Improvements in or relating to Telephone Systems.
Year: 1896

page_text: France),
Date of Application (in United Kingdom), 26th Aug., 1898.
Complete Specification Left, 27th May, 1897-Accepted, 24th July, 1897.
PROVISIONAL SPECIFICATION.
Improvements in or relating to Telephone Systems.
I, MOISE FREUDENBERG, of 44 Kouznetsnaya, Odessa, Russia, Journalist, do hereby
declaro the nature of this invention to be as follows:-
This invention relates to improvements in telephone systems by means of which
improvements the functions usually performed by attendants in central telephone
offices or exchanges are performed automatically, the object being to enable any
person on a telephone system constructed according to my invention to put himself into
communication with another subscriber on the same system, without the nid of an
operator located at a central office or exchange.
Before describing in detail the various parts used in my system I will describe the
system in a general manner and the mode of connecting the different parts of which it
is constituted.
At each subscriber's office is a telephonic apparatus connected to a switch placed at
the central office; the connection between the subscriber's apparatus and the switch
is effected by means of two wires, for I will suppose that my telephone system is
arranged to be worked with two wires, the return not being effected through earth.
The switch placed at the central office and corresponding to each subscriber's
apparatus is divided into a certain number of sectors, for example ten, and each of
these sectors is connected, as will hereinafter be seen, to a travelling table forming part
of a particular group of tables placed at the central office.
The central office, apart from the switches therefore comprises ten groups of tables,
and each subscriber has a table in one of these groups, which table is connected to
one of the sectors of the subscriber's switch.
Under the action of currents sent from the subscriber's apparatus through the
corresponding sector of the switch the table connected to this sector may be set in
action, pass successively above beams or rails placed below the path it follows, may
stop and be placed in contact with one of them, the said contact putting the
subscriber to whom the table corresponds in communication with the subscriber whose
apparatus is connected to the beam or rail in question.
At the contral office there are as many contact beams as subscribers, and the line
wires of each subscriber are connected to the corresponding beam placed at the
central office in one of the groups of tables.
Suppose that the system comprises 10,000 subscribers I divide them into groups of
1000, which gives 10 groups of subscribers, and in each group of tables which I have
mentioned I place 1000 beams, each beam corresponding to one of the subscribers of
the group and connected to his apparatus, as will hereinafter be set forth.
It will therefore be seen that if one subscriber wishes to converse with another
whose number is an ordinal of the third group, say for example the subscriber 2846, he
will by means of electric circuits place his switch upon the third sector in order to
be connected by the said switch with the table which belongs to bim in the third
group. This table being set in motion by the action of currents of defiuite direction,
will arrive above the beam corresponding to the subscriber 846 of the third group.

page_text: At this moment the communication is established between the two subscribers and
they can then converse together.
From the foregoing statement it follows that the principle upon which my system
of automatic telephone switches is based consists in the division of the subscribers
into distinct groups, ench subscriber having at the central office a special switch, as 5
many tables as the system comprises groups, and a special part, which I have termed
"beam" placed in the group to which the subscriber belongs.
The description of my automatic telephone system may be divided into four very
distinct parts:
(1) A description of the apparatus placed in the office of a subscriber on the 10
telephone systein (each subscriber's apparatus being similar to each of the others).
(2) A description of one of the switches placed at the central office and connected
directly with an apparatus in the office of the subscriber (all the switches being
alike).
(3) A description of one of the tables connected to one of the sectors of the switch 15
(all the tables are uliko).
(4) A general description of the system of connections.
(a) Between two subscribers of the same group.
(b) Between two subscribers of different groups.
1. A DESCRIPTION OF AN APPARATUS AT THE OFFICE OF ANY ONE OF THE 20
SUBSCRIBERS.
In this description I do not take account of the telephonic apparatus in itself,
which may be of any kind; I have supposed that the Ader telephonic apparatus
generally employed on the French systems, is in use.
I will describe successively all the parts which I add in order to enable this 25
telephonic apparatus to be applied to my system of automatic switches.
Above and at the rear of the telephone apparatus I place all the parts of the
apparatus in a box; these parts comprise a battery; a switch; a second switch; n
polarized electromagnet; an indientor system having three wheels.
The first switch is formed of a flat disc which carries 10 metallic contacts, between 30
which insulators are placed.
At the centre of the disa is pivoted an arm terminating at ita extremity in a knob,
which arm may be turned from left to right completely around its centre."
The arm is connected by a wire with the line wire leading from the subscriber's
apparatus to the central office, and all the metallic sectors of the switch are connected 35
by another wire to the positive pole of the battery, whose central element is connected
by a wire to the wire returning from the central office to the subscriber's office.
By reason of the mode of connection which I have set forth, it will be seen that if
the pivoted arm is turned about its centre it will come successively in contact with each
of the sectors, and each time when a contact of this nature takes place a positive current 40
leaving the battery, will pass through the wire into the contact piece upon which the
arm is held, flow into this arm and through the wire leading to line wiro and arrive
at the central office, then return through the returning wires to the battery. Therefore
ench time the subscriber turns the arm through an arc equal to a sector of the switch
he will send a positive current into the line. It is understood that the arm is 45
insulated from the material of the switch.
The second switch is composed of a disc divided into 6 sectors.
At the centre of the disc is pivoted an arm furnished with a knob by which the
said arm can be acted upon so as to cause it to perform a complete revolution from
left to right about the switch.
Of the six sectors, which the switch just mentioned comprises, the first is of
insulating material, and upon this sector the arm lies when at rest. We may inscribe
upon this sector, as also upon the first sector of the first switch, the word "Stop" in
order that any subscriber inny by a single glance ascertain whether the parts of his
apparatus are really in the position they should occupy.
50
55

page_text: Three of the conducting sectors are connected by a wire 6 to the negative pole of
the battery, while of the two remaining sectors one is insulated and the other
connected by a wire to the polarized electromagnet.
The pivoted arm is connected by a wire to the wire leading to the line wire which
leads from the subscriber's apparatus to the central office.
While the arm is upon the first insulated sector the apparatus is at rest. By
moving the arm from the first insulated sector to the second insulated sector it
passes above the first contact piece upon which the arm must never stop but only pass.
This passage of the arın ahove the first contact piece has the effect, as will be
understood, of sending a negative current into the line. In fact the first contact piece
is connected to the negative pole of the battery. The current coming from this
negative pole arrives in the said first contact piece, passes into the arm and to the line
wire. It returns from the ceutral office and finally arrives in the battery.
The same phenomena occur when the subscriber causes the arm to pass from the
second insulated sector to the contact piece in connection with the electromagnet, the
arm rubbing upon the intermediate contact piece connected to the negative pole of the
battery.
By moving the arm from the electromagnet contact piece on to the insulated sector
it occupies when at rest it will be caused to rub upon the intermedinte contact piece,
which will, as in the former cases, cause a negative current to be sent.
It will therefore be seen that a complete turning of the arm upon the switch will
have the effect of sending three negative currents, and connecting the positive
electromagnet to the line between the times of sending the second and third negative
currents.
It will hereinafter be seen, when describing the mode of operation what is the object
and function of each of these currents.
The three wheel disc indicator is of the kind employed as speed indicators. It
is composed substantially of a first disc, up on the axis of which is fixed a ratchet wheel
which can be actuated by a pawl through the agency of the polarized electromagnet,
the pawl being connected to the armature of the electromagnet by a rod. A retaining
pawl regulates the movement of the ratchet wheel which must turn only through an
angle equal 10 one tooth at each attraction of the armature by the polarized electro-
magnet.
The first disc bears the figures 0 to 9, and opposite each of these figures, upon the
edge of the disc, is formed a notch for engaging the arm which may be turned about
its centre by hand. This arm, like the arms of the switches before mentioned, is
similar to those employed in the Breguet switches, that is to say they can be sunk
into the notches formed at the edges of the dises upon which they are placed.
The second dise of the indicator is similar to the first dise excepting that it is not
actuated by the polarized electromagnet.
This second dise turns through our division each time the first disc inakes &
complete turn.
The mole of operating the second disc by the first disc does not present any
particular feature, and I reserve the right to employ any devices used in speed
indicators for effecting the movement of the tens wheels by the units wheels.
What I have just stated in respect of the second wheel applies also to the third
wheel which corresponds to the hundreds wheel of a speed indicator. Each time
the tens wheel or second disc bas made a complete turn the hundreds wheel or third
dise will turn through one division. Ilence it follows that the system of the three
wheels apart from the arus, and the notches formed at the edges of the wheels,
constitute a true revolution counter. The arrangement of these three wheels is
completed by certain electric connections which I will now proceed to describe.
When the hundreds wheel is at zero, the arin being in the zero notch, bears upon a
contact piece which is connected by a wire with the negative pole of the battery.
The arm of the latter wheel or disc, which is of course insulated from the rest of the
apparatus, is connected by means of a wire with the contact piece, which the arm of
the second disc bears upon when this disc is at rest and when its arm is in the notch

page_text: corresponding to zero. This arm is in turn connected by a wire with a contact
pieco situated like the preceding ones, outside the disc, but between the 0 and tho 1 o
this first diss when the latter is at rest. In this position, the arm of the first disc does
not touch the contact piece between the 0 and 1. The arm of the first disc is
connected to the line wire.
The subscriber's apparatus, as will hereinafter be seen, enable the parts placed at the
central office to be automatically operated.
2. DESCRIPTION OF ONE OF THE SWITCHES PLACED AT THE CENTRAL OFFICE
CONNECTED DIRECTLY WITH THE SUBSCRIBER'S APPARATUS.
All the subscribers' apparati are identical with the one I have just described, and
each of them is connected by two line wires with a switch placed at the central office;
now, as all the switches at the central office are alike, it will be sufficient in the
following description to specify oue of them.
This switch is composed substantially of a horizontal dise of insulating material,
which carries at its outer edge a rim divided into eleven sectors ten of which are alike
and one small sector termed "stop sector," which is one third the width of any one of
the other sectors.
This division of the switch into ten main sectors results from the grouping of the
subscribers which have adopted. The number of sectors in the switch inust
generally be equal to the number of groups of subscribers.
In this case there are ten groups of subscribers, accordingly the switch will have ten
sectors.
Each of the ten largo sectors is divided into two parts insulated from each other;
the smaller part is connected by a wire to an electromagnet operated by positive
currents, and the other part is united by a wire with one of the groups of travelling
tables which will hereinafter be described.
For facilitating the explanation 1 have supposed that all the smaller parts of the
sectors are electrically connected indirectly to the last mentioned electromagnet
In practice and for the construction of the apparatus I may of course employ any
suitable mode of connection.
The different sectors are insulated from the material of the supporting disc as well
as from each other.
Upon this disc and concentrically within the rim of sectors is fixed a ring connected
by a wire with a second polarized electromagnet operated by negative currents.
The small insulated stop sector, which is one third the width of any one of the
other sectors, is connected at its outer part to a wire which extends from the switch.
The inner part of this sector is insulated from the outer part.
Upon the disc an arin which carries two brushes can be moved. The first of these
brushes, during the rotary movement of the arm rubs upon the other sectors in such
a manner that when it is upon the smaller part of the first right hand sector for
instance, the outer brush rubs at the same time upon this smaller part, and also upon
the larger part of the sector connected to the wire, leading to the travelling table
mechanism.
When the arm is at rest the outer brush bears at the same time upon the two
insulated parts of the stop contact piece.
The second brush which is placed nearer the centre than the preceding brush, is
designed simply to connect the sectors, and the inner part of the stop contact piece to
the inner ring when the arin rubs upon them, but the inner brush is also arranged so
as never to touch the smaller parts of the different sectors nor the outer part of the
stop contact piece.
Supposing each of the sectors to be divided by radii of the disu into three equal
parts, it will be obvious that each of the parts extends exactly a third part of the
length of the sector into which it is inserted, but it has only half the width of the
sector.
The electromagnet which as hereinbefore set forth is operated by negative currents,

page_text: can actuate by its armature, a rod jointed at its upper end upon a second arm which
carries a pawi acting upon a ratchet wheel having 93 teeth. The movement of the
armature is regulated in such a manner that each time the electromagnet is traversed
by a negative current the pawl effects the rotary movement of the ratchet wheel
through a distance equal to the are formed by three teeth.
This mtchet wheel carries at its centre, which is recessed, small pawls which net
upon teeth forined upon the axis which supports the switch arm. This axis terminates
at its lower part in a point resting in a socket hearing.
Owing to this arrangement it will be seen that the rotary movement of the wheel
carrying the three pawls under the action of the pawl actuated by the second arin will
effect the rotation of the axis, and consequently of the first arm.
The first electromagnet, as has been seen, is netuated by positive currents, and its
armature, acts upon the rod which is jointed to a short arm also carrying a pawl.
This pawl acts upon a ratchet wheel having 31 teeth, and the movement of tho
armature of the electromagnet is such that in each displacement the pawi on the
short arm will cause the corresponding ratchet wheel to turn through an angle equal
to three teeth.
This ratchet wheel, like the mtelet wheel actuated by the longer arm, is also
recessed at its centre, and carries pawls which engage with the teeth formed upon
the shaft of the first mentioned arm.
Owing to this arrangement it will be understood that any one of the toothed wheels
can turn the first or switch arm without turning the other wheel in its movement, in
other words the two wheels, while they are independent of each other, enn in turn
impart rotary movement to the shaft upon which the switch arm is fixed.
From the foregoing it follows that when the second electromagnet is traversed by a
negative current the switch arn will turn through an are equal to s of the complete
circumference, that is to say ' Accordingly the arm will make a complete
revolution under the action of 31 suecessive negative currents, and it will traverse a
complete sector of the switch with three vibrations of the armature.
When on the contrary the first electromagnet is traversed by a positive current the
switch arm will turn of a revolution, that is to say each of the movements of this
arm, when it is actuated by the first electromagnet will be three times as great as
any one of the movements effected by this arm under the action of the second
electromagnet.
The line wires from the subscribers apparatus to the switch are connected: one,
with the switch arm, and the other to the electromagnets.
3. DESCRIPTION OF ONE OF THE TRAVELLING TABLES CONNECTED TO ANY OF THE
SECTORS OF ANY SWITCH AT THE CENTRAL OPPIck.
In the preceling description of the system it has been stated that from the different
sectors of any one switch, wires extend. Each of these wires are connected to certain
parts which I will now describe and which actuate the tables in the group under
consideration which corresponds to the subscriber, so as to set the said table in notion
or to stop it according to circumstances. On this subject I may mention again that
the division of the automatic switch is effected in such a manner that each subscriber
possesses a table in each group and thus each subscriber will have ten tables at the
central office.
For each group of tables placed at the central office I lave provided an electro-
motor which is actuated in a continuous manner by currents from a battery of
accumulators or from a motor. This dynamo transmits its motion through the
median of pulleys to a shaft carrying a set of two bevel wheels for encli table.
These two bevel wheels turn at the same time as the aforesaid shaft, but can he moved
along this shaft in such a manner that either one or the other gears with a third wheel
fast on a screw for operating the table.
Between the two bevel wheels a polarized electromagnet is arranged which is

page_text: connected at one terminal to the switch wire and at the other terminal to a wire
loading to the subscriber's return wire.
When no current traverses the electromagnet the two bevel wheels are placed in
their middle position, that is to say neither of them gears with the screw shaft wheel.
When the electromagnet is traversed by a negative current it moves the two bevel
wheels in a direction parallel to the shaft, so that one of these wheels comes in contact
with the screw shaft wheel, the latter rotating, turns the screw upon which it is
mounted. The electromagnet is arranged in such a manner that if it is traversed by
a second current the inoveinent of the two bevel wheels is effected in the opposite
direction so as to bring them back to their middle position, that is to say, to the position
in which the screw shaft wheel is not in contact with either of the oth r two. A third
current sent through the electromagnet causes the displacement in the same
direction as the second, so that the other wheel comes in contact with the screw shaft
wheel,
The screw therefore turns in the opposite direction, and in order to bring the two
bevel wheels back to their middle position I do not use a fourth negative current, but
a mechanical device formed by a bell-crank lever acting at one of its extremities
upon collars attached to the two bevel wheesl, the other extremity being
situated near the screw in the way of the table which is moved along this screw,
so that when the table returns to its starting position it will press against the t
extremity of the bell-crank lever thus bringing the bevel wheels back to their middle
position and stopping the rotary movement of the screw.
I reserve the right to use any arrangements which enable me to perform the three
movements which I have just mentioned.
By way of example I will describe an arrangement which consists in connecting the
armature of the electromagnet with a cam turning about its centre and having three
teeth which are arranged in such a manner that the action of the first tooth causes the
displacement of the bevel wheels in one direction, the action of the second and the third
teeth causing the movement of the two bevel wheels in the opposite direction; the
extent of each movement depending on the thickness of the teeth of the cam. But it
is understood that I describe this arrangement only by way of example, reserving the
right to use all those which may be employed for producing the effects to which I
have referred.
From the foregoing it will be obvious that the screw and screw shaft wheel may
either be motionless or may turn in one direction or the other, this being effected-
by sending currents through the electromagnet. I shall hereinafter state the object
of these movements.
Upon the screw is mounted the travelling table which forms the nut of this screw
and which is consequently moved horizontally from right to left or from left to right
according to the direction in which the screw tauns.
In order to prevent the turning of the table at the same time as the screw ] provide
two supports which bear it. The table proper is composed of a platform carrying an
index or brush which during the movements of the table will rub upon a band bearing
inetallic contact pieces at intervals. The brush or index is connected by a wire with the
subscriber's line wire, and the metallic contacts arranged along the band are connected
to a battery which itself is connected by wires to the subscriber's return wire.
The front part of the table has an inclined arm jointed to it the one extremity of
which is formed of two metallic parts insulated from each other. This inclined arm
can turn about its joint and a spring holds it normally slightly inclined toward the
front. The rear metallic part of the arm ia connected indirectly to the subscriber's
line wire, whilst the forward metallic part is indirectly connected to the subscriber's
return wire.
Below the travelling tables which constitute each group and which are placed
parallel to each other, beams are arranged perpendicularly to the direction of the
table which beams are divided into two metallic parts insulated from each other.
These beams are mounted upon vertical rods and subjected at intervals to the action
of springs which constantly tend to hold these beams at a certain level

page_text: Abutments may limit the height of the beams, the springs keeping the beams against
these abutments. If any one table passes over one of these beams the inclined arın
of the table will bear upon and lower it. If at this moment the table stops, the
arm will remain in contact with the beam but if on the contrary the table continues
its travel the arin will turn about its joint and escape from the beam which nuder
the action of its springs will rise again to its original position.
From this it follows that any one table traversing the whole length of the screw
upon which it is mounted will successively cause all the beams below to descend the
said beams returning to their position under the action of the springs directly after
the passage of the table.
As hereinbefore stated each subscriber to the systein belongs to a well defined
group at the central office in which group he possesses one beam only.
It therefore remains for me to describe the mode of connection between a
subscriber's appamtus and the apparatas which belongs to him at the central
office.
The two parts of this heam are connected, one by a wire to the wire returning
to the subscriber's office and the other by a wire to the stop contact piece of the
subscriber's switch.
I will hereinafter, when describing the connections, explain the object of this
arrangement.
If the automatic switch has to be used for a system, comprising a very large
number of subscribers, for instance 10000 subscribers, divided into groups of 1000,
I should he compelled to use 10000 tables in line in each group and although the
dimensions of each of these tables are very small I should require a shaft of great
length. In order to remedy this inconvenience I do not arrange all the tables of
the same group upon the horizontal plane, but I divide them into secondary
groups placed on horizontal planes which are parallel to each other. In this ens
the beam of any subscriber, instead of being formed in one piece if divided
into several parts placed vertically one below the other; these different parts
being connected by rods in such a manner that under the action of one of the
tables the whole of these parts will be lowered as if the beam were single.
The arrangement of the connection of the trucks with each other has for its object,
as will be understood, to prevent more than one subscriber being able to put himself
in contact at the same time with another subscriber.
Considering the case of a continuous beam not divided into parts it is obvious that
when the beam has been lowered by a table, it is impossible for another subscriber to
put his table in contact with the said beam, and such is also the case with a beam
divided into several parts, because, as has been stated I connect the different parts of
the beam.
It has herein before been mentioned that I provide a motor for each group, which
motor turns in a continuous manner as I have explained, but it is understood that at
the central office, in lieu of providing a motor for each group, I may have either a
single motor for the whole system, operating the different shafts of the groups by
meaus of transmitting mecluanism, or any number of motors according to the
arrangement of the central office.
Having thus described in detail all the parts which constitute my improved
system of automatic telephone switch I will now proceed to describe the connections
established hetween these several parts.
4. GENERAL DESCRIPTION OF CONNECTIONS.
1 inny state at once that in the description which follows I have supposed a systein
established for 20 subscribers divided into groups of two, moreover I have supposed
that in each group the travelling tables are placed upon two parallel horizontal planes
each comprising only 10 tables."
The subscribers Nos. 1 and 2 have their beam in group No. 1, the subscribers 3
and 4 in group No. 2; the subscribers 5 and 6 in group No. 3; the subscribers 7

page_text: and 8 in group No. 4; the subscribers 9 and 10 in group No. 5; the
subscribers 11 and 12 in group No. 6; the subscribers 13 and 14 in group No. 7;
the subscribers 15 and 16 in group No. 8; the subscribers 17 and 18 in group No. 9;
and the subscribers 19 and 20 in group No. 10. Accordingly the subscribers 1 and 2
2
]]
2,
will be designated respectively by the fractions, the subscribers Nos. 3 and 4 by
the fractions and...and so on, which signifies that the subscriber No. 4 is
the second of the second group. That is to say the second beam of the second group
belongs to him, in like manner as the subscriber No. 1 is the first of the first group,
that is to say, the first beam of the first group belongs to him, and so forth. In the
fraction designating a subscriber the numerator designates the group and the
denominator the ordinal number of the subscriber in that group.
I will describe:
(1) The operation of the apparatus when the communication has to be made
between two subscribers belonging to the same group, and I will set forth for this
purpose the connections between the apparatus and the apparatus 2.
1
1
(2) The connection between two subscribers of different groups, and for that
purpose I will describe the connections between the subscriber and the subscriber
1
5
2.
The subscriber wishing to communicate with any subscriber on the system must
first of all cause the arm of the switch placed at the central office to leave its position
of rest. For this purpose be will send a negative current as will be explained. With
this object he operates the aim of the Grector switch placed in his apparatus, turning
it so as to bring the said aim upon the second contact piece to the right of the
position of rest; in this movement the arm rubs over the first contact piece placed
between the two contact pieces to which I have just alluded. By rubbing upon the
first contact piece the arm closes the current including the subscriber's battery and the
second electromaguet of the central office switch. In fact a negative current leaving
the subscriber's battery passes the first right hand contact piece of the 6 sector
switch; the arm thereon, the line wire, arm of the central office switch, passes through
the brushes into the rim of the switch, and thence to the second central office
electromagnet. From this electromaguet the current passes through the return wire to
the subscriber's battery. The circuit of the latter electromagnet being closed, the
said electromagnet is traversed by a negative current. It is consequently actuated,
because it is known that polarized electromagnets can be operated by negative
currents. Its armature is attracted, and the rod jointed thereto is lowered, compelling
the pawl on the longer arm to turn its ratchet wheel through an are equal to three
1
teeth. The arm of the switch therefore turns 11 of a revolution and it will thus be
placed above the first part of the first sector to the right of the stop sector in such a
inanner that the outer brush rubs upon that contact piece occupying one third of the
length of the sector as well as upon the other part of the sector, whilst the inner
brush rubs upon the rim and upon the lower part of the first right hand sector.
As soon as the switch arm has left its position of rest it is impossible for any
subscriber on the system to put himself in communication with the subscriber to
whom the switch belongs the movement of which I have just described, because
this subscriber's beam is connected by a wire to the stop contact piece, and because
at this time, owing to the movement of the switch arm the stop contact piece is
no longer in communication with the line.
1
The switch arm having left the position of rest, I will now describe the succession
of the operations. The subscriber who wishes to communicate must find the group
of the subscriber with whom he wishes to converse. In this case it is a subscriber of

page_text: 1
the first group who is represented by 2, therefore the subscriber need not cause the
movement of the central office switch arm to another sector of the switch, because
this arm is upon the sector required (the first). The same would not be the case if
the subscriber to whom the subscriber wished to speak were of another group than
the first. It will hereinafter be seen, when reviewing the connections between the
subscriber and , that the subscriber will have to act upon the arm of his 10 sector
switch so as to bring the arm of his central office switch upon the fifth sector.
5
1
To state concisely what I have just said, the movements of the switch arm from one
sector to another of the central switch are effected by acting upon the subscriber's
10 sector switch, and in the example chosen the subscriber need not move the switch.
arm to bring it upon another sector, because it is upon the required sector.
Accordingly, as hereinbefore stated, the subscriber has not to search for the group
on which the subscriber to whom he wishes to speak is placed, because the switch
arm of the subscriber bas, by the sending of the first negative current, been placed
above the sector No. 1 connected to the group to which the subscriber belongs.
1
1
2
The switch arm of the subscriber who calls is therefore upon the sector corresponding
to the group in which the subscriber called to his beam is placed, and it is sufficient
for the subscriber t
I to move his travelling table of the group 1 until it comes in
contact with the second beam of the group which is that corresponding to the
subscriber For effecting the movement of the table, the subscriber operates the
arm of the lower disc of the revolution indicator, and causing it to turn in the
direction the reverse of clockwise be places it in the notch corresponding to the unit
of the subscriber's number, the notch No. 2. The manipulations to which the lower
disc arm of the indicator is to be subjected are terminated, for the subscriber's number
comprises neither tens nor hundreds.
It would bave heen otherwise if, in lieu of describing a system of automatic switch
for 20 subscribers divided into ten groups of 2, I had set forth a system for 10,000
subscribers divided into 10 groups of 1000. In this case, apart from the indication
of the group, certain subscribers would have had three or two figures to the numbers
which designate them; thus for instance the subscriber No. 2846 or
forms part
3
846
of the third group and possesses the beam No. 846. In this case the subscriber
wishing to speak to the subscriber No. 2846 would in the first place have to operate
his 10 sector switch in order to search for the group, as will hereinafter be seen, he
would then operate the revolution indicator so as to place the arm of the lower disc
upon the 6th notch, the arm of the intermediate disc upon the 4th notch, and the
arm of the upper disc upon the 8th notch.
From this it follows that what I am about to state in respect of the subscriber
would apply integrally, apart from the positions given to the arms of the revolution
indicator, to the subscriber No. 846 of the third group, if, instead of having 201
subscribers on the system, as I have supposed, I should have 10,000,
The subscriber, after having placed the arm of the lower disc of the revolution

page_text: indicator upon the second notch, again moves the arm of the 6 sector switch in order
to bring it from the second contact-piece to the 4th contact piece. In this moveinent
the arm rubs upon the 3rd contact piece, which has the effect of closing as before, the
circuit including the central second electromagnet and the subscriber's battery: a
negative current then traverses this electromagnet, and the armature of the said
electromagnet acts as before upon the switch arin cansing it to pass upon the middle
part of the first right hand sector of the central office switch, for it is known that
under the action of the electro-magnet three movements of the switch arm are needed
in order to traverse the complete sector.
The central switch arm, being upon the middle part of the sector, is in contact only
with that part of the sector connected by wire to the electromagnet for operating the
bevel wheels, and it has completely abandoned the part of the sector connected to the
first electromagnet at the central oflice..
The negative current to which I have just alluded, and which, being sent by tho
subscriber, has caused the displacement of the switch arm, also passes through the
first right hand sector, and through the wire lending to the bevel wheel electromagnet,
returning through the return wire to the battery at the subscriber's office.
Consequently the circuit of this electromagnet is'closed, as has been seen, causes one of
the bevel wheels to approach the screw-shaft bevel wheel. These two wheels then
gear with each other, and the screw commences to turn. The corresponding travelling
table is moved and the index or brush on this table rubs upon the first metallic
contact piece of the band or strip at its side. By reason of its contact with this piece
the index closes the circuit including the subscriber's electromagnet and the battery
at the central office.
In fact a current leaves this battery, arrives at the contact piece on the strip or
band, passes through the brush on the table, and thence through the line wire, and
reaches the subscriber through the arm of the 6 sector switch, passes thence into the
4th contact piece thereon upon which the arm rests at this time, traverses the
subscriber's electromagnet and returns to the central oflice battery. The circuit of
the subscriber's electromagnet is thus traversed by a positive current, for the central
office battery can send only positive currents.
The subscriber's electromagnet being traversed by a positive current attracts its
arinature, and the lower disc turns through an angle equal to one division, noving its
arm, because the latter has been placed in the second notch of the disc.
The travelling table while touching the first contact piece on the strip or band
with its index or brush bears with its front arm upon the beam No. 1, but, as under
the action of the motor the table continues its inovement it only lowers the beain
without stopping, and the table arm escapes from the first beain.
The subscriber's table continuing to nove will soon touch the second metallic
contact with the index on the table and, for the the same reasons as before, a second
positive current arrives at the subscriber's apparatus and actuates the electromagnet
there. The lower dise then turns again through an are equal to a division, but in
this second rotation the arm of this disc will rub upon the contact piece connected to
the arm of the intermediate disc and close the circuit including the electromagnets
of the central office switch, and the subscriber's battery. In fact a negative current
leaves the subscriber's battery, arrives by way of the contact piece to the arm of the
upper disc of the revolution indicator and thence through to the arm of the
intermediate disc, and through to the arm of the lower disc which is at this time
above the outer contact piece, and lastly into the subscriber's line wire. Thence it
arrives in the central oflice switch arm. From this switch arm it passes through the
outer brush thereon into the first right hand seator then through the inner brush into
the switch ring, and lastly into the second electromagnet. The current traverses this
electromagnet, returns through the return wire to the subscriber's battery.
The second electromagnet being traversed by a positive current is actuated, and
the switch arm which was upon the middle part of the first sector, comes upon the
last part of this sector. But, further, the negative current sent by the subscriber's

page_text: battery into the first sector is divided, one part passing to the second electromagnet,
whose effects I have just described, and the other part through the bevel wheel
electromagnet, returning by way of the return wire. Therefore the cireuit of the
bevel wheel electromagnet is also formed, and it is traversed by a current which,
as has herein before been seen, causes the displacement of the two bevel wheels so as
to place them in their middle position. The screw shaft wheel no longer gears with
either of the said bevel wheels, the table stops, and at this time it is, as has been
before mentioned, above the 2nd benm, and in contact with it. In fact the table
index or brush and the table arm are arranged in such a manner relatively to each
other that at the time when the contact between any one of the contact pieces of the
strip or band and the table index takes place the table arm commences to lower the
beam above which it is passing at the time, and further, the table arm has not
escaped from the beain when the contact between the table brush and the contact
piece on the band or strip has ceased.
In the position under consideration the table of group No. 1 which belongs to the
subscriber is in contact with the 2nd beam of the saine group belonging to the
subscriber with whom the subscriber wished to put himself in communication.
1
1
Now the beain No. 2 which has thus been lowered by the arm of t'
mentioned, is divided into two parts, one of which is connected to
piece of the switch of the subscriber to whom it belongs, and the
connected to the wire returning to the latter subscribor's offi
communication is therefore established between the two subscribers
2
lo as before
op contact
f which is
Telephonia
and the
ich do not
uts cannot
in contact
e all the
means of
et at the
subscriber may call the subscriber by means of positive curret
change the position of the parts of the system. In fact these positive
pass the first central electromagnet because the central switch ar
with the smaller contact piece of the first sector of the switch, and
other polarized electromagnets of the system act upon their armature
negative currents, except the subscriber's electromagnet. The electrc.
apparatus of the subscriber who calls is actuated by positive currents for bells or
conversations, for at this time the lever of the 6 sector switch is upon the 4th contact
piece, but the action of these positive currents upon the subscriber's electromagnet
can only cause the rotation of the wheels of the indicator, which is quite a secondary
inconvenience and which may be avoided by taking care to stop these wheels by any
suitable means before ringing the bell or talking with the subscriber with whom the
communication is established.
The positive currents for bells or for operating of the telephone proper do not give
rise to any action upon the parts of the central office switch of the subscriber with
1
whom the subscriber speaks. Indeed, these currents arrive in the stop contact
piece of the central office switch of the subscriber pass into the outer brush on the
1
2'
1
switch arm and thence into the line of the subscriber, arrive at his apparatus where
they ring the bell, returning through the return wire into the 2nd part of
the beam, and thence through the forward part of the table arm into the
subscriber's return wire. At this time no other subscriber can put himself in
communication with the subscriber ), for the switch arm of his central office switch
1

page_text: is no longer upon its stop contact piece, and in liko manner no other subscriber can
put himself in communication with the subscriber 1, because this subscriber's beam
1
is lowered by the table which corresponds in the group I to the subscriber
When the conversation is at an end it is necessary to move all the displaced parts
back to their original position.
The subscriber who called operates the arin of his 6 sector switch so as to cause
it to pass from the 4th contact piece to the 6th contact piece rubbing it over the 5th
contact piece.
1
The contact of the arm upon the 6th contact piece, as before mentioned causes a
negative current to be sent through the line wire. This negative current arrives
through wires to the arm of the central office switch belonging to the subscriber.
passes through the outer brush on the arm into the first sector and there is divided:
one part passing through the inner brush on the switch arm and the rin, will
traverse the second central electromagnet to return the apparatus of the subscriber ī,
1
1
and the other part passing from the inner terminal of the first sector arrives in the
bevel wheel electromagnet and returns to the apparatus of the subscriber. The
first of the two latter electromagnets which are traversed by a negative current, acts
upon the central switch arm to bring it from the last part of the first sector to the
first part of the second sector. The second electromagnet has the effect of moving
the two bevel wheels so as to put the first bevel wheel in gear with the screw shaft
wheel. This latter therefore begins to turn in the opposite direction to that in which
it had turned at the time of the movement of the table toward the front. This table
then returns to the rear, and having reached its starting point will abut against the
extremity of the bell-crank lever, which has the effect of bringing the bevel wheels
to their middle position, so that the table stops and remains in its position of rest.
The negative current to which I have just alluded and which has been produced by
the passage of the arm of the 6 sector switch upon the 5th contact piece of the
apparatus of the subscriber is divided in the first sector as has been seen, one part
has traversed the second central electromagnet, and the other, the bevel wheel
electromagnet, further, this current has passed into upper part of the table arm,
thence into the beam, before the separation of this latter from the table arm, and lastly
1.
into the switch of the subscriber
1
This negative current traversing the second electromagnet of the central offico
switch causes the switch arm to be placed upon the first part of the first sector. At
this time, that is to say after the sending of the last negative current caused by the
operation of the 6 sector switch in the apparatus of the subscriber
the parts
occupy the following positions:
1
1
(1.) At the apparatus of the subscriber : the arm of the 10 sector switch is in
the 1st notch, it has not moved;
The arm of the 6 sector switch has returned to its starting point;
The discs of the revolution indicator are in the position of rest.
(2.) At the central office switch of the subscriber
part of the first sector.
i
the arm is upon the first
(3.) At the travelling table corresponding to the subscriber in the first group:

page_text: mas ree
position
1
for a fresh connection.
(4.) At the central office switch of the subscriber to whom the subscriberhus
first spoken:
The switch arm is upon the first part of the first sector:
(5.) At the apparatus of the subscriber: none of the parts have changed their
places.
It is therefore sufficient, for all the parts to be brought to zero, that the arms of
the two central office switches may return to their stop contact pieces. This is very
easy, and it is only necossary for each subscriber to turn the arm of his 10 sector
switch from left to right until this arm returns to its position of rest.
The operation which I have just described has for its object to send into each
switch as many positive currents as there will be contacts with the metallic contact
pieces of the 10 sector switches.
In fact when the arm of one of the 10 sector switches comes in contact with one
of the metallic contact pieces of this switch a positive current leaving the
subscriber's battery arrives at the contact piece under consideration, passes into the
10 sector switch arm and thence through to central office switch.
Referring first of all to the arm of the central office awitch helonging to the
subscriber it will be seen that it is upon the first part and also on the smaller
insulated part of the second sector consequently the first positive current will arrive
through the outer brush on the arm to the smaller contact piece and thence to the
first central electromagnet to return through wires to the subscriber's battery; the
first central electromagnet being traversed by a positive current attmets its armature,
and the rod attached thereto, through the agency of the pawl on the short arm
causes its ratchet wheel to turn through an arc equal to three teeth; the switch arm
will thus pass from the smaller contact piece in the second sector to the smaller
contact piece of the third sector, because the displacements of the switch arm caused
by the hrst electromagnet are three times greater than those caused by the second
electromagnet. If the bscriber continues the operation of the arm of the 10
sector switch the central swtch arun continues to jump progressively from the smaller
contact piece of the third sector to the smaller contact piece of the fourth sector and
so on until it arrives at the stop contact piece. Arrived here it does not move again,
for this contact piece is not connected to the first electromagnet. All the parts of
the apparatus of the subscriber will thus be brought to zero, when this subscriber
has given a complete turn to the arm of his 10 sector switch.
1
1
1
What I have just stated in respect of the subscriber also applies to the
1
subscriber 5, and the operation of the arm of his switch will in the same manner
bring the arm of his central office switch upon the stop contact piece. Thus all the
operations are terminated.
In the description of the connection which I have just given I have supposed that
1
the subscriber communicates with the subscriber who is on the same group as
himself.
1
I will now suppose that the subscriber speaks for instance to the subscriber
who forms part of group No. 5.
5
う
The only differences which exist in respect of the operations in this case arise from
1
he operation of the arm of his 10 sector switch by the subscriber, which operation

page_text: was not required in the first instance, because the two subscribers belonged to the
same group.
1
As I have hereinbefore shown, after the sending of the first negative current
designed to cause the switch arm to leave its position of rest the subscriber
must act upon the 10 sector switch so as to place the arm of the central office switch
upon the sector corresponding to the group in which the subscriber is placed with
whom he wishes to speak. In the present case the subscriber belongs to the fifth
group.
Accordingly he has to displace the arin of the 10 sector switch so as to bring it
between the 5th and 6th metallic contacts.
He will thus have sent 5 positive currents, and the arm of his central office switch
will have been placed upon the larger part of the fifth sector, thus opening the
1
communication of this switch with the travelling table of the subscriber placed in
group No. 5.
From this time the operations recur in the same manner and in the same order,
and I will in conclusion enumerate them successively.
Manipulations which a subscriber must perform in order to put himself in
communication with another subscriber on the saine system:
(1.) To send a negative current through the 6 sector switch in order to cause the
arm of the switch placed at the central office to pass from its position of rest to the
smaller contact piece of the first sector.
(2.) To send a series of positive currents through the 10 sector switch with the
object of placing the arm of the central office switch upon the first part of the
sector corresponding to the group including the subscriber to whom it is desired to
speak.
(3.) To arrange the arms of the revolution indicator discs according to the ordinal
number which the subscriber has in the group under consideration.
(4.) To send a negative current through the 6 sector switch having for its object
to set in motion the travelling table of the subscriber in the group under
consideration.
After the sending this negative current the table as it is displaced, causes the
passage to the subscriber of positive currents which, arriving in the subscriber's
electromagnet cause all the wheels of the indicator to move.
(5.) The arms of the wheels of the indicator arriving in their position of rest send
to the central office a negative current which stops the table. It is at this time that
the subscribers can speak together.
(6.) To send a negative current through the 6 sector switch at the apparatus of
the subscriber who has called. This current has the effect of bringing the table to
its original position.
(7.) To complete the revolution of the arms of the both 10 sector switches with
the object of bringing all the parts to rest.
Improvements in or relating to Telephone Systems.
I, MOISE FREUDENBERG, of 44 Kouznetsnaya, Odessa, Russia, Journalist, do hereby
declare the nature of this invention and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
This invention relates to improvements in telephone systems by means of which 5

page_text: improvements the functions usually performed by attendants at central telephone
offices or exchanges are performed automatically, the object being to cuable any
person on a telephone system constructed according to my invention to put himself
into communication with another subscriber on the same system, without the aid of
an operator located at a central office or exchange.
Before describing in detail the various parts used in my system I will describe the
system in a general manner and the mode of connecting the different parts of which
it is constituted.
At each subscriber's office is a telephonic apparatus connected to a switch placed at
the central office; the connection between the subscriber's apparatus and the switch
is effected by means of two wires, for I will suppose that my telephone system is
arranged to be worked with two wires, the return not being effected through
earth.
The switch placed at the central office and corresponding to each subscriber's
apparatus is divided into a certain number of sectors, for example ten, and each of
these sectors is connected, as will hereinafter be seen, to a travelling table forming
part of a particular group of tables placed at the central office.
The central office, apart from the switches therefore comprises ten groups of tables
and each subscriber has a table in one of these groups, which table is connected to one
of the sectors of the subscriber's switch.
Under the action of currents sent from the subscriber's apparatus through the
corresponding sector of the switch the table connected to this sector may be set in
action, pass successively above beams or rails placed below the path it follows, may stop
and be placed in contact with one of them, the said contact putting the subscriber to
whom the table corresponds in communication with the subscriber whose apparatus is
connected to the benim or mil in question.
At the central office there are as many contact beams as subscribers, and the line
wires of each subscriber are connected to the corresponding beau placed at the central
office in one of the groups of tables.
Suppose that the system comprises 10000 subscribers 1 divide them into groups
of 1000, which gives 10 groups of subscribers, and in each group of tables which I have
mentioned I place 1000 beans, each beam corresponding to one of the sul scribers of
the group and connected to his apparatus, as will hereinafter be set forth.
It will therefore be seen that if one subscriber wishes to converse with another
whose number is an ordinal of the third group, say for example the subscriber 2846,
he will by means of electric circuits place his switch upon the third sector in order to
be connected by the said switch with the table which belongs to him in the third
group. This table being set in motion by the action of currents of definite direction,
will arrive above the beam corresponding to the subscriber 846 of the third group.
At this moment the communication is established between the two subscribers and
they can then converse together.
From the foregoing statement it follows that the principle upon which my system
of automatic telephone switches is based consists in the division of the subscribers
into distinct groups, each subscriber having at the ceutral office a special switch, as
many tables as the system comprises groups, and a special part, which I have termed
a "beam," placed in the group to which the subscriber belongs.
In order that the following explanations may be rendered as clear as possible I have
represented my improved system of automatic telephone switch by way of example iu
the accompanying drawings in which,
Figure is a perspective view of the telephone apparatus placed in the office of
each subscriber.
Figure 2 shows the details of varions parts of the apparatus represented in Figure 1.
Figure 3 is a plan of one of the switches placed at the central office, each subscriber's
apparatus being connected to a switch similar to that which is represented in this
figure.
Figure 4 is a section on the line 1-2 of Figure 3.

page_text: I may inscribe upon this sector b, as also upon the sector 1 of the switch A,, the word
"Stop" in order that any subscriber may hy a single glance ascertain whether the
parts of his apparatus are really in the position they should occupy.
"The three sectors b, b, and b, are connected by a wire 6 to the negative pole of the
battery A. The sectors b, are insulated and the sector b, is connected by a wire 7 to
to the polarized electro magnet A..
The pivoted arm b is connected by a wire 8 to the wire 1 leading to the line wire 2
which lends from the subscriber's apparatus to the central office,
While the arm b is upon the contact piece b the apparatus is at rest. By moving
the said arm 6 from the contact piece b, to the contact piece b, it passes above the
contact pieces b, upon which the arm must never stop but only pass. This passage of
the arm b above the contact pieces b, has the effect, as will bo understood, of sending
two negative currents into the line. In fact each of the contact pieces b' is connected
to the negative pole of the battery A, through the wire G. The current coming from
this negative pole arrives in the contact pieco b,, passes into the arm b and through
the wires 8 and 1 to the line wire 2. It returns from the central office through the
wire 3 and finally passes to the battery A, through the wire 5.
The same phenomena occur when the subscriber causes the arm b to pass from the
contact piece b, to the contact piece b, rubbing upon the intermediate contact.
piece by connected to the negative pole of the battery.
When the arm b is in contact with the piece b, the line will be put in
communication with the polarized electro magnet. A,, because the contact piece b, is
connected to this electro magnet through the wire 7, and because the arm b is connected
to the line through the wire 1. By moving the arm & from the contact piece b, on to
its contact piece b, for the stoppage it will be caused to rub upon the intermediate
contact piece b, which will, as in the case of the contact pieces b, and b, cause a
negative current to be sent.
It will therefore be seen that a complete turning of the arm b upon the switch A,
will have the effect of sending four negative currents, and connecting, the positive
electromagnet A, to the line between the times of sending the third and fourth negative
currents. It will hereinafter be seen, when describing the communications what is
the object and function of each of these currents.
The system of indicator having three wheels, which is represented in Figure 2, is of
the kind employed as speed indicators. It is composed substantially of a first
disc A, upon the axis of which is fixed a ratchet wheel C which can be nctuated by
a pawl C through the agency of the polarized electromagnet A,, the pawl C' being
connected to tho armature C" of the electro-mnguet through a rod C
retaining pawl regulates the movement of the ratchet wheel C, which must turn only
through an angle equal to one tooth at each attraction of the armature plate C by
the polarized electromagnet A...
The dise A", is provided with the figures 0 to 9, and opposite each of these figures,
upon the edge of the disc, is formed a notch with which engages the arm C, which may
be turned about its centre by C, by hand. This arm, like the arus band a₂ of the
switches A, aud As, is similar to those employed in the Breguet switches, that is to say
they can be sunk into notches formed at the edges of the discs upon which they are
placed.
The second disc A', of the indicator is similar to the disc A",, except that it is not
actuated by the polarized electromagnet A,.
This disc A', turns through ono division each time when the dise A", makes a
complete turn.
The mode of operating the disc A', by the disc A", has not been represented in the
drawings, for this point does not present any particular feature, and I reserve the
right to employ any devices used in speed indicators for effecting the movement of
the tens wheels by the units wheels.
What I have just stated in respect of the second wheel A', applies also to the wheel A,
which corresponds to the hundreds wheel of a speed indicator. Each time the tens
wheel A', has made a complete turu the hundreds wheel A, will turn through one

page_text: The stop sector d, which is insulated from the sectors D, and D₁, and which is
one two thirds the width of any one of the other sectors, is connected at its outer
part to a wire 15 which like the wires 13, 13, etc. extends from the switch.
Upon the disc Dan arm D which carries three brushes can be moved e e¹ ell. The
first of these brushes, the brush e during the rotary movement of the arm D" rubs
upon the sectors D, D, D,... in such a manner that when the Arm D" is upon the
smaller part d, of the sector D, the brush e only rubs upon the smaller part d, and
not upon the larger part m of the sector connected to the wire 13.
The second brush e which is placed beside or next to the preceding brush, is
designed simply to rub on the parts m n p of the sectors D, D, D, . . .
The two brushes-which in reality form one single brush, connected, as they are,
by a metal conductor-rub ou the "rest" block I provide two brushes e e¹, instead
of one, in order to avoid the necessity of employing too wide a brush. As to the
third brush, e, which is connected to the first two by the metal arm D", it rubs
against the ring ", connected to the ring D by the wire el, while the wire 10
connects it to the main or "line" wire.
Supposing each of the sectors to be divided by mdii of the disc D into three
equal juarte, np and it will be seen from Figure 3 that each of the parts d, d, d,
extend exactly a third part of the length of the sector into which they are inserted,
but it has only half the width of the sector.
The eléctromagnet El, which, as hereinhefore set forth is operated by negative
currents, can actuate by its armature, not represented in the drawings, a rod E"
jointed at its upper end upon an arın E which carries a pawl Facting upon a
a ratchet wheel having 96 teeth. The movement of the arinature is regulated in
such a manner that each time the electromaguet E' is traversed by a negative current
the pawl effects the rotary movement of the ratchet wheel through a distance equal
to the are formed by three teeth.
The ratchet wheel carries at its contre, which is recessed, small pawls which act
upon teeth formed npon the axis f which supports the switch arm D". This
axis terminates at its lower part in a point resting in a socket bearing.
Owing to this arrangement it will be seen that the rotary movement of the
wheel Funder the action of the pawl F will effect the rotation of the axis f* and
consequently of the arm D",
The electromagnet E, as has been seen, is actuated by positive currents, and its
arinature, not represented in the drawings, acts upon the rod G" which is jointed to
the arm ( also carrying a pawl G. This pawl G acts upon a ratchet wheel G
having 32 teeth, aud the movement of the armature of the electromagnet E is such
that in each displacement the pawl G will cause the corresponding ratchet wheel G1 to
turn through an angle equal to three teeth.
This ratchet wheel like the ratchet wheel F' is also recessed at its centre, and
carries pawls fix, which engage with the teeth / formed upon the shaft f of the
arm D
Owing to this arrangement it. will be understood that any one of the wheels For G'
can turn the ara D without turning the other wheel in its movement, in other
words the two wheels, while they are independent of each other, cau in turn impart
rotary movement to the shaft fl upon which the switch arm D11 is fixed.
3
From the foregoing it follows that when the electromagnet El is traversed by a
of the complete
negative current the switch arm 1" will turn an aro equal to- 96
circumference, that is to say 32 Accordingly the arm will make a complete
revolution under the action of 32 successive negative currents, and it will traverse a
complete sector D, or D, with threo vibrations of the armature.
When on the contrary the electromagnet. E is traversed by a positive current
3
the switch arm D11 will turn of a revolution, that is to say each of the
32

page_text: movements of this arm, when it is netunted by the electromagnet E will be
three times as great as any one of the movements effected by this arm under the
action of the electromagnet El.
The line wires froin the subscriber's apparatus to the switch are connected: one,
the wire 2, with the ring ", as before stated; and the other, the wire 3, to the
electromagnets E and E' by the wire 15'.
Such is the complete arrangement of all the parts which constitute any one of the
switches placed at the central office and connected to a subscriber's apparatus.
3. DESCRIPTION OF ONE OF THE TRAVELLING TABLES CONNECTED TO ANY OF THE
SECTORS OF ANY SWITCH AT THE CENTRAL OFFICE.
In the preceding description of the system it has been stated that from the
different sectors of any one switch extend the wires 13, 13, 13, Ench of these
wires are connected to certain parts which I will now proceed to describe and which
actuate the table in the group under consideration which correspouds to the subscriber,
so as to set the said table in motion or to stop it according to circumstances. On
this subject I may mention again that the division of the automatic switch is effected
in such a manner that each subscriber possesses a table in each group and thus each
subscriber will have ten tables at the central office.
In Figures 5, 6 and 7, I have represented in detail the arrangement employed for
the table and the electrical connection which unite the several parts with each
other and the switch.
For each group of tables placed at the central office I have provided an
electro-motor H which is netuated in a continuous manner by current from a battery
of accumulators It' or of any motor. This motor transmits its motion through the
medium pulleys h and to a shaft H" (Figure 5). Upon this shaft 11 is mounted
for each table a set of two bevel wheels
The screw 1,, wherenpon the travelling table presently to be described is arranged
to nove, terminates in a piece similar to the carrier of a lathe, in which there engages
a projection h, secured to an arm extending at right angles to the shaft hs, which
carries a gear-wheel A' intermediate between, but at right angles to, the other two
gear wheels 11. It will be seen that, owing to the manner in which the
slaaft. As, and screw 11 are connected, the said shaft A, whilst setting the serew Hin
rotary motion, is capable of performing a slight swinging motion in the horizontal
plane, on the pivot ..
The arin his connected to a square, revolvable on the fixed pivot h. This
square, through the medium of a fork, is connected to a bent arm or knee h
actuate by an eccentric h. The knee h, is adapted to swing on a pivot, held by
the stationary part A. The eccentric &, is capable-ns will be shown further un-of
taking up four different positions at 90° to each other, viz., two vertical and two
horizontal positions. The two vertical positions of the eccentric have the effect of
placing the wheel A, in the same position,-being the intermediate position of such
wheel A, between the wheels h" and 4", in which situation, however, it touches
neither.
The rearward horizontal position of the eccentric will bring into contact the
wheels and, while the forward horizontal position of the eccentric will effect a
contact between the wheels h and h'.
The eccentric is mounted upon a shaft or spindle which also carries a ratchet-
wheel h, having four teeth, adapted to be neted upon by a pawl connected by
joluted or toggle levers A,, to the armature , of the electromagnet A. Whenever a
current passes through such electromagnet, the armature is attracted and the pawl h
causes the ratehot-wheel to perform one-fourth of a revolution, thereby inducing the
eccentric to pass from its thien position to the next.
Owing, therefore, to the arrangement just described whenever current is sent
through the electro-magnet n the wheel 4, is thereby enabled to assume the
following positions;

page_text: (1) The intermediate position between the wheels " and ";
(2) Coutact with the wheel A
(3) The intermediate position between the wheels 4" and 4";
(4) Contact with the wheel h"; and so on, over and over again.
From the foregoing it will be seen that the screw II, which is connected with the
wheel A, may either be motionless, or it may turn in one direction or this being
effected by sending currents through the electromagnet A. I shall hereinafter state
the object of these movements.
Upon the screw H, is mounted this travelling table A, which forms the nut
of this screw and which is consequently moved horizontally from right to left,
or from left to right according to the direction in which the screw turns.
In order to prevent the turning of the table at the same time as the screw I provide
two supports II (Figure 5) which bear it. The tables proper H, is compound of a
platform carrying an index or brush i which during the movement of the table will
rub upon a band bearing metallic contact pieces "at intervals. The index or
brush i is connected by a wire 19 with the wire 2 of the line of the subscriber and
the metallic contacts i arranged along the haud are connected to a battery I, which
itself is connected by wire 18' to the wire 3 returning to the office of the subscriber
(Figure 5).
The front part of the table has two inclined arms i, and i, insulated from each other.
These inclined arms can turn about a joint i, and a spring holds them normally
slightly inclined toward the front, as shown in Figure 6. The arin i, is connected to
wire 19 and consequently to the subscriber's line wire 2, whilst the arm i, is connected
by the wires 20 and 18' to the subscriber's return wire.
Below the travelling tables which constitute each group and which are placed parallel
to each other, as shown in Figures 8 and 88, beams or cylindrical tubes K are
arranged perpendicularly to the direction of the tables.
Upon euch bean, underlying each of the screws II, aud exactly facing the arins,
and i,, there are two metal washers k, and k, insulated from each other. All the
washers k, of each beam are connected to the wire 15, and all the washers k₁, to the
wire 21.
The washers are each provided with a notch wherein the corresponding arm of the
sliding table H, is adapted to engage. As one of the tables moves along, the arms i, i,
ineat the notches of the washers, and k, of the first beam, which is thereby caused
to turn about its own axis whilst the arms continue engages in the notches. Should
the travelling table stop before the arms are released from the said notches, the
contact between the arms and the washers k, k, will be kept up; but if the notion be
not so arrested, then it will successively cause all the beams placed below to turn at
a pre-determined angle, the said beams returning to their position under the action
of the spinal springs directly after the passage of the table with which they are provided
for the purpose at each end.
lu Figure 7 I have represented to an enlarged scale a diagram of the communications
between subscriber's apparatus the corresponding switch and the table corresponding
to one of the sectors of this switch.
As hereinbefore stated each subscriber to the system belongs to a well defined group
at the central office, in which group he possesses one beam only in this group i
beam K.
It therefore remains for ine to describe the mode of connection between a subscriber's
apparatus and the benm which belongs to him at the central offier.
regard to this to Figure 7, in which I have supposed the bean K belongs to the.
apparatus represented.
The wire 21 of the beam is connected to the returu wire 3 at the subscriber's
office while the wire 15 is connected to the stop contact piece of the subscriber's
switch D.
I will hereinafter, when describing the connection explain the object of this.
arrangement.
It has hereinbefore been mentioned that 1 provide a motor for each group, which.

page_text: 4. GENERAL DESCRIPTION.
I may state at once that in the description which follows I have supposed a system
established for 20 subscribers divided into groups of two, and that ten sliding tables
only are shown in each group in the drawings.
For facilitating the description I refer to Figures 8 and 8 which show the general
arrangement of the system, making use also of the figures of detail for the different
movements of the parts which constitute the system.
By an inspection of Figures 8 and 8B it will be seen that the subscribers Nos. 1
und 2 have their beam in group No. 1, the subscribers 3 and 4 in group No. 2; the
subscribers 5 and 6 in the group No. 3; the subscribers 7 and 8 in group No. 4; the
subscribers 9 and 10 in group No. 5; the subscribers 11 and 12 in group No. 6;
the subscribers 13 and 14 in group No. 7; the subscribers 15 and 16 in group
No. 8; the subscribers 17 and 18 in group No. 9, and the subscribers 19 and 20 in
group No. 10. Accordingly the subscribers 1 and 2 will be designated respectively by
1, 1,
the fractions 1 2 the subscribers Nos. 3 and 4 by the fractions
2
1
and-
2
2
and
BO on, which signifies that the subscriber No. 4 is the secoud of the second group.
That is to say the second beam of the second group belongs to him, in like manner
as the subscriber No. 1 is the first of the first group, that is to say, the first beam of
the first group belongs to hiin, and so forth. In the fraction designating a subscriber
the numerator designates the group and the denominator the ordinal number of
subscriber in that group.
In the dingram of the connections I have represented in a complete manner only
tbe connections for the subscribers 1, 2 and 10, and in order to be complete I will
describe:
(1) The operation of the apparatus when the communication has to be
inade between two subscribers belonging to the same group, and will set.
forth for this purpose the connections between the apparatus
apparatus
1
2°
1
and the
2. The connections between two subscribers of different groups, and for that
purpose I will describe the connections between the subscriber and the
subscriber
5
The subscriber
I
wishing to communicate with any subscriber on the system must
first of all cause the arm D" of the switch placed at the central office to leave its
position of rest. For this purpose he will send, two negative currents as will be
explained. With this object he operates the arm b of the switch A, placed in his
apparatus, turning it so as to bring the said arun upon the contact piece b,; in this
movement the arm b rubs over the two contact pieces b. By rubbing upon the
contact piece b, the arm b closes the circuit of the electromagnet E¹ of the central
office switch A,. In fact a negative current leaving the subscriber's battery A' passes
through the wire 6, the corresponding contact piece b,; the arm b, thereon, the wire 8

page_text: the wire and the line wire 2; it then arrives, through the wire 19, at the rings d",
and d', of the central office switch, and thence through the wires 14 reaches the
electroimaguet E. From this electromagnet the current passes through the wire 15'
to the wire 3, and returns through the wire 5 to the subscriber's battery A,. The
circuit of the latter electromagnet E being closed, the said electromagnet is traversed
by a negative current. It is consequently actuated, because it is known that polarized
electromagnets can be operated by negative currents. Its armature is attracted, and
the rod Ei is lowered, compelling the pawl F to turn its ratchet wheel F through an
are equal to three teeth. By the time the two negative currents have thus been sent
through, arm D" of the switch therefore will have turned of a revolution and
taken up its position above the first part m d, of the sector D, in such a manner that
the brush e rubs upon the contact piece d, as whilst the brush e rubs upon the
portion m of the sector D.
2
3
As soon as the switch arin D has left its position of rest it is impossible for any
subscriber on the system to put himself in communication with the subscriber to
whom the switch belongs, the movements of which I have just described, because this
subscriber's beam is connected by a wire 15 to the stop contact piece d, and because at
this time, owing to the movement of the switch arm D the stop contact piece d is no
longer in communication with the line.
1
The position of rest, being abandoned by the arin D I will now describe the
succession of the operations. The subscriber who must find the group of the
subscriber with whom he wishes to converse.
1
1
In this case it is a subscriber of the
first group who is represented by, therefore the subscriber
1
need not cause the
movement of the arin D11 to another sector of the switch, because this arm is upon
the sector required (the first). The same would not be the case if the subscriber to
whom the subscriber wished to speak wern of another group then the first. It will
hereinafter be seen, when reviewing the connections between the subscriber and
1
1
5,
that the subscriber will have to net upon the arma, of his switch A, so as to bring
the armn D" of his central office switch D upon the fifth sector.
To state concisely what I have first said, the movements of the switch arm D" from
one sector to another of the central switch D are effected by acting upon the
switch A, and in the example chosen the subscriber need not move the switch arm
D" to bring it upon another sector, because it is upon the required sector.
Accordingly, as herein before stated, the subscriber has not to search for the
group on which the subscriber ½ to whom he wishes to speak is placed, because the
1
switch arm D" of the subscriber bas, by the sending of the first negative current,
been placed above the sector No. 1 connected to the group to which the subscriber
2
1
1 belongs. The switch arm D of the subscriber who calls is therefore upon the
sector corresponding to the group in which the subscriber called to his beam is
placed, and it is sufficient for the subscriber to move his travelling table of the
group until it comes in contact with the second beam of the group which is that
corresponding to the subscriber. For effecting the movement of the table, the
2'

page_text: subscriber operates the arm (, of the lower dise A", of the revolution indicators,
and causing it to turn in the direction of the arrow he places it in the notch
corresponding to the unit of the subscriber's number, therefore in the notch No. 2.
The manipulations to which the ann C, of the indicator is to be subjected are
terminated, for the subscriber's number comprises neither tens nor hundreds.
3
840
It would have been otherwise if, in lieu of describing a system of antointic
switch for 20 subscribers divided into 10 groups of 2, I had set forth a system for
10,000 subscribers divided into 10 groups of 1000. In this case, apart from the
indication of the group, certain subscribers would have had three or two figures to
the numbers which designate them; thus for instance the subscriber No. 846 or
forms part of the third group and possesses the beam No. 846. In this case the
subscriber wishing to speak to the subscriber No. 2846 would in the first place
have to operate his switch A' in order to search for the group, as will hereinafter be
seen, he would then operate the revolution indicator so as to place the armi C, of the
lower dise A", upon the notch, No. 6, the arm C, of the intermediate disc A¹, upon
the No. 4, and the arm C, of the upper dise A, upon the 8th notch.
1
1
From this it follows that what I am about to state in respect of the subscriber
would apply integrally, apart from the positions given to the arms C, of the revolu-
tion indicator, to the subscriber No. 846 of the third group, if, instead of having
20 subscribers on the system as I have supposed I should have 10,000.
The subscriber, after having placed the arm C, of thedisc A", upon the notch
No. 2, again moves the arm h of the switch A, in order to bring it from the second
contact piece b, to the contact piece b. In this movement the arm brubs upon the
contact piece b, which has the effect as previously to close the circuit of the electro-
magnet E' and the subscriber's battery A; a negative current then traverses this
electromagnet E', and the armature of the said electromagnet acts as before upon the
switch arm D" so as to cause it to pass upon the middle part n of the first sector D
for it is known that under the action of the electromagnet El three movements of the
switch arm D are needed in order to traverse the complete sector, a first displace-
ment to bring it upon d, m, a second to bring it upon n, and lastly a third to bring
it upon p.
The arms Du, being upon the middle part of the sector, is in contact. only with
that part of the sector connected by wire 13, to the electromagnet h, (Figure 6), and
it bus completely abandoned the part d, of the sector connected to the electromagnet E
(Figure 3).
The negative current to which I have just alluded, and which, being sent by the
subscriber, has caused the displacement of the switch arm D" also passes through
the sector D, and through the wire 13, into the bevel wheel electromagnet, Ap
returning through the wire 18 to the return wire 3 at the subscriber's office, and
Inst ly through the wire 5 to the battery A. Consequently the circuit of this
electromagnet h is closed, it acts and, as has been seen, causes the wheel h₁ to
approach the wheel ". These two wheels then gear with each other, and the
screw H, commences to turn. The corresponding travelling table H, is moved and
the index or brush on this table rubs upon the first metallic contact piece i of
the band . By reason of its contact with this piece the index i closes the
circuit including the subscriber's electromagnet A, post and the battery I
In fact a current leaves this battery, arrives at the contact place i", passes
through the brush i, and thence arrives through the wire 19 in the line wire 2,
and reaches the subscriber through the wire 1 the arin b of the switch A,, passes
thence into the contact piece b, upon which the arm rests at this time, arrives

page_text: through the wire 7 at the electromagnet A, traverses it and returns through the
wire 3 and the wire 18' to the battery I, (Figures 3 and 5): The circuit of the
subscriber's electromagnet A, is thus traversed by a positive current, for the central
office battery I, can send only positive currents.
The subscriber's electroinagnet A, being traversed by a positive current attracts the
armature, and the lower dise A", turus through an angle equal to one division,
moving its arm C, because the latter has been placed in the second notch of the
disc.
The travelling table while touching the first contact piece i" on the strip or
band with its index or brush i bears with its front arm I, upon the beam K No. 1,
but, as under the action of the motor the table continues its movement it only turns
the bean without stopping, and the table arms i, i, escape from the first beam K.
Tho subscriber's tables continuing to move will soon touch the second metallic
contact with the index on the table i and, for the same reasons as before, a
second positive current arrives at the subscriber's apparatus and actuates the electro-
magnet A The lower dise A", then turns again through an are equal to a division,
but in this second rotation the arm C₁ of this disc "A", will rub upon the contact
piece (Figure 2) and close the circuit including the electromagnets EE' of the
ceutral office switch D and the subscriber's battery A. In fact a negative current
leaves the subscriber's battery A₁, arrives the wire g by way of the contact piece q, to
the arm C, of the upper dise As, and thence through wire 10 into the contact piece;
from this contact piece the current passes through the arm C, of the disc A',, and
through the wire Il into the contact piece c, then to the arm C, of the disc A", which
is at this time above the outer contact piece, and lastly through the wire of into the
subscriber's line wire 2 (Figure 2). Thence the current arrives at the switch-sector D₁
and lastly into the electromagnet E. The current traverses this electromagnet,
returns through the wire 15' to the return wire 3 wire 5 to the subscribers battery A₁.
The electromaguet E beiug traversed by a positive current is actunted, and the
switch arin D which was upon the middle part of the sector D, comes upon the
last part of this sector. But, further, the negative current sent by the subscriber's
battery A, into the sector D, is divided, one part passing to the electromagnet E,
whose effects I have just described, and the other part passes through the wire 13,
nud through the electromagnet h, returning through the wire 18 into the return
wire 3. Therefore the circuit of the electromagnet h is also formed, and it is
traversed by a current which, as has hereinbefore been seen, causes the displacement
of the wheel hy so as to place it in its middle position. The wheel A, no longer gears
with either of the said bevel wheels "h, the table H, stops, and at this time it is,
as has been before mentioned above the beam No. 2, and in contact with it. In
fact the table index or brush i and the arms iz is are arranged in such a nanner
relatively to each other that at the time when the contact between any ouc of the
contact pieces and the table index or brush i takes place, the table arm i
cominence to turn the beam K above which they are at the time, and further, the
table arms i havo not, escaped from the beam when the contact between the
table brush and the contact piece, has ceased. Besides, the negative current
arrives at the switch of subscriber
since the said arms i, i, are in contact with the
beam; the effect of such negative current being, to cause the arm D to pass
froin the first part of the "rest" block on to the second part.
In the position under consideration the table H, of the group No. 1 which belongs
to the subscriber is in contact with the bean No. 2 of the same group belonging
1
1
1
to the subscriber with whom the subscriber wished to put himself in
communication.
Now the beam No. 2, which has thus been slightly turned by the action of the
arms i, i, has a washer which is connected to the stop contact piece d of the switch

page_text: of the subscriber
to whom it belongs, and another washer which is connected to
the wire 3 returning to the latter subscriber's office. Telephonic communication is
therefore established between the two subscribers and and the subscriber
1
1
1.
may
call the subscriber by means of positive currents which do not change the position
of the parts of the system. In fact these positive currents cannot pass to the
electromagnet E, because the arm D is not in contact with the smaller contact
piece d, of the sector D of the switch, and because all the other polarized electro-
magnets of the system act upon their armature only by means of negative currents,
except the subscriber's electromagnet A. The electromagnet A, at the apparatus of
the subscriber who calls is actuated by positive currents for bells or conversations,
for at this time the lever of the switch A, is upon the contact piece b,, but the action
of these positive currents upon the subscriber's electromagnet A, can only cause the
rotation of the wheels of the indicator, which is quite a secondary inconvenience and
which may be avoided either by taking care to stop these wheels by any suitable
means before ringing the bell or talking with the subscriber with whom the
communication is established, or by insulating the devices of the subscriber's
apparatus from the microphone for the time being.
The positive currents for bells or for operating of the telephone proper do not give
rise to any action upon the parts of the central office switch D of the subscriber
1
1
with whom the subscriber speaks. Indeed, these currents arrive in the stop contact
picce d of the switch D of the subscriber through the wire 15, pass through the
brushes and thence into the line of the subscriber
5₁ , arrive at his apparatus where
they ring the bell, returning through the return wire 3 to the wire 21 of the beam,
and thence through the arm i, into the subscriber's return wire 3. At this time no
other subscriber can put himself in communication with the subscriber
arm D of his ceutral office switch D is no longer upon its stop contact piece, aud
in liko manner no other subscriber, can put himself in communication with the
subscriber because this subscriber's beam is swung round at a pre-determined angle
1
2'
by the table which corresponds in the group 1 to the subscriber
1
1
ין
for the
When the conversation is at an end it is necessary to move all the displaced parts
back to their original position.
The subscriber who called operates the arm 6 of his switch so as to cause it to
pass from the contact piece b, to the contact piece b. rubbing it over the contact
piece b..
1
The contact of the arm upon the contact pieco b,, as is known, causes a negative
current to be sent through the line wire. This negative current arrives through the
wires 2 and 14' to the arm D" of the central office switch belonging to the subscriber
passes through the outer brushes into the sector D, and there is divided one part
traversing the second central electromagnet El to return through the wires 15 and
3 to the apparatus of the subscriber, and the other part passing from the inner

page_text: 1
terminal e, of the sector D, arrives through the wire 13, in the bevel wheel electro-
magnet and returns to the apparatus of the subscriber through the wires
18 and 3. The two electromagnets E and h, which are traversed by a negative
current, are therefore actuated: the first has the effect of moving the wheel h₁ so as
to put it in gears with the wheel A, The wheel A, therefore, begins to turn in the
opposite direction to that, in which it had turned at the time of the movement of.
the table A, toward the front. This table thus returns to the rear, and having
reached its starting point, abuts against the spring Vattached to the battery VI,
thereby causing such spring to bear on the contact block V". Now this blook v¹i
is secured to a stop V, which, just. then, owing to the position taken up by the
arm h,, is in contact with a bar V,, attached to the electro-magnet A, Electrical
contact instantly takes place, therefore, between V and V; a current traversing the
electro-magnet and the wheel h, returning to its intermediate position. "This
return of the said wheel to its intermediate position immediately severs the
contact between the binding post or screw V, and the arm V,; so that that current
cannot now reach the electro-magnet, which, however, is in readiness for a fresh
current. The negative current to which I have just alluded and which has been
produced by the passage of the arm of the switch A, upon the contact piece b, of
the apparatus of the subscriber ½ is divided in the sector D, as has been seen, one
part has traversed the electromagnet E, and the other, the electromagnet A,,, further,
this current has passed through the wires 14' and 10 into the arms i₁, thence into-
the beam, before the separation of this latter from the table arms, and lastly into the
switch of the subscriber 2.
1
1
of this switch causes the
At this time, that is to
by the operation of the
This negative current traversing the electromagnet E'
arm D to be placed upon the part m of the first sector D,
say after the sending of the last negative current caused
switch A, in the apparatus of the subscriber 1, the parts occupy the following
positious:
(1) At the apparatus of the subscriber: the arm a, of the switch A, is in the
notch No. 1, it has not moved;
The arm b of the switch A, has returned to its starting point;
The wheels A, A',, A", are in the position of rest.
(2) At the switch of the subscriber; the arm D is upon the part of the
sector D'.
(3) At the travelling table corresponding to the subscriber in the group No. 1:..
the table has returned to its position of rest and is ready for a fresh connection.
(4) At the switch of the subscriber to whom the subscriber has first spoken;
1
2
the switch arm D is upon the part m of the sector D₁;
1
1
(5) At the apparatus of the subscriber: none of the parts have changed their place.
It is therefore sufficient, for all the parts to be brouglit to zero, that the arms Dil
of the two switches return to their stop contact pieces. This is very easy, and it is
only necessary for each subscriber to turn the arm a, of his switch A, from left to
right until this arm returns to its position of rest.
The operation which I have just described has for its object to send into each
switch as many positive currents as there will be contacts with the metallic contact
piece a of the switches A,.

page_text: In fact when the arm a₂ of one of the switch A, comes in contact with one of the
metallic contact pieces of this switch a positive current leaving the battery A, arrives
through the wire 4 at the contact piece under consideration, passes into the arm da
and thence through the wires 1, 2 and 14 to the switch D.
1
Referring first of all to the arm D" of the switch D of the subscriber, it will be
seen that it is upon the part m d, of the sector D, and consequently the first positive
current will arrive at the smaller contact piece d, and thence to the electromagnet E
to return through the wires 15,, 3 and 5 to the battery A,; the electro-maguet E being
traversed by a positive current attracts its armature, and the rod G, through the
agency of the pawl G, causes the ratchet wheel G, to turn through an are equal to
tl ree teeth; the switch arm D" will thus pass from the contact piece d, to the
contact piece d, of the sector D,, because the displacements of the arm D, caused by
the electromagnet E are three times greater than those caused by the electromagnet E.
If the subscriber continues the operation of the arm a, of the switch A, the arm Du
continues to jump progressively from the contact pieca d, to the contact piece
from the contact piece d, to the contact piece d, until it arrives from the contact
piece at the stop contact piece d. Arrived here it does not move again, for
this contact piece is not connected to the first electromagnet E. All the parts of the
1
1
apparatus of the subscriber will thus be brought to zero, when
given a complete turn to the arm a, of his switch A,
What I have just stated in respect of the subscriber
1
ī
this subscriber has
also applies to the
subscriber and the operation of the arm a, of his switch A, will in the same
manner bring the arm D" of his switch D upon the stop contact piece. Thus all the
operations are termiunted.
In the description of the connection which I have just given I have supposed that
the subscriber communicates with the subscriber who is on the same group us
himself.
1
I will now suppose that the subscriber speaks for instance to the subscriber
who forms part of group No. 6.
5
The same operations which I have hereinbefore described will take place again in
the same manner, and it is sufficient, for taking account of the same, to refer to
Figures 8, 8" in which I have shown a diagram of the communications between these
two subscribers.
1
The only differences which exist in respect of the operations in this case arise from
the operation of the arm a, of the switch A, by the subscriber, which operation was
not required in the first instance, because the two subscribers belonged to the same
group.
1
As I have hereiubefore shown, after the sending of the first two negative currents
designed to cause the arm D to leave its position of rest the subscriber 1
upon the switch A, so as to place the arm D" of the switch D upon the sector
corresponding to the group in which the subscriber is with whom he wishes to speak.
In the present case the subscriber belongs to the fifth group.
Accordingly he has to displace the arm as so as to bring it between the metallic
contacts 5 and 6.
He will thus have sent 5 positive currents, and the arin D" of his switch will have

page_text: been placed upon the part d, of the fifth sector D,, thus opening the communication
of this switch with the travelling table of the subscriber placed on group No. 5.
1
From this time the operations recur in the same manner and in the same order,
5 and I will in conclusion enumerate them successively.
Manipulations which a subscriber must perforin in order to put himself in com-
munication with another subscriber on the same system:
(1) To send two negative currents through the switch A, in order to cause the
arm D of the switch placed at the central office to pass from its position of rest
to the smaller contact piece d, of the first sector D.
(2) To send a series of positive currents through the switch A, with the object of
placing the arin D of the switch upon the first part of the sector corresponding to
the group including the subscriber to whom it is desired to speak.
(3) To arrange the arms C, of the revolution indicator discs according to the
ordinal number which the subscriber has in the group under considemtion.
(4) To send a negative current through the switch A, having for its object to set
in motion the travelling table of the subscriber in the group under consideration.
After the sending this negative current the table, as it is displaced, causes the
passage to the subscriber of positive currents which, arriving in the electro-maguet
A,, cause the wheels A,, A',, A", of the indicator to move.
(5) The arms C, of the wheels of the indicator arriving in their position of rest
send to the central office a negative current which has for its object to stop the table.
It is at this time that the subscribers can speak together.
(6) To send a negative current through the switch A, at the apparatus of the
subscriber who has called. This current has the effect of bringing the table to its
original position.
(7) To complete the revolution of the arms a, of the two switches A, with the
object of bringing all the parts to rest.
Having now particularly described nud ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In an automatic telephone exchange enabling any subscriber of a telephone
system to put himself in communication with any other subscriber the use of
travelling tables adapted to move over a series of contacts such contacts being
placed in groups in each of which groups each subscriber has a table but each
subscriber has only one contact piece in one group.
2. In an automatie telephone exchange arranged in groups the use of a
commutator adapted to put a subscriber in communication with his table in any
desired group, the said commutator being also so constructed that when the
subscriber to whom it belongs las put himself in communication with any other
subscriber no third subscribers can enter into communication with him.
3. The use of contacts in the groups before alluded to such that when a subscriber
A has put himself into communication with the contact of the subscriber B no
other subscriber can put himself in communication with B until A and B have
terminated their conversation.
4. In an automatic telephone exclunge the combination for moving backwards
and forwards and stopping the table, substantially as herein described.
6. In an automatic telephone exchange the use of the counting wheels netuated
and opemting in the manner herein described for stopping the movement of the
table.
6. The current-sending device A constructed as and for the purposes herein
described.
7. The combination of the two electromagnets E and E' (or an equivalent therefor)
and the commutator D as herein described and illustrated in Figures 3, 4 and 7 for
the purposes herein described.

page_text: 8. In an automatic telephone exchange the construction of the contacts sub-
stantially as described and as illustrated in Figures 1, 5 and 6.
9. The construction of a commutator substantially as herein described and illus-
trated in Figures 3 and 4 for the purposes described.
10. In an automatic telephone exchange the arrangement of a series of tables,
connected or. intended to be connected with subscribers, running upon lines which
are crossed transversely by rods carrying contact pieces which are in connection
with or intended to be put in connection with other subscribers substantially as
described.
The thin 17th day of May 1907
HASELTINE, LAKE & CO.
45 Southampton Buildings, W.C., Agents for the Applicant.