; the line being again isolated whilst
the brush passes the gap between the contact 195 and one or other of the contacts
191, 192, 193, 194 on the same rack;
(2) A signal is sent which is variable in kind according to the adjustment of the
rack No. 6, the effect, (according as the brush passes over the two contacts 191, 192,
or over the two contacts 192, 193, or over the two contacts 193, 194) being
respectively to put wire L' to earth without resistance, or to connect wires L, 12,
in series without resistance and without earth, or to put line L2 to earth without
resistance, the effect being followed in either case by isolation ;
(3) A signal is sent which is variable according to the adjustment of rack No. 5,
(the nature of the possible signals being the same as described in the previous
paragraph,) followed by isolation.
According to the adjustment of rack No. 4, the strips 181, 182, 183, are connected
to the wire L, and the comb-shaped contacts 184, 185, 186 to the wire I², or inversely;
the signals being, as the case may be, as follows:-
(4) The wire L' is earthed once, and the wire L2 is earthed a variable number
of times according to the adjustment of rack No. 3; wire Iis earthed a second
time, and the wire L2 is earthed a variable number of times according to the
adjustment of rack No. 2; the wire Lis earthed a third time and the wire L² is
earthed a variable number of times according to the adjustment of rack No. 1, the
brush being finally engaged by its detent. Or inversely as regards the respective
effects produced on the lines I., L².
I will suppose that wire L¹ was connected with the strips 181, 182, 183, and
wire 12 with the comb-shaped contacts 184, 185, 186.
When the brush reaches the end of its course, all the signals necessary for
actuating the "connector," the "main selector" and the "manipulator" will have
been sent, and the "calling" subscriber has only to listen at his receiver to ascertain,
by the absence or presence of a buzzing or musical sound, whether the line of the
subscriber "wanted" is "disengaged" or not. Whatever may be the result of this
test, the "calling" subscriber then moves to the right the handle 162 of slide 150,
thereby pressing the two springs 172, 173 together and sending a "final signal
similar to those sent by the passage of the brush over plates 181, 182, 183, (i.e. by
hypothesis, putting line wire L₁ to earth) the further movement of the handle
releasing the brush and the racks which return to their initial positions.
"
To prevent too rapid or irregular motion of the brush if moved directly by the
hand, and consequent malformation of the signals, the brush might be actuated by
clockwork wound up by the return of the brush by hand (after sending the signals,)
to its initial position where it would be retained by a detent.
The subscriber's transmitter, receiver, and bell are as usual, except that the
spring 200 actuated by the hook switch 201 whereby the transmitter battery is
ordinarily thrown in or cut out, now connects or isolates the line wire L².
In order to completely understand the working of the subscriber's apparatus, it
is only necessary to add that, for each adjustment of a rack, a certain figure is
exhibited at the corresponding window; and reciprocally, to cause a given figure to
appear, it is necessary to move the rack to a certain extent. If then, the distinctive
number, by which a subscriber is "called," corresponds with the group of figures
exhibited on moving the racks to the positions required for producing the signals
necessary to reach that subscriber, it is only necessary, in order to call a subscriber,
to exhibit at the various windows the figures corresponding with the " "calling

page_text: 66 catchers-on,"
nections, nor does it illustrate the duplication of the "linkers" and
elsewhere herein referred to as "twin" linkers and "twin" catchers-on.
Having explained the system of grouping for the establishment of "conversation
connection," I will now explain how this connection is established; and for this
purpose I will first refer to the diagram of mechanism, Figure 2 (Sheets 2 and 3
combined). This figure shews diagrammatically the mechanisms and circuit
connections appertaining to the groups to which the "calling" subscriber and the
"called "subscriber respectively belong.
To avoid obscuring the diagram by a multiplicity of references, the contacts between
which an armature, or a contact spring, moves, have not been distinguished by
references. It is therefore necessary to note that, all the parts being indicated as in
position of repose, the resting contact is always shewn above, and the working contact
below, the corresponding armature or contact spring; except that in the case of the
electro-magnetic commutator A¹ (which is a part of the "connector,") these relative
positions are reversed in order to agree more nearly with the actual construction of
the "commutator" as shewn in Figures 7, 7^, and 7B.
A is an ordinary electro-magnet, A¹ is an electro-magnetic commutator having
four pairs of contact springs, and A2 is an electro-magnetic commutator having one
contact spring, these three apparatus constituting the "connector."
B is the coil of the "main distributor " B which comprises three sectors, each
having four pairs of contact pieces, and three brushes; the three sectors being
represented as developed in the straight and arranged one above the other so as to
shew, one above the other in the same vertical line, the three pairs of contacts which
are simultaneously touched by the three brushes. The propelment mechanism of this
distributor (shewn in plan in Figure 9) consists of a pawl 202 engaging with a ratchet
wheel 203 on the brush spindle 204 of the distributor, and connected on the one
hand with a spring 205 and on the other with the armature lever 206 of electro-
magnet B¹ so that the distributor is advanced one step by the action of spring 205
each time that its coil B¹ ceases to be excited by a current, 207 being a detent to
prevent retrograde movement.
C are relays which receive the signals from the line "calling" and by which these
signals are translated into local currents, and, as such, transmitted first to the one
and then to the other of the two groups C1, C2, (each comprising three electro-
magnets) which constitute the two "members" of the "main selector" D hereafter
,described. "Main selectors" having more than two members will be considered
later on.
E is a double relay which constitutes the "manipulator."
F is the coil of an auxiliary or "return-to-rest" distributor which is employed for
returning to initial position the "connector" of the subscriber who "called " and
the mechanisms ("selector" and "distributor ") appertaining to the group to which
that subscriber belonged and which were operated in order to establish the com-
munication desired. This distributor comprises two sectors (each having eight pairs
of contact pieces) and two brushes. Its propelment mechanisin (shewn in Figure 10,)
comprises two oppositely acting pawls 208, 209 engaging with a ratchet wheel 210
on the brush spindle 211 of the distributor and connected by a rod 212 to the arma-
ture of electro-magnet F so that the distributor will be advanced one step when, a
current excites its coil F and attracts its armature, and another step when, by the
current ceasing, the armature returns to its position of repose.
Fo is an ordinary electro-magnet. F¹ is an electro-magnetic commutator having
two contact springs. 2 is another electro-magnetic commutator having one contact
coil of the "main
spring and of which the coil is also the "return-to-rest
selector" D; the apparatus F, F, F1, F2, serving to effect the return-to-rest of the
"connector" appertaining to the "calling" line, the "main distributor " B, and the
"main selector" D.
Another similar group of mechanism, whereof only the "auxiliary distributor "F
is shewn, fulfils the same functions; the one or the other of these two groups being

page_text: brought into action according as the first signal transmitted by the " manipulator"
is a positive or a negative current, as will be hereinafter explained.
It being understood that one only of the circuits controlled by the "main selector"
is represented in the diagram, H is the polarised double receiver located at the
extremity of this circuit, whereby the signals sent by the "manipulator" are trans-
lated into local currents actuating two or more twin "catchers-on" corresponding to
this circuit. G¹ is the coil with double winding of the "catcher-on distributor" G
whereby the operative currents or signals are successively directed to the various
organisms which constitute the one or the other of the said two "catchers-on."
This "catcher-on distributor" has five sectors each comprising six pairs of contact
pieces, and five brushes, the sectors being represented as developed in the straight
and arranged the one above the other; the pairs of contact-pieces, which their
respective brushes touch simultaneously, being in a vertical line.
The propelment mechanism of this "distributor," (shewn in Figure 11) consists
of a pawl 213 engaging with a ratchet wheel 214 on the brush spindle 215 of the
distributor, and connected on the one hand with a spring 216 and on the other with
the armature lever 217 of electro-magnet G so that the distributor is advanced one
step by the action of pawl 213 each time that its coil G¹ is excited; 218 being a
detent to prevent retrograde movement. There is likewise a disc of insulating
material (not shewn) mounted on the brush spindle 215 and carrying five rounded
metallic projections. In the first four positions of the distributor this disc keeps
separated from one another the two contact springs g¹, g², (Figure 12) and in the
sixth position the metallic projections establish electric connection between the con-
tact springs g, g. To control the movements of the second or twin "catcher-on""
corresponding to the same circuit of the "main selector," there is a second "catcher-
on distributor" of which only the coil G³ and the contact pieces of the first sector
are shewo. The two "catchers-on" corresponding to the same circuit of the "main
selector" will be designated "twin catchers-on."
g and gº are two ordinary electro-magnets associated with the coils G¹ and G³.
no, n, are two contact springs which are separated by the armature of G¹ when it
reaches the end of its stroke in working position. M, M, are the electro-magnets
which actuate the two "members" of the "contact-fingers selector" which leaves
(or renders) inactive the various sets of contact fingers of the "catcher-on" except
the one set which is nearest to the line of the subscriber "wanted," on the "catcher-
on board." K is the electro-magnet which controls the mechanism whereby this set
of "contact-fingers" is brought into operative position. I will describe hereafter
as an example one of the possible constructions of these various mechanisms. N¹, N2,
are two electro-magnetic commutators with a single contact spring by means whereof
the test is made whether the line of the subscriber "wanted" is disengaged or not
and by which, according to the result of the test, the subsequent operations are
initiated. No is an ordinary electro-magnet.
O is a polarised electro-magnet in indifferent equilibrium, having. two windings in
its coil. P is an electro magnetic commutator having two contact springs and a
double winding. The combination of mechanisms H G K M M', N1 N2 O and P
constitute the instrumentalities necessary for "catching-on to the line of the
subscriber wanted."
66
Qis the electro-magnet controlling the traversing mechanism of the "linker"
which is electrically connected to the "catcher-on" which has been described, and
Qis the electro-magnet which controls the traversing mechanism of the "linker"
which is connected electrically to the "twin catcher-on"; these two "linkers" being
briefly designated "quasi-twins."
<<
R is an electro-magnetic commutator having a single contact spring. R¹ is a
small electro-magnet which controls the mechanism whereby the set of contact
fingers" of the "linker" which is nearest to the line wire of the subscriber "calling,"
on the "linker-board," is brought into operative position. I will describe later on, as
an example, one of the constructional forms of these mechanisms. The apparatus Q,
0

page_text: "
R and R comprise the parts necessary for "linking-on to, or making contact with
the line of the "calling" subscriber.
S is an electro-magnetic commutator having one contact spring and two distinct
windings in its coil. So S1, S2, are ordinary electro-magnets the two latter being of
very low resistance and low self-induction, T is the electro-magnet which actuates the
mechanism whereby the "contact fingers" of the "catcher-on" are returned to rest ;
T¹ is an ordinary electro-magnet having two windings; T2 is the electro-magnet
which actuates the mechanism whereby the whole "catcher-on" is returned to its
initial position, this magnet determining the breaking of two contacts when its
armature is attracted, the one break occurring when the armature begins to move, and
the other when it reaches the end of its stroke. T3 is a contact spring which the
"catcher-on," when in its normal position of repose, keeps raised from its contact t³.
I will describe later on an example of the construction of these mechanisms.
وو
U is an electro-magnetic commutator having two contact springs; U° is an ordinary
electro-magnet; U₁ is the electro-magnet which actuates the mechanism whereby the
contact fingers of the "linker" are returned to their initial position; U² is an
ordinary electro-magnet with two windings; U³ is the electro-magnet which
actuates the mechanism whereby the "linker is returned to its normal position;
U is a contact spring which the "linker," when in its normal position, holds
raised off its contact. The apparatus S Sº, S1, S2, T T1, T2, T³, U Uº, U¹, U², U³, U₁,
constitute the parts necessary for returning to rest, under all possible circumstances,
the "catcher-on" and the "linker."
V and Vare two current generators, the currents being either alternating in
direction or merely periodic, but always of high frequency. vv, are condensers, the
one, v separating the generator V from the rest of the circuits and the other, v¹
separating the induction coils I I¹ from the local mechanisms of the central station
V2 is a contact spring which is raised from its contact v2 by the "linker" when in
its normal position. V and v are similar pieces on the "quasi-twin-linker." 11, 12,
are two induction coils. The apparatus V V₁v vl V2 v2 11 12 constitute the parts
necessary for producing and transmitting in all necessary cases the buzzing or
sonorous signal which denotes that the communication desired cannot be had for the
moment.
'
"
W W¹ are the "service wires" appertaining to the line L1 L2 of the "calling'
subscriber on his "linker board" and "catcher-on board," the "linker board being
supposed to be on the left and the "catcher-on board" to the right. Similarly W*
and W* are the "service-wires" of the "linker board" and "catcher-on board "
appertaining to the line L* L*2 of the subscriber "wanted," the "linker board"
being to the left and the "catcher-on board" to the right.
Yo is the service contact finger" and Y¹ Y2 are the "line contact fingers" of that
one of the sets of contact fingers of the "linker" which is supposed to be the set in
use for the communication now under consideration; y° y¹ y² are similar parts of
another set not used for that communication.
Zo is the "service contact finger" and ZZ are the "line contact fingers" of that
one of the sets of contact fingers of the "catcher-on" which is supposed to be in use
for the communication under consideration; 20 being the similar parts of another
set of contact fingers of the same "catcher-on" which are not used for that
communication.
Having described the nature of the said apparatus and the nature and order
of succession of the signals sent by the subscriber "calling," I will now explain
in detail the effect of these signals and the operation of the apparatus.
In order to facilitate the comprehension of the following explanation, I have
illustrated in diagram No. 1a (Sheets 1, 1, 1º) a series of examples of the various
effects produced by the signals in a telephonic system in which, as in diagram No. 1,
the subscribers' lines are divided into six groups. The "linker boards" (outlined in
dotted lines) are distinguished as LI, L II, LIII, LIV, LV, L VI, and the
"catcher-on boards " as CI, CII, CIII, CIV, CV, CVI. Opposite to each "linker
board are the six "linkers" 11; 12; 13; 14; 15; 16; each "linker " being
"

page_text: (I). The line wire L' is put to earth without resistance. At the central station the
wire is connected (by the lower spring of the second pair II A', of the commu-
tator A¹, by the coil of electro-magnet A, by the resting contact and armature of A²,
and by the first pair of contacts of the first sector I B, of "distributor" B) to a
battery 6 which in this system is connected (as in existing central-battery systems)
permanently, and "in waiting," to the line wires of the subscribers; the voltage of
this battery being insufficient to energize the electro-magnet A so long as the
resistance of 1000 to 2000 ohms, remains interposed in the line wire L' at the
subscriber's station. But when this resistance is cut out and the wire L is put
directly to earth without resistance, (which constitutes this signal,) the electro-
magnet A attracts its armature a on to the working contact, thus closing the circuit
of the local battery b¹ through the coil B of the "main distributor" and the coil A¹
of the "electro-magnetic commutator." Two effects are thereby produced :-
(1st) The armature of B¹, being attracted, is in position to advance the "main
distributor" one step as soon as the exciting current ceases;
(2nd) The commutator A¹ is operated; the upper spring of its third pair III A¹,
comes upon its working contact, whereby the circuit of the battery f is closed through
the coil of A¹ itself with the result that the armature and contact springs of A¹ are
retained in working position independently of the current which brought them there,

page_text: 33
The upper contact spring of the first pair I A¹, which is connected to earth through
a small battery a¹, makes contact with the "service wire" W₁ of the "calling
subscriber on his "catcher-on board," whereby this isolated wire is raised to the
potential of battery a¹ with the result, as explained hereafter, that thenceforth no
other subscriber can "catch-on" to the line of the subscriber "calling." The upper
contact spring of the fourth pair IV A¹, puts the "service wire" W (appertaining to
the line of the "calling" subscriber on his "linker board") to earth through the
coil of commutator A2, whereby to prepare for the "linking" of the subscriber
calling" with the subscriber "called" if the latter is disengaged, as will be
explained hereafter. The lower contact spring of the second pair II A', disconnects
from the wire L' with which the upper contact spring of the same pair connects in
its place, whereby the line wire L is connected to the long strip of the second
sector II B, of the "main distributor" B; whilst the armature of commutator A¹,
coming on to its working contact, connects the line wire L2 (which was theretofore
isolated,) with the long contact strip of the third sector III B, of the "main dis-
tributor B.
«
"
(II) The lower contact spring of the second pair II A¹, being disconnected from
the line wire 1 (just after the battery f has been connected by the upper spring of
the third pair III A¹, with the coil of commutator A¹) the connection of the battery b
to earth at the subscriber's station is broken, the coil A becomes inert, and its
armature a returns to its resting contact, thus cutting the earth connection of the
battery through coil A¹ and the coil B¹ of the "main distributor" B. The coil
B¹ thus becoming inert allows its armature to return and the "main distributor "
advances one step. The common "battery-in-waiting" b, which was connected to
the line wires I of all the subscribers of the same group (by the first pair of contacts
of the first sector I B, of the "distributor" B, and by the lower contact spring of the
second pair II A¹, of the commutator A¹ of each subscriber,) is thus cut out, and the
indicators placed at the subscriber's stations between the resistance and the earth, no
longer receiving current, assume a position indicating that the "selector" and
manipulator" common to the group is in use.
SIGNAL No. 2.
The "main distributor" B having reached its second position, the line wires L'L
are in connection with the group of three relays C whose well known arrangement
enables the production of the three kinds of "distinct signals" possible in the two-
wire and central-battery system under consideration. Two of these relays are one on
each side of the battery c the middle of which is to earth through the third relay, and
according as the signal sent by the "calling" subscriber consists in putting to earth
without resistance the one or other of the wires L1 L2, or in joining these two wires
without interposed resistance and without earth, the one or other of the two extreme
relays and the middle relay, or the two extreme relays, will be excited by the current.
The three armatures of the relays are connected together and the three working contacts
are connected to the battery b¹ through the coil B₁ of the "main distributor," B; the
three resting contacts are connected to the one terminal of each of three electro-
magnets C the other terminals of which are to earth (through the second pair of
contact pieces of the first sector I B of the "main distributor" B,) these three
electro-magnets C¹ constituting the mechanism controlling the first "member" of
the "main selector" D whereof an example of construction will be hereafter
described.
According to the nature of the signal sent by the subscriber, the armatures of a
certain two of the relays Care depressed, and one remains at rest; consequently that
one of the three electro-magnets C¹ is actuated which corresponds to the combination
formed by the two armatures depressed. The first "member" of the main
selector" D is therefore actuated in a certain way according to the nature of the signal
sent. The current which energizes this electro-magnet C₁ also traverses the coil B
of the "main distributor" B, whose armature, being attracted, is in position to

page_text: DIGNAL NO. 5.
<
27
The signal No. 3 is sent by the "calling" subscriber in the same way as Signal No. 2
and the receptive apparatus are the same except that the "main distributor" B,
having reached its third position, the local current (supplied by the relays C in
response to the subscriber's signal) is directed to the second group of electro-
magnets C which are similar to those C¹ but are connected to earth by the third
pair of contacts of the first sector I. B of distributor B. These electro-magnets (2
constitute the controlling mechanism of the second member of the "main
selector" D). When one of those magnets is excited in response to the signal sent,
the second "member" of the "selector" will be actuated in a way corresponding
to the signal. Consequently by referring to the general explanations previously
given as to the constitution and mode of operation of the " selectors," it
will be understood that the two "members" of the "main selector D having
been successively actuated, that particular "selector" circuit which corresponds to the
combination formed by the second and third signals sent by the subscriber, will be
completed. Now, as above explained, this circuit controls a certain " twin" pair of
" catchers-on." We will suppose the "selector" circuit which is completed, to be the
one which in the diagram is represented by d d² d¹ do in position of repose, that is to
say as being still open at contact d. On the cessation of the signal No. 3 the "main
distributor B again advances one step to its fourth position, whereby the line
wires are connected with the "manipulator" by the fourth pairs of contacts of
the second sector II B and third sector III B.
"
The group No. II of diagramn Figure 1^, is shewn as at the moment when the line
"calling" (the uppermost one shewn on board L. II) having sent the signal No. 1
whereby it has been connected to the relays C of the "main selector" D and after-
wards the signals Nos. 2 and 3 which have actuated the "main selector," the
continuity of one of the "selector" circuits is established at d. The battery a¹ is
connected to the service wire W₁ of the line "calling," thereby preventing any
subscriber making contact with ("catching-on" to) this line; the other lines of the
group are cut off from the battery b.
SIGNAL No 4.
L²
It will now be convenient to distinguish as regards their function, the signals, of
invariable number, which are formed when the brush contact of the " signal-com-
posing" device passes over the straight contact strips. 181, 182, 183, of the racks
Nos. 3, 2, 1, and the signals, of variable number, formed when the brush passes over
the comb-like contacts 184, 185, 186. For distinction, I will term the former
"distribution" signals and the latter "selection" signals. These two kinds of signal-
differ in nature, since they are consequent on the one or other of the line wires
being put to earth; in response to which action, the one or other of the electro-
magnets E1, E2, (which constitute the "manipulator" E) is excited by the current of
battery e and attracts its armature. The first signal emitted, that is to say
signal No. 4, is a "distribution "signal, and it has been assumed, for the sake of
example, that this signal consists in putting to earth the line wire L', the consequence
of which is the attraction of the armature of electro-magnet E¹ on to its working
contact. Now on the one hand the armatures of the electro-magnets E¹ E2 are
connected together and to a metallic piece at do at which makes contact, or becomes
completed, the particular "selector" circuit which is determined in each case by the
combination of signals Nos. 2 and 3. On the other hand, the working contact of
electro-magnet E¹ is connected to a battery e¹ and to earth through the medium of
the first pair of contacts of the first sector I Ft of the "return-to-rest distributor "
Fand by the coil of distributor F; inversely, the working contact of E2 is connected

page_text: to a battery e² (of opposite polarity to that of battery e¹) and to earth by the first pair
of contacts of the first sector I F, of the "return-to-rest distributor" F and by the
coil of distributor Ft. The armature of E¹ coming on to its working contact, a
current is sent from battery e¹ through the "selector circuit" which has been com-
pleted by the main selector" D, which current also passes through the coil of
"distributor "F. The result is twofold:-
(1st) The polarized double receiver H which is located at the extremity of the
"selector circuit" under consideration, operates in correspondence with the direction
of the current which it receives;
(2nd) The distributor F advances one step when the current passes through its
coil and another step when it ceases, thus arriving at its third position. Thenceforth
communication is cut between the battery e² and the coil of the distributor F+ which
is rendered inactive and uninfluenced by currents which may be subsequently sent
from the battery e² when the latter is subsequently earthed through the resistance
coil 3 of the saine resistance as the coil F. Inversely, if, (by a different adjustment
of rack No. 4) the first "distribution" current had been formed by earthing the line
wire L, a current of opposite direction would have been sent to the polarized double
receiver H, the "return-to-rest distributor" F would have advanced to its third
position, and the return-to-rest distributor" F would have been rendered inactive
and insensible to currents from battery e¹.
"2
The polarized double receiver H (which receives the currents emitted by the
"manipulator" through the "selector circuit") may be composed of two single
polarized relays H₁ H2 of which the one or the other operates according to the
direction of the current emitted. Suppose the relay H¹ to work in response to the
currents emitted by battery e¹ (which are, by hypothesis, the "distribution currents")
the relay H2 will work in response to the "selection currents emitted by the
battery e². The armatures of the two relays H¹ H2 are moreover connected to the
same battery h³. Now, the circuit from the working contact of relay H¹ reaches
earth through the first pair of contacts of the first sector I G2, of the "catcher-on
distributor" G (supposed to be in position of rest), and through the electro-magnet g
and the coil G¹ of distributor G; conversely, the circuit from the working contact
of H2 reaches earth through the first pair of contacts of the first sector I G of the
"catcher-on distributor " G and by the coils 9° and G³ of the distributor G². The
effect of the first "distribution current" is then, by carrying the distributor G to its
second position, to cut off all communication of the battery h³ with the coil G³ of
the distributor G2 which is then blocked in its position of rest, and consequently it
renders inactive, and uninfluenced by any signals, the corresponding "catcher-on"
which is not represented in the diagram.
On the contrary, the "catcher-on distributor" G having been brought to its
second position, puts the first of the mechanisms, controlling the movements of that
"catcher-on" with which it is itself associated, in position to receive "selection
currents "
from the battery h³. If the first "distribution signal" had been of
opposite direction, (that is to say produced by earthing the wire 12 and the working
of the relays E2 and H2) it would have been the distributor G and the corresponding
"catcher-on" which would now be blocked; and the distributor G and the
"catcher-on" associated with this distributor (that which has been designated the
"twin catcher-on ") which would be in position to operate.
<
In group No. III of diagram Figure 1, the line "calling" (third from the top) is
shewn as at the moment when, after the signal No. 4, it transmits to the
manipulator" E the "distribution" and "selection" signals, and when those
signals (translated by the "manipulator" into the form of local currents) pass
through the "selector" circuit completed in the "main selector" D and act on the
double, polarized relay H. It has been supposed that the two "twin catchers-on
which are controlled by the "selector" circuit completed, are those c 1 which are
the first on the left of the "catcher-on boards" CI, CII, of Groups I and II;
the example represented is that wherein the "catcher-on" of group No. I is about
"

page_text: This electro-magnet M¹ receives as many current emissions from battery e² as
there are, in the "selection signal" No. 9, earthings of the wire L². The second
"member" of the "contact-fingers selector" is actuated, and its effect, combined
with that of the first "member," is to set free that set of three "contact fingers" of
the "catcher-on" which has been brought opposite to the row of contact wires or
pieces (on the "catcher-on" board) belonging to the line of the subscriber "wanted,"
and that set only. The three" contact fingers" of this set, being set free, are each

page_text: 32
on the
Supposing, first, that the line of the subscriber "wanted" is disengaged, it will be
seen by referring to the connections of the wire W₁ (shewn in Figure as in position
of repose) that the "service" wire W*1 appertaining to this line "wanted
"catcher-on board' is to earth through the coil of commutator A². Now, the
"catcher-on distributor" G, on arriving at its fourth position, has connected (at its second
sector II G,) the catcher-on "service-contact finger "%° (of the set of fingers which
has been set free) to the two test commutators N1, N2, which are themselves con-
nected to earth. When the catcher-on "service-contact finger" Z° makes contact
with a service wire W* which is to earth, no effect is produced on these com-
mutators N1, N2, the alternating current generator V remains isolated, and the
subscriber "calling," on listening at his receiver, does not hear any buzzing or
sonorous signal denoting that the line is "engaged."
The group No. IV of diagram Figure 14, shews the case where all the signals, up
to and including signal No. 9, having been sent, the "test" is made of the line
"wanted." The "calling" line is the second (from the top) of board L. IV, and it
has been supposed that the "catcher-on" actuated was the one c 3 (the third from
the left) of "catcher-on board "CIII of Group III; that the fingers of this "catcher-on "
have been brought into contact with the line "wanted" (which is the second from
the bottom of board C III); and that this line is not "engaged" in communication,
so that no sonorous signal comes through do. The "catcher-on which is the
"twin" of the one used, and which is placed in front of the board C IV has the
coil G³ of its distributor G2 blocked in position of rest. I have also shewn "com-
munication established" between the bottom line of Group III (the line " calling
being on board L III) and the bottom line of Group IV (the line "called" being on
board C IV) so as to shew the presence of the potential of "testing" battery n³ in
the service wires W and W1 of the lines "engaged in conversation.
33
23
The subscriber "calling" then sends the "final signal" which is of the same kind
as the "distribution signals" and acts like them on the return-to-rest distributor F
and on the "catcher-on distributor" G. I will first consider the latter, which
advances one step and reaches its fifth position. The current of battery g³ (by the
armature and resting contact of electro-magnet g, the contact springs nº, n', electro-
magnet "No, the fifth pair of contacts of the first sector I G, of the "catcher-on
distributor G, the armature n¹ of N¹, and its resting contact, the spring n* of
commutator N2 and its resting contact, the armature and the resting contact of the
indifferent polarized relay O) passes to the first circuit of the commutator P and attracts
its armature and the two contact springs; at the same time the armature of N° is
brought on to its working contact and forms, for the current of battery g³, a path
independent of the position of the brush of the distributor on the fifth pair of
contacts of sector I G, as long as the springs no, n, remain in contact. The current
of battery po passes through the second circuit of P the working contact and the
spring p, the "line contact finger", the line wire L*1, the resistance, the bell,
and the indicator of the subscriber "wanted."
Using preferably "trembler" bells of the kind which work by short-circuiting,
instead of by cutting-out, their coils, the circuit will remain complete and the bell
will continue to ring until the subscriber, by unhooking his receiver, cuts the con-
nection to earth and finally breaks this circuit. From this point the thread of the
description will be resumed later on.

page_text: At the second and fifth sectors II G, and V G, there is no change. At the third
sector III. G, a battery n° (which the coming in contact of the springs g¹, g²,
Figure 12, puts to earth through the armature n³ and its resting contact,) sends
(through the wire 6, 7, 8, 9, 10, the spring and its resting contact the spring u
and its resting contact) an uninterrupted current to the electro-magnet Q which
controls the general movement of the "linker." The "linker" then commences to
move across the "linker board," its "service contact fingers" rubbing against the
"service contact wires" of the various lines which it passes over on the linker
« board."
At the fourth sector IV G, the battery g³ is connected (by the circuit
already described and the first winding of the polarised relay 0) to the wire 14, 13, the
cominon commutator R, and the wire 12, 11, whence are branched the wires apper-
taining to the "service contact fingers" Y° of the different sets on the "linker";
each such branch comprising the electro-magnet R' which controls the putting in
operative position of the "line contact fingers" of its set. The circuit may thus be
completed by one or other of the "service contact fingers" as soon as one of said
"service contact fingers "'itself meets with an earth. Now, it will be seen, by
following out on Figure 2 (Sheet 2) the connections when at rest of the "linker
service wire" W, that the "linker service wire" of an "idle" line is completely isolated;
and it has already been seen that the "linker service wire" of a line "calling" is to
earth through the coil A2 of its "connector." Lastly, it will be presently seen that the
"linker service wire" of a line "in course of conversation" is connected to one of
the poles of a battery of which the other pole is to earth, and that such linker
service-wire" is raised to a potential nearly equal to that of this battery, so that if
this battery has a suitable voltage and polarity it will be in "opposition" to the
battery when a "linker service finger" comes into contact with the service wire
of an "engaged" line; and consequently then there will only pass, in the circuit
referred to, a current much too weak to operate the electro-magnets. It will thus
be seen that no current capable of actuating these electro-magnets can be formed
except when one of the "linker service contact fingers meets the linker service
66
"
wire of a line "calling"; and as on a "linker board "there can only be one line
calling" at a given moment, (since all the lines on this "linker board" belong
to the same group for which only one "selector" and "inanipulator" are provided),
a current will only pass in the circuit referred to when one of the "service contact
fingers meets the service wire of the line of the " calling" subscriber in
question.
"
The Group V of Diagram Figure 1^, shews the state of things at the moment
when the line "calling" (the bottom one on board LV) having brought the "catcher-
on c², on to the line "wanted" (in this case the top one of the board CVI) and
having ascertained that this line is "disengaged," has then sent the "final signal"
which sets the "linker" in motion. The "linker" has not however yet net with
the service wire W of the line "calling," on the "linker board" LV; but the
battery g is connected to the service contact finger Y through the commutators R
and R in readiness to arrest the movement of the linker as soon as the " service
contact finger" Y meets with the service wire W which is to earth through the
coil A of the connector "appertaining to the line "calling."
66
But at this moment the commutator R, being energized, cuts the current which
energizes the electro-magnet Q whereby the traversing movement of the "linker"
is controlled; the "linker" is therefore arrested. The electro-magnet R¹ is also
energized and allows the "line contact fingers" of its set to come into operative
position, whereby a continuous connection is established from the station of the
subscriber." calling" by his line wires L1 L2, the line contact fingers Y¹ Y, and the
wires connected thereto, to the sixth pairs of contacts of the third and fifth sectors
III G, and VG, of the distributor G. Lastly, the polarized electro-magnet () is
energized, its armature is separated from its resting contact, cuts the current of
battery g³ from the first sector of the commutator P where it has become unnecessary,
and sends it by the branch 15, 16, 17, 18, through coil G₁ of the "catcher-on
distributor "G, which advances one step and arrives at its sixth position which is the
D

page_text: "conversation" position, the current of battery g³ continuing to pass through the
armature and the working contact of No, after the brush has quitted the fifth pair of
contacts, until the armature of G¹ having entirely completed its working stroke,
separates the springs no n7.
"
The effects of this last movement are as follows:-
At the first sector 1 G, the battery 93 is cut out; at the third and fifth sectors
III G, and V G, the wires coming from the "line contact fingers" Y¹ and Y2 of the
"linker" are connected to the wires 19, 20, 21, and 23, 24, which terminate at the
resting contacts of the springs pl p² of commutator P; so that as soon as the subscriber
"called," by unhooking his receiver, returns this commutator P to position of rest,
communication is established without any obstacle between him and the subscriber
by whom he is " called." At the second sector II G, a battery n³ is connected with
the "catcher-on service contact finger "Z" whose connection with the test
commutators N1, N2, is broken, and which is connected at the fourth sector IV G,
with the "linker service contact finger" Yo. Thereby the "catcher-on service wire"
W*1 of the subscriber "called" and the "linker service wire" W of the subscriber
calling" become raised to a potential so much the nearer to that of the battery n
as the resistance of the coils A2 (of the respective "connectors" of the two lines by
which these lines are to earth) is the higher relatively to the resistance, (which is
always very low,) of the "junction" wires. The characteristic condition of an
"engaged line is thus realized on the "catcher-on board" for the line of the
subscriber called " and on the "linker board" for the line of the subscriber "calling."
Lastly, the current sent from the battery n³ to the coil of the commutator A²
appertaining to the "connector" of the line "calling," excites this commutator,
whose armature is depressed and remains fixed in working position so long as the
current in question passes. It will be seen hereafter that it endures as long as the
conversation itself. During the whole of this time all communication is cut off
between the line I and the distributor B; at the same time by its contact spring a
branch is established from the one terminal of the coil of the commutator A2 to the
lower contact spring of the fourth pair IV A', of commutator A¹ which for the
moment is isolated.
I will now revert to the "return-to-rest distributor" F which, before the sending
of the final signal," was in its seventh position. This "final signal," like the
previous "distribution signals," advances the distributor two steps; one step during
the passage of the current, which brings it to its eighth position; and the second
step on the cessation of the current, which returns the distributor to its initial
position. Now, at the passage of the brush of the second sector II F, on to the
eighth pair of contacts, the current of the local battery f¹ is closed through the
electro-magnet F°; and then, as soon as the armature of F comes on to its working
contact, another path being opened to this same current, the armature of Fo is retained
in working position even after the brush has advanced a step. On the other hand,
the eighth pair of contacts of the first sector I F, and the first pair of the second
sector II F, are connected together; the contact pieces shewn lowermost on the
diagram being connected to one pole of the battery f¹ beyond the electro-magnet Fº,
and the contact pieces shewn uppermost communicating by the wire 28, 27, 26, 25,
with the armature of the electro-magnet Q which controls the traversing motion of
the "linker"; another wire going from the other pole of the battery f¹ traverses the
commutator F1 and joins the main "selector" D, whence, by the "selector circuit "
completed and its branch d², d³, d, it reaches the resting contact g of electro-
magnet this circuit remains thus interrupted so long as the traversing movement
of the "linker" continues, and becomes closed when, the "linker" having met with
the line of the subscriber "calling," the armature of Q returns to rest. Then (whether
the brush be still on the eighth pair of contacts of the first sector I F, or has
already arrived on the first pair of contacts of the second sector II F,) and only
then, the circuit of commutator F1 is completed; this commutator operates, closing
(by its own armature and its working contact) a local circuit of battery f which
retains it in its working position. At same time the spring f³ is separated from its

page_text: "
resting contact and the spring is brought on to its working contact. The first
movement cuts off the battery that maintained, in its working position, the
commutator A¹; the latter therefore returns to rest, but the separation of the springs
of each pair being so regulated that the contacts corresponding to the position of rest
shall be established before the contacts corresponding to the working position are
broken (and vice versa), the current which reached the coil A2 of "linker service wire
W through the upper contact spring of the fourth pair IV A', continues to reach it
without interruption by the lower contact spring of the same pair, and by the
communication which the contact spring of this commutator A2 establishes with the
terminal of the coil; the latter therefore retains excited and its armature remains in
working position. At same time, by the lower contact spring of the first pair I A',
the "catcher-on service wire" W₁ is raised to the potential of wire W, a potential
The characteristic
nearly equal (as above explained) to that of the battery n³.
condition of a line "in course of conversation" is therefore fulfilled also (on the
"catcher-on board") in respect of the line of the subscriber "calling."
"
The second movement closes the circuit of battery 61 through the coil B¹ of
the "main distributor" B and the coil F2 of the electro-magnet which serves
to "return-to-rest the "main selector" D. The "return-to-rest" coil 2 being
excited (and being very powerful) returns the "main selector" D to rest, and at
the end of its stroke separates the spring f² from its resting contact. The various
local circuits which were supplied by the battery f¹ are thus cut, the electro-
magnet F and the commutator F1 return to rest, the spring fo is separated from its
working contact, and (the circuit of the battery b₁ being thus cut) the "main
Thus,
distributor" B advances one step, which brings it to its position of rest.
as soon as communication is substantially established between the line of the
subscriber "calling" and that of the "subscriber called," the apparatus for common
use are automatically returned to norinal position, that is to say, are ready for
"calling"
use by any other subscriber of the group to which the subscriber who was
belonged.
"
The Group VI of diagram Figure 1ª, shews the state of things at the moment
when the "linker," having met with the service wire W of the line "calling" (in this
case the bottom one on board L VI) has been stopped at this line, and when the
subscriber "called " (whose line is in this case the fourth from the top of board C VI)
having unhooked his receiver, "conversation connection" is established without
obstacle between the two subscribers. The service wires W and W₁ of the line
"calling
are connected together at the electro-magnet A2 of the "connector "
belonging to that line; the service wires W* and W*1 of the line "called" are
similarly connected; and lastly, the service wires of the one are connected to the
service wires of the other by the "catcher-on distributor" of the "catcher-on
employed, and communicate with the "testing" battery n³. The communication of
the other lines of the group with the battery b is restored and the apparatus for
relay C, "main selector" D and
common use (main distributor B, "selector
" employed has
"manipulator" E) are returned to rest, and lastly, the "catcher on
the coil G¹ of its "distributor " G blocked in position of rest against any currents
which may be sent by the double polarized relay H, whilst the " twin catcher-on" has
the coil G³ of its "distributor" G2 put into circuit with this same relay H whereby
this "twin catcher-on" is rendered available for use.
"
To complete the description as far as it relates to the case of a "disengaged" line,
it remains to be shewn how, the talk being finished, the "catcher-on" and "linker'
which were used, and likewise their accessory parts, are returned to rest. For this
purpose the branch 29, 30, in which is placed the central transmission battery 3º :
also comprises the first circuit of commutator S; and the electro-magnets S1, S2, are
placed one on either side of the branch 29, 30, in circuit with the two "junction'
wires 20, 21, and 23, 24, respectively. As soon as the "catcher-on" quits its position
of rest, the spring T3 comes on to the contact 3 which is to earth, and consequently
as soon as the current of the central battery 80 has once excited the first circuit of
the commutator S (which only happens when at least one of the two subscribers has
"

page_text: "
come on line" in position to talk) the armature of this commutator itself closes,
through the second circuit, the current of the battery 8 and thus retains itself in
working position; and at the same time the battery 82 is permanently connected to
the spring 8.
But the circuit of this battery (requiring for its completion the contact
of the armature of each of the electro-magnets S1, S2, with its resting contact) remains
broken in at least one point so long as both subscribers have not hung up their
receivers after finishing their conversation, and thus cut off the current of battery so
in both the electro-magnets S1, S2, at once. Then only, the interrupted current of
battery 8 passes first to electro-magnet T which actuates the return-to-rest of the
"catcher-on contact fingers." The return-to-rest mechanism of these fingers (of
which a constructional example will be described hereafter) having arrived at the end
of its stroke, presses together two springs t1, t2, and switches the current of the same
battery 82² to the mechanism by which the "catcher-on" is returned to its initial
position by a step-by-step motion. The principal element of this mechanism is an
electro-magnet T2 of which the armature actuates a pawl driving a ratchet wheel.
The current from the battery s2 passing through the resting contact and armature to
of electro-magnet T² to the first winding of the auxiliary electro-magnet T₁ attracts
its armature, which closes, at its working contact, the circuit of another battery t
through the electro-magnet T2 and the second winding of T¹. The armature of T2
being attracted, first cuts off the current of the battery s² and advances the
ratchet wheel to the extent of one tooth and then, on reaching the end of its
stroke, separates the spring from its resting contact. The two windings of T¹ thus
both ceasing to be excited, the armature of T" returns to its position of rest, similarly
for the armature of T2 since this electro-magnet also ceases to be excited. Every-
thing is therefore returned to initial position, where the current of battery 8² is
re-established to bring about another movement; and so on until the "catcher-on"
has been returned step-by-step to its initial position, and, pressing against the
spring T3 separates it from its contact. The commutator S then ceases to be retained
in working position and returning to rest, cuts off the current of the battery 82. This
mechanism differs from a "trembler" mechanism in that the arinature to of the
electro-magnet T2 is obliged to travel through the whole length of stroke given to it.
The coil of T might also be put in parallel are with the second winding of T' instead
of in series therewith, as shewn in the diagram; the branch comprising that coil
should, in that case, start from the battery t before the spring and be attached to
the armature of T¹.
At the same time as the battery 82 sends to the electro-magnet T a current through
the branch 31, 43, 45, to the second winding of the polarized electro-magnet O in
the required direction to return it to rest, and by the branch 31, 43, 46, 47, to the
second winding G₁ of the "catcher-on distributor " G which, advancing one step, is
returned to position of rest.
"
In passing from its sixth position to its position of rest, the distributor G cuts the
connection of the battery n5 with the "service contact fingers" Zº, Yo, and of these
fingers with each other. The commutator A2 ceasing to receive current, returns to
rest, which breaks the communication between the "catcher-on" service-wire and
the "linker" service-wire of the subscriber "calling" and returns the whole of his
"connector to its initial position. On the other hand, at the moment when the
"linker" quitted its position of rest, it allowed the spring U to come on to its contact
connected to the battery ut; at the same moment the commutator R is retained in
its working position so that the current of the battery u* passes first (by the
brauch 32, 33, 34, 35, 36, the armaturer and its working contact) to the first
winding of the commutator U; then through the armature of this commutator U and
its working contact to the second winding of this commutator, of which the armature
is held in working position independently of the movements of the armature r, and
establishes by its spring u¹ and its working contact, a communication between the
electro-magnet U° and the resting-contact of the armature r. As soon then as the
current of battery is cut off from the commutator R by the return
the "catcher-on distributor" G to its initial position, the armature 7 returns to rest
of

page_text: surgwashes improved system of
мотию лесертен скоканде.
and the current of the battery u' is permanently sent to the electro-magnet Uº, and
then (by the armature and its working contact) to the electro-magnet U¹ which
actuates the return to rest mechanism of the "linker contact fingers" (of which a
constructional example will be hereafter described) and lastly, the electro-magnet U¹
having operated, and its armature arriving at the end of its stroke, the current is
sent through the branch 33, the working contact and armature of U¹, to a return-to-
rest mechanism U2, U³, (similar to that which has been described for the "catcher-
on") whereby the "linker" is returned step-by-step to its initial position, this
movement being arrested when the spring U is raised from its contact and the
commutator U and electro-magnet U° return to position of rest. All of the mechanisins
Lave now been returned to their initial position.
66
SECOND CASE. "LINE IN COURSE OF CONVERSATION." 33
It has been explained above that the service-wire appertaining to a line on its
"catcher-on board" is connected as soon as this line (whether "calling" or "called ").
is in course of conversation," to one of the poles of a battery of which the other polé
is to earth, and is raised to a potential nearly equal to that of this battery. Suppose,
then, that a subscriber sends the signals above enumerated up to and including
signal No. 9, in order to put himself in communication with a subscriber who is
engaged" in another conversation. When the "catcher-on distributor" having
been brought by the "calling" subscriber, to its fourth position, and the operation
of the two "members" of the "contact-fingers selector" having set free the appro-
priate, set of "catcher-on contact-fingers," these contact-fingers come into contact
with the line and service contact wires of the subscriber "wanted" on the "catcher-
on, board," a current is established from the battery connected to the service wire W*1
of this subscriber, through this service wire W*1, the catcher-on "service-contact
finger" Z, the wire 1, 2, 3, 4, and the fourth pair of contacts of the. second
sector II G of distributor G, whose armatures and springs come into working position.
The generator V of alternating or periodic currents is connected (through a con-
denser v, spring n², and its working contact) to the "selector circuit" which is made
use of, before its entry do into the polarized receiver H; the electric impulses of the
generator V are then transmitted by the wire do, d', d², d, to the "main selector" D,
to the condenser v¹, and to the induction coils I I¹ which transmit the currents by
induction to the line wires L'; L2. The subscriber who listens at his receiver con-
nected to the wire L² receives a buzzing or sonorous signal by which he knows that
the subscriber "wanted" is "engaged."
Communication being momentarily impossible, it is required to return all the
mechanisms actuated, to their initial positions. To this end the subscriber sends
the "final signal." As will be seen, the "linker" has not quitted its position of rest,
and consequently, when the brush of the "return-to-rest distributor" F in response
to this "final signal" passes over the eighth position of the first sector I F, and
comes to rest on the first position of the second sector II F, the circuits described in
the previous case for the return-to-rest of the "connector,"
,""main distributor," and
"main selector" are already formed without interruption or gap, and consequently
these mechanisms are immediately returned to initial position.
66
As regards the "catcher-on," its distributor G moves to its fifth position; the
commutators N1, N2, being always connected to the service contact finger Z° (fourth
and fifth pair of contacts of the second sector II. G,) and to the "catcher-on service
wire" W* of the subscriber "wanted," have remained in working position. The
battery no which, in the previous case, determined the setting in motion of the
linker," is cut out, and in its place the earth is put by springs 91, 92, and by
the armature n³ to the local battery n which fixes the commutator N2 and electro-
magnet So in their working position independently of the other apparatus. Now,
the final signal" above referred to, only reaches the coil G¹ of the "catcher-on
distributor G by first traversing the small electro-magnet g of which the armature
is attracted; and consequently at the moment when the distributor reaches, its fifth
position, the battery g³ is cut off from the fifth pair of contacts of the first sector I G,
66
"

page_text: of distributor G, but when the current, which constitutes the "final signal," ceases
the electro-magnet g ceases to be excited, its armature returns to rest, and the
current of battery g³ (prolonged as above described by the electro-magnet N° after
the brush has quitted the fifth pair of contacts) is switched (by the fifth pair of
contacts of the first sector I G, the working contact of armature n', this armature,
and the wire 17, 18) to the coil G₁ of the distributor G which advances one step and
reaches its sixth position. In order that the movements shall be performed exactly
as described, it is only necessary that the armature of the electro-magnet G1 shall
return to its position of repose a little quicker than that of the electro-magnet g,
which is easily ensured by regulating the mechanism, but this result may be ensured
with greater certainty by the following means, not shewn in the diagram. The
electro-magnet g has a second winding, of which one end connects with the working
contact of its own armature, whilst the other end connects to a spring, which the
armature of electro-magnet G¹ separates slightly from an earth contact on reaching
the end of its stroke on the repose side, so that the armature of electro-magnet g is
only set free after that of G¹ has entirely returned to position of repose.
The "catcher-on distributor" G passing to its sixth position, the connection is
cut between the "catcher-on service finger" 7° and the commutators N1, N2; the
commutator N2 remains fixed in working position by the battery n, but N¹ returns
to rest, and the current of the battery n is switched (by the sixth pair of contacts of
the first sector I G, by the armature n¹ and its resting contact, the spring and
its working contact, the wire 37, 38, 39, 40, 41, 42,) through the second winding of
commutator S to the spring T3 and to its earth contact. The branch 29, 30, being
moreover cut between the armature and the resting contact of the electro-magnet Sº,
the two electro-magnets S1, S2, are therefore necessarily in position of repose. When,
therefore, the armature of S is attracted by the action of the current of battery g³ and
is fixed in working position by the current of battery s¹, everything is prepared for
battery s² to act as described in the preceding case and to return the "catcher-on-
distributor" G and the "catcher-on" itself to position of rest. By the return of
distributor G to rest, the earth connection is cut (at springs g¹³, g²) from the
battery ; and the commutator N2 also returns to rest. All the parts have then
returned to their initial positions.
3RD CASE. "CATCHER-ON " ALREADY IN USE.
It may happen that, a conversation having been cominenced by a subscriber of
a certain group with a subscriber of a certain other group, another subscriber of the
same first mentioned group desires to speak with another subscriber of the same
other group.
Now the "catcher-on" which would be suitable for this second
communication is already appropriated for the first one, and the second subscriber
desiring to call must not be able to disturb, nor to overhear, the conversation of the
other two, and must himself be notified that he cannot, for the moment, call the
subscriber he wants.
.
As regards the first point it follows, from the "catcher-on" in question being
already engaged for a conversation, that the "catcher-on distributor" is in its sixth
(or "conversation") position. Now, when the brush of the fifth sector V G passes
from the fifth to the sixth position, all communication is cut between the battery h³
and the coil G¹ of the "catcher-on distributor" G which is therefore inaccessible by
the signals which the subscriber, so desiring to call, might send. On the other hand,
since the catcher-on in question is in use for conversation, the corresponding.
"linker" is in use also, and has therefore left its initial position; consequently the
spring V2 has come on to its contact v2 and, at the moment when, the second
subscriber desiring to call, (having sent all the signals up to, and including,
signal No. 9,) listens at his receiver, the "return-to-rest distributor" F, which is then
in its seventh position, establishes electric communication between the alternating
current generator V and the induction coils I I¹ (by the seventh pair of contacts of
the first sector I F, the spring V, its contact v2, wire do, do, d, d³ d², d, the "main

page_text: selector "D, and the condenser v₁,) and the buzzing signal denoting that communi-
cation cannot be obtained will therefore be heard.
4TH CASE. "USE OF THE TWIN' APPARATUS."
وو
But the fact that a "catcher-on" is thus in use must not entail the inaction of the
"twin" apparatus which is contolled by the same circuit of the "main selector."
Now, it has been shewn that from the first step made by the "catcher-on distributor
G, the electro-magnet G³ of the "catcher-on distributor" G2 of the "twin" apparatus,
was completly cut off from the battery h³ and rendered inaccessible to any "distribu-
tion signal" which debars the "twin catchers-on" from receiving any " selection
signal." But when the distributor G passes from its fifth to its sixth or " conversation
position, that is to say, at the moment when the "main distributor and "selector"
again become available, the communication is cut at the fifth sector V G, as above
described, between the battery h³ and the coil G¹. On the other hand, one of the
five metallic pieces fixed to the disc mounted on the spindle of the "catcher-on
distributor" G makes a bridging contact between the two springs go, g², and as these
are connected respectively with the two contacts of the first pair in the first
sector I G, the connection broken at the first step of the "distributor" G is restored
and coil G³ can receive "distribution currents "; consequently the "twin catcher-on"
can receive "selection currents" and be actuated at will. The fact of a "catcher-on"
being engaged, in no way involves the sending of the buzzing or "engaged" signal
to the subscriber who desires to use the "twin catcher-on"; since the "distribution
currents" suitable for actuating the "catcher-on distributors" of the two "twin"
apparatus controlled by the same "selector" circuit, are of opposite polarities, one of
the "return to rest distributors" F responds to currents of the one kind (those which
act on G¹ for instance) whereas the distributor F* responds to those which act on the
coil G³ of the distributor of the "twin" apparatus. When F4 reaches its seventh
position, the generator V1 is connected no longer to the spring V2, but to the
spring V which fulfils the same function for the "quasi-twin" linker. On the other
hand, at the moment when the subscriber who desires to make use of this "twin "
apparatus listens at his receiver before sending the "final signal," the "quasi-twin"
linker is still in its position of rest, and consequently V₁ is separated from its
contact v. Therefore no electrical impulses can pass to the induction coils I I¹, nor,
by them, to the line wires, and consequently no "buzzing" signal is sent.
The detailed description of the circuits having been given for the various cases
which may arise, I will describe some constructional examples of the various special
mechanisms employed in the system, it being understood, however, that the
invention claimed is not limited to these particular constructions, as any structural
arrangements producing the same results may be adopted without departing from
the spirit of the invention.
As a type of the electro-magnetic commutators employed, Figures 7, 7, 7B, shew
in elevation, section, and plan, the commutator with four pairs of contact springs
forming part of the "connector." It is an ordinary electro-magnet whose armature a²
carries a cross bar a³ of insulating material which plays between four pairs of contact
springs a, a. When at rest, this cross bar a3 separates the upper springs from the
contact rings a with which the lower springs are freely in contact. When the coil
is excited by a current, it is the lower springs a that are separated from, and
the upper springs that freely touch, the contact rings a6. All the springs and rings
are insulated from each other and are regulated independently. The armature itself
establishes a contact in the manner of a relay, with an insulated contact piece a7. A
greater or less number of upper and lower springs and contact rings may be used
according to requirements. The cross bar a itself may also have fixed to it,
metallic pieces which make contact with the lower springs. In the first form, there
is one fixed contact for two springs; in the second form there is one spring for two
contacts.

page_text: "
The "main selector" shewn in Figures 8 and 8 consists of a metallic piece D° to
which are fixed nine flexible springs 1, 2, 3, 4, 5, 6, 7, 8, 9, adapted to make contact
respectively with nine short stiff springs mounted on a support by which they are
insulated from each other. This "selector has two "members" each "member"
being formed of three rods D1, D2, D3, for the first member and D4, D5, D', for
the second "member." Each is forced towards the left by a spring, but is
retained by a tooth which is engaged by a detent forming the armature of an
electro-magnet C¹; there being three electro-magnets C¹ which control the rods of
the first "member and three electro-magnets C2 which control the rods of the
second "member," although only a few of these magnets are shewn. Each rod
carries three lugs D', DS, Dº, of insulating material which, when the rod is retained
by its tooth, bear respectively against the corresponding long springs and separate
them from the corresponding short springs. Thus the rod D' acts on the
springs 1, 2, 3, the rod D2 on the springs 4, 5, 6, the rod D³ on the springs 7, 8, 9;
and for the second "member" the rod D retains the springs 1, 4, 7; the rod D³
the springs 2, 5, 8; the rod De the springs 3, 6, 9. Each spring is thus retained
by a rod of the first "member" and by a rod of the second "member" and can
only come on to its contact when these two rods have been released by means of
currents actuating those two electro-magnets C1, C2, corresponding to these rods, so
as to disengage their armature detents therefrom. This "main selector" thus
constituted enables nine "selector circuits" to be controlled. The return-to-rest is
obtained by means of the electro-magnet F2 (shewn only in Figure 8") whose armature
carries a cross har F3; when a rod is released, the pin F which it carries comes close
to the cross bar F3 and is moved back when this cross bar and armature are attracted
by the electro-magnet F2. The pins 5 serve as stops to limit the movement towards
the left.
The contact wires or pieces, by which the line wires and service wires appear
on the "catcher-on" and "linker boards, are quite inert. Such boards might
obviously be formed of any suitable metallic pieces suitably connected by wires.
But as the set of contact pieces corresponding to each line on each board comprises
three pieces, viz. :-The two line contact pieces and the service contact piece, and as
this set must be multiplied as many times as there are groups of subscribers, a more
simple arrangement is that shewn in Figures 13 and 13 which combines in one
the "catcher-on board" and the "linker board "corresponding to a group of sub-
scribers. It consists of a strong open frame of insulating material in which are
stretched wires arranged in rows each of four wires equally spaced in the same
horizontal plane. The middle two wires are connected to the line wires L1, L2, of a
subscriber, the outer wires serving the one as the "catcher-on-service wire" W¹ and
the other as the "linker service wire" W. Five such rows of wires are superposed
at suitable regular intervals; then comes a vacant space, and then five more rows,
and so on.
One side of the board thus constructed is for the "catchers-on," the other
side for the "linkers."
The "catcher-on" comprises two main members; first, a frame or support capable
of being traversed vertically and carrying with it in its movement a certain number
of sets of contact fingers, the sets being regularly spaced and each set comprising
three contact fingers movable in the same horizontal plane; the distance in the
vertical direction between two consecutive sets of contact fingers being equal to the
height occupied on the "catcher-on board" by five rows of contact wires or pieces
and the succeeding vacant space; secondly, a "contact-finger's selector," enabling
any one set of contact fingers to be selected and to be brought into operative position
to the exclusion of all the others. The vertical traversing movement, which may be
in the downward or the upward direction, enables one of the sets of contact fingers
to be brought to the level of the contact wires or pieces which correspond to the line
"wanted" on the catcher-on board." The working of the "contact-finger's
selector" enables this set of contact finger's to be brought into operative position
to the exclusion of all the other sets. With this object the "contact-fingers
selector" may act mechanically, by preventing all the sets of contact fingers except

page_text: the set selected, from touching the contact-wires or pieces which are opposite to
them, on the "catcher-on board"; or it may act electrically, by putting (or by
leaving) in the electrical circuit of conversation, only the set of contact fingers
selected.
It is obvious that the various sets of contact fingers should be mechanically in-
dependent, if they are permanently connected electrically; and that they should be
electrically independent, if they are mechanically connected. Examples of both
cases will be described hereafter.
It may be conceived that the combination of the traversing movement and of the
working of the "contact-finger's selector" may suffice without any other operation
to bring the group of contact-fingers selected into contact with the line "wanted."
It may also be conceived that this combination may only prepare, so to speak, for
the coming in contact, by bringing each finger to the required position relatively to
the general frame or support, but that the actual coming into contact only takes
place by subsequent movement of the frame or support brought about by
the action of a "special signal" as will be shewn by an example later on.
In the example illustrated in Sheet 9, the traversing movement is a descending
one, along a screw spindle 1, of rapid pitch, controlled by an escapement under the
operation of an electro-magnet K, a complete oscillation of the escapement deter-
mining a descent equal to the space between two wires on the "catcher-on board:"
The "contact-fingers selector" has two "members" acting mechanically by prevent-
ing all the sets of " contact fingers" except the proper one from touching the contact.
pieces on the "catcher-on board," the two "members" being respectively actuated
by the electro-magnets M. and M¹ (Figure 16). Lastly, the return to rest is effected
by two successive movements, of which the first returns the "contact fingers to
their initial position, whilst letting the two "members" of the "contact fingers
selector" return of themselves to normal position, and the second returns step-by-
step the whole "catcher-on" to initial position by raising it along the screw
spindle 1 (Figure 14). The electro-maguets which bring about this movement have
been indicated in the general diagram by the letters T, T¹, and T²,
"
Figures 14, 14, and 14%, shew the traversing motion. 1 is the vertical screw of
long pitch mounted on the frame in collar or ball bearings so as to rotate as freely
as possible. 2 is the nut of this screw on which is mounted the frame carrying the
sets of "contact fingers," the mechanism of the " contact-fingers selector" which
controls them and the return-to-rest mechanism of the two "members" of that
selector. The screw 1 has an escapement wheel 3 provided at its underside with
three equidistant lugs 4 which are engaged alternately by the pallets of the escape-
ment anchor 5 which is caused by a spring to normally assume the position shewn
in full lines in Figures 14ª, 14, whilst the electro-magnet K when excited, causes
the anchor to assume the position shewn by dotted lines in Figure 14%. The number
of lugs 4 and their pitch would be such, in relation to the pitch of the screw 1, that
a complete oscillation of the anchor 5 to and fro allows the nut 2 to descend along
the screw a distance equal to the interval between two wires on the "catcher-on
board."
The rotation of the screw 1 in the opposite direction for the return-to-rest motion,
is effected by the two electro-magnets T1, T2, whose electrical operation has been
already explained; the one T2 acting on the ratchet wheel 3 by a pawl 6 jointed to
its armature; a detent 7 engaging wheel 3 to prevent retrograde movement between
the impulses of pawl 6. This mechanism 6, 7, is prevented from obstructing the
descending motion (when the escapement is actuated by the electro-magnet K) by a
pin 8 fixed to that arm of the escapement anchor 5 which is in gear in position of
rest, which pin 8 at the first movement of the anchor, engages the detent 7 and
(through its arm 9 and the abutment screw 10) the driving pawl 6, and disengages
them from the ratchet wheel 3, as shewn in dotted lines in Figure 14". A latch 11
(Figure 14) jointed to a prolongation of the detent 7 and provided with a bevel
surface 12, slides at the same time over the bevelled end 14 of the armature 15
E

page_text: of electro-magnet T, passes beyond it, and is caused by a spring 13 to engage
with that armature so as to hold the driving pawl 6 and detent. 7 out of engagement
with the ratchet wheel 3 until, by the attraction of the electro-magnet T, the
armature 15 is retracted and releases the latch 11. By referring to the diagram,
Figure 2, it will be seen that the electro-magnet T is the one which, in order to
return to rest the "catcher-on contact fingers," is the first to receive the "clearing-
off"
signal, so that the pawl 6 and detent 7 will not become re-engaged until their
action is again required. The insulated metallic contact piece 16 (Figure 14') is
carried by the armature of T2 and, in its initial position, makes a bridge connection
between two springs 17, 18, and, at the end of the stroke of the armature of T2,
separates the springs 19 and 20 from each other. It thus produces the saine effect
"
33
as the springs to and t and their resting contacts, shewn on the diagram.
To the nut 2 of the screw 1 is fixed the frame supporting the "catcher-on-fingers
and the " contact-fingers selector." Each set of "contact-fingers" comprises three
contact fingers of which the stems 21, 22, 23, are shewn in Figure 15, the middle
one for instance being the "service contact finger." Each consists of a finger proper
carried by a stem which a spring tends to project forward, its forward movement
being limited by a pin 24; these stop pins being so placed that the "catcher-on
service finger cannot move beyond the "catcher-on service wire," and the two "line
contact fingers" can reach the line wires with which they are respectively to make
contact. The contact finger proper, shewn on an enlarged scale in Figure 15" as in
contact with the line wire 1*1, consists of a pointed head 24 of the form shewn, so as
to be adapted to enter between the adjacent rows of wires without catching, its
upper edge being covered with insulating material 25 to prevent electrical contact
with the row of wires above, and the underside being slightly recessed at 26 so as to
touch, over a sufficient area of surface, the wire of the row below.
It is carried by a
spring finger 27 fixed to a block of insulating material 28 which is screwed on to the
end of the corresponding stemn.
The contact fingers selector" mechanism comprises for each "member" of the
"selector," a vertical shaft 30 carrying cams 40 adapted to act on levers 31, one
lever being at the level of each set of "contact fingers"; to one end of each lever 31
is attached by a knee joint a wiper 32, the other end of the lever engaging between a
pair of studs 33 fixed to a "stopping plate" 34 which constitutes the first
member of the "contact fingers selector" imechanism for this set.
This "stopping
plate34 has three triangular apertures 35 and can slide transversely in guides 39.
Figure 15 shews separately the "stopping plate" 36 with its three apertures 37
which corresponds to the second "member" of the " contact fingers selector" for the
set of which the first "member" is formed by the plate 34 and its apertures 35.
The finger stems 21, 22, 23 are traversed by cross pins 29, one end of each of which
enters an aperture 35 of the one plate, the other end of the pin entering an
aperture 37 of the other plate. In position of rest, the spring 41 bears against the
lever 31 in such way as to force the plate 34 towards the bottom of the figure, the
spring 42 of the second "member" forcing the plate 36 (not shewn in place in
Figure 15) towards the top of the figure. Consequently the pins 29 and
stems 21, 22, 23, are brought towards the right and there retained so long as either
of said plates is in position of rest. But if shaft 30 be turned so that a cam 40 acts
on the tappet 32 and oscillates lever 31 about its fulcrum 38 (which is formed by a
spring,) the plate 34 will be moved upwards and cease to retain the pins 29.
Similarly, if the cam shaft 43 of the second "meinber" is actuated so as to move
the plate 36 downwards, the three finger stems 21, 22, 23, will be projected forwards 5
by their springs and the fingers carried by them will catch-on" to, or make contact
with, the wires on the "catcher-on board" to which they respectively correspond.
Conversely, as soon as either plate 34 or 36 ceases to be maintained by its cam shaft
in working position, it is returned to rest by its spring 41 or 42 and the cam-like
included sides of the triangular apertures 35 or 37 cause the return to rest of the
corresponding set of contact fingers. Thus the only set of contact fingers put into
operative position the set both of whose "stopping plates" 34, 36 are brought

page_text: *
Coiled
to working position by a particular combination of the angular movements of the
cam shafts 30, 43. The cam shafts 30, 43, respectively receive angular motion by
means of ratchet wheels 44, 45, (shewn by dotted circles in Figure 16) actuated by
pawls 46, 47, fixed to the armatures 48, 49, of electro-magnets M, M.
springs (not shewn) tend to return the two shafts to position of rest but are pre-
vented from so doing by detents 50, 51, which retain the shafts in position to
which they are moved by the pawls 46, 47. On each shaft there are as many
cams as there are sets of " contact fingers in the catcher-on," but the cams have
different angular positions, the angular distribution of the cams corresponding to
any one set of "contact fingers" being different for the two shafts, so that, for a
given angular motion of each of the shafts, there will be one, and only one, set of
contact fingers "whose "stopping plates" will be brought to working position.
Thus for instance, if there are twenty-four sets of "contact fingers," the cams on the
one shaft 30 (in position of rest) would bear against the tappets of sets 1, 2, 3, 4;
for an angular movement equal to one tooth of ratchet wheel 44 the cams brought
into action will be those of sets 5, 6, 7, 8, 9; for a rotation of two teeth of those
sets 10, 11, 12, 13, 14; and so on. On the other shaft 43 (in position of rest) the
cams in operative position will be those of sets 5, 10, 15, 20; for a rotation of one
tooth of ratchet wheel 45 those of sets 1, 6, 11, 16, 21, will be brought into operative
position; for a rotation of two teeth those of sets 2, 7, 12, 17, 22; and so on.
Two long pins 52, 53, fixed to the detents 50, 51 move (during the descent of the
"catcher-on") in engagement with forks 54 (Figure 14) fixed to the armature 15
of electro-magnet T, so that, when the latter is excited by the return-to-rest current,
its attracts its armature 15 and the forks 54 acting on the pins 52, 53, disengage the
detents 50, 51, from ratchet wheels 44, 45; and the shafts 30, 43 are returned to
rest by their spring barrels, at same time returning to rest the set of contact fingers
which were made use of for the conversation now terminated, this reverse rotation
of the cam shafts being permitted by the knee joints of the tappets.
33
The vertical distance apart of the sets of "contact fingers" carried by a "catcher-
on" being equal to the height on the board occupied by five consecutive rows of
wires plus the vacant space between these five rows and the next five rows; and the
various sets of contact fingers of the "catcher-on" being, when in position of
rest, opposite to the said vacant spaces, only five vertical steps at most are required
(i.e. five complete oscillations of the escapement, or five current-emissions acting on
magnet K) to bring opposite to a given line the set of contact fingers which corre-
sponds to the five rows comprising that line. It is for this reason that the comb-like
contact 186 of the rack No. 3 of the "sigual-composing device" (Figure 3) has five
limbs. The number of signals necessary to actuate in any case, the "contact-fingers
selector" depends on the number of sets of contact fingers with which the "catcher-
on" is provided. The drawing Figure which shews a comb like contact of three
limbs for rack No. 2 and one of four limbs for rack No. 1, corresponds to the case
of (3+1) (4+1)-1=19 sets of contact fingers for the "catcher-on."
But any other form of "contact-fingers selector" might be used. For instance, an
arrangement similar to that hereafter described in respect of the "linker" might be
used, each set of contact fingers being under the control of a small electro-magnet;
the two series of currents which have been employed to rotate the cam shafts being
used to rotate the brushes of two small distributors, and, according to the combinations
formed by these two brushes, the current of a "special signal" will be sent to the
one or other of these small electro-magnets and set free the one or other set of
"contact fingers." The contact strip 180 (Figures 3 and 6) in the "signal-com-
posing" device, which is shewn without connection, would be used for sending the
special signal," the said strip being for this purpose coupled to the strips 181, 182, 183.
In this case it will be necessary to add a pair of contact pieces between the fourth
and fifth pairs of each of the five sectors of the "catcher-on distributor," and two
pairs of contact pieces between the sixth and seventh pairs of the "return-to-rest
distributor "F. Similarly, all the sets of "catcher-on contact-fingers" may be connected
so as to catch on all at once to the rows of contact wires or pieces of the "catcher-on
66

page_text: •
board" to which they are opposite, the "contact-fingers selector" having in this case
for function, (by means of two distributors such as have just been referred to,) to put
(or to leave) electrically in circuit the set of contact fingers to be made use of, to the
exclusion of all the others.
a
The "linker," like the "catcher-on," comprises a supporting frame carrying
certain number of sets of "contact fingers" regularly spaced, and capable of being
moved as a whole under the influence of a single prolonged current emission. This
movement may be a vertically upward or downward traversing motion. The two "line
contact fingers" of each set of three, are normally retained out of operative position,
by suitable means, whilst the "service contact finger" is free and is held by a spring
always in operative position, so that, during the movement of the "linker," the
"service contact fingers" rub against the service wires of the "linker board," and,
as above explained, as soon as one of these "contact fingers" meets the service wire
of a line "calling," the movement of the "linker" is arrested, and the "line contact
fingers" of the set to which that "service contact finger" appertains are set free and
come into contact with the line wires which are opposite to them on the "linker
board." In the constructional example shewn in Figures 17, 18, and 19, the "linker"
is moved along a traversing screw spindle 54 of rapid pitch, mounted in collar or ball
bearings (like the screw 1 of the "catcher-on"). Upon this screw spindle 54 is fixed
a ratchet wheel 55 with which engages a detent 56, the nut which travels on the screw
54 carrying the frame on which the sets of " contact fingers" are mounted. The
descending movement of the "linker" begins when, by the electro-magnet Q being
excited, the forked end 58 of the arm 57 of its armature (which engages with a pin
fixed to detent 56,) disengages from the ratchet wheel 55 the detent 56 and the driving
pawl 59, which it does through the medium of the arm 60 and set screw 61. The
reverse rotation of the screw 54 and the consequent return of the "linker" to its
initial position, is effected in the same way as for the "catcher-on," by means of the
electro-magnet U³, whose armature carries the driving pawl 59 and also the insulated
metallic piece 63, which latter breaks in succession the electric connection between
the springs 65, 66, and 67, 68. The insulated spring 70 and contact screw 69 serve
to establish the connection (which is represented on the diagram, Figure 2 as formed
directly) between the armature of electro-magnet Q and its resting contact.
The
Figure 18 (Sheet 12) is a part sectional plan of the mechanism of one set of
"linker contact fingers," the stem 71 which carries the "service contact finger"
being constantly pressed forward by its spring towards the right of the figure.
"service contact finger" Yo which is attached to its stem 71 by an insulating connec-
tion, is T-shaped, the arms of the T, which lie in the vertical direction, being of
insulating material and slightly curved backwards so as to present a rounded surface.
whilst the conductive middle portion to which these arms are fixed is the most salient
portion of the curved face. The length of the arms is such as to prevent the " contact
finger" from entering between any two adjacent rows of wires, the metallic centre
portion of this T-head alone making contact, and that, with only one service wire at
a time. The line contact fingers "Y¹, Y2, are similar to those of the "catcher-on";
they are carried by stems 73 each provided with a tooth 74 which is engaged by a
detent 75, the two detents 75 which correspond to the two "line contact fingers
Y, Y², of a set, forming the armature of an electro-magnet R¹ connected to the
"service contact finger "Yo of this set. It is this electro-magnet R¹ which deter-
mines, as above explained, the coming of the "line contact fingers" Y, Y², into
operative position. Adjustable stops 76 limit the forward movement of each stem 73
so that the finger carried by that stem will reach the line wire of the row with which
it is intended to make contact. For effecting the return to rest of the contact
fingers Y, Y, each stem 73 has a pin 77, and for each set of fingers there is a rock
shaft 78 having two arms 79 which engage by their bent ends with the pins 77, the
rock shaft 78 having another arm 80 (at right angles to the arms 79) through the
forked end of which passes a pull rod 81 which is attached at one end to a lever 82
and at the other end to the armature of electro-magnet U¹, and which carries
collars 83. When the stems 73 are liberated from their detents 75 and moved

page_text: forward by their springs, their pins 77 oscillate the arms 79, and 80, bringing the
arm 80 close up to the corresponding collar 83, so that, when the electro-magnet U¹
is excited and attracts its armature 82, the collar 83, acting on the forked arm 80,
rocks the shaft 78 in the opposite direction and, through the armis 79, retracts the
finger stems 73 and re-engages their teeth 74 with their detents 75. The rod 81 is
common to all the sets of finger stems of the "linker," so that whichever set has
been brought into use will be retracted by the operation of magnet U¹.
The
springs 84, 85, serve to establish the contact which is described with reference to the
diagram Figure 2 as being made between the armature and working contact of
electro-magnet for the purpose of sending the " clearing off" current to the
magnets U2, U³, by which the "linker" is raised to initial position after the "linker
contact fingers "have been retracted.
If the number of subscribers is such as to require a greater number of "selector
circuits" than can be controlled by the "main selector" above described, which has
nine circuits, two means are available :-
1st. A sort of "compound selector," by making dependent on a "primary main
selector" of the kind described, a number of circuits respectively leading to the
metallic piece 1º (Figure 8) of as many "secondary main selectors"; two racks
carrying contacts exactly similar to those of rack No. being interposed between
racks 4 and 5 in the subscriber's "signal-composing" device. The first signal sent
by means of the rack, now become No. 8, will act as described on the "connector,"
whilst the four following signals (which are given, as before described, in accordance
with the adjustment of the racks now become Nos. 8, 7, 6, and 5) would determine
the choice of the "secondary main selector" which in turn would determine the
"selector circuit" dependent on that "secondary main selector"; the number of
"selector circuits" possible being in that case 9 x9=81.
"main
2nd. Such multiplicity of apparatus may, however, be avoided by using
selectors having more than two "members and controlling more than nine
"selector circuits; " for instance, a "selector" having twenty-seven contact springs
similar to those described, and having three "nembers," each "member" being
formed as before of three rods each controlled by its own electro-magnet and each
rod acting by nine insulating pins on nine contact springs. To actuate such a
"selector" having three "members," there would be introduced between racks Nos. 4
and 5 an additional rack carrying contacts similar to those of rack No. 5. In both
cases there must be added to each sector of the "main distributor" B as many
additional pairs of contact pieces as there are racks added to the "signal-composing"
device, the remainder of the apparatus remaining unchanged..
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In a system for the automatic establishment of telephonic communication, in
which the subscribers' lines are arranged in groups as described, the combination
with the line of each subscriber and with an apparatus whereby operative or
controlling signals (of the nature and in the number and order of succession suited
for each case) may be sent through the subscriber's line, of an electro-magnetic
apparatus or "connector" situated at the central station of the group to which this
line appertains and capable of establishing (in response to the first signal sent) a
temporary connection between that line and a single set of electro-magnetic apparatus
(for use in common by the lines of that group) adapted both to govern the
establishment of communication of the line "calling" with any other line, and also
to sever its own connection with the "connector" as soon as the said communication
is established.
2nd. In an automatic telephonic exchange system in which the subscribers lines
are arranged in groups and are connected with groups of contacts with which
are associated other contacts specially assigned to the service of each line, said
line and service contacts being regularly arranged so that those of any line of

page_text: the group may be accessible by the corresponding parts of as many electro-
magnetically operated "junction devices as there are groups, as described, and
in which each subscriber's line is provided with an apparatus whereby operative
signals (of the nature, and in the number and order of succession required in each
case) may be sent, and with a "connector" adapted to operate as described, the
combination with the lines of a group-and their "connectors" on the one hand,
and with a certain number of "junction devices" appertaining to this group, on the
other hand, or a single set of electro-magnetic apparatus (comprising a
❝ main
distributor," a main selector," a "manipulator," and a "return-to-rest
distributor") for use in common by the subscribers of this group, such apparatus
being capable of acting differently in response to the different signals which may be
sent to it, so as (in response to each particular combination of signals) to select
amongst the various "junction devices" that one which is suitable for the
establishment of communication with the line of the subscriber designated by the
particular combination of signals sent, and to transmit to the "junction device"
thus selected, the signals necessary for so actuating it as to cause it to establish
direct connection between the line " calling" and the line "called," the temporary
connection of the said apparatus with the line "calling" being broken by the
action of the "main distributor" itself as soon as the said direct connection is
established, or as soon as the line "wanted" has been tested "engaged." as the
case may be.
3rd. In an automatic telephonic exchange system in which the subscribers' lines
are arranged in groups as described, and in which each subscriber's line is provided
with an apparatus whereby operative signals (of the nature, and in the number and
order of succession, required in each case) may be sent, and with a ❝ connector "
adapted to operate as specified, the combination with the lines of a group and with
their "connectors," of a "main distributor" adapted to successively connect any
line, of that group, to which it may be temporarily connected by the "connector
first to the "members" whose combination constitutes the "main selector," and then
to a <
manipulator," so that each of these latter mechanisms will receive operative
signals in turn, and of electro-magnetic mechanism whereby said "main distributor "
is advanced when the operations corresponding to the previous position are
completed.
"
66
"
"
4th. In an automatic telephonic exchange system in which the subscribers' lines
are arranged in groups as described, and in which each subscriber's line is provided
with an apparatus whereby operative signals (of the nature, and in the number and
order of succession, required in each case) may be sent, and with a connector
adapted to operate as specified, the combination with each group of lines and their
adjuncts, and with a "main distributor" for the group, adapted to operate as
specified, of a "main selector" constituted by the association of a plurality of
❝ members or partial mechanisms electro-magnetically controlled, to each of which
in turn the "main distributor" is adapted to switch the signals sent by the sub-
scriber, each "member" or partial mechanism being adapted to act differently
according to the nature of the signal sent to it and to determine the production of
partial effects in other mechanisms annexed thereto, the partial effects produced on,
or by, the individual "members" conjointly producing a combined effect resulting
in the completion, without interruption, of one particular electrical circuit or
"selector circuit" going from the "manipulator" to one particular set of "junction
devices," the circuit thus formed depending on the particular combination of partial
effects, so that to each distinct combination of signals sent to the "main selector"
corresponds the completion of a particular "selector circuit," each "selector
circuit" being only formed in response to a certain combination of signals.
5th. In an automatic telephonic exchange system in which the subscribers' lines,
grouped as described, are provided each with means of sending operative signals
(of the nature, and in the number and order of succession, required for each case)
and with a "connector" adapted to operate as described, and in which system a
**main distributor" and a "main selector" (each adapted to operate as described)

page_text: are provided for each group of lines for use in common by the lines of that group,
the combination with each such group of lines, their "connectors," and the "main
distributor" and "main selector" appertaining to the group, of a "manipulator" formed
of ordinary relays and batteries suitably connected, such "manipulator," when con-
nected as described to the line "calling," being adapted to then send through the
"selector circuit" which has been completed, electrical currents or signals of various
kinds corresponding to the signals of various kinds which may be sent to it.
"
6th. In an automatic telephonic exchange system in which the subscribers' lines,
grouped as described, are provided each with means of sending operative signals (of
the nature, and in the number and order of succession required for each case) and
with a "connector "adapted to operate as described, and in which system. a "main
distributor," a main selector," and a "manipulator" (each adapted to operate as
described) are provided for each group of lines for use in common by the lines of
connectors
that group, the combination with each such group of lines, with their "
and the main distributor," "main selector," and "manipulator appertaining
thereto, of a plurality of "selector circuits respectively connected to "junction
devices," so that according as one or other of such circuits is completed by the
"main selector in response to one or other combination of operative signals, the
circuit so completed will connect the "manipulator" with the corresponding set of
"junction devices" in such manner that the "manipulator" will have electrical
control over the mechanisin of this set of "junction devices."
"
7th. In an automatic telephonic exchange system in which the subscribers' lines,
grouped as described, are provided each with means of sending operative signals
(of the nature, and in the number and order of succession, required for each case)
and with a "connector" adapted to operate as described, and in which system a
"main distributor," a "main selector," and a "manipulator" (each adapted to operate
as described) are provided for each group of lines for use in common by the lines
of that group, the combination with each such group of lines, their "connectors,"
and the main distributor," "main selector," and "manipulator" appertaining thereto,
of "return-to-rest distributors" actuated electro-magnetically and adapted to receive
such a number of signals and to make such a number of steps in a complete.
cycle of operations that when the "final signal" is sent by the subscriber, the:
brushes of these "distributors will be moved to their initial positions; the con-,
nections of these "return-to-rest distributors" with the "connector ". of the line:
by which the signals were sent, and with the "main distributor " and the "main.
selector appertaining to the group to which this line belongs, being such that:
the local connections completed by the brushes of the "return-to-rest distributors
on thus passing to their initial position, will permit the passage of currents to,
appropriate mechanisin adapted to return the said "connector," "main distributor,"
and main selector" to initial position.
8th. In an automatic telephonic exchange system in which the subscribers' lines,:
grouped as described, are provided each with means of sending operative signals (of:
the nature, and in the number and order of succession required for each case) and.
with a
"connector" adapted to operate as described, and in which system a "mains
distributor." a "main selector," a "manipulator," "selector circuits," and " return:
to rest distributors" (each adapted to operate as described) are provided for each
group of lines, the combination with the lines of each group and their "connectors,"
and with the "main distributor," the "main selector," the "selector circuits,"-
"
and the "return-to-rest distributors" appertaining to that group, of a "catcher-.
on board and a "linker board," or a combined "catcher-on and linker board".
whereon are presented by suitable contact wires or pieces in regular order the two
line wires of each subscriber of that group and also service wires assigned. to each
subscriber's line, such line and service contacts being so arranged as to be accessible.
by the corresponding parts of as many "junction devices" as there are groups of.
lines.
9th. In an automatic telephonic exchange system in which the subscribers' lines,.
grouped and connected with line contacts with which are associated service contacts:

page_text: 22
assigned to each line, as described, are provided each with means of sending operative
signals and with electrically-operated means of connection to current-distributing
and circuit-selecting mechanisms common to the lines of a group, the combination
with the groups of lines and the mechanisms appertaining to each group, and with
"catcher-on" and "linker boards" appertaining to the several groups (on each
of which boards are presented the two line wires and the service wire corresponding
to each line of the group to which the board appertains) of electro-mechanically
operated "junction devices," there being for each group as many such "junction
devices as there are groups, each "junction device" being composed of two
independently-movable parts having contact fingers electrically connected, those of
the one part to the corresponding fingers of the other part, those of the one part,
termed a "catcher-on," being adapted to make electrical connections with the
line and service wire contacts of any one of the sets of such contacts appearing on a
"catcher-on board," and those of the other part, termed a linker," being adapted
to make electrical connection with the line and service wire contacts corresponding
to any one of the lines appearing on a "linker board," all the "linkers" which are
located at the "linker board" appertaining to one group of lines being respectively
in electrical connection with "catchers-on" severally located one at each of the
"catcher-on boards" of different groups.
$
"
66
10th. In an automatic telephonic exchange system in which the subscribers*
lines are grouped, and connected with line contacts with which are associated
service contacts assigned to each line, as described, the combination with the
groups of lines and line "connectors and with the "current distributing,"
circuit selecting," and "manipulating" mechanisms appertaining to each group,
and with boards wheron are presented the line and service wires corresponding
to the lines of the group to which each board appertains, of as many electro-
mechanically operated "junction devices" there being for each group as many
such junction devices as they are groups, each "junction device" being
formed of two independently-movable parts having contact fingers electrically
connected, those of the one part to the corresponding fingers of the other part,
all those parts designated "linkers" which appertain to one group of lines being
located at the same board and the other parts designated "catchers-on being
distributed at the boards corresponding to different groups of lines, each "catcher-
on "being adapted to be moved step by step across the sets of line and service
contact wires or pieces, each step being made in response to an appropriate
operative signal or current sent to it, so that, by the transmission of a suitable
number of operative currents, a particular set of contact fingers of the "catcher-
on" may be brought opposite to any required set of contact wires or pieces on
the board, and each "linker" being adapted to receive an operative signal from
the associated "catcher-on" and to be thereby caused to move across the sets of line
and service contact wires or pieces on the board, the "linker" being provided with
a device adapted to arrest its movement and adapted to be brought into operation
when the "linker," by coming into contact with the service wire or contact which
corresponds to the line "calling," completes the circuit by which the "linker
stopping device" is controlled.
11th. In an automatic telephonic exchange system constituted as described, the
combination with each of the "junction devices" specified, of electrically-con-
trolled mechanisms adapted to actuate, to arrest, and to return to initial position,
the one or other of the two parts which constitute a "junction device," each part.
comprising all the mechanisms necessary for effecting its various movements.
39
12th. In an automatic telephonic exchange system constituted as herein specified,
the combination, with the same "selector circuit," of two or more "twin catchers-on
such as herein described, and, with each such "twin catcher-on," of a "catcher-on
distributor" adapted to distribute the operative signals successively to each of the
operative mechanisms of the said "twin catcher-on" so as to cause the same to be
actuated each in turn, each such "catcher-on distributor" being also adapted to
twin catcher-on
control the circuits by which the signals can reach the associated
"

page_text: apparatus so as to intercept said signals and block such associated "twin" apparatus
so long as the apparatus to which the distributor appertains is in course of being
operated, and also adapted to isolate the apparatus to which it appertains when
such apparatus bas established communication with the line of the subscriber.
wanted."
13th. In an automatic telephonic exchange system constituted as described, the
combination with a known kind of electrically-operated commutator capable, under
the action of suitable signals, of seeking for, and making contact with, a given
contact piece among a limited number of similar contact pieces, of an electrically-
operated "catcher-on distributor" capable, in response to signals received from the
subscriber's line, of switching local signals of appropriate kind successively to the
different mechanisms constituting said commutator, so as to actuate each in turn, and
of service contact fingers adapted to make contact with the service wires or contacts
on a "catcher-on board," the said "service fingers" being connected with a system
of electro-magnetic commutators adapted to furnish the appropriate signal in the
case of the line "wanted" being " engaged."
"
14th. In an automatic telephonic exchange system constituted as described, the
combination with a known kind of electrically-operated commutator capable, under
the action of suitable signals, of seeking for, and making contact with, a given
contact piece among a limited number of similar contact pieces, and with a "catcher-on
distributor," of a certain number of similar sets of contact fingers, each set being
adapted to make contact with the line and service contact wires or pieces of a
"catcher-on board," and of a "contact fingers selector" composed of a certain number
of electro-magnetically controlled "members or mechanisms, the "distributor "
being adapted to switch the signals sent by the subscriber successively to each of
such "members or mechanisms so as to actuate each in its turn, each of said
"members or mechanisms being capable, according to the signals which it receives,
of acting in a different way on the mechanisms which control the various sets of
"contact fingers," so that the bringing of the one or other set of "contact fingers"
into contact with the contact wires or pieces of the "catcher-on board" will be
determined by the combination of the particular effects severally produced by the
"members" or mechanisms of the "contact fingers selector," such combination of
mechanisms constituting a "catcher-on."
"
"
"
99
15th. In an automatic telephonic exchange system constituted as described, the
combination with a "linker board on which are presented in regular order the sets of
line and service wire contacts of a group of lines, of a number of "linkers," each
"linker "comprising one or more sets of line and service contact fingers adapted to make
contact with any set of line and service wires or contact pieces on the "linker board,'
and each "linker" being adapted to be automatically moved across all the sets of
wires or contact-pieces on the "linker board," and each "linker" being combined
with an electro-magnetic releasing device whereby the setting in motion of the
"linker" is controlled and which device is itself electrically controlled by the
corresponding "catcher-on" and also an electro-magnetic stopping device adapted to
instantaneously arrest the motion of the "linker" and to be operated by a current
which it receives when contact is made by one or other of the "service contact
fingers" of the "linker" with the service wire or contact on the "linker board
which appertains to the line "calling" from which emanated the signals that deter-
mined the operation of the "catcher-on" corresponding to that "linker."
16th. In an automatic telephonic exchange system constituted as described, the
combination with a "linker board" and with a "linker
" constituted as herein
specified, of an electro-magnetically operated "contact fingers selector" adapted to
be operated by the current which passes when a "service contact finger" of the
"linker" makes contact with the service wire or contact that corresponds on the
"linker board" to a line "calling," and which same current determines the arrest of
the traversing motion of the "linker" so that this same current will also effect the
bringing into contact with the "line wires or contact pieces" on the "linker board"
F
"

page_text: of the "line contact fingers" forming part of the set to which the "service contact
finger" in question appertains.
17th. The herein described automatic telephonic exchange system, constituted and
adapted to operate substantially as herein set forth.
Dated this 27th day of August. 1898
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.