Improvements in or relating to Multiple Telegraphy.
Year: 1893

page_text: Date of Application, 24th Aug., 1893-Accepted, 13th Jan., 1894
COMPLETE SPECIFICATION.
Improvements in or relating to Multiple Telegraphy.
I, ALFRED PIEDFORT, of Rue Gambetta 14, Arras (Pas de Calais) in the
Republic of France, Chemist and Electrician, 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 present invention relates to a mechanical arrangement to be called
"auto-distributor for telegraphs" by means of which it is possible to send at one
and the same time more than eighty telegraphic communications either in the same
direction or in opposite directions through a single wire each communication going
straight to its destination without stopping anywhere or becoming mixed up with
any of the others.
The invention relates to the application of the following principles in conformity
with the laws of Helmholtz on resonance.
A body the vibratory movement of which is dependent on an electric current,
(1) begins to vibrate as soon as the current at any point of the circuit is
influenced by another vibrating body which is in unison with the first one,
(2) remains silent when the current at any point of the circuit is influenced by
another vibrating body not in unison with the first one,
(3) remains silent when the current in its circuit comes under the influence of
any number of vibrating bodies none of which emit the same sound as the first one.
The resultant of these modifications in the current caused by the various vibrating
bodies may here be considered as a number of forces in equilibrium relatively to
the body to be vibrated, the various effects are not in harmony and reduce one
another almost to zero.
If to these vibrating bodies (not in unison with the first one) is added a sound
which is in unison with the first body the latter sound will act immediately and as
if alone upon the first body and cause it to vibrate.
These are the principles forming the basis of the said "auto-distributing
telegraph" by means of which I can simultaneously send a great number of
telegraphic communications through a single wire either in one direction or in
opposite directions.
In connection with the construction of the apparatus for transmitting telegraphic
messages I ordinarily make use of the "Morse" alphabet. But in any case each
transmitter is adapted to communicate at each contact to the line wire not a
continuous current of a certain duration but rather an undulatory current answering
to a definite pitch of musical sound which is different for each transmitter.
Although the transmitters send their messages through the one wire so that the
said messages become mixed up together they become again separated into as many
messages as have been sent off by the transmitters as soon as they arrive at the
receivers of the auto-distributing telegraph where each message is distributed on
to the receiver for which it was intended.
The accompanying drawings show a complete installation for multiple telegraphy
according to my system.
Sheet I shows an installation of a station comprising one simple transmitter and
one simple receiver.
Sheet II shows a complete installation of the "auto-distributing telegraph
apparatus" comprising a compound receiver connected either to a series of simple
transmitters or to a single compound transmitter.
In the drawings like letters indicate like or corresponding parts.
The transmitter shown on Sheet I consists of a tuning fork D of a certain pitch

page_text: one of the prongs d of which is provided with a contact screw or surface h adapted
to vibrate in unison with the said tuning fork D in consequence of which the
current in the wire z becomes interrupted at each vibration. The tuning fork D
is vibrated as soon as a message is sent, and the vibration is kept up by means of
an electro-magnet i for instance or by any other suitable means.
The line wire communicates at each end with an ordinary transmitter M
through wires t t with a tuning fork D through wires z 2' and with a resistance F
through wires y y¹.
This resistance F consists of a preferably carbon block f" held between two
clamps and the clamp f being adapted to be adjusted on the carbon block in
such a manner as to either increase or diminish the resistance to the current.
The result from this arrangement is that the current from the line wire passes
under ordinary circumstances almost entirely through the wires and and not
through the wire y' and resistance F.
5
Moreover as long as the key of the transmitter M forms contact at m¹ the
interruptions of the current produced by the fork D during its vibration, through
the contact screw h have no influence whatever on the line x, but as soon as the
contact at m' is broken by the depression of the key m of the transmitter M the
passage of the line-current is interrupted on the wire tt as long as the key m is
kept down, and the current being also interrupted on the wires zz at each vibration
of the tuning fork D, is obliged to pass through the wires y y' and resistance F
and thereby the vibrations from D are transmitted to the wire of the main line a
during the whole time the key m is depressed.
By a suitable regulation of the proportions of the resistance of F and the wire
and the resistances of the wires and z by variations in the diameters of those wires,
respectively, I am enabled to obtain characteristic and excessively sensitive
pulsations in the line wire a.
This system enables at least eighty transmitting forks D to be connected up at
various parts to the main line so as to connect eighty stations all by one single
wire on condition however that the various tuning forks have each a different
pitch.
The "self induction" is zero and it is easy to calculate the amount of resistance
of F and the strength of the current through according to the required results.
This may be more clearly understood by studying Figure 2. In the table the
numbers 1 to 9 represent the various transmitting forks and the thick horizontal
lines indicate the extent of the vibrations during the passage of the current through
the wire z. The zigzag line ww' indicates the resultant of the undulatory vibra-
tions which the various fork transmitters 1 to 9 impart to the current of the main
line, the transmitters being supposed to be operated all at the same time.
The simple receiver which I have constructed with a view of rendering it as
sensitive as possible consists in a tuning fork D¹ having between its prongs d an
electro-magnet i. A small electro-magnet i¹ is quite sufficient to set a strong fork
vibrating. On account of the small diameter of the core of the electro-magnet ¹
the vibrations produced are thoroughly distinct and as the winding of the electro-
magnetic coil is only short all self induction is avoided, which therefore enables
more than eighty receiving forks to be connected to a single wire and consequently
enables eighty messages to be received at one and the same time.
Each receiving fork D' is in unison with the corresponding transmitting fork D.
The extremities of the prongs d of the fork D' (Figs. 1 and 3) are each provided
with a thin plate of glass or other transparent material. These plates PP' are
arranged parallel to each other in the plane of the vibrations and as close to each
other as possible without being in contact or without striking against the opposite
prong d of the fork D. Each of the plates P P is divided into narrow strips
alternately transparent and opaque.
The respective strips on the two plates are arranged parallel and in such a
manner that a transparent strip of the one plate comes always opposite an opaque
strip of the other plate.

page_text: The fork D¹ with its plates or screens P P₁ is placed between two lenses n n
(Fig. 3) having respectively a focus u and j. At the focus u is placed a luminous
body while at the focus j is placed, close behind a screen j¹ provided with a slot or
hole in the direction of the focal axis of the lenses a roller or roll of sensitized
paper hereinafter referred to by the letter j.
When the fork D' is not vibrating the light shining from the point u passes
through the lens and a number of parallel rays fall onto the first plate P. The
light which traverses the transparent fields of this plate is intercepted by the opaque
fields of the second plate P₁ so that thereby the light from the source u is prevented
from affecting the sensitized paper roller j. But at the slightest vibratory move-
ment of the fork D¹ the opaque strips or fields of both plates P P become displaced
so as to bring the transparent fields of the said two plates P P¹ more or less into
line and allow the light from the source u to pass through and print on the
sensitized paper on the roll ; which latter at the same time unrolls the paper strip
very slowly.
The vibrations of the fork D¹ produce as it were a series of rays of light which
are more or less extended as indicated in Figure 4.
Sometimes it may be advantageous to connect two acoustic tubes to the fork D'
in such a manner that while one end of the said tube is in contact with the prongs
of the fork D the other end is directed towards the ear of the attendant so as to
enable him to audibly receive the message.
The simple receiver being extremely sensitive is exceedingly well adapted for
use for long distances and especially for submarine telegraphy.
In order to draw the attention of the employé at the receiving station the sender
of the message holds the button m of the key on the transmitter depressed for a
few moments which then causes the receiving fork D' at the other office to vibrate
strongly which thereby strikes against the point k and causes the armature p to
make contact with the electro-magnet 7 where it is retained by means of the
hook for the purpose of causing a call bell E to ring.
In connection with submarine telegraphy I preferably employ a "Melloni
battery" in place of the sensitized paper roll (Figure 3). As soon as the
plates P P begin to vibrate the heat from the luminous body u passes through the
said plates so as to cause the pointer of a galvanometer connected to the Melloni
battery to move and strike against a contact stop when the current operates an
ordinary bell.
"
Sheet II. The compound receiver A which I prefer to call the "auto-distributor
consists mainly of a straight electro-magnet a (but if desired a horse-shoe magnet
may be employed) in the vicinity of one of the poles of which is one prong of each
of several tuning forks D' having each a different musical pitch. The electro-
magnet a may be made to act on different forms and groupings of forks D' placed
round it without at all affecting the principle.
In the arrangement shown in the drawing a circular cast iron table c is provided
with say ten copper supports e e¹ &c. for supporting ten forks D1 D2 D3 &c. It is
clear that any other number may be chosen equally as well. The supports e are of
variable height and are made solid enough to prevent the vibrations of any one of
the forks from being communicated to the others and it is therefore that I give the
name of "isolators to the supports e.
The number of forks is equal to the number of telegrams to be sent at one aud
the same time.
It is also possible to utilize both poles of the electro-magnet for the purpose of
grouping a double number of forks round them. Each of the forks Di &c. must
always be tuned to the same pitch as the corresponding fork D of the transmitter.
The electro-magnet a is here constructed in the form of a column supporting a
truncated conical head of a larger diameter than that of the said column. The
truncated cone is made hollow so as to weigh less and the winding of the electro-
magnet is arranged in such a manner as to produce the most intense magnetic field
at its effective part. The forks D' are made as far as possible of small dimensions

page_text: so as to reduce the inertia and because a small magnetic field is less costly to
provide for than a large one of the same intensity.
In the auto-distributor each receiving fork D₁ begins to vibrate as soon as there
is passed through the line x a current the pulsations or interruptions of which
correspond with the vibrations of said fork D¹. The same fork D¹ remains silent
when the current is interrupted by a transmitting fork out of unison with it.
The same if the current is affected simultaneously by three or a greater number
of vibrating forks the three or more corresponding forks and these only will be
vibrated. The vibrations are quite instantaneous and the transmission of the
message is just as rapid as in the ordinary "Morse" telegraph.
In the arrangement adopted for the compound receiver I place close to the end
of each fork D¹ a small pendulum p or pl adapted to be adjusted so as to increase
or decrease the oscillatory movement imparted to it by the fork D¹. The point of
suspension of the pendulum p or pl is insulated from the compound receiver which
latter is connected to the earth while the pendulum is connected by a wire z to a
Morse receiver R and to a battery S for operating it.
When the battery S is connected up the vibrations of the fork D' cause the
extremity o' of the pendulum p¹ to vibrate which vibrations, although not
suppressing entirely the current of the Morse receiver R are strong enough to
prevent the electro-magnet from attracting the armature. The lever of the
armature therefore drops at each vibration of the fork D' and is again raised when
the vibrations cease.
In order to print the telegraphic communication on the paper strips I pass the
latter (from the roller on which it is wound) below the lever lin such a manner as to
receive the printed signs whenever the electro-magnet does not attract the armature
i.e. during the vibrations of D' corresponding to those of the transmitter D. Before
receiving a message it is necessary to establish the current through the Morse
receiver R by means of a commutator for instance.
The auto-distributor operating in conjunction with a series of forks D arranged
near the key M at the transmitting station may be adapted to print the telegrams
without the use of a Morse receiver. For this purpose each fork D' &c. of the
compound receiver is provided with a pencil or style the point of which slides
over the paper strip s' which is slowly moved along.
Figure 6 shows a telegram indicating the word "Paris" obtained by means of
the foregoing apparatus.
In order to call the attention of the operator at the receiving station I connect a
call bell to the auto-distributor A. This is done in the following manner; a strip
of soft iron o² is fixed to the extremity o of the pendulum p. If now the fork d is
kept vibrating the above soft iron strip o² strikes against and makes the necessary
contact with the pole of the electro-magnet g to animate the latter. A small
hook g' keeps the iron strip o² in contact with the pole of the electro-magnet q and
thereby causes the bell g³ to ring continuously.
The compound transmitter to be used in stations where several telegraphists are
employed consists in uniting all the wires coming from the various transmitting
forks D of the stations Nos. 1, 2, 3, 4, &c. (Sheet II Fig. 5). These wires
constitute the primary wire y of an induction coil B placed in the transmitting
station. The induced or secondary winding of the coil B passes onto the line and
into the electro-magnet a of the compound receiver or into the receiving fork D¹
(Sheet I) of a single receiver.
In order to lessen the resistance in the line a where a great number of receiving
forks D¹ (Sheet I) are connected to it, I propose to connect the electro-magnet i
which is attached to the prongs of the fork D' so that it may vibrate in unison with
the transmitting fork D, with a secondary circuit of an induction coil L in which
the wire of the line a forms the primary circuit.
The operation for sending messages is as follows ;-
1. Each operator in a single post-office (Sheet I) vibrates the transmitting fork D
through the influence of an electro-magnet i during the whole time he sends the

page_text: message by depressing the key m of the transmitter M for a longer or shorter time..
In this manner he can send along the line an undulatory current of a longer or
shorter duration which current goes straight to the particular station where a
receiving fork D¹ is alone capable of vibrating in unison with the transmitting
fork D.
2. In stations where several employés are in charge each employé having his own
transmitting fork D (Sheet II) of a certain musical pitch the fork is kept vibrating
through the influence of the electro-magnet i during the whole time it takes to send
the message. By depressing the key m of the transmitter M for a longer or
shorter time an undulatory current of a longer or shorter duration is sent along
the line & the interruptions of which current correspond with the vibrations of the
fork D.
As all the forks D at each station (Sheet 2 Fig. 5) are connected to the primary
wire of an induction coil B (at the transmitting office) the secondary circuit of
which coil is connected to the line wire r the result of this arrangement is that
the various messages sent at one time by the employés from their own apparatus at
one and the same station run along the same line and pass each into the particular
receiving office provided with the fork D' which alone is capable of vibrating in
unison with the fork D through which the particular message has been sent.
The
receiving station may either be fitted with a single receiver as shown in Fig. 1 or
with compound receiver as shown in Sheet 2, Fig. 5.
The number of messages which may be sent in this manner at one time through
a single wire is very great; the mass or the inertia of the receiving fork D' being
very great relatively to the small electro-magnet there is no tendency of the
fork D to vibrate except under the influence of a current which is rigorously
isochronous with its own normal vibrations. I have found by experience that with
a difference of only eight vibrations the current leaves the fork unaffected. It is
obvious therefore that starting with do³ (being 512 single vibrations per second) the
number of forks used will be considerable as it only requires a difference of
eight vibrations between each.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is;-
1. In a multiple telegraphic system the combination of a normal fork such as D
fitted with an electro-magnet i between its prongs for the purpose of vibrating the
latter a resistance and a transmitter M these three apparatus being suitably
connected on both sides to the line wire in such manner as to modify the current
in the line according to the vibrations of the fork D each transmitting fork D
having a particular musical pitch so as to form an undulatory current along the line
which can only be received at the receiving station whose fork D' is adapted to
vibrate in unison with the transmitting fork D, substantially as described and
illustrated in the accompanying drawings.
2. In a multiple telegraphic system a receiving fork D' for printing telegraphic
messages having fixed to its prongs closely together two thin parallel plates P P¹
divided into narrow alternately transparent and opaque strips but arranged in
opposition on the plates in such a manner as to intercept the passage of the
luminous or calorific rays coming from a source u placed in the focus of a lens n
when the fork D' is not vibrating while the rays from the source u are enabled to
pass through the said plates at the moment of vibration and proportional to the
amplitude and the duration of the vibrations of the plates for the purpose of
affecting (in lines of correspondingly greater or less length) a moving strip of
sensitized paper placed at the focus of a lens n' the said moving strip of sensitized
paper being used instead of the ordinary roll of paper in the Morse receiver
substantially as described and illustrated in the accompanying drawings.
3. In a multiple telegraphic system a receiving fork Di the prongs of which are
provided each with a thin plate P and P¹ respectively having alternately transparent

page_text: and opaque strips arranged on said plates. to oppose each other when the fork is
not vibrating but disclosing a source of heat u as soon as the fork begins to vibrate
the rays of heat from the source u being adapted to act on a Melloni battery placed
at j for the purpose of moving the pointer of an ordinary galvanometer and thereby
draw the attention of the attendant at the receiving station substantially as described
and illustrated in the accompanying drawings.
i
4. A system of multiple telegraphy through a single wire comprising in each
station a transmitting fork D adapted to vibrate through the action of an electro-
magnet placed between the prongs of the fork which latter is connected to an
ordinary transmitter M for the purpose of transforming the constant current
generated by a suitable source of electricity S into an undulatory current corre-
sponding to a predetermined musical pitch of the fork D the undulatory current
passing through a single line a into a compound receiver provided with a number
of forks D' which correspond to those at the transmitting station to which they
are connected the forks being arranged around the pole of an electro-magnet a
substantially as described and illustrated in Figure 5 of the accompanying.
drawings.
5. In a system of multiple telegraphy through a single line the employment of
an auto-distributor consisting of a series of forks each of which has a predetermined
but particular musical pitch which varies for each station the wire connections of
the various transmitting forks belonging to one station being arranged so as to form
the primary winding of an induction coil B the secondary winding of which passes
onto the line and to the electromagnet a of the compound receiver or to the
receiving fork at a single station substantially as described and illustrated in
Figure 5 of the accompanying drawings.
6. The combination and arrangement of parts constituting the complete multiple
telegraphic apparatus substantially as described and illustrated in Figure 1 of the
accompanying drawings.
7. The combination and arrangement of parts constituting the complete multiple
telegraphic apparatus substantially as described and illustrated in Figure 5 of the
accompanying drawings.
Dated this 24th day of August 1893.