IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to Henry Harris Lake of the firm of Haseltine, Lake,
& Co Patent Agents, Southampton Buildings, London for an Invention of
"IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC
APPARATUS communicated to him from abroad by Francois van Ryssel-
berghe of Schaerbeck in the Kingdom of Belgium
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 24th July 1883.
HENRY HARRIS LAKE of the firm of Haseltine Lake & Co. Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC AND TELEPHONIC APPARATUS" [A communication to him from abroad
by Francois van Rysselberghe of Schaerbeck in the Kingdom of Belgium]
This invention relates to a system of Duplex telegraphy or of simultaneous
telegraphy and telephony, which system is based upon the two following principles,
that is to say :-
First When sudden currents are caused to pass through a telegraphic wire
(currents for example which are produced by putting the said wire in direct
communication with a battery by means of a Morse manipulator), a telephone,
intercalated either directly or by means of a branch in the circuit of this wire or an
adjacent parallel wire, produces an intense sound at each emission and at each
interruption of the current, which proves that, at the commencement and at the
end of each emission, the electric flow is intermittent; because, if it was continuous
and regular, the membrane or diaphragm in the telephone would merely yield
but not vibrate. But if, instead of sending sudden currents gradual currents are
sent, that is to say, currents which, at each emission, increase in intensity gradually
up to a constant maximum, afterwards decreasing gradually until they are entirely
or partially extinct, the membrane or diaphragm in the telephone merely yields
without vibrating and therefore produces no more sound on the passage of the
current, or it produces a very feeble sound, which proves that, in this case, the
electric flow is no more intermittent but sensibly continuous.
•

page_text: Second Let C¹ C² (See Figure 1) be two condensers of slight capacity (a
quarter of a microfarad is sufficient) established in derived or branch circuits at
the extremities A and B of a telegraph wire and respectively connected to a
telephone transmitter T2 and to a telephone receiver T'; and let R¹ and R² be two
. other derived or branch circuits (but direct ones, that is to say, without any
condensers being inserted) the resistance of which is not less than five hundred
(500) Ohms. The derived or branch circuits R¹ R² may then be suppressed or
established during the telephonic conversation without any diminution being
perceived in the intensity of the sounds received by the telephone, and this being
still the case when the telephone receiver has a resistance greater than two thousand
(2000) ohms. If, therefore in Figure 1 R' and R2 are two telegraphic installations
employing gradual currents their working cannot in any manner obstruct the
operation of the telephone, and vice versa the installation of this telephone does
not interfere with the telegraph, as the currents used for the latter cannot branch
off through the condensers. Two distinct services can thus be established entirely
independent of each other but capable of being operated by a single wire.
According to a previous invention based upon the principles hereinbefore
mentioned, a system of, simultaneous telegraphy and telephony was obtained in
which the telegraph and telephone stations were entirely independent of each
other, and in which only ono telegraph wire was used for the establishment of
each telephonic communication. But this simultaneity of transmission, the two
services being mutually independent, may also be obtained (always by the
application of the principles above enumerated) when the double wire is employed
for each telephonic cominunication, in order to completely avoid the effects of
induction.
I will describe some arrangements for carrying out the system of simultaneous
telegraphy and telephony by means of two parallel wires.
First arrangement in which each double wire system furnishes a telephonic
communication and a single telegraphic communication. Let L1 L2 (Figure 2) be
two parallel wires. Let A1, A2, A3, be three electro magnets of about 500 ohins ;
the two first occupying the two sides of a Wheatstone bridge; the third being
interposed between the battery P and the manipulator M. Let R be the receiver
of a telegraphic installation M R P. Let C¹ C be two condensers of about half a
microfarad intercalated with a telephonic installation T upon the diagonal P Q of
the Wheatstone bridge. Finally let S be a suitable resistance placed either upon
one of the two lines, or upon one of the sides of the two lines, or upon one of the
sides of the said bridge, or upon each of the two lines. By properly regulating the
resistance S, the points P and Q can always be maintained at the same potential
for all currents emitted at M, or for all currents of equal intensity sent in the same
direction, and at the same time, upon the two lines L¹ and L². The telephone T
will then neither be influenced by the telegraphic currents nor by the induction
currents acting simultaneously upon the two lines L' and L2. But the telephonic
connection will be made by the double wire as if the telephonic installation alone
existed. It is not indispensable but it is useful that A1, A2 and A³ should be
electro-magnets, they may simply be resistances, each of about 500 ohms. L' may
be an artificial line being reduced to a simple resistance S connected on the one
hand to the point Q and on the other hand to the earth. Thus a telephonic
communication and a telegraphic communication are obtained by means of a single
wire L¹.
Second arrangement in which each double wire system furnishes one telephonic
communication and two telegraphic communications. Let L¹ and L³ (Figure 3) be
two parallel wires, let M R¹ A¹ P¹ and M² R² A² P² be two telegraphic
installations similar to that above described in the first arrangement with this
supplementary condition that the resistance of the receivers R must be equal to
the sum of the resistances of A and P. Let P, Q be a connection between the two
wires L' L² and including the condensers C¹ C³ of half a microfarad at the most,

page_text: with a telephonic installation T. Finally let S be a suitable resistance placed upon
one of the two wires or upon each of them.
In the present case it is indispensable that A1 and A2 should be electro-magnets,
of a resistance of about a thousand ohms, which render the telegraphic currents
gradual and consequently imperceptible to the telephone. And by properly
regulating the resistance S, the telephonic conversation may take place without
inconvenience at the same time that ordinary telegrams are transmitted by the
wires L' and L%
In order to more perfectly graduate the telegraphic currents, the telegraph
stations may be arranged in the manner shown in Figure 4 which only differs
from the arrangement shewn in the preceding figures by the addition of a
condenser C connecting the battery terminal of the manipulator with the line
terminal, in order to ensure the better discharge of the graduating electro-
magnet, A.
Instead of using a telephonic installation T of any description (Figures 2 and 3)
intercalated in the connection P Q the telephonic installation shewn in Figure 5
may, with great advantage, be employed in the arrangement shewn in Figure 2,
and especially in the arrangement shewn in Figure 3. In this case C¹ and C³ are
two condensers of about half a microfarad. B is the secondary wire of the
induction coil of the microphone. S is.a suitable resistance and T is the telephone
receiver characterised by this fact that its coil is composed of two circuits of equal
resistance wound parallel with each other and connected in such a manner as to
form a differential receiver. These two circuits are represented in Figure 5, one
by a full line and the other by a dotted line. The telephonic currents then
circulate exclusively through the circuit represented by the full line through the
coil B and the line L¹, at the same time that the induced currents exist on the
line L. Whilst equal induced currents arising by the line L2 pass through the
resistance S and the circuit represented by the dotted line in order to annul in
the telephone the induced currents of the line L¹. Instead of a real telephone T
with differential double circuit, the following arrangement (Figure 6) may be
employed. L1 and L2 are two parallel telegraph lines, C¹ and C2 two condensers
of about half a microfarad each, and S is a suitable resistance placed either upon
B is
the connection P, Q, or upon one of the two lines, or upon each of the same.
an induction coil with three circuits that is to say. First, two primary differential
circuits represented one by a thick black line and the other by a dotted line.
Second, a secondary circuit represented by a fine line, one end of which is
connected with the earth, the other end being connected with a single wire L³
leading to the telephone station where an ordinary telephonic installation of any
description is arranged
The separation of the telephonic currents from the telegraphic currents is then
effected by induction by. means of the coil B and of the condensers C1 and C2 and
the necessity for employing a special differential receiver at the telephonic station
is obviated; the ordinary receivers may be used.
The arrangement shown in Figure 7 may also be employed on the connection
PQ-C C are two condensers of about half a microfarad. B1 B2 are two similar
induction coils each composed of two wires wound parallel to each other and side
by side throughout their whole length.
To indicate how these wires should be connected to each other as well as to the
different parts of the circuit, I will designate respectively by E¹ S₁ e¹ 8¹ the
entrance and departure ends of the first and second wires of the coil B¹ and by
E2, S2, e, s², the entrance and departure ends of the first and second wires of the
coil B² In this arrangement it is necessary to put E¹ in communication with the
line L' by means of the condenser C¹.
S2 in communication with the line L2 by means of the condenser C³.
el e in communication with the single branch which leads towards the
installation T, and S¹, 81, E2 82 in communication with the earth

page_text: It might be possible to unite the two, coils B¹ B² preserving the same electrical
connections.
Third arrangement in which each double conductor furnishes two telegraphic
communications and one telephonic communication. This arrangement is shown
in Figure 8 in which like letters indicate the same instruments as in the
preceding Figures. The only condition to be fulfilled as regards the value of the
resistance is that.
.
S¹ x *L³ S2 x 'L¹
-
and it will be sufficient to fulfil the said condition approximately providing S¹
and S are electro magnets instead of simple resistances.
Any of the telephonic installations shewn in Figures 5 and 6 may be placed
upon the connection P¹ Q¹
Fourth arrangement
In the above described arrangements it is assumed that the two.telegraph
wires constituting the double conductor, terminate at the two places between
which the telephone is established, but this is not indispensable Let L', L³
(Figure 9) be two telegraph wires connected with telegraphic installations of any
description origin and destination, but parallel between the places O and V. These
places will be in telephonic communication by means of the arrangement shewn in
Figure 9 in which A', A2, A3, A4, are electro-magnets. of at least 500 ohms;
C1, C2, C3, C4, C5, C6, C7, C8, are condensers of half a microfarad, and T1 T2 two
telephonic stations of any description, or the telephonic installations shewn in
Figures 5 and 6.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Patent Office on the 24th January
1884.
HENRY HARRIS LAKE of the firm of Haseltine, Lake, & Co, Patent Agents,
Southampton Buildings, London " IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC AND TELEPHONIC APPARATUS."-A communication to me from abroad
by Francois van Rysselberghe, of Schaerbeck, in the Kingdom of Belgium
This invention relates to an improved method or system of duplex telegraphy or
of simultaneous telegraphy and telephony.
This method or system is based upon the two following principles, which have
been discovered by the inventor, that is to say :-
First. When sudden currents are caused to pass through a telegraph wire
(currents for example which are obtained by putting the said wire in direct
communication with a battery by means of a Morse manipulator) a telephone
intercalated, either directly; or by means of a derived or branch circuit, in the
circuit of this wire or an adjacent parallel wire, produces at each emission, and at
each interruption, of the current an intense sound, which proves that at the
commencement and at the end of each emission, the electric flow is intermittent ;
because, if it was continuous and regular, the membrane or diaphragm of the
telephone would simply yield and not vibrate. But if, instead of sudden currents,
gradual currents are caused to pass through the wire, that is to say; currents
which at each emission gradually increase in intensity up to a constant maximum
and afterwards gradually decrease until they are entirely or partially extinct, then
the membrane or diaphragm of the telephone merely yields without vibrating and,
therefore, no longer produces sound on the passage of the current, or it produces a
very feeble sound, which proves that in this case the electric flow is no longer
intermittent but perceptibly continuous.
Second. Let C1, C2 Figure 1 be two condensers of slight capacity (a quarter of
a microfarad is sufficient) placed in derived or branch circuits at the extremities A
and B of a telegraph wire and respectively connected to a telephone transmitter T²
and to a telephone receiver T¹; and let R' and R2 be two other derived or
branch circuits) but direct, that is to say, without any condensers interposed), the
resistance of which is not less than five hundred (500) ohms. The derived or
branch circuits R¹, R2 may then be suppressed and established, during the
telephonic conversation, without any diminution being perceived in the intensity
of the sounds received by the telephone, and this is still the case when the
telephone receiver has a resistance greater than two thousand (2000) ohms. If,
therefore, in Figure 1, R¹ and R2 are two telegraphic installations employing
gradual currents, their working cannot in any manner obstruct the operation of
the telephone, and vice versa the telephonic installation does not in any manner
interfere with the telegraph, since the currents used for the latter cannot branch
off through the condensers. Two distinct services can thus be obtained entirely
independent of each other, but capable of being operated by a single wire.
In the specification of former Letters Patent dated May 24th A.D. 1882, N° 2466,
will be found details of installations permitting, in accordance with the second
principle herein before mentioned, a system of simultaneous telegraphy and
telephony to be obtained wherein the telegraph and telephone stations are entirely
independent of each other.
In the said former specification it was assumed that, for each telephonic
communication to be established, only one telegraph wire. was used. But this,
3

page_text: simultaneity of transmission with mutual independence of the two services may also
be obtained (always by the application of the principles above enumerated), when
the double wire is employed for each telephonic communication in order to
completely avoid the effects of induction.
In the present specification I will indicate some arrangements for carrying out
the system of simultaneous telegraphy and telephony by means of two parallel
wires.
First arrangement in which each double wire system furnishes a telephonic
communication and a single telegraphic communication. Let L1, L2 (Figure 2) be
two parallel wires. Let A1, A2, A³ be three electro-magnets of about 500 ohms.
the two first occupying the two sides of a Wheatstone bridge; the third being
interposed between the battery P and the manipulator M. Let R be the receiver
of a telegraphic installation M. R. P. Let C¹, C² be two condensers of about half a
microfarad, intercalated, with a telephonic installation T, upon the diagonal P Q
of the Wheatstone bridge. And let S be a suitable resistance placed either upon
one of the two-lines, or upon one of the sides of the said bridge, or upon each of
the two lines. By properly regulating the resistance S, the points P and Q can
always be maintained at the same potential for all currents emitted at M, or for
all currents of equal intensity sent in the same direction and at the same time
through the two lines L' and L. The telephone T will then neither be influenced
by the telegraphic currents nor by the induction currents acting simultaneously
upon the two lines L' and L. But the telephonic connection will be made by the
double wire as if the telephonic installation alone existed. It is not indispensable
that A1, A2 and A³ should be electro-magnets, they may simply be resistances, each
of about 500 ohms. L² may be an artificial line being reduced to a simple
resistance S connected on the one hand to the point Q and on the other hand to
the earth. Thus a telephonic communication and a telegraphic communication are
obtained by means of a single wire L
Second arrangement in which each double wire system furnishes one telephonic
communication and two telegraphic communications. Let L' and L² (Figure 3) be
two parallel wires. Let M1, R, A¹, P' and M2, R2, A2, P² be two telegraphic
installations similar to that above described with reference to the first
arrangement, with this supplementary condition, that the resistance of the
receivers R must be equal to the sum of the resistances of A and P. Let P Q be
a connection between the two wires L1, L2 and including two condensers C¹, C
of half a microfarad at the most, with a telephonic installation T. And let S be a
suitable resistance placed upon one of the two wires or upon each of them.
In the present case it is indispensable that A¹ and A should be electro-magnets
of a resistance of about a. thousand ohms, which will render the telegraphic
currents gradual and consequently imperceptible to the telephone. And by
properly regulating the resistance S the telephonic conversation may take place
without inconvenience, at the same time that ordinary telegrams are transmitted
by the wires L' and L².
In order to more perfectly graduate the telegraphic currents, the telegraph.
stations may be arranged in the manner shewn in Figure 4, which only differs
from the arrangement shewn in the preceding figures by the addition of a
condenser C connecting the battery terminal of the manipulator with the line
terminal, in order to more effectually ensure the discharge of the graduating.
eléctro-magnet A.
For the same purpose, the arrangement shewn in Figure 4a may be employed,
wherein A¹ is an electro-magnet of about 500 ohms, placed between the battery
and the manipulator M; A' is an electro-magnet of about 500 ohms intercalated in
the line at the point of departure; and. C is a condenser of about two microfarads
placed in a derived circuit on the line between the two electro-magnets.
Instead of a telephonic installation T, Figures 2 and 3, intercalated in the connection
P, Q, the telephonic installation shewn in Figure 5 may with great advantage be.
employed in the arrangement shewn in Figure 2, and especially in the arrangement

page_text: shewn in Figure 3. In Figure 5, C¹, and C² are two condensers of about half a
microfarad, B is the secondary wire of the induction coil of the microphone. S is
a suitable resistance, and T is the telephone receiver characterized by this fact,
that its coil is composed of two circuits of equal resistance wound parallel with
each other and connected in such a manner as to form a differential receiver.
These two circuits are represented in Figure 5, one by a full line and the other by
a dotted line. The telephonic currents then circulate exclusively through the
circuit represented by the full line, through the coil B and the line L', at the same
time that the induced currents exist on the line L¹, whilst the equal induced
currents arriving by the line L2 pass through the resistance S and the circuit
represented by the dotted line in order to annul in the telephone the induced
currents of the line L'. Instead of a real telephone T with a differential double
circuit, the following arrangement (Figure 6) may be employed. L' and L² are
two parallel telegraph lines; C¹, C2 two condensers of about half a microfarad
and $ a suitable resistance placed either upon the connection P Q, or upon one
of the two lines, or upon each of the same. B is an induction coil with three
circuits, that is to say :-Two primary differential circuits represented one by a
thick black line and the other by a dotted line; and a secondary circuit represented
by a fine line, one end of which is connected with the earth, the other end being
connected with a single wire L³ extending to the telephone station where an
ordinary telephonic installation T of any description is arranged.
'
The separation of the telephonic currents from the telegraphic currents is then
effected by induction by the coil B and condensers C³, C² simultaneously, and the
necessity for employing a special differential receiver at the telephonic station is
obviated, the ordinary receivers being adapted for use in this case.
The arrangement shewn in Figure 7 may, if desired, be employed on the
connection P, Q. In this figure, C1, C2 are two condensers of about half a
microfarad; B1, B2 are similar induction coils each composed of two wires wound
parallel to each other and side by side throughout their length. To shew how
these wires should be connected to each other and to the different parts of the
circuit, I will designate respectively by the letters E¹, S¹, e', s¹, the points of ingress
and egress of the primary and secondary wires of the coil B¹, and by the
letters E, S, e², s, the points of ingress and egress of the primary and secondary
wires of the coil B². E must be put in communication with the line L¹, by the
medium of the condenser C¹; S2 in communication with the line L2 by the medium
of the condenser C²; e¹, e² in communication with the single branch leading to the
telephonic installation T; and S¹, s¹, E2, 82 in communication with the earth. It is
possible to form the two coils B1, B2 into a single coil, whilst preserving the same
electrical connections, as shewn in Figure 7, wherein the same letters indicate
parts corresponding to those in the preceding figures, except that B1, B2, B³ form a
single induction coil having a single secondary circuit B³ and two 'similar primary
circuits B, B². This induction coil may be advantageously constructed as shewn
in Figure 7b, that is to say:-N is a core of soft iron upon which is. wound the
secondary circuit B³; over this secondary coil and capable of sliding thereon, are
two similar primary coils B₁ and B². The latter can readily be caused to exert an
equivalent action upon B³, by giving them a suitable position relatively to B³.
T, T1, T2 L and L2 are terminals for making the following connections, viz :-
T with the telephonic station; T¹ and T with the earth; L' and L2 with the two
lines by the medium of the condensers C and C³, Figure 7.
Third arrangement in which each double conductor furnishes two telegraphic
communications and one telephonic communication. This arrangement is shewn in
Figure 8, in which like letters indicate the same parts as in the preceding figures.
The only condition to be fulfilled as regards the value of the resistances is that
S¹× LS × L¹
and it will be sufficient to fulfil the said condition approximately providing S₁

page_text: installations shown in Figures 5, 6, 7 and 7ª may be placed upon the con-
nection P¹ Q¹.
Fourth arrangement.
In the above described arrangements it is assumed that the two telegraph wires
constituting the double conductor terminate at the two places between which the
telephone is to be used, but this is not indispensable. Let L', L2 (Figure 9) be two
telegraph wires connected with telegraphic installations of any description, origin
and destination, but parallel between the places O and V. These places will be in
telephonic communication by means of the arrangement shewn in Figure 9, in
which A', A2, A3, A* are electro-magnets of at least 500 ohms; C1, C³, 0³, 0, 0³,
C, C7, Os are condensers of half a microfarad, and T¹, T2 two telephonic stations of
any description, for example, the telephonic installations shewn in Figures 5, 6, 7
and 7ª.
Having thus fully described the said invention as communicated to me by my
foreign correspondent and the manner of performing the same I wish it understood
that I claim :-
First. The above described method or system of simultaneous telegraphy and
telephony by means of two parallel wires in order to completely avoid the effects of
induction and to permit the transmission of telephonic messages by means of
telegraph lines, the simultaneity of transmission being obtained with a mutual
independence of the two services.
Second. The above described peculiar arrangements of apparatus commonly used
in telegraphy and telephony, comprising the electro-magnets, the condensers and
the induction coils, the electro-magnets serving to render the telegraphic currents
imperceptible to the telephone, and the condensers and induction coils serving to
separate the telephonic currents from the telegraphic currents.
Third. An induction coil with three circuits, that is to say, a double, differential
primary circuit and a single secondary circuit, substantially as, and for the purpose,
set forth.
Fourth. The employment of two induction coils with two wires wound parallel
to each other side by side throughout their length and connected substantially as,
and for the purpose, set forth.
Fifth. The construction of the triple circuit induction coil, described in the third
claiming clause, in the manner shewn in Figure 7b to permit the adjustment of
the primary circuits so as to ensure an equivalent action upon the secondary
circuit.
In witness whereof I the said Henry Harris Lake have hereunto set my hand
and seal this Twenty fourth day of January in the year of Our Lord one thousand
eight hundred and eighty four.