Improvements in or relating to Multiple Telephonic Systems and Apparatus.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Multiple Telephonic Systems and
Apparatus.
We, PROSPER MOREAU. and JOSEPH MUNIER, 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 :-
The capacity of efficiency of a telegraph-wire is in a notable degree augmented
by the substitution in place of the method of working called "single" (that is to say
communication between two stations by manual transmission, at a speed variable
but relatively limited), of a method of "time division," wherein several operators,
at one and the same station may in succession and during equal periods of time,
transmit a signal, or the constituent elements of a signal or message to another
station with which the first is in communication, by the aid of an apparatus which
establishes synchronous connection between the line, at each end and the instruments
of the same order, viz., collector at the point of dispatch and separator at the
point of arrival.
That apparatus is a "distributor."
There is no difficulty in understanding how the capacity of the wire is increased
as a consequence of the emission of signals which are not simultaneous but successive.
Thus each station has to prepare its signal at a special moment indicated by the
"cadence" (or rhythm of vibration) and so preserves its independence electrically.
With the telephone, the circuit-capacity may also evidently be augmented as a
consequence of an increased rapidity of utterance; but this solution is by no
means satisfactory.
There is however a method whereby the procedure of multiple telegraphy, to
which reference has been made, may be applied to telephony, without, be it
understood, exacting a cadenced conversation, as indispensable.
Given, four operators or interlocutors, A B C and D in communication
respectively with four others A' B¹ C₁ and D¹, by the intermediation of a
distributor. In the absence of any other agency than that of the electric
connection established by that apparatus, firstly between A and A', next between
B and B, etc., each operator of each pair would perceive only one fourth of the
sounds emitted by his interlocutor, the line-connection being transferred, during
the other three-quarters' interval, to the three other groups.
This mode of procedure can also certainly not constitute a satisfactory solution.
What is essential is, that each group or pair of operators or interlocutors shall
have the entire use of the circuit as if they were the only operators; and that
consequently they may speak normally, each in his own habitual manner, and
similarly receive the answers.
It is with this object in view that we have designed the apparatus which
constitutes the subject of this invention, as shown, by way of example, in the
accompanying drawings; wherein ;-
Figures 1 and 1ª are two parts divided at the line c-d of the same elevation of
the apparatus.
Figure 2 is a plan drawn to a sinaller scale.
Figure 3 is a vertical section, on the line (a-b) of Fig. 1.
Figure 4 shows the brush corrector.
Figure 5 is a section on the line cd of Figure 1

page_text: corrector.
Figure 6 a section on the line (e-) of Figure 5.
Figure 6ter shows the mode of driving the pulley G' by pulley O'.
Figure 7 shows a mechanical detail of the corrector.
Figure 8 shows the receiver in section and front elevation.
Figure 9 is a diagram illustrating the scheme of communications, showing their
independence.
Figure 10 shows the line instruments in four phases for the same group.
Figure 11 shows the concordance of the positions of the line-instruments in each
group at one and the same moment.
Figure 12 is an elevation of the inscriber or recorder, showing the mode of
mounting.
Figure 13 is an elevation of the distributor.
Figure 14 a cross section of the same on the line ab of Figure 13.
Figure 15 is a view of the inclined plane or cam vin a straight or developed
form.
Figure 16 is supplementary to Fig. 4, and gives the details of brush corrector,
and Figs. 16, 16, and 16° are sections taken respectively on the lines op, rs,
and m n of Fig. 16.
Figures 17 and 18 are diagrams illustrating the general installation and working
of the multiple telephone system.
Let it be supposed, for the sake of simplicity, that four persons are speaking
into the wire at the same time, at any one station. The telephonic currents
simultaneously emitted being distinguished by no differentiating character, cannot
possibly be separated on their arrival at any other station, and will be mingled in
one confused sound at each receiver. No interpretation can be put upon them.
But, if we can so arrange that the currents emitted by A during, say, four
seconds, for instance, can be transmitted in one-fourth of the time, i.e. in one
second, the other three seconds will be free and can be utilized for the other
speakers B C and D.
If then, on arrival, we are enabled to arrange, contrariwise that the telephonic
emissions of A, singled out into the receiver of A¹ by the aid of a distributor,
though actually arriving during one second, shall be made perceptible during four
seconds, the result obtained amounts to this, that A, speaking continuously, is heard
by A' under exactly similar conditions, i.e. without discontinuity. The line-current
having thus put A and A' in communication for one second of time, passes to the
second group or couple B and B, thence to the third, C and C¹ etc., each couple
being put in communication for the space of one second only, in succession,
recommencing again, at the end of four seconds with A A' and so on.
"
To render this combination possible we employ a suspense instrument, which
we call the "register" and which is designed to enable us, while recording and
preserving the trace of the phonetic vibrations, to regulate the conditions of
transmission or of reception of those original vibrations.
The device selected and adopted for this purpose in our improved apparatus is a
mechanical register phonograph or graphophone.
We would here remark that, in our system, the plastic substance, endowed with
a certain amount of flexibility (being an admixture of stearate of soda, Chinese wax
and asphalte) covers a strip or band of parchment paper B d (Figs. 1 1 and 2),
called sulphuric" paper and is drawn round a disc or drum dp (Fig. 5), always in
the same vertical plane without lateral displacement.
There are of course four such disc carriers for the recording band in a multiple
telephone apparatus of the type described, and designed for a quadruplex
service.
The telephonic currents arriving at the apparatus must in the first place, leave
their traces on the register. To that end they traverse the inscriber or recorder I
(Fig. 10 left side). This part of the work is purely local. The transmitter tr

page_text: which is a line-instrument, passing over that trace, emits currents which faithfully
reproduce the vibrations, under the conditions, as to speed, which we have now to
explain. We shall hereinafter see the diagram or scheme of the communications.
At the receiving station, the emissions, created, as we have seen, not by the operator
or correspondent himself, but by the register, which is an auxiliary instrument,
reach the receiver (r c, Fig. 10, right side) also a line instrument, which passes
them on in its turn, to the register E. Lastly the reproducer (Rp) receives and
transmits them to their destination.
The different phases are, therefore, as follows:
(see the diagram or scheme of communications, Figure 9).
The line-instruments-(transmitter tr and receiver rc)-alone are movable.
Figure 10 represents four of their characteristic positions. The local instruments
(inscriber I. and reproducer Rp) are fixed.
The travelling band or strip, as well as the register cylinder E which draws it
along, is first presented to the inscriber, passing thence to the transmitter; under
the receiver, thence to the producer. In Figure 10 the left side only shows, beside
the register, the instruments of transmission, i.e. inscriber I (local instrument) and
transmitter tr (line instrument); and the right side, the receiving instruments,
i.e. receiver rc (line instrument) and reproducer Rp (local instrument).
We have illustrated on the accompanying drawings, a distributor with five
sectors, each sector being in connection with a group of instruments; but here, the
four phases indicated refer to the work of group No. 1. There are obviously
simultaneous corresponding positions in each of the other groups. An examination
of Fig. 11 will serve to make this correlation clear.
The
We will now study the working of the register and line-instruments (Fig. 10).
We will assume that our distributor is applied to a quintuple apparatus.
arm or index L, which pivots on its centre, puts the line simultaneously in
connection with each sector at the two stations.
Let it further be assumed that the distributor arm L rotates with a velocity
equal to 3, that of the register being represented by unity, or 1,-a purely con-
ventional relation. It follows, therefore, that while the arm traverses a single
sector, i.e. th of the circumference of the distributor, the register will rotate over
an angular opening equivalent to 15th only of the circumference.
We have also supposed that the group selected for illustration has its line-
instrument, or transmitter connected with sector No. 1 that is to say, that it has
command of the line-service so soon as the rotating arm L of the distributor has
entered upon the sector. The moment of entry of that arm upon the said sector
will therefore mark, for the line instruments (tr on the left, and rc on the right, of
Fig. 10) the commencement of the active, or, as it is herein called the "working
phase."
The time which elapses, between the moment when that arm passes from the
sector No. 1, and the moment of its return thereto, will constitute, for the same
instruments, a period of rest, herein called the "return phase." It is evident that,
during its working phase, the group No. 1 alone commands the line-service; and
that during its return phase, the other groups or couples 2, 3, 4, and 5 in succession
have command of the line, each during an equal period. In other words, each
apparatus has possession of the line-service during a period represented by í, and
loses possession thereof during a period represented by 4.
In order that these alterations may come to pass, let it be supposed that, at the
moment the distributor-arm L enters on sector No. 1, the transmitter tr, is
at 120° of the inscriber, the inscription being continuous. The arc y corre-
sponding to 5th or 120° of the circumference, is covered with traces emanating
from the inscriber. The register having a uniform movement, at a speed equal to

page_text: unity, as has already been stated, the transmitter tr begins its movement in the
opposite direction, shown by the arrow in Fig. 10, with a speed four times as
great.
Seeing that the arrangement of our apparatus requires that the line-work
(transmission or reception) is to be effected at a speed five times as great as that of
the local work (inscription or reproduction) it would seem necessary that the line
instruments should be worked at a speed equal to 5. This would be so, were the
register itself stationary; but as the latter is moving regularly with a speed
represented by unity, it will suffice, for the line instrument to have a relative speed
of 5 and that it should be actuated by an angular velocity of 4, because its own
motion is in the opposite direction.
For the same reason, and taking into account the ratio of the speeds, it is clear
that, for the line instrument to traverse the arc of 120° on the register, it will
suffice that its own displacement should be no more than 96° or ths of the
circumference-inasmuch as the other extremity of the arc has meanwhile
undergone a contrary displacement, to the extent of 13th of the circumference
or 24°
In consequence of these two contrary movements, the sum of the velocities giving
the absolute displacement, the transmitter t r will, therefore, while the arm L is
traversing th of the distributor have traversed an arc of 120° of the register,
i.e. 96° for its own displacement, and 24° for that of the register, thus emitting,
through the line-wire, by means of the distributor, the currents provoked by the
traces left on the register during the time occupied by one complete revolution of
the latter; those impressions, be it observed, being continuously produced, even
during the working phase since they are due to a local working.
The phase I (Fig. 10, left side) shows the commencement of that phase. The
phase II shows the transmitter midway in its course, its own displacement
being ths and that of the register 36th. Cross-hatching indicates the arc in
transmission.
If we examine the right side of the drawing Fig. 10 representing the reception,
we find an absolute identity of movement with this distinction only; that, whereas
the transmitter t r travelling to meet the inscriber I (i.e. in the opposite direction),
effects the dispatch of the emissions over the line wire with a five-fold greater
frequency of succession, than that imparted to them by the local work of inscription,
the receiver rc, in its identical working phase, travelling away from the
reproducer Rp acts, in a manner exactly the reverse dispersing in advance of the
latter, the imprints or traces furnished by the line currents, thus by retardation and
extension making exactly equivalent compensation and acceleration effected by the
transmitter.
The ratio of speed between the register and the line-instrument, at each station,
being exactly the same, the results obtained are contrary and equal, owing to the
arrangements above described.
When the transmitter has arrived at (phase III), the limit of its course, the
distributor arm L has attained the extremity of the sector 1. At this moment the
transmitter changes the direction of its movement and retraces its course, partaking
in the movement of the register. Its speed, is therefore, equal to unity. Whilst
the distributor arm L, on its return to the commencement of sector No. 1 traverses
in succession sectors 2, 3, 4, and 5, corresponding to the working phases, respec-
tively, of the other groups or couples (not shown in the drawing), the transmitter,
remaining on the limiting line of the arc corresponding to the vibrations already
transmitted, retrogrades over an angular distance which is equal to ths of the
circumference. It consequently returns to its starting point (X) but in a period
of time four times as long as that which it required to traverse the 96° during its
working phase. Phase IV shows the positions corresponding to the half of that
period. Its arrival at a (phase I) coincides with the return of the distributor
arm L at the commencement of sector 1.
In connection with the preceding exposition, we may remark that the rapidity of

page_text: the transmission, and, consequently the yield or useful effect of the telephonic
circuit, depend, neither upon the absolute speed of the distributor nor on that of
the register, but only on the number of the sectors, which number determines the
ratio which must exist between the speed of the register and that of the line
instrument.
At the other station the phenomena occur in exactly similar manner, the receiver
meeting the reproducer (phases III and IV, on the right of Fig. 10).
The inscriber continuing its work, the same series of movements, with periodic
changes of speed and direction, is repeated indefinitely, and in this manner is
realized, upon the line-wire, the dispatch and the receipt of telephonic currents,
whereof the frequency is multiplied on departure and in the same proportion
retarded on arrival, in such manner that the arc covered with traces during a
period which corresponds to one complete revolution of the distributor passes
under the transmitter during a period of time five times less and reciprocally, the
vibrations, on arrival, are registered during a period equivalent to the duration of a
single revolution of the distributor, these various phases succeeding and completing
one another for one and the same group or couple, without any interval or
interruption between the working phases of the different groups; so that it may
easily be understood that it becomes quite possible to utilise a single telephonic
circuit for five different groups or couples of correspondents each of which preserves
its independence the while.
Such is the principle on which is based the apparatus represented in the
accompanying drawings.
It has been stated that the distributors rotate synchronously. It is therefore
essential that at each station, there should be an apparatus whereby that result
can, with certainty and accuracy, be obtained; or at least an apparatus which
admits of adjustment for making such correction as may be required, and as
necessitated by the impossibility of maintaining an absolute and permanent
synchronism between two instruments working independently of one another.
The speeds having been regulated with every possible approximation to accuracy,
the correction of any deviations, due to a slight excess or defect of speed will have
to be effected, not by any modification of speed itself, but by an absolute and real
rectification of position.
This work of correction must, therefore, be repeated at regular intervals, so
as to avoid any accumulation of such errors, and its magnitude and importance
are given by the amount or error arisen since the last preceding correction.
This work is provided for in our apparatus by a battery-current (a telegraphic
current, in contradistinction to telephonic currents) emitted once in each revolution
of the distributor by one of the stations, called thence the correcting station.
This work of rectification is, as will be seen, hereinafter fully explained.
The battery-current intended for this indispensable correction, could not, without
involving some disturbance, be sent along the line-wire at the same time as the
telephonic currents, which would unavoidably occur if our distributor comprised
five distinct working sectors, like that which has been described in our explanation
of the principles of our invention; the distributor arm passing, in fact, without
interruption from one to the other of the sectors, there would not be a single
moment at liberty, so as to be available for the emission of the correcting current.
To obtain the desired result, without having recourse to any arrangement or
device of simultaneous telegraphy or telephony, so-called, our apparatus is simply
limited to a quadruple effect, in lieu of a quintuple effect, while still preserving the
five sectors, one of these being consequently set apart for the transmission or
reception of the correcting current (Figure 104).
It is evident however that the multiplication continues to be five-fold, and that
the distributor-arm traverses this particular sector (indicated by hatching in
Figure 10) during the period in which, for all the four groups or couples of
correspondents the line-instruments are in their "return phase."
Apart from this modification in the distributor itself, each and every period of

page_text: work or inaction of the line-instruments will be found in the following description,
as well as their assured connection with the line-wire at the proper moment by the
intermediation of the distributor, the local work of inscription before transmission
or of reproduction after receipt, being continuously carried on meanwhile.
GENERAL DESCRIPTION.
In the telegraphic printing apparatus of Mr. Hughes, two type-wheels rotate
synchronously at each station, and offer, consequently, both at one and the same
moment, a particular point of their circumference, say a certain letter, at a fixed
point; the emission of a current, provoked at the transmitting station at the moment
of the passage of the selected letter, finds the same letter in exactly the same
position at the receiving station, and causes it to be printed. According to the
succinct statement of this principle, it is obviously necessary to make use of an
unwinding apparatus with regulating device and equally obvious that there may be
a possible correction to be made. We employ this unwinding apparatus in connec-
tion with our apparatus. It is shown, in elevation, in Figures 1 and 1^ and in plan in
Figure 2. It is composed of a train of geared wheels mounted between two
parallel plates, the speed increasing in proportion with each remove from the motive
agent which in this example is formed by a weight which can be wound up to the
required height by means of a treadle or otherwise and acts directly on the first
shaft, I, of the train. The last of the series V carries the fly-wheel V L and
the regulator, consisting of a vibrating blade P which is not fixed to the table of the
apparatus, but fitted into a recess in a bracket attached to a fixed point outside the
apparatus, this being, however, solidly mounted to avoid all vibration. The polarised
electro-magnet of Hughes is retained; this is our electric corrector E c.
detent-lever d¹ which by its oscillating movement effects the throwing into gear of
the pawl c (Figure 2) and the momentary connection of the shaft B¹ with the fly-
wheel-shaft, and serves also to connect the scroll-cam with the armature of the
electro-magnet, has also been preserved. The cams by which the disengagement,
the printing, and the movement of progression, are effected, have been dispensed
with; only the correcting cam K is preserved, arranged and mounted in similar
manner. On the forward end of the shaft IV of the train, is mounted outside the
front plate, as in Hughes' apparatus, a ratchet-wheel U, so as to be operated by
that shaft, by means of a spring disc T the connection of which with the shaft
itself can be regulated at will. With this ratchet wheel U is engaged, by means
of a pawl cy (Figure 3) the solid steel wheel M, called the corrector-wheel, which
has been preserved just as it is, although only a single one of its recesses is adapted
to be of use for our purposes. Further towards the front are the visible parts, a
pulley O the distributor D, the brush-carrier N and pulley O, the object and use
of which will subsequently be explained, as well as those of the other pulley O¹.
The arrangement or device shown at G G¹ is used for the correction.
T'he
The table of the Hughes' apparatus, limited to its gearing and its mode of
correction, has been prolonged in front towards its centre. Upon this prolongation
are disposed, in parallel positions, and mounted on the same shaft, the four
registers 1, 2, 3 and 4, whereof 1 and 2 alone are shown in Figure 2, and 1 only in
Figure 1 of the drawings.
The local instruments, in each group, the inscriber and the reproducer, are fixed,
as has already been stated. The inscribers are shown at 11 12 etc.; and the
reproducers R p¹, R p² etc. of which one only appears in Figure 1, which shows that
Rp belonging to the first group. The line-instruments are connected for each
group, and occupy variable positions, according to the moment under consideration.
The amplitude of their displacement is normally ths of the circumference
say 96°, the brush-carrier of the distributor having a corresponding movement
of th, and the register 15th.
Figure 11 which illustrates the development of the said are of 96° shows
the corresponding positions of the instruments in motion, for each group.
The

page_text: work of inscription and of transmission is effected in that part of the diagram
which is to the right, the inscriber being then in front, and the reception and the
reproduction to the left.
For greater simplicity, these instruments have only been shown for one of the
groups, in Figure 1. It is always possible, by noting the position at the moment of
the distributor-arm, to determine the positions of the similar parts in the other
groups. In Figure 11, tr and rc indicate the two line-instruments which are
always in connection; and it is supposed that they are at the commencement of the
working phase in the group I, each inscriber being to the right of its register,
and the reproducer to the left. The diagram of transmission is a¹ b' that of
reception a¹ b¹.
The registers are made of preferably ebonite; the greater part of their circum-
ference is encircled by the band B D, which is fed from a reel located beneath
the table, ascends on the left, passes in succession under the inscriber and the
transmitter, thence under the receiver and the reproducer, finally returning under-
neath the table. It is guided in its movement by a slight depression dp (Figure 5)
on the periphery of the register, and by the guide-discs or rollers m and m¹
Figures 1 and 14.
The registers are mounted on hollow gudgeons or shafts rotating on the rims of
small pulleys fixed on the supports S.
The description of the inscriber, almost identical with the receiver, as well as of
the transmitter and its analogue the reproducer, will hereinafter be given.
By means of the wheel R, fixed to Hughes' shaft III, movement is communicated
to the shaft X, which extends throughout the entire length, passing through the
hollow shafts of all the registers. On the right, a small auxiliary or counter shaft.
transmits the movement to the pulleys P1 P2 etc., each mounted on one of the
faces of a register. The diameters are calculated and the arrangement such that
each register rotates in the same direction and with the same speed as the shaft X.
On the main shaft are as many internally-toothed wheels A' as there are registers.
Each of these wheels, by means of a pinion H, causes the double ratchet-wheel J,
with alternating teeth, to rotate in the opposite direction and with a speed four
times as great.
In front is the mechanism securing the displacement of the line-
instruments, and the electro-magnets E d of despatch, so-called, the use and object
of which is hereinafter explained.
We will now proceed to describe the distributor, the conditions of the despatch
of the corrector-current, the actual work of correction, the mechanism which has
only just now been indicated, as serving to impart motion to the line instruments,
and lastly the line-instruments themselves, which are, in pairs, analogous to the fixed
local instruments.
THE DISTRIBUTOR.
We have already stated, that, although our apparatus is only quadruple in effect,.
the multiplication by five still subsists, owing to the division into five sectors; and
that, because we reserve one of the sectors for the despatch or receipt of the battery-
current, called "corrector-current." Our distributor, like that shown in Figure 1,
would therefore have its sector No. 1 following that which serves for the correction
(No. 5), the last operative sector bearing the number 4. Nevertheless, there is no
change whatever, in the calculations of speed, nor in the amplitudes of displacement
of the line-instruments. Moreover, it may be supposed that the line-wire, instead
of being placed at the service of each group through the distributor, is so placed
by means of a contact established by that part which carries the line-instruments of
that particular group, at the moment when the working phase commences.
this purpose it suffices that the commencement of that phase be determined by the
position of the arm upon the distributor. In this manner the telephonic currents,
instead of passing through the distributor, as happens with telegraphic currents in
multiple systems where this device is employed, pass directly through the line-wire.
But the distributor has, none the less, its special function to discharge, namely to
For

page_text: ensure concordance at each end of the line, between the active phases of each
connected group.
The result will be the same, whether that concordance be
brought about, as has already been stated in setting forth the principle, on the
supposition of a similar concordance with the mechanical parts, or whether the
distributor exercises a determining action on the moment of commencement of
the working phase, by the displacement of a commutating device whereby contact
with the line is effected at that very moment. The telephonic currents, then, do
not pass into the distributor, around the periphery of which are arranged simply
the contacts connected with the electro-magnet at the despatching station for each
group, in turn, and with the local battery. The arm carries three brushes, whereof
two (and b) are coupled. The third (611) has a special use.
The distributor-disc carries two concentric series of contacts, as may be seen in
Figures 3, 13 and 14 and in the diagram of communications, Figure 9. The one
comprises a contact stud L' in connection with one of the telephonic lines, line / for
instance, together with four other oblique contact studs, which will be treated of
when the correction is under consideration. Of the outer series, a contact-stud C,
adjustable by means of a small rack, is in connection, either with the electro-
corrector, which is the same as that of Hughes' apparatus, or with a battery, the
other pole being on the telephonic line 21. These two series of contacts may be
thrown into connection by means of the coupled brushes (61) and (11). Outside
of these, two small contact-studs t m, t m¹ (Figures 3, 13 and 14) situated in the
same radial line, and jointly adjustable by means of a rack * (Figures 13 and 14)
may be momentarily connected by the large brush (6") at the moment of its
passage. The outer of these two studs (t m) is connected with the telephonic line 2¹
and also with one of the poles of the battery; the other small stud is connected
with an ordinary telephone Tt and then to earth. Lastly, the crown or segment P¹
is in connection with a local battery, and is only operative when in front of the four
oblique studs d¹ d² d³ d' already mentioned.
The distributor only plays indirectly the part hypothetically assigned to it in our
exposition of the principle of this invention. Its object is to establish concordance
between the moment of despatch of the pair of instruments (transmitter and
receiver) in each corresponding group, A A¹ for instance, at the two ends of the
line, by which we mean to say at the two stations in communication, whether the
telephonic circuit is completed by earth as return, or metallically. The distributor
is shown in elevation and in section, respectively, in Figures 13 and 14. It is also
seen in the diagram of communication, Figure 9, in that part of the figure which is
indicated by the square in dotted lines, for the purpose of indicating that electrical
connections inside that square are concerned with the general working of the
apparatus as a whole, not with that of any one group of instruments.
Each one of
these moreover has also in this diagram been isolated, for the sake of clearness, the
electrical communications being identical in each of the four separate divisions.
The distributor is therefore shown in the general diagram but without its inclined
plane or came, which indeed fulfils no electrical purpose. At tm, t m¹ (Fig. 13)
the two small contact-studs of what we call the "attesting telephone" or ❝ tell-tale
are shown electrically insulated the one from the other but solidly connected by an
ivory or equivalent tablet i v and adjustable in either direction by the pinion and
milled head b t. A similar device also regulates the displacement of the contact-
stud C by means of a milled head 6 t¹. Situated in the same circumferential line
as the contact-stud C is the crown or segment P¹ within which are arranged in a
circle the five contact-studs L' d' d² d³ d4 which like P' are fixed. It will be seen
that the four contacts d¹ d² d³ d are oblique and that their obliquity increases in
proportion to their distance, successively from L¹. All these contacts, as well as
the segment P are metallic, as will be understood. Figure 14 illustrates the mode
of mounting them by means of screws and nuts. As regards the cam vits outline
is interrupted for a certain distance by the inclined planes which limit the extent of
its height aud length as most clearly shown in a developed form in Figure 15. The
distributor, whereof the case is made of preferably ebonite is fixed to the front
,,

page_text: plate of the Hughes winder. Its centre is hollowed out for the passage as shown in
Figure 3 of the shaft and sleeve which transmit motion to the mechanism in
front.
CORRECTOR CURRENT.
Our system requires an absolute concordance between the instruments in circuit,
It becomes essential,
as well as between the four groups in each instrument.
therefore, to correct the errors which periodically arise by default of synchronism,
and which might, by accumulation, render working impossible. But, to that end,
it is necessary that the battery-current, by which the rectification is to be effected,
should be subject to no delay whatever, and the exact moment of its emission, as
well as of its reception should be precisely determined by the true value of the
speed of each instrument. In telegraphy this is done by suitable adjustment of the
contact-stud at the receiving station.
In our system, it is the correcting station to which is assigned the duty of
adjustment and correction, by a suitable variation in the position of the contact-
stud which brings the battery-current into operation. Some of the causes which
tend to delay the current are constant, and it suffices to take account of them;
others are variable and must, so to speak, be guarded against, so as to modify the
adjustment, accordingly.
In order the better to comprehend the method adopted, it is necessary, in the
first place, to consider the course of the current transmitted to make the cor-
rection at the corresponding station. Our commutator-key (d) being upon the
contact-stud (a) Figure 9, the battery-current is brought to the contact-stud C.
The coupled brushes (61) and (6) in their passage over L and C transmit the
current on the telephonic line 1¹ and the other pole of the battery being
connected with the telephonic line 2', the current will return by that second
line. But, at the other station, the current, transmitted through line 1¹ has
traversed the contact-stud L' the coupled brushes (and b) and contact-stud C.
It is supposed, in fact, that these brushes are on any point of the two studs L'
and C, ie, that the concordance between the two distributors, though not
absolute, is nevertheless sufficiently approximate to admit the current, the width
of the contact-studs constituting the latitude of the admission. The key do being
on the position for the reception of the corrector-current, the current arrives at
the electric-corrector E c traverses the disconnecting springs (i and i¹) at the same
time putting line 1' to earth by the device T'; as soon as the electro-magnet has
done its work of correction, the current ceases to traverse the bobbin, and goes
directly to earth, by way of M¹ N' T¹.
Our object is so to regulate the position of the contact-stud C, at the correcting
station, that the instruments rotate synchronously, and supposing, in consequence
that the work of correction is nil, the current will arrive at the receiving station
exactly in the centre of the contact-stud C.
In this position the operation of the correcting station is as follows:-The two
small contact-studs being in line with a fixed or zero point, corresponding to the
centre of C, when C is the contact-stud at the receiving station; then the stud C
which is supposed to be in circuit with the battery at the point of contact (d³ a³) is
moved forwards until we perceive in the attesting telephone T t the sound testifying
the passage to earth of the current at the receiving station, by way of M¹ N¹ Ti
as has just been explained. That perception may be considered as having been
exactly coincident with the passage of the current to earth; because from the pole
of our line-battery which is in circuit with line 2', the return-line of the current,
a wire proceeds which may be put to earth through the attesting telephone by means
of its contact-studs. The line 2' now becoming inactive, by the disconnection of the
springs i and i at the receiving station, and line L' being connected to earth by way of
M' NT a current traverses the earth-line t¹ and the attesting telephone Tt if
the large brush is at that moment on the double contact-studs. If the sound ceases
to be produced in T t it is because some variation in the position is requi: then,

page_text: before displacing the contact-stud C, which represents the battery, the coupled
contact-studs are moved in one direction or the other, until the sound reappears in
the telephone. Being thus informed as to the direction in which C must be moved,
we bring back the coupled contact-studs to zero-point, and cause the contact-stud C
to advance or recede until the earth connection is again perceptible. It may
bappen, however, as must be evident from the foregoing, that the corrector-current
does not, for all that, arrive at the receiving station on the centre of the contact-
stud C; and that will be so, in fact if there be any default in synchronism, having
no relation to the exact adjustment of the instruments under consideration and
their contact-studs. The correcting station being provided with the means for
controlling and regulating this departure, the receiving station is only concerned
with the regulation of its own speed, and is not liable to misunderstand the current
transmitted to it.
CORRECTION.
It has been said that the nature of the correction, in the Hughes printing
telegraph, was really that of an actual rectification. The two instruments working
at different speeds, the desired effect is produced on the type-cylinder by the
intermediation of a corrector-wheel. Every current intended to effect an impression
of a type is at the same time a corrector-current, i.e., its conjoint function is to
ensure an absolutely perfect impression of the type by a sudden arrest of the
movement of the type-cylinder. This stoppage is effected by means of an instan-
taneous attachment of the printing-shaft which, being retained in our apparatus,
we will call the "corrector-shaft" B-during a single revolution, with the fly-
wheel shaft, the two being for that period, thrown into connection by the
engagement of a pawl, primarily brought about by the lifting of the armature.
The correcting device on the said shaft is, in this case, a cam / shown in section in
Figure 7, engaging, as though it were a single or only tooth of a pinion, with one
of the teeth of the corrector-wheel, so-called, into which it gears without shock if
the actual position of the said wheel is correctly what it should be, and which it
pushes suddenly forward with its beak h or repels with its heel t if rectification be
required, as illustrated in dotted lines. The corrector-wheel is not fixed upon the
shaft which thus, for the time being, actuates it; it is only temporarily engaged by
a pawl with the ratchet-wheel U, which is, itself driven by the motor-shaft IV,
by the intermediation of a friction-disc T. By this arrangement the perfect
independence of the corrector-wheel and the shaft, in point of rotary movement,
is ensured.
In the Hughes apparatus, there is, therefore rectification consequent on a
displacement of the corrector-wheel on the shaft which carries it.
We preserve this mechanism, indeed, while utilizing it as follows:-As has
already hereinbefore been stated, our distributor is provided with four contacts d'
d2 d d Figures 9 and 13 designed to bring about, in regular order, the movement
of the line-instruments as soon as that phase commences. What happens, then, is
precisely the same as if, in reality, the line-current reached the group through the
distributor while the arm of the latter was traversing an are limited to the distance
apart of two consecutive contact-studs.
By analogy, we will call that distance a sector. But in telegraphy, where the
currents are transmitted to the contact-studs in pre-arranged order, there is, for
the reception of the said currents at the other station, a certain latitude, determined
by the breadth of the studs, the useful effect being produced to a certain extent,
independently of the precise point on the stud where the reception of the current
begins.
In our system of multiple telephony, we do not limit ourselves to using a single
contact-stud as in telegraphy; we are concerned with the sector in relation to the
working group, to ensure that it be utilized, throughout its amplitude, for the
despatch and reception of telephonic currents.
It will easily be understood that, if we rectify the position of our brush-carrier at

page_text: one and the same point only of its revolution, we certainly prevent the errors, que
to default of synchronism, from accumulating, from one revolution to the next
following; but we make the rectification only at that very moment, and, from the
cessation of the working phase, the error begins to be produced anew, increases in
proportion to the advance made from the point under consideration and attains the
same value as before, at the moment of a new rectification.
The concordance does not therefore subsist among all the instruments in circuit.
But what we must accomplish is perfect and absolute concordance throughout, from
the moment that the brush-carrier enters upon the sector at each station, and when
it leaves that sector, that is to say, at the moment of its entry on the next following
sector.
Rectification only at its entrance on the sector would not suffice, in fact, the
working phase, or duration of the passage over the sector, being prolonged, in
an instrument whereof the speed is in defect, and shortened if the speed is in
excess. The nature of the movements communicated to our line instruments, the
periodic changes of direction and speed, combine to enable us to attain the desired
end (which is twofold) by correcting only the entrance on the sector, and by
making the working phase continue only until a moment which is marked by a
fixed point, which is invariable in our apparatus. That is to say, that we determine
the exact moment, when the working phase ought to begin, by the emission of a
local current, rendering operative one of the electro-magnets of despatch Ed
(Figures 1, 2 and 9). If then we gain, it is because our working phase is shorter
than that of our correspondent; the correction applied will retard the coming in
contact of the brush with the stud d' d' d³ or d as the case may be according
to the group in question, and, in consequence, the duration of our working phase
will be proportionately prolonged. In fact, as has already been shown, in Figure 10,
the line instrument becomes relatively stationary on the limit of the arc next
in order and to be traversed, until the moment comes for the working phase,
to be resumed, meanwhile participating in the speed and direction of rotation of
the register; therefore, the arc to be traversed during the active stage will be
by so much the greater as the signal of retrogression is retarded, the end of that
phase remaining always determined by the position of a fixed point on the
apparatus.
In our exposition of principle, we gave, as the absolute value of the amplitude
of the rotary movement of our line-instruments, an angle of ths of the circum-
ference, or 96°. It follows from what has just been said, that this value is rigidly
exact only at the correcting station, or at any two stations where the concordance
is perfect, and no correction is necessary. The return phase never commences
beyond the point Figure 10; but the working phase may commence either beyond
the point a, i.e., after that point has been passed in the return phase, whereby the
amplitude of the arc az is augmented-that is to say when we are gaining-or on
this side of a i.e., before it is reached, so as to diminish the amplitude of the are a z
in case we are losing.
The value of the condensation and acceleration, or of the dispersion and retarda-
tion effected by our line-instruments, nevertheless, remains entirely unaffected by
this adjustment in time-division.
There is no connection between our line-instruments in the different groups, and
our distributors, other than emission of the local current which brings about the
The rectification in position
commencement of the working phase in each case.
of the brush-carrier, taken by itself, as well as the work of the corrector-wheel,
therefore, takes place quite independently of the work of the line-instruments,
though the latter is determined thereby. In other words, the line correction
rectifies the adjustment of the brush-carrier and the local currents rectify the
moment of the commencement of those line-instruments for each group.
accordance therewith, the end of the working phase i.e. of the sector, being
supposed to have been rectified, let us now examine what the error is at the time
In

page_text: when the working phase is resumed. That is to say, by how much the moment
of emission of the local current must be retarded, in order to prolong the working
phase of a line-instrument which gains, or, vice-versa, by how much it must be
accelerated to shorten that working phase for an instrument which loses. That
will appear from one single consideration. In each of the five sectors the pro-
portion of the total error is one-fifth. The group being supposed rectified at the end
of the working phase, when the brush-carrier, in consequence, has arrived at the
extreme limit of the sector, the error in the line-instruments, at the end of the
return phase, will obviously be only ths of the total error, because the distributor-
arm has reached the commencement of the sector .e. has traversed ths of the
circumference. By determining the commencement of the working phase at that
exact moment, by the emission of the local current, the duration of that phase will
be prolonged or shortened in the required proportion, by giving it an amplitude
greater or less than 96°, the instruments changing, on the instant, the direction of
their movement, and undergoing by their movement in common with the register,
an angular displacement relatively to the latter, represented by 5.
The total
error (gths, taking into account the portion due to the passage over the sector
itself) being cleared in fivefold less time than was consumed in its production, the
rectification is, therefore, perfect.
on the
It only remains to examine the behaviour of the brush-carrier during correction.
It has already been said that the rectification produced by the cam
corrector-wheel has the effect of displacing it by a certain angle, and with it the
brush-carrier which so far at least as rotary movement is concerned, is associated
with it.
Commencing from the front plate of the apparatus and proceeding outwards, we
find, on the motor-shaft IV the following mechanical parts, in succession ;-the
ratchet-wheel U, its spring or friction-disc T, the pawl cq and corrector-wheel M;
then a pulley O', attached to the wheel M, and whereof we shall explain the object,
after giving the description of the mode of displacement of the line-instruments.
Further to the front is the distributor D, traversed by the sleeve L' of the
corrector-wheel, on which is mounted with slight friction a second sleeve Q carrying,
firmly attached to it the brush-carrier N. These two sleeves are connected, the
one to the other, in regard to their joint rotary movement; but the second or
brush-carrier sleeve Q is movable longitudinally (i.e. in the direction of their
common axis) under the influence of a small circular spring or spring disc r¹ cl, and
guided by the stud g fixed on the inner sleeve and engaging in suitable slots in Q.
The sleeve Q of the brush-carrier arm N is provided at its end nearest to the
distributor D, with a projections (shown in dotted lines in Figure 3) adapted to
slide on the inclined plane or cam v which is attached to the distributor, or fall
momentarily into a notch or recess in v. In front of the spring r¹ a friction
cone W, fitted with an indiarubber or equivalent ring on its bevelled edge, is
attached to a second pulley O. The diameter of this second pulley is exactly the
same as that of the other pulley O¹, already mentioned as being attached to
the corrector wheel M and we shall hereinafter treat of them both together. The
arm N (Figs. 2, 3, 4 and 16) fixed radially on the sleeve Q, carries the brushes or
rubbers 16 and 6-the last two band 6, being ordinary brushes and the other bl
taking the form of a blade all these brushes having their extremities in the same
radial line. The brush 61 is insulated. The two others are electrically connected
together; the brush 6 being fixed and the blade 1 movable in
slide-way gl (Figures 4 and 6). Its movement is derived from the friction cone w,
fixed to the base of the brush-carrier arm, and caused to rotate by frictional
contact with the cone W, brought about by the projections (Figures 3, 13 and 15)
ascending the cam v. This disc W (Figure 16) transmits its movement to the
eccentric e (Figures 4, 16, 16B and 16) to the collar or frame c² and so to the
blade b¹.
a small
These two cones wand W whereof the smaller is loosely mounted within a bracket e q

page_text: (Figures 16 and 16°) fixed underneath the brush-carrier N, change their relative
positions slightly; inasmuch as the one W represents the shaft, and the other w the
sleeves L' and Q-that is to say the corrector-wheel itself.
Figure 4 which clearly shows how the smaller friction-cone or pulley w shifts the
blade ', may be regarded rather as showing diagrammatically (somewhat modified
for the sake of clearness) the position of the different parts which are shown in
detail in Figure 16. In this last-named figure 30 is the axle or spindle of the
friction-cone or pulley w; e the eccentric mounted on that spindle and rotating
thereon within the bracket e q which embraces the underside of the brush-carrier
The eccentric e touches at one and the same time, both sides of the collar or
frame to which is affixed the connecting rod which transmits to the blade b¹
the movements of the said collar. Finally a spring-blade lm (Figs. 16 and 16^)
which under normal conditions rests on a flat surface cut on the axis or spindle 30,
comes into action when the said spindle rotates in either direction.
arm.
two
To recapitulate: The working of the device is as follows:-The
cones W and w are in frictional contact and have been moving hitherto as if they
permanently geared together. If now we receive a corrector-current in our electro-
magnet E c (Figures 1, 2 and 9) and the mechanical work of the correction must
not be nil, the effect of the cam results in causing the two cones W and w to roll
upon one another by a small but definite quantity. (We may here point out that
the small cone w need not necessarily be a complete cone, but may only represent
a conical segment of a few degrees.) The small cone w (as has been seen) operates
the blade 6 which is thus caused to move to and fro, in a direction parallel with the
axis of the brush-carrier arm N within its slideway g' on the said arm N, with a
view to its encountering or coming into contact with the oblique contact-
studs dd2 d d (Figs. 9 and 13) under conditions which are dependent on the
amount and direction of its displacement.
The frictional contact of the cones was brought about by the ascent of the
inclined plane or ramp by the projections; an ascent which must have taken
place shortly before the reception of the corrector current. But, from the moment
that the blade b¹ has cleared the fourth oblique contact stud, the said projection s
drops into the recess or notch cr of the ramp or cam v (Figs. 13 and 15), the
circular spring r c reacts and pushing the sleeve Q of the brush-carrier arm N
causes the frictional contact of the two cones W and w to cease inasmuch as the
larger cone W has undergone no displacement from front to rear. That friction
having ceased the blade-spring Im (Figs. 16 and 164) which had been energized by
the flat surface cut on the periphery of the shaft 30, reacts upon the latter and so
restores to their former position the collar or frame c² the connecting-rod K' and
the blade b'. The entire device is then ready for a fresh correction. It will be
understood that the foregoing represents what happens at the receiving station to
which the corrector current is transmitted. (This remark applies also to the
working of the pulleys O O¹ which are hereinafter more particularly referred to.)
In the general plan Fig. 2, for the sake of clearness, only the brush-carrier is
indicated without its mechanism for the displacement of the blade, as those details
would have created confusion.
The obliquity of the contact studs d' d' d³ d calculated in any suitable manner,
indicates that these studs will be reached so much the earlier or later, according as
the displacement takes place in one or the other direction and is greater or less in
extent; the amount of such obliquity increasing in proportion to the distance away
from the correction-sector, and the rectification varying in accordance with that
fact alone, for any given displacement of the adjustable blade. The distributor
fulfils therefore the function of a simple intermediary between the corrector current
received from the line and the contact-studs of departure for the various groups.

page_text: instruments alone are movable elements. They comprise, for each register, a
transmitter working on the traces or imprints of the inscriber, at the departure
station, and, at the arrival station, the receiver furnishing, in advance of the
reproducer, and at the same time dispersing, by way of compensation, those traces
or imprints which work the reproducer, and through it, the correspondent's
telephone, or are even rendered directly perceptible to the hearing.
In each group, we have treated the line-instruments as exactly similar. The
only difference which actually exists in their mode of operation, if we limit
consideration to their displacement only, consists therein, that the one, the
transmitter, is moved, during its period of activity (or working phase), towards the
inscriber, whereas the other, the receiver, moves away from the reproducer, during
the same period or phase. In our exposition of the principle of this invention we
have already dwelt upon the fact-as indeed we have maintained throughout the
apparatus that a period of repose in each group, succeeds a period of activity,
and corresponds in point of duration with the total duration of the working phases
of the other groups.
It is evident, at first sight, that the working phase being alone active, it would
be possible, by a suitable arrangement of the line-instrument, of their electrical
connections, and of their registers, to dispense with the return phase, by passing
without interruption the same line-instruments from one group to the next following.
We have, however preferred to maintain, in our apparatus, the alternations of
working and repose for the line-instruments of each separate group. The following
is the mode in which are realized the changes in speed and direction of movement
which respectively characterize those two phases; the description of one register
applies to all the difference existing only in the actual position of the instrument
at any movement in each case.
In the diagram Figure 11 is represented the concordance in all the groups.
We have said previously, that the shaft X was actuated by the third shaft of
the Hughes' apparatus. The ratio of speed of the third to the fourth shaft being
equal to th, it follows that if the shaft X is to rotate at a speed equal to one-
third of the speed of shaft IV, on which the distributor is mounted, the ratio of the
diameter of the driving wheel to that of the wheel fixed on the shaft X must be
one-half. That shaft will, therefore, rotate twice as quickly as its driver, shaft IV,
but three times less quickly than the distributor. But as set forth in our exposition
of principle, we have also supposed that ratio of 3 to 1 to exist between the speed
of rotation of the distributor and that of the register. It follows therefore that the
latter will be driven by the shaft X without change of speed; the communication
between the two is effected by means of the pulleys Z1 Z2 and the auxiliary shaft x'
acting on the hollow gudgeons or shafts of each register. Parallel to the latter
and mounted on the shaft X are the following mechanical parts the internally-
toothed wheel A fixed on shaft X, and driving by means of pinion H the double
ratchet wheel J, with a speed four times greater than its own and rotating in the
opposite direction, consequently in a direction contrary to that of the register.
Further towards the front (Figs. 2 and 5) a disc 12 similarly mounted on shaft X
1s driven by the latter, by means of the circular or friction spring 21, whereof the
adhesion may be regulated at will. Towards the periphery of that disc and on
the same side of it as the ratchet wheel are mounted on one and the same pivot
two pawls 3 and 4'; with their springs. The extremity of these pawls is or may be
lifted by the pin 5 as shown in Figure 6, fixed on the auxiliary lever 6, whereof
the pivot 7 is on the prolongation of that of the pawls, and mounted on the opposite
side to the latter; the pin 5 connects the pawls during their rising and falling
movement when the lever 6 is in operation; but their fall, and the resulting
engagement, is not brought about under the same conditions. The double ratchet
wheel bas in fact its teeth inclined towards the side of the inscriber, but one series
alternating with the other; this arrangement enables us, as far as possible, to
secure an instantaneous engagement. The auxiliary lever 6 is operated by the
beak of the rod 8, which is pivotted in a bracket fixed to the disc 1, and of which

page_text: the lower part hangs parallel to that disc, with its forked end 9 jointed to the
collar 10 which it may displace in turning. On its face this collar carries a bent
finger 11 which, so soon as the collar is thrust forward, engages in a kind of
gallery 12, fixed on the support of the register. The other end of this gallery is
formed by a strong spring 25 (section g- Figure 5), in such manner that the bent
finger when engaged in the gallery encounters the spring, slides up its slope, and in
so doing sets it in action, and is thereby strongly driven back, at the point where
the flange which limits the gallery, terminates.
The section g Figure 5 shows this gallery which admits on the right hand side
the introduction of the finger 11 at the moment of the engagement, or forces the
finger out at the other end by the release and reaction of the spring 25 whereby
the mechanism is thrown out of gear the collar is immediately seized and with-
drawn by the bevel end of the detent 18 hereinafter described and the couple is
brought back by the frictional action of the disc 2¹ to the position in which the
next throwing into gear will take effect.
On the table of the apparatus, parallel to the shaft X, is situated the electro-
magnet of despatch or transmission E d. This is the element which, by its action,
brings about the change in direction and speed of the disc I', with which are
connected the line-instruments at the moment when a current emitted by the
distributor marks the commencement of the working phase. To that end, its
armature a pivotting on 6 carries obliquely a short lever arm 13, jointed at 9¹ to a
vertical rod 14 guided by the pin 15 and the fork 16. The upper extremity of
this vertical rod, which the spring 17 continually tends to thrust away from the
lever arm 13, carries a detent 18 with a bevelled end, and pivotted to the upright
arm 14 in such manner that it will yield, in one direction, to the pressure exercised
by the spring 19, but it resists any effort in the opposite direction. The flange of
the collar 10 comes in contact, at a given moment with this detent 18 and is held in
place thereby.
We know that the disc 1' must periodically change in speed and direction of
movement, since it carries or is connected with the line instruments. But, as the
arrows indicate the direction of rotation of the movable elements, it is easily seen
that the adherence of the spring, fixed on the shaft X, to that disc, will drive it in
the same direction of rotation and with the same speed as that shaft, and con-
sequently as the register. But for that it is necessary that the pin 5 should keep both
pawls lifted, leaving the double ratchet wheel free to turn idly. That pin will be and
remain uplifted (with the pawls) on the condition that the lever 8 and collar 10
are kept in close proximity to the disc I'. And it is the end of lever 8 which
maintains that position, notwithstanding the flexure of the springs and the action
of the pawls. This return driving movement, in the same direction and with
the same speed as the register is characteristic of the "return phase or period
of repose. The 66
working phase" will therefore correspond with the reverse
driving movement by the pawl engagement with the speed of 4, of the ratchet
wheel. This gearing is driven by the distributor. A local current arrives in the
electro-magnet of departure Ed; the vertical rod 14 is withdrawn by being
lowered, and the springs bring about the fall of the pawls and consequent throwing
into gear with the ratchet wheel. At the same time the bent finger 11 is engaged
in the gallery, where it shortly energizes the disengaging spring, which closes
the end of the gallery, and when it reaches the part where it is no longer
sustained by the gallery-flange, it is strongly repelled by the reaction of the
spring 25. This spring, by reason of the lever arm with which it is fitted, over-
comes the resistance offered by the pawl-springs, which are therefore again lifted.
Thereupon the collar 10 returns towards the disc I¹, passing the rod 14 by
displacing the detent 18 against the action of its spring 19. The reversed rotary
movement which ensues, brought about by the spring 2¹, once more brings the
bent finger 11 in contact with the front part of the projection forming the gallery 18,
and is there maintained until towards the end of its course, after moving over an
angle of about 90°. At this moment, only the detent 18 retains the collar.
It

page_text: will be seen that by this arrangement while the disengagement or commencement
of the period of repose or "return phase" invariably occurs at the same point, it
is not so with the engagement, or throwing into gear, this being dependent upon
the receipt of the departure current. The detent 18 alone holds back the collar 10,
from the moment that the bent finger has passed beyond that projection. The
collar 10 in the position of disengagement, separates the two springs 20 and 21,
which thus break the line-communication; but when the collar 10 is again pushed
forward, the springs re-make the contact and restore the line-communication until
the end of the working phase. In short, when driven by the spring 2', the disc 11
and the line-instruments are carried in the same direction and with the same speed
as the register; whereas the pawl engagement and gearing drives them in the
opposite direction and with quadruple speed.
The bracket 26 to which the armature as is pivotted, and which supports the
guide-pin 15, guide-fork 16, and the small block of ebonite or equivalent carrying
the two blade-springs 20 and 21, is mounted on the support S of the register-disc.
We have already explained under what conditions and at what moment the
departure current comes into action to animate in succession the electro-magnets of
each group; we now know how the working phase is established, from group to
group, at the same station (not forgetting, be it understood, the solution of
continuity caused by the presence of the correction-sector), and how these phases
are in absolute concordance with those of the corresponding station, owing to the
mode of correction, as herein before explained.
It remains to describe the device adopted for nullifying one cause of mechanical
derangement inherent in the nature of the movements and the mode employed for
their realization.
It is obvious that the displacements of the line-instruments-wbereof the speed
is at first the quadruple of that of the register, and the movement in the opposite
direction to that of the latter (if we consider first the "working phase"), and
subsequently, are changed, both speed and movement becoming identical with those
of the register, throughout the period of repose or "return phase "-must, apart
from the correction, have a duration equal to that of the displacement of the
movable distributing device. But, however quickly a pawl engagement may take
effect, or however perfect and powerful the adhesion of a driving spring, such
as 21, some slight retardation is inevitable at each change in the direction of rotary
motion, whether arising in the engagement of the pawl or in the prompt action
of the driving effect of the circular spring. This "slip," so to say, having for
the same parts always the same value, it would no doubt suffice simply to take
account of it, under ordinary circumstances; but that is not the case here, and
notwithstanding the insignificance of the errors arising in each revolution, those
errors would accumulate, and would not fail ultimately to destroy the concordance
shown in Figure 11. We obtain that compensation for the "slip" by cutting out,
from our electro-magnet of transmission a small resistance, which is made adjustable,
at a given moment: or rather, it is our disc I' connected with the line-instruments,
which itself brings about that suppression. This is effected by means of a roller
or equivalent (Figure 1) suitably located on the disc, which at the proper moment,
causes two springs K' and K³ (Figures 9 and 1) to make contact, and join up to
the electro-magnet a circuit of more feeble resistance, owing to the suppression
of rh. The question arises ;-How is this to be done?
Let it be assumed that the instruments are absolutely synchronous and the
correction nil. The effect of a retardation in the driving by the pawl engagement
and gearing would be equivalent to a slight correction by retrogression, .e. as if as
it were our instrument gained; inasmuch as the commencement of the return phase
being always the same, the length of the working phase, or in other words, the
amplitude of the arc to be traversed at the speed of 4, will be so much the greater
as the commencement of the movement has been delayed; the "slip therefore
tends to prolong the working phase. Correlatively the correction being always
assumed to be nil, not only is the return phase shortened, but also the subsequent
"

page_text: "
working phase, if the "slip" of the pawl does not exactly compensate for its
predecessor. In short, under all circumstances, at any given moment, the " slip'
owing to change in the direction of rotation will be translated into delay in the
working phase. The contrary effect producing itself reciprocally, we can arrive
at a means of compensation in either case. We have selected, as the index of
the "slip" the delay in the working phase, i.e. its prolongation; and we apply the
compensatory correction when the group of line organs moves too far from the
inscriber (or too near to the reproducer).
But as has been seen, the correction for concordance prolongs or shortens the
duration of the working phase; and the "slip" produces exactly similar effects,
though of a value excessively small, from one revolution to another. How are
we to distinguish between them? Let us, at the outset, say that the work of
compensation takes place within very restricted limits, allowing to remain none
but the smallest errors, to be attributed to "slip."
If now we mark on our disc I¹, in connection with the line-instruments, a zero
or index point, in such manner that, at the very moment when the working phase
commences, it coincides exactly with a fixed or starting point, the correction for
concordance and the "slip" being both nil, that index point will return to the
same point, at the given moment. But if there be default in one or the other, an
error will result. In order to distinguish between that part of the error which is
attributable to discordance, and that part which is due to "slip," it will suffice to
move the second fixed point, concentrically on the disc exactly the distance
corresponding to the value of the correction." Whatever error remains arises from
slip; and it is by means of the disc itself that we compensate for it.
To this end we provide a cam or crank pin j in some convenient and suitable
position on the disc I', (Figs. 1 and 9) and we make the movement of vertical
displacement of the adjustable plate-springs K2 and K³ dependent on that of the
correction devices. Under the action of the roller or equivalent; the springs are
brought into contact and join up the electro-magnet of transmission E d to a circuit
which has no resistance such as rh, thus diverting the current. The resistance r h
being adjustable as well as the springs K2 K3 it is obviously possible to compensate
for the error due to slip within extremely narrow limits. The amplitude of
movement of the line instruments will be greater or less than 96° according to the
direction of the correction i.e. the error of the speed; and also greater or less
than 96°, according to the value of the
"slip
of the mechanical devices
employed. The error in speed is corrected by contact being made on the
studs d¹ d² d³ d; and the compensation for "slip" is engrafted on the correction
proper, by means of the elimination from circuit of a small resistance, inserted in
the primary circuit of the electro-magnet. The errors which are compensated for
by this arrangement are too insignificant for the line-work to be injuriously
affected by the compensation being thus provided for.
"
Figures 1, 2, 6 and 6ter show how the springs are displaced, suitably as regards
direction and extent, by the momentary disconnection effected by the cam of the
corrector-wheel, with relation to its shaft.
The pulleys and O¹ are of equal diameters; by means of driving-belts F
and F they actuate respectively G and G₁; O drives G by a belt in tension,
while O drives G₁ by a slack belt which lightly encircles the small belt-tightener
or tension-roller td (Figure 6ter) pivotting on an axial point near the outer edge of
the distributor, shown at D (Figure 6ter) where it would entirely conceal the
pulley if it were completely represented. A small roller gt (Figures 6ter and 3)
fixed near the periphery of the pulley O is arranged so that it may press the
tension pulley td outwards when required and thereby slacker the driving belt
previously tight. G and G' are mounted on the ends of the shaft y, the
former (G) being fixed, the latter (G¹) being mounted on a screw-threaded
part (Figure 6), and maintained on the same point of the shaft, longitudinally, by
a spiral spring rb, being prolonged towards the left of Figure 6 by a short-
sleeve mh with a flange cl. The latter is held in the fork ƒh of lover e¹,

page_text: pivotting at pv on a suitable arm or prolongation of the standard carrying the
journal of the shaft y' and provided at its outer end with a pin or stud gp engaging
in an inclined or cam-groove hi formed in a suitable enlargement to on the shaft
whereby the latter is caused to pivot or turn in one direction or the other, as
indicated by the arrows, according to the lateral displacement, on the screwed
shaft y' of the pulley-nut G¹.
Thus the shaft n (Figs. 1 2 and 6) which corresponds in length to the entire
length of the apparatus of groups 1, 2, 3, and 4, displaces the four pairs of
springs K2 K³. In Figure 2 the shaft n alone is shown without its blade-
springs.
So long as the two last-named pulleys are driven at the same speed by the first-
named pair O and O¹, they are, so to speak, made one by that equality of speed,
and as if they were both keyed to the shaft. But so soon as any angular
displacement of O in relation to O¹ is produced, the driving speed being no longer
the same for G and G, the latter will be slightly displaced on the small shaft by
means of the screw-thread in its sleeve. This displacement is communicated to
the shaft n which commands the four series of compensating springs by the
intermediation of the small vertical lever e¹ and the part of the helix or cam
groove h¹.
The dimensions of the parts, the pitch of the screw thread in the
sleeve or nut G¹, of the cam-groove h' etc., are all calculated so as to give to the
displacement of the springs K' and K³ a convenient and suitable value. These
springs remain in their normal position until the moment of departure for the last
group occurs. Thereafter, the roller gt mounted upon the pulley O', by deflecting
the tension roller td, allows the belt F¹ to "skid" or slide momentarily on the
pulley G, which the before-mentioned spring rb promptly recalls to its former
position, imparting to it a slight rotary and lateral movement.
All the parts
resume their positions, ready for the next correction. This arrangement, analogous
to that which displaces the blade of the distributor, does not repeat the work of
the latter, but only, to speak supplements it and completes the effect.
INSTRUMENTS OF TELEPHONIC WORK.
The economy of our system exacts, as we have said, the use of a register which
shall also act as a suspense instrument.
The diverse transformations necessitated by the multiple system of transmission
have been set forth. The words spoken directly into the inscriber I or recording
telephone are registered on the phonographic band under the conditions of speed
that have also been indicated; the transmitter despatches them over the line; the
receiver collects them on arrival, and records them, as transmitted, on the phono-
graphic baud, whence the reproducer finally repeats them inversely, i.e., disperses
what has been condensed, and gives them forth at the normal rate of speed (the
speed of utterance) and makes them directly perceptible to the ordinary hearing.
The inscriber and reproducer are identical and consist, the former of a membrane
provided with a tracer-style, and the latter of a membrane attached to a blunt-
pointed style.
We make mention here, to make our explanation complete, of the possibility of
direct inscription and reproduction, by which we mean in this case the fact of
speaking into the inscriber or hearing from the reproducer, by the intermediation
of a pipe or tube, or of a combination of acoustic tubes.
We must dwell upon the special arrangement necessitated by one person desiring
to hold communication with another person at a distance from the multiple
apparatus, the latter being connected with the station by a telephonic circuit-a
much more general case. In such case the inscriber receives and registers; the
transmitter sends the currents over the line; the receiver takes them up on arrival
and transfers them to the register; the reproducer transmits them to the corre-
spondent.
Considering that the inscriber fulfils the functions of receiver, that the receiver

page_text: has also the duty of inscription; that the sole function of transmitter and reproducer
is to follow accurately the phonographic traces, it is easily seen that the pairs of
instruments are exactly identical.
INSTRUMENTS: THE RECEIVER AND INSCRIBER.
The inscriber, a local instrument-we call local instruments those which have
no connection with the main telephonic line-consists of a cylinder of preferably
ebonite of no great height, and a little smaller diameter than that of the register
(Figures 1 2 and 8).
Figure 8 represents a receiver which is analogous to the inscriber.
The latter
An
is divided internally by three parallel vibrating diaphragms, two of these a and 66
are active i.e., they vibrate under the direct action of the currents received.
electro-magnet (2) having its core polarized by the small permanent magnet (m¹)
is attached to the diaphragm 66 and ends at a little distance away from a². Parallel
to the latter, and fixed by means of a collar-fastening and rubber rings, is the
aluminium diaphragm O' with concentric corrugations. This diaphragm carries, at
its centre the steel style t' formed as shown in the drawing (Figure 8) and fixed in
such manner that its point impresses the phonographic substance at an acute angle,
and not at right angles to the surface. A cross-piece, forming almost a full
diameter, carries a hemispherical stud, designed to slide over the band of the
register and nullify all defects in centreing the same by ensuring a constant depth
of penetration of the style. Further the inscribing cylinder is placed vertically
or nearly so and fixed to a fork on one of the branches of which it may turn.
inscriber is fixed in front of the plane of transmission and situated to the right of
the median line of the register supposing it to be viewed from the front.
The
This apparatus is represented in Figures 1, 2 and 12 at 1, 12, etc.; its centreing
cam is shown at c m² (Figure 2).
The wire connections are omitted for simplicity sake; they can easily be imagined
by referring to the general diagram of communications (Figure 9).
The receiver is identical with the inscriber; its case is of aluminium and it
carries a crosspiece with a hemispherical stud or cam. It is carried by the disc to
which it is attached by a forked bracket F¹ of which the pivots are arranged on
the chord of an arc, not on a full diameter, and in such manner as to put the
instrument in tension during working. A spring, ensures penetration. Such a
receiver is represented in Figure 8, which shows its rear-diaphragm 6 with the
polarised electro-magnets e² and their magnet m' the front diaphragm a' and the
corrugated receiving diaphragm O' with its inscribing style t¹.
That cam
The arrangement of the drawing does not permit of the cam being shown which
is intended to remedy any defect in centreing the recording disc.
appears in Figure 2 at cm.
INSTRUMENTS: THE TRANSMITTER AND REPRODUCER.
These instruments are not provided with vibrating diaphragms; they are
identically alike, (Figure 1A). Two blades, the first 1', thick and broad, the
second 2 flexible and slender, are fixed in almost parallel positions by means of a
They
set-screw 3. Their distance apart is regulated by the adjusting screw 41.
are electrically insulated by the ebonite or equivalent pivot 5, which is fixed to
the forked bracket of the receiver or on the support S of the register.
1.
The front part of the blade I', is bent round, so as to return upon itself, and at
the inner side of the return-end is a small enlargement having a sharp edge, on
which is mounted, by means of two small springs (Figure 1^) forming one a
prolongation of the other, the piece 6'1, provided with three projections, whereof
the point 71, is preferably of ivory.
The seat or focus of the variations of conductivity determined by the ridges and
coding trace is in fact the carbon tablet ch;
1.11
L

page_text: interpolated with the blades 11, and 2¹, (Figure 1^) into a primary circuit of an
induction coil, it produces therein the same effects as the tablet in the Edison
microphone.
1
It has been considered unnecessary and useless to complicate the general
drawings of the entire apparatus by introducing the communicating wires. The
upper part of 6', composed of the two projections 8, and 9₁₁ is of metal. A sharp
edged projection on the piece 6', makes a flush joint with that of the blade 1', so
that the blade-springs only serve as pivots of oscillation and prevent lateral
distortion. The projection 91, is surmounted by a small carbon pellet and the
projection 81, by a small disc of ebonite or equivalent, insulating the latter from
the spring 2. The two blades 1, 2, represent respectively the two poles of the
battery, and the connection is made by the carbon pellet.
Lastly the cam 10¹, remedies any defect of centreing in the register. The form
of the piece 6', with its three projections 7, 8 and 9, enables us to follow the
working. The point 7 follows the inequalities of the trace, while the adhesion of
the spring varies accordingly in one direction, on the carbon pellet, and the
projection 81 exaggerates the variations of pressure on 9₁₁. These variations of
pressure determine changes of resistance in the primary circuits and, correlatively,
of the induced currents in the secondary induction coils.
The transmitter, by the method of its mounting on the fork fo of the receiver,
and its two pivot screws vi and vi¹, may correspond in operation with the
inscriber; in the same manner as the reproducer may correspond in working with
the receiver.
These are the instruments employed for the telephonic working properly
so-called.
CORRELATION OF THE PRACTICAL APPLICATIONS WITH THE THEORETICAL
DEVELOPMENT OF THE DIFFERENT PARTS EMPLOYED IN THE ENTIRE
APPARATUS.
In an urban telephonic system the different private or public apparatus are
connected together either at a central station where communications are established
as required and called for, or at several central stations, each serving a separate
district and themselves in connection by circuits with each other.
Between two towns the telephonic circuit connects the two chief central stations
with the two secondary stations. This is the kind of interurban circuit for which
our apparatus is designed to provide the means of enabling it to be utilised
simultaneously by four couples of interlocutors; whereas, under existing arrange-
ments and conditions no more than one couple can be put in communication, at the
same time, by a telephonic circuit.
We premise by observing that the word "circuit" must be understood to mean
and include any case in which earth is utilised as in telegraphy, just as well as any
case where the circuit is throughout metallic, whether it be in interurban com-
munication or in intercommunication between urban sections or districts, where the
circuits put the private or public instruments in connection with their respective
district centres or chief centres.
In our diagram of communications, Figure 9, we have supposed the circuit
to be entirely metallic, which is a matter of indifference as regards the general
working.
Our apparatus is placed at each of the central stations which are the points of
departure of the interurban lines. (We refer here solely to the interurban circuits,
the construction and working of which are costly; although we may employ the
system for an urban section, but with less advantage.)
At CA (Figure 17)-the central office, say, of Brussels-is one of our
apparatus; at CB-the central office, say, of Antwerp-is another. A, B, C, D are
four apparatus distributed at Brussels which may be in communication and corre-
spondence simultaneously with A', B, C, D₁, at Antwerp, each group or

page_text: It
couple A A, B B', preserving its complete independence, and, in fact, each
pair or group of operators being entirely ignorant of the fact that the
circuit CA, 1, C B, 2, is utilised by other groups at the same moment.
must be understood that the central stations C A, C B, may reserve the use or
place of one of the groups for the purpose of holding converse with each other,
in which case the series of groups A A', etc., is reduced to three in number,
CA, C B constituting the fourth, but without effect on the general working.
Here we have a general combination. But others are possible. Thus A night
be elsewhere than at Brussels, provided only that he or it be connected in
telephonic circuit with central CA. Similarly B might not be at Antwerp,
subject to the same condition in relation to central C B, etc. Fig. 17 represents
the most simple case, that of 4 entirely independent groups. Fig. 18 represents
the other, riz. on the supposition that centrals C A and C B have at their disposal
one place in combination. Moreover, therein is also represented a first corre-
spondent or interlocutor A not at Brussels but at Mons, for example in
communication with A' at Antwerp; a second B at Brussels in communication
with B', not at Antwerp but elsewhere, for instance at St. Nicolas; and a third C
at Brussels, in communication with C at Antwerp.
Here we have, practically, all the combinations possible. But in all these cases,
the one and only circuit, utilised in multiple, is the single chief-circuit, 1-2,
connecting CA with C B, for our apparatus is indivisible; it is located at CA
and at C B, and, starting from those two points, the sections B-C A, C-C A,
C B-A', C B-C', or the circuits A-CA (Mons-Brussels) and CB-B¹
(Antwerp-St. Nicolas), are all treated in precisely the same way; that is to say,
that the modifications introduced in the regime of the electrical vibrations or
undulations, due to the simple telephonic work, by our multiple arrangement exist
solely between our two apparatus on the line CA, 1, CB, 2; and that beyond C A,
as well as beyond C B, the telephonic work becomes simple, and naturally the
same on the supplementary circuits A-C A, C B-B¹, as on the urban
sections B-C A, C B-A', etc.
We will here confine our study of the mode of putting the apparatus into use
to the simplest case, Fig. 17. We will also eliminate from consideration the case
where, while employing an inscriber without electrical organs, i.e. formed of a
simple diaphragm and style, and of a reproducer also formed of a diaphragm and
soft-pointed tracer, both instruments being provided with an acoustic pipe, the
respective correspondents would be obliged to speak or to listen at or at least
close by our apparatus, for which purpose they must of necessity go to the
central station where the apparatus is installed, whereby the advantages of its use
would be considerably diminished. We need, only, therefore, here mention such
possible cases.
We will now describe the simple case (Fig. 17);—
Let it be supposed that the four public or private apparatus (Fig. 9) are united
with the central station by an entirely metallic telephonic circuit. In this diagram
of the communications, a double line separates those of the apparatus from those
of the four others I, II, III, IV, as well as these the one from the other, as
shown in the lower part of the drawing (Fig. 9); these others being at any four
places in the town, or even in the district of some other central station. Dotted
lines separate the corresponding communications which are identical in each of the
four groups I, II, III, IV, and also separate therefrom the part which
comprises the distributor, which belongs to none of the groups but affects them all.
Further, to make the diagram more general, the particular movement has been
selected, when the line communication is not at the service of any one of the
groups, by reason of the contact being broken with all the coupled blade-
springs 20-21-a moment which corresponds with the reception of the corrector-
current, as has been seen. On the other side of the line all is exactly
symmetrical.
The apparatus having been set in operation by the depression of the hand-

page_text: brake FR (Fig. 2) which is copied from the Hughes apparatus, if it is arranged
that the corrector current is to be transmitted, the key d³ (Fig. 9 central or
distributor section) is pushed to the right, against a', while L', is shifted over to
the left, against a8; at the other station d' being shifted over to the left, against b*,
and L', remaining insulated in order that it may not receive the corrector current,
i.e. a relatively intense current, in telephonic apparatus. This key is only shifted
over, against a when the correspondent is satisfied that the current sent to him
arrives properly upon the corrector contact piece. The description herein before
given explains in detail how to proceed in order to impart to the dispatch contact
of the corrector C the suitable advance upon the reception-contact of the corre-
spondent, i.e. in order to suitably adjust the said contact C.
So much being said in relation to the distributor, we know under what conditions
the circuit of the local dispatch battery is closed by the passage of the couple
brushes successively over the oblique contacts di d² d³ d" to set in action the
first despatching electro-magnet, by way of d¹, 40, 41, 42, the second by way of d³,
43, 44, 45, and so on for the 3rd and 4th groups.
A modification is brought about in the course of the work in this circuit by the
approximation of the springs K' K³. The cause and signification of that approxi-
mation have already been explained. This contact establishes at 42, 45, 48, 50 an
alternative route for the current from the battery, which of course follows
proportionately the line of least resistance i.e., K2 K³, and actuates the corre-
sponding electro-magnet a little sooner. The resistance rh moreover is adjustable
in both these circuits.
Such is the local electric work of our apparatus; it appertains solely to the
correction, as will be seen, and to the despatch of the movable instruments
(coupled transmitter-receiver) of each group.
The apparatus being set in action, and no correspondent having as yet demanded
communication, the double keys B₁₁ are still insulated. Their function is at the
opportune moment to close the primary circuits of the telephonic batteries p m and
pml. These local circuits are closed in the group assigned to the correspondent
on the receipt of his call.
Let it be supposed that the subscriber marked III' on our diagram desires to
His call
telephone on the line or circuit on which our apparatus is at work.
having reached the central station of the district, the latter is put in communi-
cation with him in the ordinary way and the central station at the end of the line
is advised; then each central station advises its own subscriber that he is put in
communication with his interlocutor, which is done by assigning to them group III¹
by switching on the keys B' and B₁₁.
1°
Conversation can then take place between this couple or group of corre-
spondents.
Let it be supposed that, in our diagram III' represents the corresponding
communication, commencing with the first speaker, whose apparatus, by a carbon
pencil mi mounted on two small blocks of the same material, and making part of
the primary circuit of its own battery pm, gives rise, in the primary wire of its
own induction coil, to induced currents which are transmitted along the line in the
direction of the central station and through receiver and sounder Te appropriated to
the other member of this couple.
It may be useful to make a digression here in order to explain the part played
by the double-wire induction coils, shown in our diagram at G¹ and G₁₁ in each
group. One of these coils is connected with the receiver and the principal line;
the other with the inscriber and the urban circuit. In the circuit between two
telephonic apparatus singly connected, there is, as is well-known, firstly the
secondary wire of the induction-coil (whereof the primary forms part of a distinct
circuit), the instrument or instruments, and the line wire; and, secondly, at the
other station the instrument or instruments, identical with the first-named, the
secondary wire, and the return line wire (or earth). The two stations being
symmetrical, when either of them, by speaking into the instrument determines the

page_text: formation of induced currents, these latter traversing its own instrument as well as
that of the corresponding station, the speaker might be sensible of the transmission
in his own telephone, were it not that the sense of hearing is so absolutely
confounded with that of speech, and with the sounds issuing from the mouth, that
all perception of their simultaneous reproduction, almost exactly coincident, would
be lost. That, however, would be no source of trouble, because the act of speech
and its transmission as pointed out, are instantaneously associated.
But, in our multiple apparatus, it is not the same; consequently, we have
introduced an arrangement, whereby the transmitter, while operative, is prevented
from reacting upon the receiving instrument at its own station, so as to avoid what
might otherwise occur, viz. the confusion arising from the vibrations being
recorded anew on its register, which render the work of communication quite
impossible. Thus the induced currents from the transmitter would annihilate each
other in the receiver at the outset, intended as they are solely for the receiver at
the corresponding group at the other station. For the same reason, therefore the
reproducer must operate without having any analogous effect upon its own receiver.
We will now resume with the course of our currents. We left the corre-
spondent III' speaking into his microphone (m i). His induced currents, entering
in the group III, which is assigned to him, reach us by 60 or 61 (contact B₁
Figure 9) according to their direction. Arrived at the secondary coil S₁, they pass
through it, and reach the point 62, where two alternative routes divide; the
currents thence passing on the one hand, through the inscriber I³, returning by 63
and 60, and on the other, through the rheostat R and the other secondary coil,
and subsequently by the route 63, 60.
But, to annihilate the induced currents in the inscriber 13, when the reproducer R p³
is operative, it has been necessary to make the resistance at R¹ equal that of the
double line 60, 61, augmented by that of the secondary coils s d and of the hearing
instrument of the subscriber. In the shunt R-S¹ the current is much more
feeble than in that in S₁₁, 62, 13 and 63; thus that part of the current which passes
through this latter section tends to induce the coil S¹, and the currents so
engendered supplement it so as to strengthen the effect in the inscriber.
Our currents thus actuate the inscriber, a stationary instrument, under which the
phonographic strip is unwound. Its diaphragms are caused to vibrate in the magnetic
field of its electro-magnets e2 Figure 8 this figure representing the receiver, which
is identical internally with the inscriber. The correspondent III' may speak
When the
continuously. The phonographic strip moves away from the inscriber.
local current arrives by the oblique contact-stud d bringing the electro-magnet Ed
into operation, and the engagement of the two line instruments, the transmitter and
receiver, and at the same time the contact of the blade-springs 20 and 21 which
establishes communication between the line 1¹ and induction coil G¹, dependent on
the receiver r c³, the transmitter t³ rapidly passes over the sector on which the
imprints are traced which the inscriber is throughout continually engaged in
producing. Its ivory point 71 (Figures 14 and 9) for the relief of the trace and
brings about corresponding variations of pressure between the carbon plate ch
(Figure 1) and the spring 24, variations which are exaggerated or intensified by
the projection mounted on 84 (Figure 1A). The current originating in the
telephonic line battery p m, traversing the closed circuit m, 65, 66, 21, 1'₁,
passing along the primary wire 66, 67 of the coil G³, undergoes, in consequence,
variations of intensity corresponding with the variations of pressure and con-
sequently of electrical resistance engendered by the carbon plate c h (Figure 14).
The induced currents engendered in the coil G¹ will pass along the line 11, 2¹; but
they must, at the same time, be annihilated in the receiver c³. This is effected
in the following manner ;-
Let it be supposed that the induced currents in the secondary coil 68, 69 traverse
the receiver in the direction 69, r c³, 70, and rejoin line 21 at 71; those of the
secondary coil 70, 72 pass through the receiver in the opposite direction, by 70, r c³,
69, r', ', and annul the opposite currents just referred to. For that purpose, it

page_text: R R¹
K+K
has been necessary to give to the rheostat, r³, h², a resistance equal to that of the
lines 1, 2, augmented by that of a secondary coil at the other station, as well as
by that of the shunt at 70 calculated by the formula
in which formula R
and R respectively represent the resistance of the two shunts. In this condition
the receiver is silent in the couple where the transmitter is at work.
.
The induced currents pass through the line modified as to their frequency by the
movement impressed on the transmitter in the opposite direction to the register.
At the corresponding station, the line currents reach the receiver under the saine
conditions. To the induced currents arriving by the line 2' a duplicate course is
presented at 70; what has been said previously in relation to the inscriber will
serve to show how the line of least resistance, re³, 69, 68, 20, 21 and 1, on which
the receiver is placed, receives the greater part of the current, and how the coil
with the greatest resistance serves to intensify its effects.
The receiver vibrates exactly in consonance with the inscriber and like the latter,
produces imprints on the phonographic band or strip; only, being movable, an
being at a distance from the reproducer while it is at work, it is in advance of the
latter that it disperses or expands the imprints, spacing them at normal intervals,
that is to say producing the inverse and correlative effects of the transmitter.
The work of these line instruments is thus terminated for this group III', and
for the single revolution of the distributor under consideration; it will recommence
at the next current emitted from the despatching electro-magnet and will deal with
the adjacent following sector covered with imprints.
It is
The last work is done by the reproducer R p³; this is a further local work.
We have left our receiver restoring the normal spacing between the traces.
under these conditions that the said traces or imprints move forward to the
reproducer, a fixed instrument. This works like the transmitter, not on the main-
line, however, but only on the district circuit which connects with the corresponding
subscriber of our III.
1*
For the reasons previously specified, its induced currents must be annihilated in
the inscriber. Its microphonic battery is shown at p m l, its ivory point at 71,
It will be observed that in the diagram absolute accuracy in the position of some
of the instruments has been sacrificed for the sake of clearness, as in the case of the
switches, springs, etc.
We
e may remark in conclusion that there is nothing that differentiates the
induction coils employed from those in common use. The secondary wire is only
double, and the effects strengthened by a bundle of soft-iron wire introduced as a
core in the primary coil.
"
"
It will be observed that in the description, we have established the "solidarity
or unity of the line-instruments. We do so advisedly. The "orientation or
synchronous adjustment of the receiving instruments is indispensable. In telephony
this cause of trouble may safely be neglected, if the distributor rotates at a low
speed. It would suffice, nevertheless, if a high speed were desired, though
otherwise profitless, to arrange for "orientation " or adjustment in the following
manner; we know that, in reality the necessity is shown by a retardation in the
commencement as well as in the end of the working phase of the receiver; the
duration of that phase remaining, in other respects, the same, and dependent only
on the correction.
"
or adjustment of the receiving
It would suffice therefore for the "orientation
instrument c;
1. To add to the distributor or a small interior crown or ring, four other contact-
studs of despatch, formed obliquely in the same manner as those of the existing
crown P¹, but made movable, and otherwise serving the same purpose;
2. To make the interval between the contact studs of each crown correspond
with an angle exceeding the fifth part of the circumference and taking the excess
from the part allotted to the sector of correction, which would in no way modify
the movements of the line instruments.

page_text: 3. To arrange for another method of disconnecting gear for the receiver, and
make a corresponding change in the gallery so-called, which determines the end
of the working-phase,--a modification which only needs to be referred to here,
without being dwelt upon.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is ;-
1. In apparatus for the purpose described a distributor comprising a number of
sectors equal to the number of corresponding groups or couples (working sectors)
plus one which last is appropriated to the correction of the brush-carrier upon which
distributor a single contact-stud marks the entrance into each working sector the
contact-studs purely local in action being intended to place the line successively in
relation with the various groups of correspondents without the telephonic currents
traversing the said distributor substantially as described.
2. In apparatus such as described oblique contact-studs by which the work of
correction can be accomplished and of which the obliquity increases from the first
onwards in order to correspond in this manner with the different values of the
discrepancy or error arisen in the interval between two successive corrections
between the brush-carriers of the two stations of each group or couple of interlocutors
the said obliquity however having its cause only at the station where the correction
is made substantially as described.
3. In apparatus such as described a brush or contact such as 6 which passes over
contact-studs such as d' d' da d' and of which the displacement takes place under
the influence of the retarding or accelerating action of a corrector-cam such as 7 on
the wheel M at the moment of engagement of the said cam between two teeth of the
wheel M the device which brings about contact or engagement between the friction
cones w and W (ie., which throws them into gear) being caused to change and so,
by the intermediation of a short shaft 30 the eccentric e and frame c² causing the
displacement of the said brush & the device throwing into gear the cone w, which
drives the brush ' and the cone W which is mounted on the driving-shaft IV of
the apparatus, remains the same as long as no disengagement occurs between the
said shaft IV and the sleeve L together with the sleeve of the brush-carrier the
adhesion or friction between the said cones being secured by the ascent of
the projections on the ramp or inclined plane and continuing until the said
projections drops into the notch ex which takes place a short time before the next
following correction substantially as described and illustrated in the accompanying
drawings.
4. In apparatus such as described a device whereby a mode of adjustment is
secured that is to say the advance of the contact of despatch of the corrector-current
obtained (a) by the utilization of the complete metallic circuit for the battery-
current which serves to make the correction without any return to earth; (b) by
the establishment on one of the poles of the battery of correction of a permanent
shunt to earth through an attesting telephone Tt that pole of the contrary
sign (positive or negative) to that which is connected to the correction contact-
piece C; (c) by the use, at the station where the correction is made of a Hughes
electro-magnet which permits by its action of the line in communication with a
contact such as L₁ being put to earth so that the shunt temporarily established at
the correcting station through the attesting telephone Tt shall only be traversed by
a current at the moment when the electro-maguet at the station where the
correction is made is energised the said moment being exactly determined at the
correcting station by the displacement of two contacts mounted on the permanent
derivation or shunt t¹² substantially as described and illustrated in the accom-
panying drawings.
5. A type of telephonic apparatus called receiver-inscriber consisting of an
aluminium diaphragm with concentric corrugations carrying a style or inscribing

page_text: point and vibrating under the influence of two other diaphragms whereof one
-carries the electro-magnet substantially as described.
6. A type of telephonic apparatus called transmitter-reproducer wherein a piece
with two projections in the form of a U provided with a smooth ivory or equivalent
point or tracer intended to follow the phonographic outline pivots in its own plane
between two metallic blades the first of the said projections made of an insulating
substance further accentuating the work of the second projection which carrying a
-carbon tablet constitutes an electric conductor with variable resistance substantially
as described.
7. In apparatus such as described a transmitter connected with a receiver by
being secured to the communicating fork fo of the latter with means of regulation
such as the screws viv the receiver being mounted on a bracket F¹ by the
intermediary fork fo which acts by drawing upon it during its operative period the
lateral regulation being assured by the screws of the said fork and the penetration
by the blade-spring r¹ substantially as described and illustrated in the accompanying
drawings.
8. In apparatus such as described a disc on which are fixed the line-instruments
transmitter and receiver and provided with pawls which serve to unite it firmly in
one direction with ratchet-wheels; the said disc being subjected permanently
to the friction of an adjustable disc which causes it to rotate in the opposite
direction to that of the said ratchet-wheels the rotation caused by the said pawls
overcoming, when in action the friction of the disc and corresponding with the
working phase of the instrument during which the disc which carries the phono-
graphic band or strip rotates constantly in the opposite direction to the ratchet-
wheels and consequently opposite to the motion of the line instruments substantially
as described and illustrated in the accompanying drawings.
Dated this 21st day of March 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicants.