Improvements in and relating to Telephone Systems.
Year: 1895

page_text: Date of Application, 23rd Feb., 1895
Complete Specification Left, 23rd Dec., 1895-Accepted 1st Apr. 1896
PROVISIONAL SPECIFICATION.
Improvements in and relating to Telephone Systems.
We, SALOMON BERDITSCHEWSKY called APOSTOLOFF, and MoÏSE FREUDEN-
BERG, both of 95 Boulevard Beaumarchais, Paris, in the Republic of France, do
hereby declare the nature of this invention to be as follows:-
Our invention relates to telephone systems.
The central station which puts the subscribers of a telephone system in com-
munication in accordance with their indications necessitates a considerable
number of employees who occasion very great general expense for working
telephone systems.
In order to remedy on the one hand this inconvenience and to augment on the
other hand the rapidity of the telephonic communications, we have devised a
telephone switchboard enabling any subscriber to put himself in communication
with another subscriber without necessitating the intervention of employees placed
at the central station, irrespective of the number of subscribers of the system.
1
An automatic telephone switchboard adapted to be used for an indefinite number
of subscribers must fulfil the following conditions.
(1) It must require the use of only a single wire for each subscriber.
(2) It must occupy little space and in any case no more than the apparatus now?
existing at central stations.
(3) The manipulation of the same must be easy and likewise the repair in case
it should get out of order.
(4) It must operate with rapidity and with absolute precision while requiring
nly a minimum expenditure of electric energy.
These essential conditions we have endeavoured to fulfil in the construction of
the telephone switchboard which constitutes the subject of our said invention.
Before commencing the detailed description of our apparatus we will set forth
the principal means upon which it is based.
Suppose that at a given point of the telephone system corresponding to the
actual central station is a surface of ebonite or other appropriate material, upon
which, are arranged contacts so that each of them communicates exclusively with
the line wire of a single subscriber of the system, and admitting for a moment that
over this surface of ebonite à movable metallic contact can be caused to move the
said contact being connected to the wire of the subscriber to which the plate under
consideration corresponds. Each subscriber having at the central station a plate
similar to that just mentioned, if any one of the subscribers can at will, in his
office, displace the corresponding point upon the surface of ebonite he can evidently
put himself into connection with any one subscriber of the system without the
intermediary of an employee whose part is fulfilled by the plate in question.
The displacement of the point cannot be effected in a straight line, because for a
considerable number of subscribers the distance which this point would have to
travel would be too considerable and to avoid this incouvenience we have
thought of utilizing a system of co-ordinates rectilinear or otherwise, that is to say
enabling the subscriber to displace the point, not in a single direction but in two
directions not parallel, either two perpendicular lines or simply two lines oblique
one to the other, or a circle and a radius or two series of concentric circles..
The advantage will at once be seen of not displacing the point in a single
direction but in two directions not parallel, which we will suppose to be
perpendicular in order to deal with a definite proposition.
In the first case (single direction) if the point as it is displaced passes contacts

page_text: E
it will pass contacts in the second case (two directions not parallel) and the
amount of the displacement of the point in each direction may thus be very small
It is therefore necessary
while having on the plate a great number of contacts.
to find a means enabling a subscriber to move from his office and with few
manipulations, the contact which is above the corresponding plate situated at the
central station, to receive the signals which he requires, to establish a telephonic
communication and afterwards bring all the parts of the mechanism back to the
position which they occupied originally.
Having thus set forth the principle underlying our system of automatic telephone
switchboard we will now describe in detail all the arrangements which we have
devised for realizing the same in practice, referring in this description to the
accompanying drawing in which we have illustrated by way of example one form
of carrying our invention into practice.
Figure is a plan of the ebonite plate arranged for each subscriber at the
central station.
Figure 1s is a plan giving in detail metallic contacts arranged upon the path K L
passed over by the carriage F2.
Figure 1ter shows the metallic contact for the carriage F1.
Figure 2 gives a front view of the plate and of the parts which it comprises.
Figure 3 is a section on the line 1-2 of Figure 1.
Figure 4 gives the detail of the mechanism permitting the displacement of one
of the electromagnets above the plate carrying the contacts.
Figure 5 is a section on the line 3-4 of Figure 2 showing the carriage of one
of the electromagnets.
Figures 6 and 6bs are front views and side views of a special relay electromagnet
to which we give the name of impulsator and whose object will be hereinafter
'explained.
Figures 7 and 7b1s are a plan and a section respectively of a special commutator'
placed by the side of each subscriber's plate at the central station.
Figure 8 is a front view of the mechanisin of the apparatus placed in each
subscriber's office.
(In the example represented we have supposed that the telephonic apparatus
employed is on the Ader system as used in France at the present time).
Figures 9 and 10 are transverse sections taken through the case of the apparatus
in the direction of the arrows A and B respectively and showing parts of the
mechanism seen from the front in Figure 8.
Figures 11 and 11 are plans showing the commutator in the two positions
which it may occupy in the apparatus placed in the subscriber's office.
Figure 12 is a perspective view of an Ader, apparatus provided with the
mechanism necessary for the operation of our system.
Figures 13 and 14 are a plan and section respectively of a plate of the central
station, on which the point instead of being displaced in two perpendicular
directions can be displaced about two points taken as centres.
Figure 15 represents in diagram a central station arranged for three subscribers
and also the apparatus placed in the said subscribers' office.
Our automatic telephone switch-board is substantially composed of two parts:
(1) An apparatus having a movable contact point, which is arranged at the
central station.
(2) A mechanism or manipulator combined with the telephonic apparatus placed
in the house of each subscriber.
We will now describe successively each of these parts and then explain in detail
their operation, using for this latter purpose the diagram of the communications
(Figure 15).
The apparatus having a movable contact comprises among other parts two
ebonite plates A-B and C-D which are arranged horizontally and parallel to
each other (Figure 3). Upon these two plates are fixed contacts (contacts a upon
the upper plate, and contacts b upon the lower plate).

page_text: The line wire from any subscriber arriving at the central station is connected to
two metallic strips or wires one of which passes below all the lower plates of the
station, and the other passes above all the upper plates. In each of the plates of
the station the metallic strips or wires corresponding to the line wire of a subscriber
have a contact and moreover for a group of two parallel plates the two contacts
corresponding to the same subscriber are on the same vertical line. We will
hereinafter set forth the utility of this arrangement. Between the parallel
plates A-B, C-D can move the contact point S, which is a permanent magnet
placed freely in the interior of a solenoid S2. According to the direction of the
current which traverses the solenoid S., the movable contact point can be displaced
either upwards or downwards in the solenoid. Normally, that is to say when the
solenoid is not traversed by any current the movable contact S₁ under the action
of a spring constantly tends to come in contact with the lower plate.
The contact point S, forms part of a system of double carriages, one of which F₁
(Figure 1), can be displaced in the direction M N, while the other, F2, can be
displaced in directions parallel to K L. The carriage F2 is compelled to follow
the carriage F, in its displacement, but it can moreover be displaced freely in the
direction KL without moving in its displacements the carriage F. Upon the
carriage F is mounted an electromagnet E₁, provided with a plate 1 constantly
kept away from the poles of the electromagnet by a spring 2. At the lower part
of this plate 1. (Figure 4) is pivoted a plate 3 terminating at its front part in a
hook 4. A second hook 5 independent of the plate 3 is pivoted upon an axis 6.
These two hooks are in engagement with the teeth of a rack 7 which extends
below the carriage over the whole side M N (Figure 1) of the ebonite plate. If
at a given moment, as will hereinafter be seen a current be passed through the
coils of the electromagnet E, the plate 1 is attracted and the hook 4 passes over a
tooth of the rack and engages with the following tooth, whilst the hook 5 still in
engagement with the rack keeps the carriage upon the said rack.
The current being immediately interrupted, the plate 1 under the action of the
spring 2 tends to move back to the rear, but as this movement is rendered
impossible by the hook 4 engaging with a tooth of the rack, the whole of the
carriage will advance to the left until the plate 1 butts in its backward movement
against a stop which limits its motion. In this forward movement of the carriage
to the left the second hook 5 has likewise passed over a tooth of the rack 7 and
has engaged, with the next adjacent tooth, so that when a current is again sent
through the electromagnet the same phenomena recur and the carriage F₁ will
advance again, passing a tooth of the rack each time.
1
2
It will therefore be easily understood that a series of impulses is due to an
interrupted current flowing through the coils of the electromagnet E₁ moves the
carriage F, forwards to the left a number of teeth equal to the number of impulses.
Upon this carriage F₁ are fixed perpendicularly to its axis two rods 9 and 10
which support the whole of the carriage F, including its rack (Figure 1). Owing
to this arrangement it will be seen that when the carriage F₁ is displaced in the
direction M N, the carriage F₁₂ supported by the plates 9 and 10 will follow the
carriage F₁ in its displacements and the whole of the system will thus be displaced
to the left of the ebonite plate. When the carriage F₁ bas arrived in the position
which it must occupy it will be possible to displace the carriage F, relatively
to the carriage F₁, by sending through the electromagnet E, a series of impulses
by means of an interrupted current which will displace this carriage along the
plates 9 and 10 in a direction parallel to KL in the same manner as the carriage Fi
is displaced in the direction M N. It is evident that if the carriage F₁ has not
moved, the carriage F₂ may be displaced along the line K L and not along a
parallel line. lu order that we may be understood let us take an example.
Suppose that the subscriber, to whom the plate at the central station under
consideration corresponds wishes to bring the movable contact point of his
apparatus in contact with the wire of another subscriber, whose line is connected
to the plate at three divisions further along the line M N and five divisions on the

page_text: line K L. The subscriber, by the means hereinafter set forth will move forwards
'the carriage F, of his plate by 3 divisions on the line M N, then he will displace
the carriage F, by 5 divisions on a line parallel to K L. At that moment the
point of his apparatus will be in contact with the connection to his plate of the
line wire of the subscriber with whom he wishes to put himself in communication.
At the end of the path of the carriage F₁ is an electromagnet 11 (Figure 1) and
an electromagnet 12 is likewise arranged at the end of the path of the carriage F.
The object of these electromagnets which we will term return electromagnets is to
bring the carriages F₁ and F₂ instantly back to their starting points. For this
purpose each of these return electromagnets, for example the electromagnet 12
(Figure 3), on being traversed by a current, attracts the plate 13 which normally
keeps the rod 14 (Figure 1) below the level of the rack parallel to the said rack.
The rod 14 is controlled by a spring 15 (Figure 3) which tends to raise it, and can
turn about the axis 14. As long as the rod 14 is kept below the level of the rack
by the plate 13 of the electromagnet 12 the hooks of the carriage F₂ (Figure 3)
are in contact with the teeth of the rack, but if at a given moment we send a
current through the electromagnet 12 the plate 13 is attracted and under the action
of a spring similar to the spring 15 the rod 14 is raised and in being raised lifts the
hooks of the carriage F₂ which thus cease to be in engagement with the rack.
The carriage F, which is thus no longer held by the rack is submitted to the action
of the very powerful spring 16 which moves the carriage F, back to its starting
point; the carriage F₁ is likewise moved back to its starting point by the spring 17
when a current is sent through the electromagnet 11 (Figure 1).
2
The spring 17 is arranged at or near the extremity of a lever 18 pivoted at 19
to the frame of the ebonite plate and at 20 to the carriage F₁. The spring 17 being
placed very near the pivot 19 will be compressed to a very small extent for a great
displacement of the carriage F₁. For the same reason a rod 21 is pivoted at one
end thereof to the carriage F2 and at its other end to the arm 23 by means of the
pivot 22, the said arm 23 being connected to the carriage F1. The spring 16 placed
very near the pivot 22 causes the return movement of the carriage F, and as will
be understood from Figure 1 for a very great displacement of the carriage F,
spring is compressed to a small extent.
the
The movable contact point S₁ is of course carried by the carriage F, and for
maintaining the equilibrium of the whole system so that the two carriages are
always displaced in a perfectly horizontal plane we have arranged a wheel 25
(Figure 4) and a slide 25' (Figure 3) upon the side N N of the frame of the
ebonite plate and a wheel 26 on the side parallel to the said plate (Figure 1).
Parallel to the rack of the carriage F₁ are arranged:
1
(1) A metallic plate t₁ insulated from all the parts of the mechanism and
presenting a series of metallic contacts (Figures 1er and 15) between which are
interposed parts of ebonite or other insulating material. The metallic parts are of
the same length as the parts of ebonite, and a tooth of the rack corresponds to two
parts of the metallic plate t₁ that is to say to a metallic part and to a part of
ebonite. A contact spring or brush t₂ (Figures 1ter and 15) fixed upon the
carriage F, rubs during the displacements of the carriage along the part t₁, thus
passing successively in each displacement of the carriage upon a non-metallic part
and upon a metallic part. At the time when the carriage F₁ is not displaced the
spring to bears upon an insulating part. If the carriage Fi advances one tooth on
the rack the spring t₂ will again come in contact with an insulating portion
of the part t, after having traversed the metallic portion lying between the
two insulating portions under consideration. A second contact-spring or brush t
is secured to the carriage F₁ without interposition of insulating material
that is to say, that this spring 3 is not insulated from the carriage. When the
carriage F, is at the beginning of its path, that is to say when it is not displaced
the metallic contact spring t3 makes contact with the metallic plate t (Figures 1er
and 15), but as soon as the carriage F₁ is displaced, if only one tooth, the spring t
abandons the plate ti.
1

page_text: (2) A second plate f similarly to the plate t₁ has a succession of metallic
portions and insulating portious of equal lengths (Figures 1ter and 15).
The metallic and insulating portions of the plate f are arranged rather
differently to the metallic portions of the plate t₁, in that a metallic portion is
placed at the right hand extremity of the plate fe in lieu of an insulating portion
as on the plate t₁. During the displacement of the carriage F₁ a metallic spring t
which is fixed to the carriage F, but which is insulated therefrom, makes contact
with the said plate fo
To sum up what we have just stated, at the beginning, that is to say before any
displacement of the carriage F1, the contact spring t, which communicates with
the carriage F2 bears upon an insulating portion of the plate t₁, the contact
spring t, which is insulated from the carriage F, bears upon a metallic portion of
the plate, and the spring t, insulated from the carriage F, is in contact with the
plate
When the carriage F, has advanced the distance of one tooth of the rack
the same phenomena will take place again, but the spring t, will no longer be in
contact with the plate . During this forward movement of the carriage F, the
spring t, will pass on to the metallic portion of the plate t₁ and the spring t, will
likewise pass on to an insulating portion of the plate fo
We will now examine the carriage F. Parallel to the rack along which this
carriage is displaced are arranged.
6
(1) A plate, similar to the plate f, and commencing like it by a metallic part..
Over this plate can be caused to move one of the extremities of a brush or contact
spring which is fixed upon but insulated from the carriage F₂; the other
extremity the spring te makes contact with a metallic strip or band f. (Figures 1bts
and 15); this metallic strip or band f₂ commences only from the second tooth of
the rack, so that at the beginning when the carriage F, is at its starting point,
one end of the contact spring to is in contact. with a metallic portion of the plate fi
and the other end thereof with a plate f₂. As soon as the carriage is moved one
tooth, one end of the spring te is drawn out of contact with the plate f, and is.
brought into contact with the plate f3 herein before referred to.
2°
(2) A plate t (Figures 1 and 1bs) similar to the plate t, and commencing like
it by an insulating portion; however this metallic plate commences only in front
of the second tooth of the rack. After the second movement of the carriage F2 a
contact spring to is moved along this plate t..
When studying the connections we shall see the object of these various plates.
Outside the ebonite plate upon which the carriages are moved and very near it
is a third electromagnet E, (Figure 15) which when traversed by a current
attracts a plate 27 (Figure 13). This plate is provided with a prolongation 28.
(Figures 7 and 13) which carries an arm 29 at the extremity of which is fixed a
pawl 30 which is adapted to engage with the ratchet wheel H₁ (Figure 7) keyed
upon the vertical axis O. When the attraction of the plate 27 takes place, the
arm 29 descending compels the pawl 30 to turn the wheel H₁ in the direction of
the hands of a watch (Figure 7). A retaining pawl 301 forms a brake and
regulates the rotation of the ratchet wheel H₁ in such a manner that the latter
turns one tooth each time the plate 27 is attracted. On the axis Og set in motion.
by the ratchet wheel H₁ are fixed:
(1) A metallic wheel ₁ (Figures 7 and 7 bis) insulated from the axis O and
provided with four projecting parts 11, 1, 13 placed at the extremities of two
perpendicular diameters;
(2) A second wheel H, of ebonite which carries four metallic rods forming
two groups of two parallel rods, the two groups being perpendicular to each other.
The extremities of these rods which are curved can be moved over a series of
contacts which we will hereinafter. describe. The same is the case with the
projecting parts 11, 1, 1, secured to the wheel r₁, it being understood that the
extremities of the metallic rods carried by the wheel H, cannot touch the contacts
over which the projecting parts 1, 1, 13 are adapted to move, and that vice versa.

page_text: the projecting parts 11, 12 13 cannot touch the contacts over which the extremities
of the metallic rods are inoved;
2
(3) The ratchet wheel H, hereinbefore mentioned. This wheel is directly fixed
upon the axis O3 and is not insulated therefrom. It has on its periphery 20 teeth.
(4) A disc H, whose circumference is divided into 40 parts, 20 of which are
metallic and 20 of insulating material. This disc is situated above the ratchet
wheel H, and is insulated from therefrom. Upon the circumference of this wheel,
at the extremities of the same diameter, rub two brushes H, and H, (Figure 7).
When studying the diagram of the connections we shall see the object of the
whole of the wheels mounted upon the axis O3.
By the side of each ebonite plate is also a special relay electromagnet R to which
we have given the name of "impulsator" (Figures 6 and 6bis); this electromagnet
is arranged in the following manner. It is of the horseshoe form and one of its
poles is divided into two branches Q2 Q3 on which are arranged the bobbins 91 ??
Above the horseshoe is an ebonite plate q3 above which are secured two metallic
Between the
bars 9, 9, to which the contact screws 76 and 7, are attached.
branches of the electromagnet Q2 and Q3 is balanced a small iron armature 98.
adapted to move about the axis g, through a recess formed in the upper pole of
the magnet R. The bobbins q₁ and q₂ are so wound that when they are traversed
by a current in a given direction one of the bobbins, say the bobbin g₁, tends to
augment the magnetism of the core Q3, whilst the bobbin 9, tends to diminish
the magnetism of the core Q. If the current takes an opposite direction
the magnetism increases in the core Q2 and diminishes in the core Q3. Hence it
follows that in the first case the armature q, is attracted towards the core Q3 aud
in the second case towards the core. Q2. For preventing the armature from
If the subscriber
adhering to the cores we have provided it with small springs 10-
whose line wire terminates at this relay electromagnet sends positive or negative
currents through the bobbins and
71
is attracted in one case to
the armature
92
98
one core and in the other case to the other core, and its upper part makes contact
alternately with the contact pieces 96 and 9: The armature 9 is connected as
shown in Figure 15 to the positive pole of the battery at the central station and
consequently according to the position of the armature the current from the
battery will be directed either to the terminal qe or to the terminal We shall
hereinafter see when studying in detail the connections at the central station the
object of this relay electromagnet and its operation.
97:
The apparatus arranged in the subscriber's office from the point of view of the
telephone system may be of any system. We have supposed that the telephone
employed is the Ader system generally used in France, but we may observe here
that we do not touch at all the telephonic apparatus itself and that we merely
add certain arrangements which we may of course add equally well to any
telephonic apparatus.
The whole mechanism which we add to the telephonic apparatus is arranged
above the post in a case, on the front face of which are placed the various buttons
and indications for the manipulation of our system. The mechanism placed at
the subscriber's office consists substantially of a relay electromagnet U (Figure 8)
similar to the electromagnet R which is placed at the central office, three ordinary
electromagnets E, E, E, and a commutator K₁; this commutator is represented in
detail in Figures 11 and 11s. It is substantially composed of a drum of insulating
material through which are passed two rectangular metallic rods K, K. These
rods are insulated from each other and form at the surface of the cylinder four
metallic plates. Two other metallic plates K, and K, are moreover fixed upon
this ebonite cylinder; they are connected with each other by a wire which
traverses the drum of the commutator; the two metallic plates K, and K, as
shown in Figure 11, cover almost the whole circumference of the drum for a
certain width, and they leave free only two bands which correspond to the
extremities of the rods K, and K3. Around the cylinder of the commutator and
held in contact with it are arranged springs T₁ T₂ T3 T4.T, T6 T.. These spring
2
5

page_text: 2
are insulated from each other and we shall hereinafter see from the diagram of
the.connections the function of these several springs. On one of the extremities
of the axis of the commutator is fixed a toothed wheel P. which gears with the
toothed wheel P, keyed upon an auxiliary axis (Figure 8). Upon this same
auxiliary axis is keyed the toothed wheel P3 which engages with the toothed
wheel P submitted to the action of a spiral or other spring tending to turn the
wheel P, and consequently the commutator K₁. The spiral spring is wound up
when such is necessary by means of a crank P (Figure 12) placed upon the front
surface of the case in which the mechanism is enclosed.
1
As shown in Figure 11 the commutator K₁ is mounted upon an axis along which
it can be moved axially. In its normal position the commutator is caused to bear
against the front surface of the case under the action of the spring 34 and it is.
prevented from turning by the point which is placed in one of the holes formed
in one of the faces of the commutator. As long as the operator does not press
upon the button V₁ the point v₁ remaining in one of the holes vs the commutator
will be immovable, but if at a given moment the operator presses upon the.
button V₁, the lever v3 oscillating about its axis will disengage the point v
from
the hole and the commutator will begin to turn under the action of the spiral
spring. If instead of pressing upon the button V, the operator presses upon the
button V, the lever Ve oscillating about its axis will act, as indicated in Figures 11
and 11, upon the lever v, which will move the commutator along its axis thus
compressing the spring 34. In this axial movement of the commutator the point v
will be drawn out of engagement with the hole vs so that the commutator will again
be left free to turn under the action of the spiral spring. In this latter case the
commutator, being moved along its axis, the position of the rods K, K, and of the
plates K, K, will be altered relatively to the springs forming the metallic
contacts T, T, T3 etc., and we shall see later on the object of this movement.
Three other buttons V3 V4 V, are arranged upon the apparatus; the button V3
is provided at the extremity of a rod n, (Figures 8 and 9) terminating in a plate
carrying three metallic fingers or contacts ng nang. Normally, that is to say when
no pressure is exerted upon the button V3, the rod n, under the action of the
spring n, is maintained in the position represented in Figure 9. But if at a given
moment the operator exerts a pressure upon the button V3 the rod n, will turn
upon its axis. By reason of this rotation the finger na will come in contact with
the plate 'n, whilst the two fingers na ng will successively come in contact with the
plates n nn
When the pressure upon the button V3 is discontinued the spring n
will move the lever n, to its original position.
4
The button V, is mounted at the extremity of the lever mġ (Figures 8 and 10)
terminating in three fingers or contacts my mg and m. By exerting a pressure
upon the button V, the finger m, comes in contact with the plate ma and the
finger m3 comes in contact with the plate m, by continuing the pressure the
fit.ger m₁ comes in contact with the plate mg. When the pressure on the button V
is discontinued the lever m3 returns to its original position under the action of the
spring my, hence it follows that the finger m, abandons the plate m, while the
fingers in ms pass again upon the plates m, and mg.
We have above stated that the essential parts which constitute the mechanism
of the apparatus were composed of the relay electromagnet U similar to the
electromagnet R and of three ordinary electromagnets E, E, E.
g"
The relay electromagnet U has for its object like that hereinbefore described
to distribute the currents. The electromagnet E. operates a plate e, to which is
pivoted a lever ₁ connected at its upper part to a rod pa which carries a pawi p2.
A spring tends to keep the pawl p, pressed against the teeth of a ratchet wheel W
The rod pa is movable about the axis W₁, hence it follows that if a current is
sent through the electromagnet E, an attraction of the plate e, takes place, the
lever p₁ is drawn downwards and the pawl p, passes over a tooth of the ratchet
wheel. As soon as the attraction ceases owing to the interruption of the current
through the electromagnet E. the spring W draws back the plate e and the

page_text: 1
2
pawl p compels the wheel W, to turn through a distance of one tooth. Upon
the axis W, which carries the ratchet wheel W, is mounted a circular plate W2
provided near its circumference with a tongue W. When the wheel W3 has
made a complete turn the tongue W, encountering the teeth of the wheel W
placed by the side will cause this latter to turn one tooth. It will be easily 5
understood, that if the axes of the wheels W, W, carry plates upon which the
mumbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, are inscribed these two plates may indicate the
number of impulses which traverse the electromagnet E4, one giving the units,
the other the tens, providing that the ratchet wheel W, has ten teeth like the
wheel W. The two wheels W, W may evidently be completed by a third 1
wheel giving the figures of the hundreds etc. This is in fact the usual mechanism
of all revolution counters. Upon the front face of the case which contains the
whole mechanism in the subscriber's office are formed two openings d₁ d
through which the operator can successively perceive the figures of the plates
just referred to.
The electromagnet E. operates a system of toothed wheels similar to that which
we have just described, so that the operator may likewise ascertain, by looking
through the openings d3 d, the number of impulses which have traversed the
electromagnet E. It is however necessary to observe one feature of the system of
toothed wheels connected with the electromagnet E. When the two wheels are at
zero, that is to say when no impulse has traversed the electromagnet E, a pin is
fixed upon the wheel, presses the bell-crank lever or arm 4 against the spring i„,
but as soon as the wheel i, under the action of an impulse traversing the electro-
magnet E, is moved one division the lever being no longer held by the pin i3
turns upon its axis i and under the action of the spring (Figure 8) the other
branch of the lever, will break contact with the plate and will make contact
with the plate . We shall later on, when studying the electric connections, see
the object of this arrangement.
"
The electromagnet E, is designed to attract a plate l, so as to act upon the rod l
aud consequently cause the lever la to turn about the axis j. This lever l3 bears a
pawl arranged in such a manner that when the plate is attracted the pawl
passes over a tooth of the ratchet wheel 7. A spring 1, moves the plate ₁ to its
original position when the current ceases to traverse the coils of the electro-
magnet E, and the lever, in returning to its original position compels the pawl
to turn the ratchet wheel the distance of one tooth. The ratchet wheel is
mounted upon the axis j, which moreover carries a toothed wheel which engages
with the wheel je.
On the same axis as the wheel je is mounted a wheelj, provided with four pro-
jecting parts placed at the extremities of two perpendicular diameters; two of these
projecting parts placed at the extremities of the same diameter are, when the
apparatus is not being operated, in contact with the two metallic plates ja ja
(Figure 8). The wheel₁ carries on its front surface a dial divided into four
sectors bearing the following inscriptions. "Rest "_"Call"-"Ring _"Speak."
The operator can perceive through the sector shaped opening d. the correspond-
ing inscription on the plate. Where no current is traversing the plate E, the
inscription visible through the opening d, is "Rest."
"
The button V, placed on the side of the apparatus is designed to bring back to
zero the wheels operated by the electromagnets E. Eл. We do not insist on the
connection of this button and the character wheels aforesaid as we may employ any
known appropriate arrangement.
Having thus described the various parts which constitute our improved system
of automatic telephone switchboard we will now proceed to set forth the operation
of the same giving also the details of all the connections established between the
various parts which constitute our system. For facilitating this study we have in
Figure 15 represented in diagram ist. a central office with 3 subscribers' plates
2nd the three posts placed in the subscribers' offices. We may however observe
that the central office as we suppose it to be for three posts may without any other

page_text: modincation receive 222 other similar plates, each of the plates represented in this
figure having 225 contacts utilized and each subscriber being thus able to put
himself in relation at his will with 224 subscribers, and it is of course understood
that what we state in respect of the lower plates CD applies to the upper plates.
The battery which is arranged at the central post is divided into two parts as
shown in Figure 15.
The wire 40 corresponds to the positive pole of the battery, the wire 41 to the
negative pole, and the wire 42 is put to earth.
We will consider the plate of the subscriber X and the corresponding post
placed in the subscriber's office and study on this plate all the electrical connections
established, which will be the case in an identical manner in the plates and in the
osts of the subscribers Y and Z.
The line wire 43 arrives in the central office and terminates at the metallic rod
or strip 44 placed below all the plates of the office in each of which it terminates
at the places assigned upon these plates to the subscriber X. In the example
chosen all the contacts of the plates having for obscisse 4 and for ordinate 3 will
Le in relation with the rod or strip 44 connected to the line wire of the subscriber X.
The rod or strip 45 which corresponds to the line wire of the subscriber Y will
likewise be in connection with all the contacts which in all the plates of the central
office will have for absciss 2 and for ordinate 4; in like manner the rod or
band 45 which corresponds to the line wire of the subscriber Z will likewise be in
connection with all the contacts which in all the plates of the office will have for
absciss 3 and for ordinate 5.
The line wire 43 of the subscriber X terminates at the relay electromagnet R is
wound round bobbins, as herein before stated, and is put in connection by the wire 46
with the earth wire 42.
=
For facilitating the study we will suppose that the subscriber X wishes to put
himself in communication with the subscriber Z represented as we have seen by the
fraction, that is to say absciss = 3 and ordinate 5; for it is understood that
all the subscribers of the telephone system, in lieu of being designated by a single
umber will be designated by a fraction whose numerator will represent the absciss
and the denominator the ordinate.
The subscriber X must therefore in order to bring the movable point S₁ of his
plate above the contact corresponding, to the line of the subscriber Z cause it to
move three divisions along the absciss and six divisions along the ordinate.
For
as indicated in Figures 1 and 1ter, at rest the point S₁ touches a plate S, which
as the length of two contacts in the direction of the ordinates, so that in order to
arrive on the first line of the abscisses the point S, must move two divisions in the
direction of the ordinates.
1
We will now describe how this result may be obtained. By pressing upon the
button V₁ the subscriber X liberates, as before stated, the commutator K₁ of his
apparatus which will turn as long as the subscriber X continues the pressure upon
the button V1. As soon as the commutator is set in motion the extremities of the
od K, have come in contact with the plates T, and T, while the extremities of
the rod K, have come in contact with T2 and T. Now the plate Ti is connected
by the wire 47 with the negative pole of the battery placed in the subscriber's
office and the plate T, is connected with the earth wire 48 whence it follows that
the contact of the extremities of the rod K, with the plate T₁ and with the plate T
produces no effect. The plate T, is connected by the wire 49 to the position pole
of the battery and the plate T is connected by the wire 50 to the line wire 43,
whence it follows that the contact of the extremities of the rod K₁ with the
plates T T connects the line wire to the positive pole of the battery. A positive
current therefore traverses the line 43 and arrives in the relay R, thence it passes
through the wire 46 into the earth wire 42 and returns to the subscriber through
the earth and the plates T₁ and T. Under the action of this current the
armature q is attracted by the core Q3 and the upper extremity of the armature
touches the screw 9s. Now the armature 9, is constantly connected to the positive
B

page_text: pole of the battery of the central post by the wire 51 and the terminal q is con-
nected by the wire 52 with the plate f₁. A current therefore traverses the wire 51,
the armature 78, the terminal ge, and the wire 52 and arrives in the plate f₁; from
this plate and through the contact spring te in contact with a metallic part of the
plate, because the carriage F, has not moved, the current arrives at the plate f2.
From this plate the current arrives at the electromagnet E₁ by means of the
wire 53, it traverses the electromagnet and finally arrives through the wire 54 in
the wire 41 of the negative pole of the battery. The circuit of the electromagnet F₁
is thus closed and when traversing the electromagnet E₁ the current causes the
carriage F, to advance one rack tooth as before specified.
In Figure 15 the parts of the plate of the subscriber X have been represented
when the carriage F₁ is displaced 3 divisions and the carriage F, is displaced six
divisions; on the contrary the parts of the plates of the subscribers Y and Z are
represented in their original position.
As soon as the positive current sent through the commutator K₁ into the line
has ceased, that is to say as soon as the extremities of the rod K3 are no longer in
contact with the plates T, and Te the armature gg being no longer attracted by the
part Q3 returns to the original position between the two parts Q3 and Q2 and the
circuit of the electromagnet E₁ is open; it will be closed again only after a half
rotation of the commutator K, causing the contact of the extremities of the rod K,
and of the plates T₂ and Te, which as we have seen has the effect of a positive
current being sent into the relay R.
We will now examine what happens at the central post at the moment when the
first positive current coming from the post of the subscriber ceases, that is to say
as soon as the extremities of the rod K3 have left the plates T, and T. The circuit
of the electromagnet E₁ is open and the carriage F, has advanced one tooth of the
rack, but in this forward movement the movable contact t₂ fixed to the carriage F₁
has made contact with the metallic part of the plate t₁ and has consequently
brought the carriage F₁ into connection with the negative pole of the battery at
the central station by the wire 55. Now the carriage F₁ is connected by the
wire 56 to the line wire 43 and consequently at the moment of the passage of the
contact to over a metallic part of the plate t₁ the line 43 is put in connection with
the negative pole of the battery at the central station. A negative current there-
fore arrives in the relay U through the wire 57, traverses the relay and through
the wire 58 arrives at the plate T₁, traverses with the aid of the plates K and K,
the commutator and passes through the plate T, to earth whence it returns to the
central post.
We may observe that the plates K, and K, will permit the circuit of the relay U
to be closed only when the commutator K₁ does not send currents through the line
wire, in other words when there is no current in this wire, for the interval which
serves to isolate the plates K and K, from each other will correspond
precisely to the space occupied on the commutator by the extremities of the
rods K, and K3.
Let us now examine the effect produced in the subscriber's office by this negative
current arriving through the line wire in the relay electromagnet U. The
armature u is attracted towards the core U3 and the upper extremity of the
armature therefore touches the contact us; now the armature u, is connected by
the wire 60 with the positive pole of the battery placed in the subscriber's office.
A current thus arrives at the armature u, through the wire 60 passes into the
contact U6 down the wire 61 into the lever, flows into the plate and arrives
through the wire 62 in the electromagnet E, which is connected by the wire 47 to
the negative pole of the battery. The circuit of the electromagnet E, is then
closed, this electromagnet is therefore energized and it attracts the plate e, which
has for its object as before stated to cause the wheel W2 (Figure 8) to turn one
division, and consequently cause the number 1 to appear in front of the opening do.
It should be observed that at the moment when a negative current is sent into the
line wire of the central post at the subscriber's office this negative current

page_text: traverses likewise the electromagnet R at the central post. The armature 9, is
therefore attracted towards the core Q2 and by its front extremity touches the
part g, which is connected by the wire 64 with the electromagnet E₂. The electro-
magnet E, is connected in its turn by the wire 65 with the plate r₂ (Figures 15
and 7) which is itself at this moment in connection by the projecting parts 13 of
the wheel r with the plate r3 which is itself connected by the wire 66 with the
plate f. We thus see that as far as this plate the circuit of the electromagnet E2
is closed and a positive current could pass through the wire 51, armature 78,
terminal 97, wire 64, electromagnet E₂, wire 65, plate r₂, wheel, plate r3, wire 66
and finally arrive at the plate f. But at the moment when this current could
flow, that is to say at the moment when the negative current is sent from the
central post to the subscriber, the spring t, which is connected by the wire 67 to
the negative pole of the battery is in contact with an insulating part of the
plate, so that at this moment the circuit of the electromagnet E, is opened
by the plate f and it follows from this that the negative current sent to the
subscriber by the central office has no action upon the parts situated in the central
office itself.
When the negative current acts upon the electromagnet E. at the subscriber's
office the commutator still continues to turn, a fresh positive impulse is sent from
the subscriber's office to the central station and a negative impulse from the central
office to the subscriber, as long as the subscriber presses upon the button V₁.
By this means in the case which we have chosen the subscriber ceases the
pressure at the moment when the number 3 appears through the opening d₂, because
the absciss of the subscriber Z with whom the subscriber X wishes to put himself
into connection is equal to 3. Directly after having ceased the pressure upon the
button V, the subscriber presses upon the button V2. The pressure exerted upon
the button V, has the effect, as indicated in Figure 11 and as before stated, of
displacing the commutator, so that the extremities of the rods K, will in consequence
of the rotation of the commutator come in contact with the plates T2 and T. and the
extremities of the rod K, will come in contact with the plates T, and Tê
The
pressure exerted upon the button V, will moreover have the effect of causing the
rotation of the commutator as herein before explained.
line.
2
6
3
2
.
We will now examine the effect of this pressure on the button V, with regard to the
sending of the currents into the line. As soon as the commutator is set in motion
the extremities of the rods K₂ will be brought in contact, with the plates T2 and T, ;
this will have no effect on the line as before stated; for the plate T2 is in connection
with the positive pole of the battery in the subscriber's office and the plate Ts with
the earth. Also the extremities of the rod K, will come into contact with the
plate T, and the plate Te; now the plate T, is in connection by the wires 68 and 47
with the negative pole of the battery and the plate T is in communication with the
A negative.current coming from the subscriber's office will therefore arrive
in the relay R at the central post and will return through the earth, and the plates T₂
and T. The action of this current which traverses the relay R has the effect of
causing the attraction of the armature 9 upon the terminal Q, and the upper
extremity of the armature 7, will come in contact with the part 97. Now the circuit
of the electromagnet. E, is formed by the wire 64 which leaves the part 7, the
electromagnet E, itself, the wire 65, the projecting parts 4, and l₁, the wheel 115 the
wire 66, the plate fe, the spring, and the wire 67. This circuit is therefore closed
when the armature gg touches the contact 9, because the spring ts is in contact with
a metallic part of the plate fe
As soon
The electromagnet E, is therefore traversed by a current which compels the
carriage F2, as above set forth, to move forward one tooth on its rack.
as the extremities of the rod K3 have broken contact with the plates T3 and T in
consequence of the rotation of the commutator the negative current sent from the
subscriber's office to the central station ceases, the armature g, passes back to its
position and the circuit of the electromagnet E, is opened. The commutator Ki
continuing to turn, a second negative current is sent from the subscriber's office to

page_text: the central post and the carriage F advances a second tooth, but at this moment
and as indeed happened when we examined the effect of the pressure upon the
button V, a positive current is sent automatically from the central station to the
subscriber in the following manner: the plate t, over which is moved the spring
secured to the carriage F, is connected by the wire 69 with the positive pole of the
battery at the central office and moreover the carriage F, is connected by the wire 70
with the line wire 43. Accordingly at the moment when the spring tg fixed upon
the carriage F, passes above a metallic part of the plate t, a positive current coming
from the central station through the wire 69, the plate t, the carriage F, and the
wire 70 will arrive through the line wire 43 in the relay U at the subscriber's
office. This current will traverse the relay U and flow through the wire 58 to the
plate T and thence to the plate T, through the metallic parts K, K., finally flows
to earth through the wire 48 and will return by this way to the central station.
The relay electromagnet U is thus traversed by a positive current. This positive
current will effect the contact of the armature on the core U, and the upper
extremity of the armature u, will touch the contact u, and as will be seen the
circuit of the electromagnet E, will be closed. In fact the armature us is connected
as we have seen by the wire 60 with the positive pole of the battery at the
subscriber's office. The current thus passes through the wire 60, armature us,
contact u, wire 71, plates ja j2, wheel, wire 72, electromagnet E, and finally the
wire 47 which terminates at the negative pole. As the current passes round the
electromagnet E, it causes the attraction of the plate which it operates and which
as we have before explained makes the number 1 appear at the opening d. As
long as pressure is exerted upon the button V₂ the same phenomena occur in the
same order, that is to say a negative current will pass from the subscriber's office to
the central post and a positive current which is in a way a controlling current will
arrive at the subscriber's office from the central station so as to indicate to him the
number of divisions passed over by the carriage F2. For the same reasons as those
above explained the positive current sent from the central office to the subscriber
produces no action upon the parts situated at the central station, for this positive
current arriving in the relay R causes the armature g, to make contact with the
contact pin But at this moment the circuit of the electromagnet E₁, is opened,
for the carriage F₂ being moved the spring to is no longer in contact with the
plate connected to the electromagnet E, but with the plate f3; also at the
moment when the positive current flows the spring to passes over an insulating part
of the plate 1, the circuit of the electromagnet E₁ is therefore open for these two
reasons and at this moment no current can pass round its coils. The subscriber
will continue to press upon the button V, until he perceives through the openings d, d
a number equal to that of the denominator of the fraction of the subscriber with
whom he wishes to put himself in communication; for this purpose we have
supposed that he wished to put himself in communication with the subscriber Z, he
will press his finger until the number 5 appears through the opening d4 at this
moment the point S₁ will be upon the fifth line of the abscisses, although the
carriage 4 is displaced six divisions, for it should be observed that the first displace-
ment of the carriage has not been controlled by the subscriber, because at this
moment the point was not in contact with the plate t
2
These first operations having been effected, the point S₁ will be upon the contact
which in the plate of the subscriber X is connected to the line wire of the
subscriber Z. As soon as the subscriber X has placed his point S, upon the
contact which he required, the action of the electromagnets E1 and E2 which have
no other object than to cause the movement of the carriages Fi and F, becomes
useless. It is therefore necessary to break the circuit, of these electromagnets E₁
and E. With regard to the electromagnet E, this object has already been obtained.
In fact when the carriage F, has passed over the first tooth of his rack, that is to
say when it has left its first position, the spring te leaves the plate 2 which
communicates with the winding of the electromagnet E₁, and is moved along the
piate or strip f3 which communicates with the winding of the electromagnet E3; the

page_text: spring remains in communication with this latter plate to the end of the movement
of the carriage F
From this it follows that the positive currents which will be sent into the
winding of the relay electromagnet R will no longer actuate the electromagnet E₁
but the electromagnet E, provided that these positive currents are sent at the
moment when the spring to touches a metallic part of the plate fi
By an analogous process the circuit of the electromagnet E, which is in the
subscriber's office and which corresponds in part to the electromagnet E₁ of the
central station has broken its connection with the contact 6: Indeed as soon as.
the wheel has turned one tooth the lever i being no longer held by the pin i is
submitted to the action of the spring i̟, which displaces it and brings it in contact
with the plate i,, so that the screw u, instead of communicating with the electro-
magnet E, communicates by the wire 61, lever ₁, terminal i, wire 80 with the
finger n, fixed to the extremity of the rod n, actuated by the button V3 and as we
shall hereinafter see this finger ng will at a given moment close the circuit of the.
electromagnet E. The electromagnet E, at the central station serves in its turn
for breaking the circuit of the electromagnet E
Let us now see in what manner the action takes place :
2
As soon as the subscriber X has ceased to press upon the button V, he presses:
upon the button V;; the action of the finger on the button Va has for its object to
send to the central station and in the order which we indicate (1) a positive current ;.
(2) a negative current; (3) again a positive current.
When the lever n₁ turns
about its axis of rotation in the direction of the arrow Figure 15, the fingers ng na
slide upon the three metallic plates n ns The plate n is connected with
the negative pole of the battery at the subscriber's office through the wires 81 and 47
and the plates nд and n communicate with the positive pole through the wires 82
and 83. As soon as the lever n, is displaced in consequence of the pressure on the
button V, the finger ng touches the plate n, and the finger n, touches the plate 5.
Now the finger n, is connected by the wires 84 and 50 with the line wire and the
finger n3 is connected by the wires 85 and 48 to earth so that a positive current.
flows through the wire 82 into the plate n₁, passes through the finger n, and thence-
through the wires 84 and 50 into the line wire 43, then to the relay, and away to
earth and returns to the subscriber by way of the finger na and the plate n5.
3
It will be understood that the fingers ng n, are isolated on the lever n.
The positive current passing round the electromagnet R causes the lever 38 to
be attracted towards the part 7 and closes the circuit of the electromagnet E,. In
fact this circuit is as follows: the wire 51, armature qg, screw 9, wire 52, plate f 19.
spring te, plate, wire 86, electromagnet E,, wire 87 and lastly the wire 41 which
terminates at the negative pole of the battery. The positive current by traversing
the electromagnet E, causes the attraction of the plate 27 (Figure 7) which.
descends, compelling the pawl 30 to turn the ratchet wheel H₁ one tooth.
As the ratchet wheel turns it carries with it the axis O, upon which it is fixed.
and consequently the wheel r₁ will be moved forward a distance corresponding to
one tooth of the ratchet wheel. The projecting parts ₁₂ will break contact with.
the plates re rand will be brought in contact with the plates 7. Accordingly
the action of the positive current sent through the electromagnet E, will have for
its object to open the circuit of the electromagnet E₂. which will prevent any
ulterior movement of the carriage F2. In addition to the action produced upon
the circuit of the electromagnet E, the movement of the wheel has had the
effect of bringing the projecting parts into contact with the plates ₁rs..
Now the plate r is connected by the wire 90 with the line wire and the plate r
is connected through the wire 91 with the point S₁.
Besides the connection which exists between the movable contact S, and the
plate this contact S, is connected through the wire 92 with a plate which
is in contact with the contact t (Figures 1 and 15) secured to the carriage Fi
which latter is itself connected to the line by the wire 56 so that as long as the
carriage F₁ has not moved, the contact S₁ is in connection with the line wire-

page_text: through the wire 92, plate t4, point t₁, carriage F, and wire 56; but as soon as the
carriage F₁ is moved by reason of the button V₁ being pressed the point t, breaks
contact with the plate 4, and the point S, is thus momentarily cut off from the line
wire and it is not again connected with this wire until the electromagnet E, has
been actuated as we have just seen. This temporary interruption of the connection
between the contact point S, and the line wire is indispensable for eliminating the
influence of the currents which serve to move the contact point over the contacts,
otherwise these currents by entering the line of contact of some other subscriber
would penetrate into the contact finger or point of this subscriber and thence into
the overhead conducting wire, thus setting in motion apparatus foreign to the
communication which it is intended to establish.
The movements of the distributing wheel r₁ are controlled in the post of the
subscriber.
4
.
Upon the axis O, is keyed, as herein before stated, a wheel H₂ whose circumfe-
rence is provided successively with metallic and insulating parts. Two brushes or
contact springs H, and H, make contact with this wheel H₂. One of these
contacts H, is connected by the wire 100 to the line wire 43, while the other
contact His connected by the wire 97 to the negative pole of the battery of
the central station. When the wheel-r, is in its unmoved position, that is to say
when the projecting parts are in contact respectively with the plates r₂ and 13'
the contact pieces H. and H, touch the wheel H₂ at insulating parts therein and
consequently no current flows. When the wheel turns one tooth, the wheel H₂
likewise turns and during this rotation the contact pieces H and H, make contact
with the metallic parts in order to arrive again on the insulating parts.
Accordingly during this movement a circuit is established comprising the wire 41
corresponding to the negative pole of the battery, the wire 97, contact spring H.,
wheel H2, contact H,, wire 100, line wire 43, wire 57, electromagnet U, which as
we know is connected by the wire 58, plate T, and plate T, to earth. The circuit
of the electromagnet Ŭ is therefore closed when the contact pieces H4 and H,
touch metallic parts of the wheel H2, and the coils of the electromagnet U are at the
same period traversed by a negative current coming from the central station.
4
The armature u is then brought in contact with the contact us, which as we shall
see closes the circuit of the electromagnet E. This circuit comprises the positive
pole of the battery in the subscriber's office, the wire 60, armature u,, contact
screw u, wire 61, lever 4, contact screw 7, wire 80, finger ng,
plate ng wire 101,
electromagnet E, wire 102 and the negative pole of the battery.
The circuit of the electromagnet E, is therefore closed. The pawl (Figure 8),
when the current ceases in the electromagnet E, turns the ratchet wheel, under
the action of the spring .
The wheel je is mounted on the same axis as the ratchet wheel ; a wheel j₁
divided into four sectors is actuated by a toothed wheel keyed upon the axis of
the wheel in such a manner that when the ratchet wheel turns one tooth, the
wheel is turned or rotated one quarter of a complete revolution. The wheel jis
divided into four sectors, upon each of which is one of the following inscriptions:
"Rest"-
Call" Ring
"-" Speak". During each complete revolution of the
wheel all these inscriptions will be at the opening d, at the subscriber's office,
one after the other, commencing with the inscription "Rest."
_ 66
When
The object of these inscriptions is explained in the following manner.
the apparatus of the subscriber is not being operated the inscription "Rest" will
be seen at the opening d, and this inscription remains at the opening as long as the
buttons V₁ V2 are depressed.
As soon as the subscriber presses upon the button V3 as we have seen the first
negative current sent by the station to the subscriber X has closed the circuit of
the electromagnet E has turned the ratchet wheel 1, one tooth and consequently
the wheel a quarter of a complete revolution and the inscription." Call then
.appears at the opening ds.
After having thus examined the actions of the positive current sent to the

page_text: 3
central station by the contact of the finger n, and of the plate n, and of the control
current sent from the central station to the subscriber, let us see what will happen
when the lever continues to turn under the action of the button V, which is
depressed. The points nz and n2 come respectively in contact with the plates n
and n. A negative current passes through the plate n plate n₂, wires 84 and 50,
and thus to the line. The contact between the finger n and the plate serves
718
for the return of the current through the earth. The negative current flowing
through the line wire passes around the electromagnet R, passes to earth and
thence to the subscriber. The action of the negative current upon the electro-
magnet R has the effect of bringing the armature gg in contact with the part 97,
but as the circuit of the electromagnet E, is open the action of the negative
current in the relay electromagnet R has no effect on the apparatus of the
subscriber X at the central station, but this negative current passes moreover through
the wire 90 into the plate . it flows through the projection l into the wheel ri
and thence through the projection ₁ into the plater, then through the wire 91
into the contact point S₁ and from the latter it flows through the wire 45 of the
contacts Z into the contact S, then into the contact S₁ to the subscriber Z. From
the point S the current flows to the plate t24, passes into the point to the
carriage F1, thence through the line wire of the subscriber Z it reaches the relay
electromagnet R² and thence flows to earth. The action of this current upon the
electromagnet R² has the effect of bringing the armature g, in contact with the
contact screw, which closes the circuit of the electromagnet E2. The electro-
magnet. Ez, being actuated compels the carriage F, to shift one tooth, which as
previously described breaks the circuit of the electromagnet E³, by means of the
spring and the plate f₂; at the same time the spring as it is moved will bear
upon the plate 23, thus establishing a connection between the winding of the
electromagnet E², and the relay contact screw 9. Hence it follows that the
negative current sent by the subscriber X produces in the plate of the subscriber Z
the effects which we have just studied, moving the contact point S, in the direction
of the ordinate, which does not yet bring the point S₁ upon the contacts of the
subscribers because as previously described there is a plate S in the direction of
the ordinates having two contacts which are not connected to wires of subscribers.
The negative current sent by the subscriber X into the plate of the subscriber Z
produces the effects which we have just described, but a current also flows to the
office of the subscriber Z, traverses the electromagnet U, which closes the circuit
of the electromagnet E, and the number 1 appears at the opening 2. The first
movement of the carriage F2 produces no control current and therefore we have
not to take such movement into account.
.
Let us now examine the effect of the third current sent by the subscriber X to
the central station, when under the action of the spring n, the button V3 returns to
its original position. This current, as we have said, is a positive current, for it is
produced by a fresh contact between the plate n, and the finger n₂. This positive
current flows to the relay electromagnet R and closes the circuit of the electro-
magnet E3, the electromagnet E, then acts again upon the plate 27 and the wheel r₁
turns through an angle equal to one tooth of the ratchet wheel. In addition to
this first effect the consequences we have just described the positive current flows
also to the plate r, projection l, wheel projection 4, plater, wire 91, contact
point S, and thence passes into the plate of the subscriber Z, it enters the relay R*
and closes the circuit of the electromagnet E3. This electromagnet turns the
distributing wheel one tooth (the first relatively to its original position). In
this manner, exactly the same effects happen as in the apparatus of the subscriber X
the circuit of the electromagnet E, is opened and the contact point S, is put into
connection with the line wire terminating in the office of the subscriber Z. This
positive current likewise passes to the office of the subscriber Z, which closes
the circuit of the electromagnet E. The number 1 appears at the opening d
and the circuit of the electromagnet E is opened.
Now the wheel r₁ turning sends, as we have before seen, a negative current into
"

page_text: the line wire of the subscriber Z (this being the control current). This current
traverses the electromagnet U and the armature us is attracted towards the
contact, but this has no action upon the apparatus of the post of the subscriber Z,
because this attraction could only close the circuit of the electromagnet E, but
this circuit is opened by the finger n², and the plate n², as long as the subscriber Z
does not press upon the button
3°
The two negative control currents one of which is produced by the wheel
and the other by the wheel are combined in the post of the subscriber X and
passing into the relay U they close the circuit of the electromagnet E, which is
possible, because the finger n, is in contact with the plate no, the wheel turns
one quarter of a revolution and the inscription "Ring" appears at the opening d³¸
and then the subscriber X by pressing on the button M of his apparatus causes
the inscription "Speak" to appear of itself.
Thus after the button V3 has been depressed the apparatus of the central station
corresponding to the subscribers X and Z will be in the following position in the
apparatus of the subscriber X the electromagnets E, and E, which direct the
movement of the contact piece S₁ will be blocked and consequently the pieces S₁
in the two apparatuses cannot be displaced. The distributing wheel will have
advanced two teeth from its original position and the distributing wheel, a single
tooth. The contact pieces S, and S, will be in communication with the overhead
conducting wires of the subscribers X and Z.
The negative currents sent by one of the two subscribers will cause no impulse
on their respective apparatus. On the other hand each positive current sent by
one of the subscribers will cause the distributing wheels 1 and 2, to advance one
tooth in the two apparatus simultaneously.
The subscriber X profiting by the fact that a negative current produces no
effect either in one or in the other apparatus sends the call signal which is given
by means of a bell. With this object he presses upon the special button of the
Ader apparatus designed for the bell and which, as shown in the diagram of the
connections, sends a negative current into the line. The subscriber Z, after having
heard the call bell, presses upon the button V3 of his apparatus which as before
stated produces successively three currents (a positive current, a negative current,
a positive current).
The first positive current closes the circuit of the electromagnet E3, which has
the effect of turning the distributing wheel one tooth, and it moreover closes the
circuit of the electromagnet E3, which has the effect of turning also the
distributing wheel in such a manner that after this positive current the dis-
tributing wheel ₁ has been actuated three times, while the distributing wheel
has been actuated only twice.
The
As the wheel turns it sends, as before described, a negative control current
which traverses the electromagnet Uz and closes the circuit of the electro-
magnet E, because at this moment the finger touches the plate n
inscription "Call" will therefore appear in the office of the subscriber Z: this
negative current passing into the apparatus of the subscriber X has no action
thereon as we have already explained, because the finger n³, is no longer in contact
with the plate n
Moreover the wheel as it turns sends a negative control current which has no
action upon the apparatus of the subscriber ✗, nor upon the plate of the
subscriber Z, but which arriving in the post of the subscriber Z traverses the
electromagnet Uz and the armature u², closes the circuit of the electromagnet E
which has the effect of causing the word "Ring" to appear at the opening d².
The wheel turning for the third time produces moreover certain effects which
we will now proceed to describe.
When the wheel is turned for the third time the end h₂ of the rod h₂ h₁ makes
contact with the plate r, and the end 4 makes contact with the plate 10, whilst
the rod h₁s touches by one of its ends the plate r, and by the other end the
plate 11
Now the plate r, is connected by the wire 94 to the solenoid S, and the

page_text: plate r, is connected by means of the wire 95 to the other end of the winding of
the same solenoid; moreover the plate rio is connected to the positive pole of the
battery by means of the wire 96 also the plate r₁ is connected by the wire 97 to
the negative pole of the battery. Hence it follows that when the wheel ₁ has
turned for the third time the rods h₂ h, and h₂ h, close the circuit of the solenoid S,.
The winding of the solenoid is such that when a current flows through it the
movable piece S₁, which is really a permanent magnet, is drawn away from the
lower plate CD which we have called connection plate into contact with the upper
upper plate A B which we will call conversation plate, and the part S, which up to
the present was in contact with the contact on the plate CD corresponding to the
wire of the subscriber Z, now engages with the contact which also corresponds on
the plate A B to the wire of the subscriber Z. We may observe that the
subscriber X has not been able to put himself in a position to speak to the
subscriber Z except when the latter has pressed upon the button V3 of his apparatus
which causes the part S, to be brought in contact with the conversation plate.
This has its importance, for admitting for a moment that the two subscribers X
and Y should be about to speak and that a third subscriber Y should wish to hear
their conversation he cannot do so because it would be necessary for this purpose
that it should be one of the two subscribers X or Z who has placed the contact
piece S upon the conversation plate.
Thus after the first positive current sent by the subscriber Z the piece S is in
contact with the upper plate A. B and in the office of the subscriber Z the wheel r³₁
has turned twice and the word "Ring" appears at the opening 25.
As above stated the second negative current which the subscriber Z sends by
pressing the button V² produces no effect either in the apparatus of this subscriber
or in that of the subscriber X.
The third positive current also sent by the same subscriber Z, by reason of the
pressure of the button V3, will act only upon the relays R², because the
subscriber X, whose contact point S, is already upon the second line of contact
of the platform A B has no communication at this moment with the subscriber Z
whose contact point S, remains upon the line of contacts of the platform C D.
The action of this positive current in the relay R² has the effect of turning for the
third time the wheel, which, as we have explained for the wheel, effects the
closing of the circuit of the solenoid S, and consequently causes the point S², to
be moved from the plate CD into contact with the plate A. B.
Hence it follows
that after the pressure of the button V, the subscribers X and Z will be in com-
munication in such a manner that no third party can overhear their conversation,
because the two points S, and S, are upon the contacts of the plates A B and
because they will remain there until the signal announcing the end of the conver-
sation has been given, that is to say, as we shall see later on, until one of the two
persons holding a conversation has pressed the button V
""
The wheel turning for the third time, sends as we know a negative control
current which acts only in the post of the subscriber Z, closing the circuit of the
electromagnet E, which turns the wheel one quarter of a revolution in such
a manner that behind the opening d, the inscription "Speak" will be seen, by the
Subscriber Z.
We have herein before seen that the inscriptions "Call" and "Ring" appear
successively to the subscriber X when he presses upon the button V, but we
should observe that as the sending of the currents produced when the button Vis
pressed is very rapid, the word "Call" does not remain and gives place immediately
to the inscription "Ring." On the contrary at the office of the subscriber Z who
is called the negative currents which enter his apparatus are produced when he
presses upon the button V3 so that the inscriptions "Call" and "Ring" will pass
very rapidly and that only the inscription "Speak" will remain visible through
the opening s
From this it follows that subscribers between whom communication is established
C

page_text: can converse together only when the inscription "Speak" has appeared at the
opening of the apparatus of the subscriber Z.
When the conversation is terminated the subscriber X who has put himself in
communication with the subscriber Z presses upon the button V and we shall see
later on what the subscriber Z has to do. The pressure on the button V* has the
effect of sending successively two positive currents.
The first is produced by the contact of the finger m, with the plate or contact.m
and of the finger m, with the plate or contact ms; the pressure continuing to be
exerted, the finger m2 passes beyond the plate m, and the finger m3 passes beyoud
the plate ms, but coming afterwards again under the action of the spring m, a fresh
contact is established between the finger m, and the contact plate m, and between
the finger m3 and the contact plate m, which produces the second positive
current.
In the diagram of the connections (Figure 15) we have indicated by an arrow
the direction of the turning movement of the lever m³.
Before studying the effect produced in the apparatus by the pressure exerted
upou the button V it may be observed that the finger m, which closes the circuit
upon the electromagnet E comes in contact with the plate m, only after the first
contact of the fingers m, m3 with the plates m, m, respectively.
6
4
The pressure exerted. upon the button V produces therefore in the following
crder (1) a positive current passing from the subscriber X to the central post,
(2) a negative current passing from the central post to the subscriber and which
can act upon the electromagnet E, because at this moment the finger m³, is in
contact with the plate m³, (3) a positive current passing from the subscriber X to
the central station and (4) a negative current passing from the central station to
the subscriber X, which current has no action upon the apparatus, because at this
moment the circuit of the electromagnet Ex is open, the finger m³, being no longer
in contact with the plate m³.
We will now study successively the action of these currents in the apparatus.
The first positive current sent by subscriber X by pressing the button V. of his
apparatus passes to the relay R₁, thereby closing the circuit of the electro-
magnet E This current continues in the line, passes to the relay R1, which
closes the circuit of the electromagnet E², also so that the wheels and will
each turn one tooth.
Let us now study the effect produced by this fresh turning movement.
One end of the rod h₂, h4 will make contact with the plate r, and its other
end with the plate r while the ends h₁ h3 of the rod h₁ he will make contact
with the plates r, and r12 respectively; the circuit of the solenoid S2, like that of
the solenoid S2, is therefore closed and both solenoids will be traversed by a current
which will be in the opposite direction to that which has originally traversed them,
so that the point S, like the point S₁ will be in engagement with the contacts on
the plate CD.
By the contact springs or brushes H. and H, and the wheel H, a negative
current is sent into the line of the subscriber X as into the line of the subscriber Z;
this negative current arriving in the relay U closes the circuit of the electro-
magnet E, which is possible because the finger m, is at this moment in contact
with the plate m³,; the electromagnet E being actuated turns the wheel, as
we have seen, a quarter of a revolution so that the subscriber X will see through
the opening d, the word "Rest."
6
The negative control current produced by the turning movement of the wheel r²₁
has no action upon the devices in the office of the subscriber Z, because the circuit
of the electromagnet E is open (the subscriber Z pressing at this moment neither
on the button V, nor on the button V4).
The second positive current which is produced by the second contact of
the fingers m, m³, and of the plates m³, m, when these fingers are drawn back
again by the spring m³, has the effect, as we will proceed to explain, of bringing

page_text: back the apparatus X and Z of the central station to their starting point. In fact
this positive current arrives in the relay R, and in the relay R, thereby closing
the circuit of the electromagnets E*, and E. The wheels ³, and ₁ will therefore
turn again one tooth.
°
During this fresh turning movement the ends h₂ h₁, of the rods 2 h and h
will pass over the contacts g₁ and 2, thereby closing the circuit of the electro-
magnets 11 and 12, for while the ends ₁₂ of the rods pass over these contacts
the ends h h will come in contact with the plate r₁, which latter is connected to
the positive pole of the battery by means of wire 96. Now, the electromagnet 11
is connected with the negative pole the battery by the wire 110 and the electro-
magnet 12 is connected with the same pole by the wire 111. From this it follows
that at the moment the rods h₁ h₁ pass over the contacts 91 92 these two electro-
magnets 11 and 12 will be traversed by a current; they will be energized and, as
previously described the rods parallel to the racks will be raised and the
carriages F, F, in the two apparatus being no longer retained by the racks will
each return to their starting point under the action of springs.
The two apparatus at the central post are in this case brought to rest and the
negative current sent at the same time through the contact brushes H, H, and the
wheel H₂ at the office of a subscriber will have no effect upon the apparatus of
that subscriber, because in the two posts, the circuit of the electromagnet E, is at
this moment opened by the finger m₁.
To put the apparatus into condition for a fresh operation it will be sufficient for
each of the subscribers to press at his office upon the button V, so as to bring back
to zero the characters visible through the openings d₁ d₂ da d, and furthermore the
subscriber called that is to say in this case the subscriber Z must bring the wheel
to the rear until the inscription "Rest" appears through the opening, by turning
the button M, fixed to the extremity of the axis of the said wheel.
1
We may observe that not only the carriages F, F, will have now returned to
their original position in the apparatus, but that the wheels have also taken
up again not their original position, but a corresponding position, for they are
turned a quarter of a revolution, because the various manipulations which we have
just enumerated have turned the ratchet wheel five teeth and this wheel has
altogether twenty teeth, so that at the moment when the carriage F, and F, have
moved back to their starting point the projecting parts ₁₂ of the wheel r, come in
contact with the plates r2 rs, which is of no importance, because the four quarters
of the wheel r₁ are arranged in the same manner. The next time the connection.
has to be established the rods h, h4, h₁ he will no longer act, but the rods which are
perpendicular; in like manner the projecting parts l3, will not effect the connections
but the projecting parts 1 l.
Such is the apparatus which forms the subject of this invention and we may sum
up the operations to be effected in the following manner :
1
The subscriber who desires to enter into conversation with another subscriber
bears upon the button V₁ and maintains this pressure until in the openings d₁ de
appears the numerator of the fraction attributed in the list of subscribers to the
subscriber with whom he wishes to hold a conversation; he then presses the
button V₂ until in the openings d2 d4 there appears the denominator of the fraction
corresponding to the same subscriber.
When the numbers visible through the openings correspond exactly to the desired
fraction the subscriber presses with bis finger upon the key V, and makes sure that
the inscription visible is that of "Ring." He then rings and after having rung be
causes the inscription "Speak" to appear at the opening d, and waits for the
subscriber called to speak to him.
When the conversation has terminated the
which announces the end of the conversation.
the button V4.
subscriber calling gives the signal
With this object he presses upon
In practice all the buttons except the button M₁ are provided with inscriptions
thus the button V bears the word "Numerator," the button V, "Denominator,"
>>>

page_text: the button V3 "Call," the button V₁ "End of Conversation," the button Vs
"Numbers."
The subscriber called, after having heard the bell approaches bis telephonic
apparatus and presses the button V3 and when the inscription "Speak" appears at
the opening dg he proceeds with the conversation.
On the conversation being once terminated the subscriber called acts upon the
button M as we have herein before stated.
At the beginning of this Specification we have said that we described only by
way of example the employment of perpendicular co-ordinates, and it will be
understood that the operation of our apparatus would be the same if the carriages F
and F2, instead of being moved in two perpendicular directions, were moved in two
oblique directions. Nothing would be changed in the apparatus. But if instead of
employing rectilinear co-ordinates we wish to use polar co-ordinates for example,
the arrangement of the apparatus while remaining the same as regards the electric
connections is modified from the point of view of the arrangement of the
carriages F, and F2. In this case as shown in Figures 13 and 14, we replace the
carriages F1 and F2 by slotted bars F₁ and F. These said bars can turn freely
about axes O, and O2. Upon the axis O₁ are mounted the ratchet wheels G
and G₂, and upon the axis O, are likewise mounted ratchet wheels G, and G. The
wheels G, and G, have teeth inclined in the same direction, while the wheels G₂
and G, have teeth inclined in opposite direction. The bar F₁ may be attached by
means of the pawl G, to the wheel G2, so that as soon as the axis O₁ turns in the
direction indicated by the arrow the bar turns with it. The rotation of the axis O₁
is effected by means of the second ratchet wheel G in the following manner: that
is to say, when the electromagnet E₁ is traversed by a current it attracts the
armature which is attached by means of the hinged rod c₂ to the lever C3 which
moves freely about the axis O₁. On this lever is fixed the pawl c which is pressed
against the teeth of the wheel G₁ by the spring c. When the armature c₁ is
attracted by the electromagnet E₁ the pawl c4 passes over one of the teeth of the
wheel G₁ for preventing it from passing over a greater number of teeth the
screw E, is provided which plays the part of a stop, regulating the movement of
the lever (3.
As soon as the current is interrupted the spiral spring c, draws back
the armature and at the same time causes the pawl 4 to pass over a tooth of the
wheel G₁ and also causes the bar F, which participates in the movements of the
axis O₁ to turn a corresponding distance. In this manner each time a current
passes round the coils of the electromagnet E₁ the bar F₁ is moved over a distance
corresponding to a tooth of the ratchet wheel and thus it is caused to pass
successively from one series of contacts to another and at the same time carries the
contact point S₁.
2
2
A similar movement also takes place in the bar F, which is moved by the
electromagnet E, each time the current passes through it; the bar F₂ is displaced
similarly as described with regard to the bar F₁. It will be easily seen that
the contact point S₁ can thus pass over all the contacts arranged upon the
plate CD.
It is evident that in this modified arrangement the electromagnets E, and E, are
fixed and are not moved as in the arrangement described in the first part of the
Specification.
As regards the electrical connections we use in this modified arrangement all the
parts previously described besides others such as the axis O3 and all the wheels
keyed upon this axis, the plates f5 f 7 1 3.
Dated: 11
1005
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.

page_text: Improvements in and relating to Telephone Systems.
We, SALOMON BERDITSCHEWSKY called APOSTOLOFF, and MOISE FREUDEN-
BERG, both of 95 Boulevard Beaumarchais, Paris, in the Republic of France,
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:-
Our invention relates to telephone systems.
The central station which puts the subscribers of a telephone system in
communication with each other in accordance with their indications necessitates a.
considerable number of employees who occasion very great general expense for
working telephone systems.
In order to remedy on the one hand this inconvenience, and to augment on the
other hand the rapidity of the telephonic communications, we have devised a
telephone system switchboard enabling any subscriber to put himself in com-
munication with another subscriber without necessitating the intervention of
employees placed at the central station, irrespective of the number of subscribers.
of the system.
An automatic telephone switchboard adapted to be used for an indefinite number
of subscribers must fulfil the following conditions:-
(1.) It must require the use of only a single wire for each subscriber.
(2.) It must occupy little space and in any case no more than the apparatus now.
existing at central stations.
(3.) The manipulation of the same must be easy and likewise the repair in case.
it should get out of order.
(4.) It must operate with rapidity and with absolute precision while requiring.
only a minimum expenditure of electric energy.
°
These essential conditions we have endeavoured to fulfil in the construction of
the telephone switchboard which constitutes the subject of our said invention.
Before commencing the detailed description of our apparatus we will set forth
the principles upon which it is based.
Suppose that at a given point of the telephone system corresponding to the
actual central station is a surface of ebonite or other appropriate material, upon
which, are arranged contacts so that each of them communicates exclusively with
the line wire of a single subscriber of the system, and admitting for a moment that.
over this surface of ebonite a movable metallic contact can be caused to move the
said contact being connected to the wire of the subscriber to which the plate under
consideration corresponds. Each subscriber having at the central station a plate:
similar to that just mentioned, if any one of the subscribers can at will, in his
office, displace the corresponding point upon the surface of ebonite he can
evidently put himself into connection with any one subscriber of the system with-
out the intermediary of an employee whose part is fulfilled by the plate in.
question.
The displacement of the point cannot be effected in a straight line, because for a
considerable number of subscribers the distance which the point would have to
travel would be too considerable and to avoid this inconvenience we have thought of
utilizing a system of co-ordinates rectilinear or otherwise, that is to say enabling
the subscriber to displace the point, not in a single direction but in two directions
not parallei, either two perpendicular lines or simply two lines oblique one to the
other, or a circle and a radius or two series of concentric circles.
The advantage will at once be seen of not displacing the point in a single
direction but in two directions not parallel which we will suppose to be perpen--
dicular in order to deal with a definite proposition.

page_text: In the first case (single direction) if the point as it is displaced passes a contacts
it will pass contacts in the second case (two directions not parallel) and the
amount of the displacement of the point in each direction may thus be very small
while having on the plate a great number of contacts. It is therefore necessary to
find a means enabling a subscriber to move, from his office and with few manipu-
lations, the contact which is above the corresponding plate situated at the central
station, to receive the signals which he requires, to establish a telephonic com-
munication and afterwards bring all the parts of the mechanism back to the
position which they occupied originally.
Having thus succinctly set forth the principle underlying our system of automatic
telephone switch-board we will now describe in detail all the arrangements which
we have devised for realizing the same in practice.
Referring to the drawings left with our Provisional Specification in which we
have illustrated by way of example apparatus for carrying our invention into
practice,
Figure 1 is a plan of the ebonite plate arranged for each subscriber at the
central station.
Figure 1 is a plan showing in detail metallic contacts arranged upon the
path K L passed over by the carriage F₂.
Figure 1 shows the metallic contact for the carriage F.
Figure 2 is a front view of the plate and of the parts which it comprises.
Fi
Figure 3 is a section on the line 1-2 of Figure 1.
Figure 4 is a detail of the mechanism permitting the displacement of one of the
electro-magnets.
Figures 6 and 6 show a front view and side view respectively of a special
relay electromagnet to which we give the name of Impulsator and the object of
which will be hereinafter explained.
Figures 7 and 7 show a plan and a section respectively of a special commutator
placed by the side of each subscriber's plate at the central station.-
Figure 8 is a front view of the mechanism of the apparatus placed in each
subscriber's office. In the example represented we have supposed that the tele-
phonic apparatus employed is on the Ader system as used in France at the present
time.
Figures 9 and 10 are transverse sections taken through the case of the apparatus
in the direction of the arrows A and B respectively and showing parts of the
mechanism seen from the front in Figure 8.
Figures 11 and 11 are plans showing the commutator in the two positions
which it may occupy in the apparatus placed in the subscriber's office.
Figure 12 is a perspective view of an Ader post provided with the mechanism
necessary for the operation of our system.
Figures 13 and 14 are a plan and section respectively of a plate of the central
station, on which the point instead of being displaced in two perpendicular
directions can be displaced about two points taken as centres.
Figure 15 represents in diagram a central post arranged for three subscribers
and also the apparatus placed in the said subscribers' office.
Our automatic telephone switchboard is substantially composed, of two parts:
(1) An apparatus having a movable contact point, which is arranged at the
central station.
(2) A mechanism or manipulator combined with the telephonic apparatus placed
in the house or office of each subscriber.
We will now describe successively each of these parts and then explain in detail
their operation, using for this latter purpose the diagram of the communications
(Figure 15).
The apparatus having a movable contact comprises among other parts two
ebonite plates A-B and C-D which are arranged horizontally and parallel to
each other (Figure 3). Upon these two plates are fixed contacts (contacts a upon
the upper plate, which contacts I make by preference in the shape of a hollow cone

page_text: which fits on the upper part of the contact point S, and holds it in place and.
contacts b upon the lower plate).
At the central station exist two metallic strips or wires for each subscriber one
of which passes below all the lower plates of the station, and the other passes above
all the upper plates. In each of the plates of the station the metallic strips or
wires corresponding to a subscriber have a contact and moreover for a group of
two parallel plates the two contacts corresponding to the same subscriber are on
the same vertical line. We may further mention that in the plates of black dyed
caoutchouc of a subscriber, the metallic contact of each of the strips or wires of
the said subscriber is connected to an insulated metallic plate the utility of which
will be hereinafter referred to. Between the parallel plates A-B, C-D can move
the contact point S, which is a permanent magnet placed freely in the interior of a
solenoid S. According to the direction of the current which traverses the
solenoid S, the movable contact point can be displaced either upwards or down-
wards in the solenoid. Normally, that is to say until the solenoid is traversed by a
current the movable contact S₁ under the action of a spring constantly tends to
come in contact with the lower plate, but when a current has been sent through the
solenoid S, causing the point S₁ to come in contact with the upper plate and the
current ceases the point S, remains in contact with the upper plate until a reverse
current is sent through the solenoid owing to the point S, fitting on to the point on
the upper plate and the spring tending to press it downwards being too weak.
to detach it.
At the
The contact point S₁ forms part of a system of double carriages, one of which,
F₁ (Figure 1), can be displaced in directions parallel to K L. The carriage F, is
compelled to follow the carriage F₁ in its displacements, but it can be displaced
freely in the direction K L without moving in such displacement the carriage F1.
Upon the carriage F, is mounted an electromagnet E₁ provided with a plate 1
constantly kept away from the poles of the electromagnet by a spring 2.
lower part of this plate 1 (Figure 4) is pivotted a plate 3 terminating at its front
part in a hook 4. A second hook 5 independent of the plate 3 is pivotted upon an
axis 6. These two. hooks are in engagement with the teeth of a rack 7 which
extends below the carriage over the whole side M N (Figure 1) of the ebonite
plate. If at a given moment, as will hereinafter be seen a current be passed
through the coils of the electromagnet E, the plate 1 is attracted and the hook 4
passes over a tooth of the rack and engages with the following tooth; whilst the
hook 5 still in engagement with the rack keeps the carriage upon the said rack.
The current being immediately interrupted, the plate 1 under the action of the
spring 2 tends to move back to the rear, but as this movement is rendered
impossible by the hook 4 engaging with a tooth of the rack, the whole of the
carriage will advance to the left until the plate 1 buts in its backward movement
against a stop which limits its motion. In this forward movement of the carriage
to the left the second hook. 5 likewise passes over a tooth of the rack 7 and
engages with the next adjacent tooth, so that when a current is again sent through
the electromagnet the same phenomena recur and the carriage F₁ will advance
again, passing a tooth of the rack each time."
It will therefore be easily understood that a series of impulses due to an
interrupted current flowing through the coils of the electromagnet E, moves the
carriage F, forwards to the left a number of teeth equal to the number of
impulses.
Upon this carriage F₁ are fixed perpendicularly to its axis two rods or
plates 9 and 10 which support the whole of the carriage F, including its rack
(Figure 1). Owing to this arrangement it will be seen that when the carriage Fi
is displaced in the direction M N, the carriage F, supported by the rods or plates 9
and 10 will follow the carriage F, in its displacements and the whole of the
system will thus be displaced to the left of the ebonite plate. When the
carriage F₁ has arrived in the position which it must occupy it will be possible to
displace the carriage F, relatively to the carriage F₁, by sending through the electro:

page_text: magnet E, a series of impulses by means of an interrupted current which will
displace this carriage along the rods or plates 9 and 10 in a direction parallel to
KL in the same manner as the carriage F₁ is displaced in the direction M N.
It is evident that if the carriage F₁ has not moved, the carriage F, may be
displaced along the line K L and not along a parallel line. In order that this
action may be understood we will take an example: Suppose that the subscriber,
to whom the plate at the central station under consideration corresponds, wishes to
bring the movable contact point of his apparatus in contact with the wire of
another subscriber whose line is connected to the plate at three divisions further
along the line M N and five divisions on the line K L. The subscriber, by the
means hereinafter set forth will move forwards the carriage F₁ of his plate by three
divisions on the line M N, then he will displace the carriage F, by five divisions on
a line parallel to K L. At that moment the point of his apparatus will be in con-
tact with the connection to his plate of the line wire of the subscriber with whom
he wishes to put himself in communication.
At the end of the path of the carriage F₁ is an electro-magnet 11 (Figure 1)
and an electromagnet 12 is likewise arranged at the end of the path of the
carriage F. The object of these electromagnets which we will term return
electromagnets is to bring the carriages F, and F2 instantly back to their starting
points. For this purpose each of these return electromagnets, for example the
electromagnet: 12 (Figure 3), on being traversed by a current attracts the plate 13
which normally keeps the rod 14 (Figure 1) below the level of the rack parallel
to the said rack. The rod 14 is controlled by a spring 15 (Figure 3) which tends
to raise it, and can turn about the axis 14. As long as the rod 14 is kept below
the level of the rack by the plate 13 of the electromagnet 12 the hooks of the
carriage F, (Figure 3) are in contact with the teeth of the rack, but if at a given
moment we send a current through the electromagnet 12 the plate 13 is attracted
and under the action of a spring similar to the spring 15 the rod 14 is raised and
in being raised lifts the hooks of the carriage F, which thus cease to be in engage-
ment with the rack. The carriage F2 which is thus no longer held by the rack is
submitted to the action of the very powerful spring 16 which moves the
carriage F₂ back to its starting point; the carriage F₁ is likewise moved back to
its starting point by the spring 17 when a current is sent through the electro-
magnet 11 (Figure 1).
2
The spring 17 is arranged at or near the extremity of a lever 18 pivoted at 19
to the frame of the ebonite plate and at 20 to the carriage F1. The spring 17
being placed very near the pivot 19 will be extended to a very small extent for a
great displacement of the carriage F₁. For the same reason a rod 21 is pivotted
at one end thereof to the carriage F2 and at its other end to the arm 23 by means
of the pivot 22 the said arm 23 being connected to the carriage F₁. The spring 16
placed very near the pivot 22 causes the return movement of the carriage F, and
as will be understood from Figure 1 for a very great displacement of the
carriage F2 the spring is extended to a small extent.
"
The movable contact point S, is of course carried by the carriage F2 and for
maintaining the equilibrium of the whole system so that the two carriages are
always displaced in a perfectly horizontal plane we have arranged a wheel 25
(Figure 4) and a slide 25 (Figure 3) upon the slide M N of the frame of the
ebonite plate and a wheel 26 on the slide parallel to the said plate (Figure 1).
Parallel to the rack of the carriage F, are arranged :
(1) A metallic plate t₁ insulated from all the parts of the mechanism and
presenting a series of metallic contacts (Figures 1ter and 15) between which are
interposed parts of ebonite or other insulating material. The metallic parts are
of the same length as the parts of ebonite, and a tooth of the rack corresponds to
two parts of the metallic plate t, that is to say to a metallic part and to a part of
ebonite. A contact spring or brush t₁ (Figures 1ter and 15) fixed upon the
carriage F, rubs during the displacement of the carriage along the part t₁, thus
passing successively in each displacement of the carriage upon a non-metallic part

page_text: and upon a metallic part. At the time when the carriage F₁ is not displaced the
spring t, bears upon an insulating part. If the carriage F₁ advances one tooth
on the rack the spring t, will again come in contact with an insulating portion of
the part t, after having traversed the metallic portion lying between the two
insulating portions under consideration. A second contact spring or brush 3 is
secured to the carriage F, but is not insulated therefrom. When the carriage Fi
is at the beginning of its path, that is to say when it is not displaced, the
metallic contact spring ³ makes contact with the metallic plate * (Figures 1 ter
and 15), but as soon as the carriage F, is displaced, if only one tooth, the spring t
abandons the plate t4.
6
(2) A second plate f similarly to the plate has a succession of metallic
portions and insulating portions of equal lengths (Figures 1er and 15). The
metallic and insulating portions of the plate are arranged rather differently
to the metallic portions of the plate t₁, in that a metallic portion is placed
at the right hand extremity of the plate in lieu of an insulating portion
as on the plate t₁. During the displacement of the carriage F₁ a metallic spring t
which is fixed to the carriage F₁ but which is insulated therefrom, makes contact
with the said plate ƒ
To sum up what we have just stated, at the beginning, that is to say before any."
displacement of the carriage F1, the contact spring t, which communicates with
the carriage F₂ bears upon au insulating portion of the plate t₁, the contact
spring t, which is insulated from the carriage F₁ bears upon a metallic portion of
the plate, and the spring t, is in contact with the plate 4. When the carriage F1
has advanced the distance of one tooth of the rack the same phenomena will take
place again, but the spring a will no longer be in contact with the plate t
During this forward movement of the carriage F₁ the spring t, will pass on to
the metallic portion of the plate t₁ and the spring t will likewise pass on to an
insulating portion of the plate fo
We will now examine the carriage F.
carriage is displaced are arranged:
6
Parallel to the rack along which this
(1) A plate similar to the plate f, and commencing like it by a metallic
part. Over this plate can be caused to move one of the extremities of a brush or
contact to which is fixed upon but insulated from the carriage F2, the other
extremity of the spring to makes contact with a metallic strip or band f3 (Figures 1bis
and 15); this metallic strip or band f³.commences only from the second tooth of
the rack, so that at the beginning when the carriage F, is at its starting point, one
end of the contact spring to is in contact with a metallic portion of the plate fi
and the other end thereof with a plate 2. As soon as the carriage is moved one
tooth, one end of the spring to is drawn out of contact with the plate f, and is
brought into contact with the plate 3 herein before referred to.
(2) A plate t, (Figures 1 and 1b) similar to the plate t₁ and commencing like it
by an insulating portion; however this metallic plate commences only in front of
the second tooth of the rack. After the second movement of the carriage F, a
contact spring to is moved along this plate t..
When studying the connections we shall see the object of these various plates.
Outside the ebonite plate upon which the carriages are moved and very near it
is a third electromagnet E, (Figure 15) which when traversed by a current
attracts a plate 27 (Figure 13). This plate is provided with a prolongation 28
(Figures 7 and 13) which carries an arm 29 at the extremity of which is fixed
a pawl 30 which is adapted to engage with the ratchet wheel B₁ (Figure 7) keyed
upon the vertical axis O3. When the attraction of the armature 27 takes place, the
arm MI descending compels the pawl 30 to turn the wheel H, in the direction of
the hands of a watch (Figure 7). A retaining pawl 30 forms a brake and regulates
the rotation of the ratchet wheel H, in such a manner that the latter turns one
tooth each time the plate 27 is attracted. On the axis O, set in motion by the
ratchet wheel H₁ are fixed: (1) A metallic wheel r₁ (Figures 7 and 7bis) insulated
from the axis O, and provided with four projecting parts ₁₂, placed at the

page_text: extremities of two perpendicular diameters; (2) A second wheel H, of ebonite
which carries four metallic rods forming two groups of two. parallel rods,
the two groups being perpendicular to each other. The extremities of these
rods which are curved can be moved over a series of contacts which we will
hereinafter describe. The same is the case with the projecting parts i l₁ 12 13 secured
to the wheel 1, it being understood that the extremities of the metallic rods carried
by the wheel H3 cannot touch the contacts over which the projecting parts 11₁₂ 3
are.adapted to move, and that vice versa the projecting parts l₁l, la cannot touch
the contacts over which the extremities of the metallic rods are moved.
(3) The ratchet wheel H, herein before mentioned. This wheel is directly fixed
upon the axis O, and is not insulated therefrom. It has on its periphery 20 teeth.
(4) A disc H, whose circumference is divided into 40 parts, 20 of which are
metallic and 20 of insulating material. This disc is situated above the ratchet
wheel H₁ and is insulated therefrom. Upon the circumference of this wheel, at
the extremities of the same diameter, rub two brushes H, H, (Figure 7).
When studying the diagram of the connections we shall see the object of the
whole of the wheels mounted upon the axis 03.
By the side of each ebonite plate is also a special relay electromagnet R to
which we have given the name of "impulsator" (Figures 6 and 6*); this electro-
magnet is arranged in the following manner: It is of the horse shoe form and
one of its poles is divided into two branches Q, Q3 on which are arranged the
bobbins 91 92
Above the borse shoe is an ebonite plate 3 above which are
secured two metallic bars 4%, to which the contact screws 96 97 are attached.
Between the branches of the electromagnet Q2 Q3 is balanced a small iron
armature g adapted to move about the axis 9, through a recess formed in the
upper pole of the magnet R. The bobbins 9, and 2 are so wound that when they
are traversed by a current in a given direction one of the bobbins, say the
bobbin qi, tends to augment the magnetism of the core Q3, whilst the bobbin 92
tends to diminish the magnetism of the core Q2. If the current takes an opposite
direction the magnetism increases in the core Q2 and diminishes in the core Q3.
Hence it follows that in the first case the armature gg is attracted towards the
core Q3 and in the second case towards the core Q. For preventing the armature
from adhering to the cores we have provided it with small springs 910- If the
subscriber whose line wire terminates at this relay electromagnet sends positive or
negative currents through the bobbins 1 9, the armature 9, is attracted in one
case to one core and in the other case to the other core, and its upper part makes
contact alternately with the contact pieces 96 97. The armature q, is connected as
shown in Figure 15 to the positive pole of the battery at the central station and
consequently according to the position of the armature the current from the
battery will be directed either to the terminal 9 or to the terminal q We
shall hereinafter see when studying in detail the connections at the central
station the object of this relay electromagnet and its operation.
The apparatus arranged in the subscriber's office from the point of view of the
telephone system may be of any system. We have supposed that the telephone
employed is of the Ader system generally used in France, but we may observe
here that we do not touch at all the telephonic apparatus itself and that we merely
add certain arrangements which we may of course add equally well to any telephonic
apparatus.
The whole mechanism which we add to the telephonic apparatus is arranged
above the post in a case, on the front face of which are placed the various buttons
and indications for the manipulation of our system. The mechanism placed at the
subscribers' office consists substantially of a relay electromagnet U (Figure 8)
similar to the electromagnet R which is placed at the central office, three ordinary
electro-magnets E, E, E, and a commutator K₁; this commutator is represented
in detail in Figures 11 and 11. It is substantially composed of a drum of
insulated material through which are passed two rectangular metallic rods K, K.
These rods are insulated from each other and form at the surface of the

page_text: cylinder four metallic plates. Two other metallic plates K, K, are moreover fixed
upon this ebonite cylinder; they are connected with each other by a wire which
traverses the drum of the commutator; the two metallic plates K, K, as shown in
Figure 11, cover almost the whole circumference of the drum for a certain width,
and they leave free only two parts which correspond to the extremities of the
rods K2 K3. Around the cylinder of the commutator and held in contact with it
are arranged springs T, T, T, T₁ T, T, T. These springs are insulated from
each other and we shall hereinafter see from the diagram of the connections the
function of these several springs. On one of the extremities of the axis of the
commutator is fixed a toothed wheel P4 which gears with the toothed wheel P₂
keyed upon an auxiliary axis (Figure 8). Upon this same auxiliary axis is keyed
the toothed wheel P, which engages with the toothed wheel P₁ submitted to the
action of a spiral or other spring tending to turn the wheel P₁ and consequently
the commutator K. The spiral spring is wound up when such is necessary by
means of a crank P (Figure 12) placed upon the front surface of the case in which
the mechanism is enclosed.
2
As shown in Figure 11 the commutator K₁ is mounted upon an axis along
which it can be moved axially. In its normal position the commutator is caused
to bear against the front surface of the case under the action of the spring 34 and
it is prevented from turning by the point v₁ which is placed in one of the holes vs
formed in one of the faces of the commutator. As long as the operator does not
press upon the button V₁ the point v remaining in one of the holes vs the
commutator will be immovable, but if at a given moment the operator presses
upon the button V₁, the lever 3 oscillating about its axis will disengage the
point from the hole บ
and the commutator will begin to turn under the action
of the spiral spring. If instead of pressing upon the button V₁ the operator
presses upon the button V₂ the lever V6 oscillating about its axis will act, as
indicated in Figures 11 and 11bts, upon the lever v, which will move the commutator
along its axis thus compressing the spring 34. In this axial movement of the
commutator the point vд will be drawn out of engagement with the hole u, so that
the commutator will again be left free to turn under the action of the spiral spring.
In this latter case the commutator, being moved along its axis, the position of the
rods K2 K3 and of the plates K, K, will be altered relatively to the springs
forming the metallic contacts T₁ T₂ and we shall see later on the object of this
movement. The commutator K, being operated by a spring may turn very quickly;
this is inconvenient for it may happen that owing to the rapidity of the rotation
of the commutator the operator may not stop pressing on one of the buttons Vi
or V2 at the moment when the desired number appears in the opening. To remedy
this inconvenience we may form an electric circuit comprising: an electro-magnet
causing a brake to act on the commutator K, and the subscriber's battery; the
said circuit being capable of being closed by the dials carrying the figures. The
closing of the contact at the proper moment is effected by adjustable contact
makers oue on each dial which can be set to any number and when set move with
the dial, and contact is made between them when the proper number is shewn on
the dials. Three other buttons V3 V4 V, are arranged upon the apparatus; the
button V3 is provided at the extremity of a rod n₁ (Figures 8 and 9) terminating
in a plate carrying three metallic fingers or contacts n₂ ng ng. Normally, that is to
say when no pressure is exerted upon the button V3, the rod n₁ under the action
But if at
of the spring n, is maintained in the position represented in Figure 9.
a given moment the operator exerts a pressure upon the button V3 the rod n₁ will
turn upon its axis. By reason of this rotation the finger n, will come in contact
with the plate n, whilst the two fingers ng n₂ will successively come in contact with
the plates n n5 No.
When the pressure upon the button V3 is discontinued the
spring n, will move the lever / n, to its original position.
The button V, is mounted at the extremity of the lever m, (Figures 8 and 10)
terminating in three fingers or contacts m₁ m, and m3. By exerting a pressure
upon the buttou V, the finger m₂ comes in contact with the plate m, and the

page_text: finger m3 comes in contact with the plate m₁; by continuing the pressure the
finger m, comes in contact with the plate mo. When the pressure on the button V₁
is discontinued the lever m3 returns to its original position under the action of
the spring my, hence it follows that the finger m₁ abandons the plate m, while the
fingers my m3 pass again upon the plates m and m5.
We have above stated that the essential parts which constitute the mechanism of
the apparatus were composed of the relay electro-magnet U similar to the
electromagnet R and of three ordinary electro-magnets E, E, E。.
2
As
The relay electro-magnet U has for its object like that herein before described to
distribute the currents. The electro-magnet E. operates a plate to which is
pivotted a lever p₁ connected at its upper part to a rod p3 which carries a pawl 12.
A spring tends to keep the pawl pa pressed against the teeth of a ratchet wheel W.
The rod P3 is movable about the axis W₁1, hence it follows that if a current is sent
through the electro-magnet Е, an attraction of the plate e, takes place, the lever 1'1
is drawn downwards and the pawl p2 passes over a tooth of the ratchet wheel.
soon as the attraction ceases owing to the interruption of the current through the
electromagnet E the spring W, draws back the plate e, and the pawl p₂ compels
the wheel W, to turn through a distance of one tooth. Upon the axis W₁ which
carries the ratchet wheel W, is mounted a circular plate W, provided near its
circumference with a tongue W, When the wheel N has made a complete turn
the tongue W encountering the teeth of the wheel W, placed by the side will
cause this latter to turn one tooth. It will be easily understood, that if the axes
of the wheels W, W₂ carry plates upon which the numbers, 1, 2, 3, 4, 5, 6, 7, 8, 9,0
are inscribed these two plates may indicate the number of impulses which traverse
the electro-magnet E, one giving the units, the other the tens, providing that the
ratchet wheel W, has ten teeth like the wheel W. The two wheels W, W may
evidently be completed by a third wheel giving the figures of the hundreds and so
on. This is in fact the usual mechanism of all revolution counters.
Upon the
front face of the case which contains the whole mechanism in the subscriber's office
are formed two openings d₁ d, through which the operator can successively perceive
the figures of the plates just referred to.
4
6*
2
4
The electro-magnet E. operates a system of toothed wheels similar to that which
we have just described, so that the operator may likewise ascertain, by looking
through the openings d d the number of impulses which have traversed the
electro-magnet E,. It is however necessary to observe one feature in the system
of toothed wheels connected with the electromagnet E. When the two wheels
are at zero, that is to say when no impulse has traversed the electromagnet Es, a
pin i fixed upon the wheel i, presses the bell-crank lever or arm is against the
spring is, but as soon as the wheel i under the action of an impulse traversing the
electromagnet E, is moved one division the lever i being no longer held by the pin i
turns upon its axis i, and under the action of the spring (Figure 8) the other
branch of the lever i will break contact with the plate i and will make contact
with the plate. We shall later on, when studying the electric connections, see
the object of this arrangement.
The electromagnet E is designed to attract a plate ₁ so as to act upon the rod 12
and consequently cause the lever 13 to turn about the axis j. This lever l, carries
a pawl arranged in such a manner that when the plate is attracted the pawl 74
passes over a tooth of the ratchet wheel . A spring moves the plate, to its
original position when the current ceases to traverse the coils of the electro-
magnet E and the lever 3 in returning to its original position compels the pawl 4
to turn the ratchet wheel the distance of one tooth. The ratchet wheel
mounted upon axis j, which moreover carries a toothed wheel which engages with
the wheel je
is
On the same axis as the wheel je is mounted a wheel ji provided with four
projecting parts placed at the extremities of two perpendicular diameters; two of
these projecting parts placed at the extremities of the same diamèter, are when the
apparatus has not been operated, in contact with the two metallic plates j3 12

page_text: "2
_ 66
(Figure 8). The wheel carries on its front surface a dial divided into four
sectors bearing the following inscriptions: "Rest"-"Call"-" Ring Speak."
The operator can perceive through the sector shaped opening d, the corresponding
inscription on the plate. Until a current has traversed the electro-maguet E, the
inscription visible through the opening d, is "Rest."
5
The button V, placed on the side of the apparatus is designed to bring back to.
zero the wheels operated by the electromagnets E. E.. We do not insist on the
connection of this button and the character wheels aforesaid, as we may employ any
known appropriate arrangement.
Having thus described the various parts which constitute our improved system
of automatic telephone switch-board we will now proceed to set forth the operation
of the same giving also the details of all the connections established between the
various parts which constitute our system. For facilitating this study we have in
Figure 15 represented in diagram 1st. A central office with 3 subscribers' plates ;.
2nd. The three posts placed in the subscribers' offices. We may however observe
that the central office as we suppose it to be for three posts may without any other
modification receive 222 other similar plates, each of the plates represented in this.
figure having 225 contacts utilized and each subscriber being thus able to put.
himself in relation at his will with 224 subscribers, and it is of course understood
that what we state in respect of the lower plates CD applies to the upper-
plates.
The battery which is arranged at the central post is divided into two parts as.
shown in Figure 15.
The wire 40 corresponds to the positive pole of the battery, the wire 41 to the.
negative pole and the wire 42 is put to earth.
We will consider the plate of the subscriber X and the corresponding post placed
in the subscriber's office and study on this plate all the electrical connections-
established, which will be the case in an identical manner in the plates and in the-
posts of the subscribers Y and Z.
The metallic rod or strip 44 placed below all plates of the office has on each a
contact at the place designed for the subscriber X. In the example chosen all the-
contacts of the plates having for abscissa 4 and for ordinate 3 will be in relation.
with the rod or strip 44 connected to the line wire of the subscriber X. The rod
or strip 45 which corresponds to the line wire of the subscriber Y will likewise be
in connection with all the contacts which in all the plates of the central office will
have for abscissa 2 and for ordinate 4; in like manner the rod or band 45 which.
corresponds to the line wire of the subscriber Z will likewise be in connection with.
all the contacts which in all the plates of the office will have for abscissa 3 and for
ordinate 5.
The line wire 43 of the subscriber X terminates at the relay electromagnet R is
wound round bobbins, as herein before stated, and is put in connection by the wire 46.
with the earth wire 32.
=
For facilitating the study we will suppose that the subscriber X wishes to put
himself in communication with the subscriber Z represented as we have seen by the
fraction 3, that is to say abscissa = 3 ordinate 5; for it is understood that all the
subscribers of the telephone system, in lieu of being designated by a single number
will be designated by a fraction whose numerator will represent the abscissa and the
denominator the ordinate.
The subscriber X must therefore in order to bring the movable point S, of his
plate above the contact corresponding to the line of the subscriber Z cause it to
For as-
move three divisions along the abscissa and six divisions along, the ordinate.
indicated in Figures 1 bts and 1ter, at rest the point S, touches a plate S, which has
the length of two contacts in the direction of the ordinates, so that in order to arrive.
on the first line of the abscisse the point S₁ must move two divisions in the direction
of the ordinates.
We will now describe how this result may be obtained. By pressing upon the-
button V, the subscriber X liberates, as before stated, the commutator K, of his.

page_text: 2
apparatus which will turn as long as the subscriber X continues the pressure upon
the button V. As soon as the commutator is set in motion the extremities of the
rod Ke have come in contact with the plates T₁ and T, while the extremities of the
rod K3 have come in contact with T, and T. Now the plate T, is connected by
the wire 47 with the negative pole of the battery placed in the subscriber's office
and the plate T, is connected with the earth wire 48 whence it follows that the
contact of the extremities of the rod K3 with the plate T and with the plate T
produces no effect. The plate T₂ is connected by the wire 49 to the positive pole
of the battery and the plate T, is connected by the wire 50 to the line wire 43,
whence it follows that the contact of the extremities of the rod K3 with the
plates T T connects the line wire to the positive pole of the battery. A positive
current therefore traverses the line L C and arrives in the relay R, thence it passes
through the wire 46 into the earth wire 42 and returns to the subscriber through
the earth and the plates T₁ and T.
Under the action of this current the
armature q is attracted by the core Q and the upper extremity of the armature
touches the screw 98* Now the armature 7, is constantly connected to the positive
pole of the battery of the central post by the wire ol and the terminal 96 is
connected by the wire 52 with the plate ₁. A current therefore traverses the
wire 51, the armature 98, the terminal q, and the wire 52 and arrives in the plate fi ;
from this plate and through the contact spring in contact with a metallic part of
the plate, because the carriage F, has not moved, the current arrives at the
plate f. From this plate the current arrives at the electro-magnet Ej by means
of the wire 53, it traverses the electro-magnet and finally arrives through the
wire 54-in the wire 41 of the negative pole of the battery. The circuit of the
electro-magnet E, is thus closed and when traversing the electro-magnet E₁
the current causes the carriage F₁ to advance one rack tooth as before
specified.
1
In Figure 15 the parts of the plate of the subscriber X have been represented
when the carriage F, is displaced three divisions and the carriage F, is displaced
six divisions; on the contrary the parts of the plates of the subscribers X and Z
are represented in their original position.
As soon as the positive current sent through the commutator K into the line has
ceased, that is to say as soon as the extremities of the rod K, are no longer in
contact with the plates T, and T, the armature 9, being no longer attracted by the
part Q returns to the original position between the two parts Q, and Q2 and the
circuit of the electromagnet E₁ is open; it will be closed again only after a half
rotation of the commutator K, causing the contact of the extremities of the rod K,
and of the plates T, and T, which as we have seen has the effect of a positive
current being sent into the relay R.
2
.
The
We will now examine what happens at the central post at the moment when the
first positive current coming from the post of the subscriber ceases, that is to say
as soon as the extremities of the rod K, have left the plates T, and T.
circuit of the electromagnet E, is open and the carriage F₁ has advanced one tooth
of the rack, but in this forward movement the movable contact t₁ fixed to the
carriage F has made contact with the metallic part of the plate t₁ and has
consequently brought the carriage F₁ into connection with the negative pole of the
battery at the central station by the wire 55.
Now the carriage F₁ is connected by the wire 56 to the line wire 43 and
consequently at the moment of the passage of the contact to over a metallic part of
the plate t, the line 43 is put in connection with the negative pole of the battery,
at the central station. A negative current therefore arrives in the relay V through
the wire 57 traverses the relay and through the wire 58 arrives at the plate T₁,
traverses with the aid of the plates K, and K, the commutator and passes through the
plate T, to earth, whence it returns to the central post.
7
We may observe that the plates K, and K, will permit the circuit of the relay U
to be closed only when the commutator K, does not send currents through the line
wire, in other words when there is no current in this wire, for the interval which

page_text: serves to isolate the plates K. and K, from each other will correspond precisely
to the space occupied on the commutator by the extremities of the rods K,
and K3.
3
Let us now examine the effect produced in the subscriber's office by this negative
current arriving through the line wire in the relay electromagnet U. The
armature น is attracted towards the core U, and the upper extremity of the
armature น therefore touches the contact u; now the armature u, is connected by
the wire 60 with the positive pole of the battery placed in the subscriber's office.
A current thus arrives at the armature u, through the wire 60 passes into the
contact, down the wire 61 into the lever, flows into the plate i and
arrives through the wire 62 in the electromagnet E, which is connected
by the wire 47 to the negative pole of the battery. The circuit of the electro-
magnet E, is then closed, this electromagnet is therefore energized and it attracts
the plate e, which has for its object as before stated to cause the wheel W,
(Figure 8) to turn one division, and consequently cause the number 1 to appear in
front of the opening d. It should be observed that at the moment when a negative
current is sent into the line wire of the central post at the subscriber's office this
negative current traversés likewise the electro-magnet R at the central post. The
armature is therefore attracted towards the core Q, and by its front extremity
touches the part q, which is connected by the wire 64 with the electromagnet E.
The electromagnet E, is connected in its turn by the wire 65 with the plate ra
(Figures 15 and 7) which is itself at this moment in connection by the projecting
parts of the wheel r₁ with the plate r3 which is itself connected by the wire 66
with the plate f
We thus see that as far as this plate the circuit of the electro-
magnet E, is closed and a positive current could pass through the wire 51,
armature 98' terminal 972 wire 64, electromagnet E₂, wire 65, plate r2, wheel ri
plate r, wire 66 and finally arrive at the plate fe. But at the moment when this
current could flow, that is to say at the moment when the negative current is sent
from the central post to the subscriber, the spring, which is connected by the
wire 67 to the negative pole of the battery is in contact with an insulating part of
the plate, so that at this moment the circuit of the electromagnet E, is opened by
the plate and it follows from this that the negative current sent to the subscriber
by the battery of the central office has no action upon the parts situated in the
central office itself.
When the negative current acts upon the electromagnet E, at the subscriber's
office the commutator still continues to turn, a fresh positive impulse is sent from
the subscriber's office to the central station and a negative impulse from the central
office to the subscriber, as long as the subscriber presses upon the button V1.
By this means in the case which we have chosen the subscriber ceases the
pressure at the moment when the number 3 appears through the opening d₂,
because, the abscissa of the subscriber Z with whom the subscriber X wishes to
put himself in connection is equal to 3. Directly after having ceased the pressure
upon the button V₁ the subscriber presses upon the button V. The pressure
exerted upon the button V2, has the effect, as indicated in Figure 1119 and as
before stated, of displacing the commutator, so that the extremities of the
rods K, will in consequence of the rotation of the commutator come in contact
with the plates T, and T., and the extremities of the rod K, will come in contact
with the plates T3 and T. The pressure exerted upon the button V₂ will more-
over have the effect of causing the rotation of the commutator as hereinbefore
explained.
2
We will now examine the effect of this pressure on the button V, with regard to
the sending of currents into the line. As soon as the commutator is set in motion
the extremities of the rods K, will be brought in contact, with the plates T, and T.;
this will have no effect on the line as before stated; for the plate T, is in connection
with the positive pole of the battery in the subscriber's office and the plate T, with
the earth; also the extremities of the rod K, will come into contact with the
plate T3 and the plate T.; now the plate T, is in connection by the wires 68 and 47

page_text: with the negative pole of the battery and the plate T is in communication with
the line. A negative current coming from the subscriber's office will therefore
arrive in the relay R at the central post and will return through the earth, and
the plates T, and T. The action of this current which traverses the relay R
has the effect of causing the attraction of the armature 7s upon the terminal Q
and the upper extremity of the armature 9, will come in contact with the part q
Now the circuit of the electromagnet E2 is formed by the wire 64 which leaves
the part 97, the electromagnet E, itself, the wire 65, the projecting parts, and la,
the wheel r, the wire 66, the plate fe, the spring t, and the wire 67. This
circuit is therefore closed when the armature 9, touches the contact 9,, because the
springt, is in contact with a metallic part of the plate f
8
7
The electromagnet E, is therefore traversed by a current which compels the
carriage F, as above set forth, to move forward one tooth on its rack. As soon
as the extremities of the rod K, have broken contact with the plates T, and T. in
'cousequence of the rotation of the commutator the negative current sent from the
subscriber's office to the central station ceases, the armature 7 passes back to its
position and the circuit of the electromagnet E, is opened. The commutator K₁
continuing to turn, a second negative current is sent from the subscriber's office
to the central post and the carriage F, advances a second tooth, but at this moment
and as indeed happened when we examined the effect of the pressure upon the
button V, a positive current is sent automatically from the central station to
the subscriber in the following manner: The plate t7 over which is moved
the spring T secured to the carriage F2 is connected by the wire 69 with the
positive pole of the battery at the central office and moreover the carriage F, is
connected by the wire 70 with the line wire 43. Accordingly at the moment when
the spring to fixed upon the carriage F, passes above a metallic part of the plate t
a positive current coming from the central station through the wire 69, the
plate t, the carriage F2 and the wire 70 will arrive through the line wire 43 in the
relay at the subscriber's office. This current will traverse the relay U and flow
through the wire 58 to the plate T, and thence to the plate T, through the metallic
parts K, K, finally flows to earth through the wire 48 and will return by this
way to the central station. The relay electromagnet U is thus traversed by a
positive current. This positive current will effect the contact of the armature u on
the core U, and the upper extremity of the armature u will touch the contact u
and as will be seen the circuit of the electromagnet E, will be closed. In fact the
armature 245 is connected as we have seen by the wire 60 with the positive pole of
the battery at the subscriber's office. The current thus passes through the wire 60,
armature us, contact u,, wire 71, plates ja, ja, wheel ji, wire 72, electromagnet E, and
finally the wire 47 which terminates at the negative pole. As the current passes
round the electromagnet E, it causes the attraction of the plate which it operates
and which as we have before explained causes the Number 1 to appear at the
opening d As long as pressure is exerted upon the button V₂ the same
phenomena occur in the same order, that is to say a negative current will pass
from the subscriber's office to the central post and a positive current which is in a way
a controlling current will arrive at the subscriber's office from the central station so as
to indicate to him the number of divisions passed over by the carriage F. For the
same reasons as those above explained the positive current sent from the central
office to the subscriber produces no action upon the parts situated at the central
station, for this positive current arriving in the relay R causes the armature gs to make
contact with the contact pin 9** But at this moment the circuit of the electro-
magnet E is opened, for the carriage F, being moved the spring to is no longer in
contact with the plate f₂ connected to the electromaguet E, but with the plate fa;
also at the moment when the positive current flows the spring to passes over an
insulating part of the plate fi, the circuit of the electromagnet. E, is therefore open
for these two reasons and at this moment no current can pass round its coils.
The subscriber will continue to press upon the button V, until he perceives
through the openings dз d₁ a number equal to that of the denominator of the fraction.
2

page_text: of the subscriber with whom he wishes to put himself in communication; for this
purpose we have supposed that he wished to put himself in communication with
the subscriber Z, he will press his finger until the number 5 appears through the
opening d; at this moment the point S, will be upon the fifth line of the abscissae,
although the carriage 4 is displaced six divisions, for it should be observed that
the first displacement of the carriage has not been controlled by the subscriber,
because at this moment the point tg was not in contact with the plate t,.
These first operations having been effected, the point S, will be upon the contact
which in the plate of the subscriber X is connected to the line wire of the
subscriber Z. As soon as the subscriber X has placed his point S₁ upon the
contact which he required, the action of the electroniagnets E, and E, which have
no other object than to cause the movement of the carriages F1 and F, becomes
useless. It is therefore necessary to break the circuit, of these electromagnets E₁
and E. With regard to the electromagnet E, this object has already been
obtained. In fact when the carriage F, has passed over the first tooth of his
rack, that is to say when it has left its first position, the spring te leaves the
plate f, which communicates with the winding of the electromagnet E, and is moved
along the plate or strip f3 which communicates with the winding of the electro-
magnet Es; the spring te remains in communication with this latter plate to the
end of the movenient of the carriage F.
From this it follows that the positive currents which will be sent into the winding
of the relay electromagnet R will no longer actuate the electromagnet E, but the
electromagnet E3 provided that these positive currents are sent at the moment
when the spring touches a metallic part of the plate 1.
By an analogous process the circuit of the electromagnet E, which is in the
subscriber's office and which corresponds in part to the electromagnet E₁ of the
central station has broken its connection with the contact us. Indeed as soon as
the wheel i has turned one tooth the lever i being no longer held by the pin i
is submitted to the action of the spring which displaces it and brings it in
contact with the plate i, so that the screw ug, instead of communicating with the
electromagnet E, communicates by the wire 61, lever i̟, terminal i,, wire 80 with
the finger ng fixed to the extremity of the rod n₁ actuated by the button V, and as
we shall hereinafter see this finger ng will at a given moment close the circuit of
the electromagnet E. The electromagnet E, at the central station serves in its
turn for breaking the circuit of the electromagnet F₂.
Let us now see in what manner the action takes place :
As soon as the subscriber X has ceased to press upon the button V, he presses
upon the button V3; the action of the finger on the button V3 has for its object_to
send to the central station and in the order which we indicate (1) a positive current ;.
(2) a negative current; (3) again a positive current. When the lever n₁ turns
about its axis of rotation in the direction of the arrow Figure 15, the fingers ng ng
slide upon the three metallic plates nn no The plate n, is connected with the
negative pole of the battery at the subscriber's office through the wires 81 and 47
and the plates " and communicate with the positive pole through the wires 82
and 83. As soon as the lever ₁ is displaced in consequence of the pressure on the
button V3 the finger n, touches the plate n, and the finger n3 touches the plate n.
Now the finger n, is connected by the wires 84 and 50 with the line wire and the
finger na is connected by the wires 85 and 48 to earth so that a positive current flows
through the wire 82 into the plate n, passes through the finger n₂ and thence
through the wires 84 and 50 into the line wire 43, then to the relay R, and away to
carth and returns to the subscriber by way of the finger n3 and the plate ns.
It will be understood that the fingers ng ng are isolated on the lever n₁.
The positive current passing round the electromagnet R causes the lever 98 to
be attracted towards the part q, and closes the circuit of the electromagnet E3.
In fact this circuit is as follows: The wires 51, armature 9g, screw 9, wire 52,
plate f, spring to plate f, wire 86, electromagnet E3, wire 87 and lastly the
E

page_text: wire 41 which terminates at the negative pole of the battery. The positive
current by traversing the electromagnet E, causes the attraction of the plate 27
(Figure 7) which descends, compelling the pawl 30 to turn the ratchet wheel H₁
one tooth.
As the ratchet wheel turns it carries with it the axis O3 upon which it is fixed
and consequently the wheel r will be moved forward a distance corresponding to
one tooth of the ratchet wheel. The projecting parts l₁ will break contact with
the plates rr and will be brought in contact with the plates r Accordingly
the action of the positive current sent through the electromagnet E will have for
its object to open the circuit of the electromagnet E,, which will prevent any
ulterior movement of the carriage F. In addition to the action produced upon the
circuit of the electromagnet E, the movement of the wheel r, has had the effect of
bringing the projecting parts ₁ 13 into contact with the plates r r. Now the
plate r, is connected by the wire 90 with the line wire and the plate r, is connected
through the wire 91 with the point S₁.
1
Besides the connection which exists between the movable contact S₁ and the
plate 4
this contact S, is connected through the wire 92 with a plate t which is in
contact with the contact t3 (Figures 17 and 15) secured to the carriage F₁ which
latter is itself connected to the line by the wire 56 so that as long as the carriage F
has not moved, the contact S₁ is in connection with the line wire through the wire 92,
plate ta, point fa, carriage F, and wire 56; but as soon as the carriage F₁ is moved
by the button V₁ being pressed the point t3 breaks contact with the plate 4, and
the point S, is thus momentarily cut off from the line wire and it is not again
connected with this wire until the electromagnet E3 has been actuated as we have
just seen. This temporary interruption of the connection between the contact
point S, and the line wire is indispensable for eliminating the influence of the
currents which serve to move the contact point over the contacts, otherwise these
currents by entering the line of contact of some other subscriber would penetrate
into the contact finger or point of this subscriber and thence into the overhead
conducting wire, thus setting in motion apparatus foreign to the communication
which it is intended to establish.
The movements of the distributing wheel are controlled in the post of the
subscriber.
Upon the axis O, is keyed, as hereinbefore stated, a wheel H₂ whose circumference
is provided successively with metallic and insulating parts. Two brushes or
contact springs H₁ and H. make contact with this wheel H₁. One of these
contacts H, is connected by the wire 100 to the line wire 43, while the other
contact H, is connected by the wire 97 to the negative pole of the battery of the
central station. When the wheel r, is in its unmoved position, that is to say when
the projecting parts ₁₂ are in contact respectively with the plates r, and r
the contact pieces H4 and H. touch the wheel H, at insulating parts thereon
and consequently no current flows. When the wheel r₁ turns one tooth, the
wheel H, likewise turns and during this rotation the contact pieces H₁ and H, make
contact with the metallic parts in order to arrive again on the insulating parts.
Accordingly during this movement a circuit is established comprising the wire 41
corresponding to the negative pole of the battery, the wire 97, contact spring H
wheel H₂, contact H, wire 100, line wire 43, wire 57, electromagnet U, which as
we know is connected by the wire 58, plate T, and plate T, to earth. The circuit
of the electromagnet U is therefore closed when the contact pieces H. and H, touch
metallic parts of the wheel H., and the coils of the electromagnet U are at the
same period traversed by a negative current coming from the central station.
The armature u, is then brought in contact with the contact ue, which as we shall
see closes the circuit of the electromagnet E.. This circuit comprises the positive
pole of the battery in the subscriber's office, the wire 60, armature us, contact
screw u, wire 61, lever i, contact screw 7, wire 80, finger n, plate n, wire 101,
electromagnet E, wire 102 and the negative pole of the battery...

page_text: The circuit of the electromagnet E. is therefore closed. The pawl 1 (Figure 8)
when the current ceases in the electromagnet E, turns the ratchet wheel under
the action of the spring
The wheel is mounted on the same axis as the ratchet wheel ; a wheel j
divided into four sectors is actuated by a toother wheel keyed upon the axis of the
wheel j in such a manner that when the ratchet wheel turns one tooth, the wheelj,
is turned or rotated one quarter of a complete revolution. The wheel ji is divided
into four sectors, upon each of which is one of the following inscriptions: "Rest
-"Call "" Ring _ 26 Speak." During each complete revolution of the wheel j
all these inscriptions will appear at the opening d at the subscriber's office, one
after the other, commencing with the inscription "Rest."
"
The object of these inscriptions is explained in the following manner.
"
When
the apparatus of the subscriber is not being operated the inscription "Rest" will
be seen at the opening d, and this inscription remains at the opening as long as the
buttons V, V, are depressed.
1
As soon as the subscriber presses upon the button V, as we have seen the first
negative current sent by the station to the subscriber has closed the circuit of
the electromagnet E, has turned the ratchet wheel one tooth and consequently
the wheel, a quarter of a complete revolution and the inscription "Call" then
appears at the opening d.
3
After having thus examined the actions of the positive current sent to the
central station by the contact of the finger n₂ and of the plate n, and of the control
current sent from the central station to the subscriber, let us see what will happen
when the lever n₁ continues to turn under the action of the button V, which is
depressed. The points nz and ", come respectively in contact with the plates no
and ng
A negative current passes through the plate ns, plate n₂, wires 84 and 50,
and thus to the line. The contact between the finger n, and the plate ng serves
for the return of the current through the earth. The negative current flowing
through the line wire passes around the electromagnet R, passes to earth and
thence to the subscriber. The action of the negative current upon the electro-
magnet R has the effect of bringing the armature g, in contact with the part 97,
but as the circuit of the electromagnet E, is open the action of the negative current
in the relay electromagnet R has no effect on the apparatus of the subscriber X at
the central station, but this negative current passes moreover through the wire 90
into the plate r, it flows through the projection into the wheel r, and thence
through the projection ₁ into the plate r, then through the wire 91 into the contact
point S₁ and from the latter it flows through the wire 45 of the contacts Z into the
contact S, then into the contact S₁ to the subscriber Z. From the point S³, the
current flows to the plate 4, passes into the point to the carriage P1, thence
through the line wire of the subscriber Z it reaches the relay electro-magnet R²
and thence flows to earth. The action of this current upon the electromagnet Rz
has the effect of bringing the armature q², in contact with the contact screw q
which closes the circuit of the electromagnet E2. The electromagnet E', being
actuated compels the carriage F, to shift one tooth, which as previously described
breaks the circuit of the electromagnet Ez, by means of the spring and the
plate fat the same time the spring t as it is moved will bear upon the plate 3,
thus establishing a connection between the winding of the electromagnet E, and
the relay contact screw 9. Hence it follows that the negative current sent by
the subscriber X produces in the plate of the subscriber Z the effects which we
have just studied, moving the contact point S, in the direction of the ordinate
which does not yet bring the point S₁ upon the contacts of the subscribers,
because as previously described there is a plate S in the direction of the ordinates
having two contacts which are not connected to wires of subscribers.
6
7"
The negative current sent by the subscriber X into the plate of the subscriber Z
produces the effects which we have just described, but a current also flows to the
office of the subscriber Z, traverses the electromagnet U², which closes the circuit
of the electromagnet E, and the number 1 appears at the opening d. The first

page_text: 2
movement of the carriage F, produces no control current and therefore we have
not to take such movement into account.
Let us now examine the effect of the third current sent by the subscriber X to
the central station, when under the action of the spring n, the button V, returns
to its original position. This current, as we have said, is a positive current,
for it is produced by a fresh contact between the plate n and the finger no. This
positive current flows to the relay electromagnet R and closes the circuit of the
electromagnet E, the electromagnet Ea then acts again upon the plate 27 and the
wheel turns through an angle equal to one tooth of the ratchet wheel. In
addition to this first effect the consequences of which we have just described the
positive current flows also to the plate r, projection 3, wheel r₁. projection ₁.
plate 7, wire 91, contact point S₁ and thence passes into the plate of the sub-
scriber Z, it enters the relay R and closes the circuit of the electromagnet E3.
This electromagnet turns the distributing wheel one tooth (the first relatively
to its original position). In this manner, exactly similar effects happen as
happened when the first of these three currents was sent into the apparatus of the
subscriber X the circuit of the electromagnet E, is opened and the contact
point S is put into connection with the line wire terminating in the office of the
subscriber Z. This positive current likewise passes to the office of the subscriber Z,
which closes the circuit of the electromagnet E. The number 1 appears at the
opening d, and the circuit of the electromagnet E is opened.
Now the wheel turning sends, as we have before seen, a negative current into
the line wire of the subscriber Z (this being the control current). This current
traverses the electromagnet U and the armature us is attracted towards the con-
tact us, but this has no action upon the apparatus of the post of the subscriber Z,
because this attraction could only close the circuit of the electromagnet E, but
this circuit is opened by the finger n', and the plate n", as long as the subscriber Z
does not press upon the button V3.
8
The two negative control currents one of which is produced by the wheel and
the other by the wheel 2, are combined in the post of the subscriber X and passing
into the relay U they close the circuit of the electromagnet Ex, which is possible,
because the finger g
is in contact with the plate no, the wheel j, turns one quarter
of a revolution and the inscription "Ring" appears at the opening d³, and then
the subscriber X by pressing on the button M of his apparatus causes the inscription
"Speak" to appear of itself.
65
5'
Thus after the button V, has been depressed the apparatus of the central station
corresponding to the subscribers X and Z will be in the following position; in the
apparatus of the subscriber X the electromagnets E, and E, which direct the
movement of the contact piece S, will be blocked and consequently the pieces S'
in the two apparatus cannot be displaced. The distributing wheel will have
advanced two teeth from its original position and the distributing wheel a single
tooth. The contact pieces S1 and S2, will be in communication with the overhead
conducting wires of the subscribers X and Z.
The negative currents sent by one of the two subscribers will cause no impulse
on their respective apparatus. On the other hand each positive current sent by
one of the subscribers will cause the distributing wheels and 721 to advance
one tooth in the two apparatus simultaneously.
The subscriber X profiting by the fact that a negative current produces no
effect either in one or in the other apparatus sends the call signal which is given
by means of a bell. With this object he presses upon the special button of the
Ader apparatus designed for the bell and which, as shown in the diagram of the
connections, sends a negative current into the line. The subscriber Z, after having
heard the call bell, presses upon the button V3 of his apparatus which as before
stated produces successively three currents (a positive current, a negative current,
a positive current).
The first positive current closes the circuit of the electromagnet E², which has
the effect of turning the distributing wheel one tooth, and it moreover closes
1

page_text: the circuit of the electromagnet E3, which has the effect of turning also the
distributing wheel in such a manner that after this positive current the dis--
tributing wheel, has been actuated three times, while the distributing wheel ³
has been actuated only twice.
The
As the wheel ₁ turns it sends, as before described, a negative control current
which traverses the electromagnet U, and closes the circuit of the electro--
magnet E, because at this moment the finger n², touches the plate n
inscription "Call" will therefore appear in the office of the subscriber Z; this
negative current passing into the apparatus of the subscriber X has no action
thereon as we have already explained, because the finger n³, is no longer in contact-
with the plate n³,
1
The negative current produced by the turning of the wheel ₁, as before
described. amalgamates with the current produced by the turning of the wheel ²₁
as described in the last paragraph. The wheel turning for the third time
produces moreover certain effects which we will now proceed to describe.
1
When the wheel is turned for the third time the end ², of the rod h₂h makes
contact with the plate r, and the end h makes contact with the plate whilst the
rod touches by one of its ends the plate re and by the other end the plate 11.
Now the plate r, is connected by the wire 94 to the solenoid S2, and the plate r, is
connected by means of the wire 95 to the other end of the winding of the same.
solenoid; moreover, the plate 10 is connected to the positive pole of the battery by
means of the wire 96 also the plate r₁ is connected by the wire 97 to the negative.
pole of the battery. Hence it follows that when the wheel r₁ has turned for the
third time the rods h, h, and h₂ h₁ close the circuit of the solenoid S2. The winding
of the solenoid is such that when a current flows through it the movable piece S,
which is really a permanent magnet, is drawn away from the lower plate C D
which we have called connection plate into contact with the upper plate A B which
we will call conversation plate, and the point S, which to the present was in contact
with the contact on the plate CD corresponding to the wire of the subscriber Z,.
now engages with the contact which also corresponds on the plate A B to the
wire of the subscriber Z and owing to the form of the contact point S₁ and the
point on the plate A B the contact point s₁ remains attached to the point on A B
until a reverse current passes through the solenoid S2. We may observe that.
the subscriber X has not been able to put himself in a position to speak to the
subscriber Zexcept when the latter has pressed upon the button V, of his
apparatus which caused the part S₁ to be brought in contact with the con-
versation plate. This has its importance, for admitting for a moment that the
two subscribers X and Z should be about to speak and that a third subscriber Y
should wish to hear their conversation he cannot do so, because it would be
necessary for this purpose that it should be one of the two subscribers X or Z
who has placed the contact piece S₁ upon the conversation plate.
Thus alter the first positive current sent by the subscriber Z the piece S* is.
in contact with the upper plate A B and in the office of the subscriber Z the-
wheel has turned once and the word "Call" appears at the opening d².
As above stated the second negative current which the subscriber Z sends by
pressing the button V2, produces no effect either in the apparatus of this subscriber
or in that of the subscriber X.
The third positive current also sent by the same subscriber Z, by reason of
the pressure of the button V, will act only upon the relays R², because the
subscriber X whose contact point S₁ is already upon the second line of contact of
the platform A B has no communication at this moment with the subscriber Z
whose contact point S³, remains upon the line of contacts of the platform C D..
The action of this positive current in the relay Rz has the effect of turning for the
third time the wheel 2, which, as we have explained for the wheel 1, effects the
closing of the circuit of the solenoid S², and consequently causes the point S², to be
moved from the plate C D unto contact with the plate A B. Hence it follows
that after the pressure of the button V, the subscribers X and Z will be in

page_text: communication in such a manner that no third party can overhear their conversation,
because the two points S₁ and S₁ are upon the contacts of the plates A B
and because they will remain there until the signal announcing the end of the
conversation has been given, that is to say, as we shall see later on, until one of the
two persons holding a conversation has pressed the button V.
The wheel turning for the third time, sends as we know a negative control
current which acts only in the post of the subscriber Z, closing the circuit of the
electromagnet E, which turns the wheel one quarter of a revolution in such a
manner that behind the opening d², the inscription "Ring" will be seen by the
subscriber Z.
We have herein before seen that the inscriptions "Call" and " Ring" appear
successively to the subscriber X when he presses upon the button V3, but we
should observe that as the sending of the currents produced when the button V*3 is
pressed is very rapid, the word "Call" does not remain and gives place immediately
to the inscription "Ring." On the contrary at the office of the subscriber Z who
is called, the negative currents which enter his apparatus are produced when he
presses upon the button V, so that the inscription "Call" will pass very rapidly
and that only the inscription "Ring" will remain visible through the opening ds.
The subscriber Z then makes the inscription Speak" appear by turning the
button M, by hand.
66
From this it follows that subscribers between whom communication is established
can converse together only when the inscription "Speak "has appeared at the
opening d² of the apparatus of the subscriber Z.
When the conversation is terminated the subscriber X who has put himself in
communication with the subscriber Z presses upon the button V4 and we shall see
later on what the subscriber Z has to do. The pressure on the button V has the
effect of sending successively two positive currents.
The first is produced by the contact of the finger an, with the plate or contact m
and of the finger m, with the plate or contact m; the pressure continuing to be
exerted, the finger ma passes beyond the plate m, and the finger ma passes beyond
the plate ms, but coming afterwards again under the action of the spring m, a
fresh contact is established between the finger m, and the contact plate m, and
between the finger m3 and the contact plate m, which produces the second positive
current.
In the diagram of the connections (Figure 15) we have indicated by an arrow
the direction of the turning movement of the lever mg.
Before studying the effect produced in the apparatus by the pressure exerted
upon the button V, it may be observed that the finger m, which closes the circuit
upon the electromagnet E, comes in contact with the plate m, only after the first
contact of the fingers m₂ m3 with the plates m, m, respectively."
The pressure exerted upon the button V produces therefore in the following
order (1) a positive current passing from the subscriber X to the central post
(2) a negative current passing from the central post to the subscriber and which
can act upon the electromagnet E6, because at this moment the finger m³, is in
contact with the plate m³,, (3) a positive current passing from the subscriber ✗ to
the central station and (4) a negative current passing from the central station to
the subscriber X, which current has no action upon the apparatus, because at this
moment the circuit of the electromagnet E is open, the finger m, being no longer
in contact with the plate m³.
8
We will now study successively the action of these currents in the apparatus.
The first positive current sent by subscriber X by pressing the button V of his
apparatus passes to the relay R₁, thereby closing the circuit of the electro-
magnet E3. This current continues in the line, passes to the relay R₁, which
closes the circuit of the electromagnet E3 also so that the wheels and will
each turn one tooth.
Let us now study the effect produced by this fresh turning movement.
One end 2 of the rod h₂, h will make contact with the plate ", and its other

page_text: end with the plate while the ends h₁ 3 of the rod h₁ 3 will make contact
with the plates r and r₁₂ respectively; the circuit of the solenoid S₂, like that of
the solenoid S2 is therefore closed and both solenoids will be traversed by a
current which will be in the opposite direction to that which has originally
traversed them, so that the point S, like the point Sz, will be in engagement with
the contacts on the plate C D.
By the contact springs or brushes H, and H. and the wheel H₂ a negative
current is sent into the line of the subscriber X as into the line of the subscriber Z;
this negative current arriving in the relay U closes the circuit of the electro-
magnet E which is possible because the finger m, is at this moment in contact
with the plate m³,; the electromagnet E*, being actuated turns the wheel 1, as
we have seen, a quarter of a revolution so that the subscriber X will see through
the opening d, the word "Rest."
6'
The negative control current produced by the turning movement of the
wheel has no action upon the devices in the office of the subscriber Z, because
the circuit of the electromagnet E is open (the subscriber Z pressing at this
moment neither on the button V3 nor on the button V4).
The second positive current which is produced by the second contact of the
fingers m3 m2 and of the plates m, m³ when these fingers are drawn back again
by the spring n, has the effect, as we will proceed to explain of bringing back the
apparatus X and Z of the central station to their starting point. In fact this
positive current arrives in the relay R, and in the relay R₁, thereby closing the
circuit of the electromagnets E, and E. The wheels and will therefore
turn again one tooth.
During this fresh turning movement the ends h, h₁ of the rods ha h₁ and h₁ he will
pass over the contacts g, and go, thereby closing the circuit of the electromagnets 11
and 12, for whilst the ends h₁ h, of the rods pass over these contacts the ends h3 4
will come in contact with the plate r₁, which latter is connected to the positive pole
of the battery by means of the wire 96. Now the electromagnet 11 is connected
with the negative pole of the battery by the wire 110 and the electromagnet 12 is
connected with the same pole by the wire 111. From this it follows that at the
moment the rods h₁ h, pass over the contacts g₁₂ these two electromagnets 11
and 12 will be traversed by a current; they will be energized and, as previously
described the rods parallel to the racks will be raised and the carriages F₁ F2 in
the two apparatus being no longer retained by the racks will each return to their
starting point under the action of springs.
The two apparatus at the central post are in this case brought to rest and the
negative current sent at the same time through the contact brushes H, H, and the
wheel H, at the office of a subscriber' will have no effect upon the apparatus of that
subscriber, because in the two posts the circuit of the electromagnet E, is at this
moment opened by the finger m₁.
'
To put the apparatus into condition for a fresh operation it will be sufficient for
each of the subscribers to press at his office upon the button V, so as, to bring
back to zero the characters visible through the openings d₁ da da d₁ and furthermore
the subscriber called that is to say in this case the subscriber Z, must bring the
wheel ji to the rear until the inscription "Rest " appears through the opening, by
turning the button M₁ fixed to the extremity of the axis of the said wheel.
2
We may observe that not only the carriages F₁ F, will have now returned to
their original position in the apparatus, but that the wheels have also taken
up again not their original position, but a corresponding position, for they are
turned a quarter of a revolution, because the various manipulations which we have
just enumerated have turned the ratchet wheel five teeth and this wheel bas
altogether twenty teeth, so that at the moment when the carriages F₁ and F, have
moved back to their starting point the projecting parts l₁l, of the wheel r₁ come in
contact with the plates r3 7, which is of no importance, because the four quarters
of the wheel r₁ are arranged in the same manner. The next time the counection
has to be established the rods h, h₁, h₁ hз will no longer act, but the rods which are

page_text: perpendicular; in like manner the projecting parts 13 ₁ will not effect the connection
but the projecting parts 1 12.
Such is the apparatus which forms. the subject of this invention and we may
sum up the operations to be effected in the following manner:
The subscriber who desired to enter into conversation with another subscriber
bears upon the button V₁and maintains, this pressure until in the openings d₁ d
appears the numerator of the fraction attributed in. the list of subscribers to the
subscriber with whom he wishes. to hold a conversation; he then presses the
button V2 until in the openings da da there appears the denominator of the fraction
corresponding to the same subscriber.
When the numbers visible through the openings correspond exactly to the
desired fraction the subscriber presses with his finger upon the key V3 and makes
sure that the inscription visible is that of "Ring." He then rings and after having
rung he causes the inscription "Speak
to appear at the opening d, and waits for
the subscriber called to speak to him.
When the conversation has terminated the subscriber calling gives the signal
which announces the end of the conversation. With this object he presses upon
the button V4.
"
In practice all the buttons except the button M₁ are provided with inscriptions;
thus the button V bears the word "Numerator," the button V2. "Denominator,"
the button V3 "Call," the button V₁ "End of Conversation," the button Vs
" Numbers."
The subscriber called, after having heard the bell approaches his telephonic
apparatus and presses the button V3 and when the inscription Speak" appears at
the opening d he proceeds with the conversation.
On the conversation being once terminated the subscriber called acts upon the
button M as we have herein before stated.
At the beginning of this Specification we have said that we described only by
way of example the employment of perpendicular co-ordinates, and it will be
understood that the operation of our apparatus would be the same if the
carriages F, and F2, instead of being moved in two perpendicular directions, were
moved in two oblique directions. Nothing would be changed in the apparatus.
But if instead of employing rectilinear co-ordinates we wish to use polar
co-ordinates for example, the arrangement of the apparatus while remaining the
same as regards the electric connections is modified from the point of view of the
arrangement of the carriages F₁ and F, In this case as shown in Figures 13
and 14 we replace the carriages F₁ and F, by slotted bars F, and F. These said
bars can turn freely about axes 0, and O2. Upon the axis O₁ are mounted the
ratchet wheels G₁ and G₂, and upon the axis O, are likewise-mounted ratchet
wheels G and G. The wheels G₁ and G, have teeth inclined in the same
direction, while the wheels G, and G4 have teeth inclined in an opposite direction.
The bar F1 may be attached by means of the pawl G, to the wheel G2, so that as
soon as the axis O₁ turns in the direction indicated by the arrow the bar turns
with it. The rotation of the axis O₁ is effected by means of the second ratchet
wheel G, iu the following manner; that is to say when the electromagnet E₁ is
traversed by a current it attracts the armature c₁ which is attached by means of
the hinged rod c₂ to the lever c, which moves freely about the axis O₁. On this
lever is fixed the pawl c, which is pressed against the teeth of the wheel G₁ by the
spring
When the armature c₁ is attracted by the electromagnet E₁ the pawl c
passes over one of the teeth of the wheel G₁; for preventing it from passing over
a greater number of teeth the screw E, is provided which plays the part of a stop,
regulating the movement of the lever c3. As soon as the current is interrupted the
spiral spring c, draws back the armature c, and at the same time causes the pawl c
to pass over a tooth of the wheel G, and also causes the bar F₁ which participates
in the movements of the axis O₁ to turn a corresponding distance.
In this manner
each time a current passes round the coils of the electromagnet E₁ the bar F₁ is
moved over a distance corresponding to a tooth of the ratchet wheel and thus it is

page_text: aused to pass successively from one series of contacts to another and at the same
ime carries the contact point S₁.
A similar movement also takes place in the bar F, which is moved by the
electromagnet E, each time the current passes through it; the bar F2 is displaced
similarly as described with regard to the bar F₁. It will be easily seen that
the contact point S₁ can thus pass over all the contacts arranged upon the
plate C D.
It is evident that in this modified arrangement the electromagnets E, and E, are
fixed and are not moved as in the arrangement described in the first part of the
Specification.
As regards the electric connections we use in this modified arrangement all the
parts previously described besides others such as the axis O, and all the wheels
keyed upon this axis, the plates fff..
Instead of placing the two fixed contact points belonging to each subscriber on
separate plates, one above and one below the mechanism which actuates the
movable contact points, I may place the said points on one plate in such manner
that the two points which in the two plate arrangement before described are in the
same vertical line are placed in contiguous positions on one plate. In such case it
is obvious that the position of the solenoid connected with the movable contact
point must be modified so that the said point is. displaced laterally instead of
vertically. Or the said contact points may be situated on different planes in one
plate so that the depth of penetration of the contact-making point determines the
contact made, in such case the displacement by the solenoid will be vertical.
I may also adapt my apparatus so that it may be used for conversing on a
system of double wire telephones.
In such a case the points making contact may be made double the two halves
being insulated from each other and the points on the plates with which they make
contact must be correspondingly modified in construction.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what mauner the same is to be performed, we declare that what we
claim is :-
1. In an automatic telephone exchange wherein each subscriber by operating his
own instrument is enabled to actuate mechanism situate at the central or other
exchange so as to place himself in electrical contact with the wire of any desired
subscriber, the method of making the required.contact by means of a metallic point
situated on a movable carriage which is capable of being moved by suitable
mechanism in two directions at right angles to one another and which point is moved
in and out of contact by apparatus upon the carriage.
2. In mechanism of the kind claimed in the last preceding claim the arrangement
of the fixed contact points connected with the line wires of the various subscribers
on the system in one plane or in two or more parallel planes at the intersections of
two series of equidistant parallel lines, at right angles to one another on such plane
or planes substantially as described.
3. The use, in connection with the method described in Claim 1 of two (or if
required more than two) fixed contact points for each subscriber, such points being
situated wholly on one plane or on different planes, in combination with suitable
mechanism for displacing the movable point so as to make contact in proper
sequence with the points corresponding to a given subscriber substantially as
described.
4. In a switchboard (for use in a telephonic system) the contacts on which are
to be regulated from a distant point the use of a system of points as described in
Claim 1 in combination with the use of carriages for moving the point which
establishes contact to any desired point on the switchboard substantially as
described.
5. In apparatus for automatic telephone exchanges an apparatus for recording
F

page_text: at the sender's end the motion of the contact point at the exchange, the said
apparatus consisting substantially of:
A. relay magnet as described in Claim 9 serving to control the destination of
the currents at the senders end according to the direction of the currents
reaching it through the line wire and electro-magnets which by suitable
mechanism cause dials carrying figures to turn in a manner depending on
the number and direction of the currents arriving through the line
wire.
6. The use in connection with an automatic telephone exchange of an apparatus
such as claimed in the last preceding claim actuated through:
(1) plates or other devices such as wheels composed of alternate metallic and
insulating portions which plates or other devices are insulated from the rest
of the apparatus but connected (as to the metallic portions) to one of the
poles of the battery at the central station
(2) and contact springs making contact with the metallic portions of the
plates or other device constructed as described above.
7. In an automatic telephone exchange the berein described method of trans-
mitting to the sender's instrument control currents for registering the movements of
the two carriages at the central station consisting of the use of a contact spring
attached to each carriage and so arranged as to make and break an electrical
contact at each forward step of the said carriage so as to send a current of such a
nature or in such a path as not to affect the motion of such carriage.
8. In connection with an automatic telephone exchange the use of a commutator
which can be displaced along its axis and which also is capable of rotation for the
purpose of transmitting currents of which the sign is different according to the
position of the commutator on its axis.
C
9. In an automatic telephone exchange in which carriages carrying electro-
maguets as hereinabove described are employed the combination of such carriages
with a special form of electromagnet for each pair of plates, (that is to say for each
subscriber) terminating on the one hand at the earth and on the other hand in the
line wire of the subscriber, the said electromagnet (which is herein called a relay
electromagnet" and which serves to close the circuits of the electromagnets placed
in each apparatus at the central station) being formed of a horseshoe magnet, one
of the poles of which is divided into two branches upon each of which is placed a
bobbin; an armature connected to the positive pole of the battery at the central
station being suspended between the two bobbins and its upper extremity being
situated between two terminals connected to the apparatus as hereinbefore described
and for the purpose specified.
10. In an automatic telephone exchange a relay magnet as described in the last
claim in combination with the commutator as described in Claim 8 (both at the
subscriber's office), and with the above described carriages having electromagnets
such relay magnet being so adapted by the aid of the commutator that the currents
which pass through the line wire and cause the above mentioned carriages to move,
do not affect the said relay magnet.
11. In an automatic telephone exchange the use of the lever i̟ (Figure 15)
adapted to make contact between the contact point ue and the contact plates is or i
which is caused to act by the first positive current arriving at sender's end
substantially as described.
12. In an automatic telephone exchange the use of the plates f and f2 and of
the contact spring t6 (Figure 15) for the purpose of opening the circuit of the
electromagnet El by the first motion of the carriage F2 substantially as
described.
r
13. In an automatic telephone exchange the use of the two plates 2 and 3, in
conjunction with the wheel 1 for the purpose of making and breaking the circuit
of E2 (by the first motion of the wheel r1) substantially as described.¨.
14. In an automatic telephone exchange the use of the plates f1 and ƒ 3 and of

page_text: the contact spring t6 (Figure 15) for the purpose of making the circuit of the
electromagnet E 6 substantially as described.
15. In an automatic telephone exchange the use of the rods h₂ h₁, h₁ h¸ and of.
the plates r10 r11 r 1 2 r 6 r 7 r 8 r9 for the purpose of regulating the current in
the solenoid S 2 substantially as described.
16. In an automatic telephone exchange the use of the rods ha h₁, hy h, and of the
plates r 12 g 1 g 2 for the purpose of closing the circuits of G 1 and G2 which by
their action allow the carriages F, and F, to return to their zero position
substantially as described.
17. In an automatic telephone exchange of the type claimed in Claims 1 and 2
each pair of plates, that is to say for each subscriber, a current distributor actuated
by a fixed electromagnet connected with each pair of plates i.e. for each subscriber,
the said distributor being substantially formed of a ratchet wheel which under the
action of a pawl actuated by a lever attracted by the electromagnet turns an axis
which carries (a) a metallic wheel insulated from the axis whose circumference
formed of segments, successively metallic and of ebonite or other insulating
substance is in contact with two brushes one of which is connected to the line of
the subscriber and the other with the negative pole of the battery at the central
station, for the purpose of sending from the central station to the apparatus of the
subscriber a negative current each time the ratchet wheel turns a tooth; (b) a
metallic wheel insulated from the axis, with four projecting parts placed at the
extremities of two perpendicular diameters and rubbing upon the metallic contacts
two of which, are connected on the one hand to the movable point on the contacts
and on the other hand to the line wire of the subscriber, and the other two of
which are included in the circuit of the electromagnet of the distributor; (c) four
metallic rods in two pairs insulated from the axis and perpendicular to one another
and closing successively the circuits of the solenoid surrounding the contact making
point and those of the electromagnets causing the return of the carriage to their
points of departure as hereinbefore described.
18. In an automatic telephone exchange the special forms of contact makers n 1
and m 8 adapted to be moved by pressure on the buttons V 3 and V 4 substantially
as and for the purposes described.
19. In an automatic telephone exchange the combination of the hooks used for
moving the carriages referred to in Claim 24 with the rods adapted to detach the
said hooks from the racks in which they engage, and the electromagnets adapted
to raise the said rods the said combination forming a means whereby on passing a
current through the electromagnets the carriages return to their zero positions
under the action of springs and levers so that when the first and all subsequent
operations described are performed by the subscriber at his office the series of
currents thereby transmitted reproduce the requisite cycle of operations
hereinbefore described.
as
20. In an automatic telephone exchange the combination of the distributing
wheel as referred to in Claim 17 with the relay magnet referred to in Claim 10 and
an electromagnet for working an indicating dial.
21. In an automatic telephone exchange the combination of the commutator as
referred to in Claim 8 with the relay magnet referred to in Claim 9 and the
electromagnets on the carriages as described in Claim 24 so that by the revolution
of the commutator in its different positions one or other of the carriages is moved
along its path.
22. In an automatic telephone exchange the combination of the relay magnet
referred to in Claim 9 with the two carriages referred to in Claim 24 so that
according to the sign of the current flowing into the relay magnet one or other of
the two carriages is moved.
23. In an automatic telephone exchange the arrangement at the office of each
subscriber, in combination with the ordinary telephone post, of a relay electro-
magnet similar to the electromagnet placed at the central station and which
distributes to the parts of the mechanism placed at the office of each subscriber the

page_text: currents arriving at the office of this subscriber and sent either automatically from
the central station when the said subscriber manipulates or by another subscriber
who wishes to put himself in communication with the first, the currents being
distributed by the relay electromagnet to three ordinary electromagnets, the first
two of which act upon wheels having figures, and the third of which acts upon a
wheel bearing other indications.
24. In the telephone switchboard described in the second claim the provision in
each pair of plates, that is to say for each subscriber, of two carriages one of which
carries the point connected to the line wire of the subscriber in question, adapted,
by means of hooks provided for this purpose, to be displaced between the two
plates along racks forming between each other a suitable angle, each of these
carriages being provided with an electromagnet which moves the corresponding
carriage one tooth forward on its rack each time the said electromagnet is
traversed by a current, the hooks which allow the carriage to be displaced along
the racks being adapted to be raised at any given moment so that under the action
of appropriate springs the carriers may return to their point of departure.,
"
25. In an automatic telephone exchange a telephone switchboard enabling any
subscriber of a telephone system to communicate with any other subscriber of the
same system without the intervention of special employees placed at the central
station, the said system being specially characterized by two horizontal parallel
plates of ebonite or other insulating material placed at a certain distance from each
other and arranged for each subscriber at the central station, all the plates
carrying metallic contacts ranged in the same order and connected to the line wires
of the several subscribers, in such a manner that on the one hand the contacts
occupying the same place upon the several plates correspond exclusively to the line
wire of a single subscriber, and that on the other hand in each pair of parallel
plates the contacts of the same subscriber may be placed exactly opposite one
another, the line wire of any subscriber being moreover connected to a point
surrounded by a solenoid adapted to be displaced between the two plates which at
the central station correspond to the said subscriber.
26. The herein described automatic telephone exchange consisting essentially
of as many pairs of parallel horizontal plates as there are subscribers on the system,
each plate of the pair having as many contacts as there are subscribers, said
contacts being arranged in co-ordinate lines and the contacts of the two plates of
each pair being exactly opposite each other, the contacts of corresponding position
in all the plates being connected together and corresponding each exclusively to
the line of a single subscriber, the subscriber's line being also connected to a
movable contact surrounded by a solenoid and capable of being moved between
each pair of plates along the co-ordinate lines of contacts such motion being
imparted in the two non-parallel directions by two mechanisms whereof the one is
carried by the other as described.
Dated this 23rd day of December 1895
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents.