Improvements in Automatic Repetition on Telegraph Cable and other Lines.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Automatic Repetition on Telegraph Cable and
other Lines.
We, HERBERT ARNAUD TAYLOR, M.I.C.E., and JOSEPH ARTHUR LOVEL
DEARLOVE, Electrical Engineer, both of 4 Great Winchester Street, in the
City of London, do hereby declare the nature of this invention to be as follows:-
-
On a submarine telegraph line consisting of two or more sections of cable, it
has up to the present time been found impracticable, when the sections exceed a
few hundred miles in length to "repeat" or "translate" the signals from one
section to another by means of relays on account of the low speed of transmission
attainable by this method.
By the usual practice the signals received by means of the syphon recorder on
one section are retransmitted on the next by a clerk, such re-transmission
obviously increasing the chance of error and limiting the speed to that of hand
sending.
The unsuitability of relays arises from the character of the arrival current on a
cable circuit worked at syphon recorder speed, for if a succession of impulses of
equal strength and duration and of the same polarity is applied to one end of a
cable, the first impulse may be quite competent to carry the tongue of the relay
at the other end against its "marking stop" " but instead of breaking contact
between the impulses as it should do to simulate the original sending, the tongue
remains against the stop because the variation in the strength of the received
current is too small to allow the tongue to fall away during the interval of time
between the impulses.
On the other hand when the polarity of the current sent to line is reversed, the
tongue of the relay responds readily and is carried by the current against the
opposite stop.
"
Thus if the current impulses sent into the cable and corresponding with the
symbol for "understand are represented by Figure 1 of the drawing annexed
the current at the receiving end of the line would, under the conditions supposed,
be represented nearly by Figure 2 from which it is obvious that the relay at the
intermediate station could only send into the second section of the line, three
At the
impulses of unequal duration, instead of five impulses of equal duration.
receiving end of the second section the signals would be hopelessly distorted.
We propose to counteract this failure on the part of the relay to respond to
repeated current impulses of like polarity and to take advantage of its greater
sensitiveness to reversals as follows:-
The signals at the originating station are sent into the line by means of an
automatic transmitter working at a constant speed.
The receiving instrument at the intermediate station consists of a compound
polarized relay, or of a pair of single polarized relays, in circuit with a device we
shall call a synchronous repeater by means of which the missing beats or impulses
are reproduced and the correct sequence of impulses applied to the second section
of the line.
We shall assume that a pair of relays are used. The synchronous repeater
consists in effect of an insulated contact lever which by a suitable train of

page_text: clockwork is caused to oscillate between a pair of contact stops one of which is
spoken of as the "earth" stop and the other as the "live" stop.
The speed of the clockwork is adjustable so as to oscillate the contact lever at
the same rate as the contact levers of the automatic transmitter at the originating
station and the lever of the repeater is also kept "in step" with the movements of
the tongues of the relays by means of an electromagnetic governor controlled by
the relays.
The said contact lever is in electrical connection with the second section of the
line, the "earth" stop is of course connected with earth, aud the "live" stop is
joined up in such a manner with the local circuits of the receiving relays and with
the line battery that its polarity is positive, negative or neutral according to the
positions of the relay tongues.
Thus to retransmit the symbol "understand" the action of the relays and of the
synchronous repeater would be as follows:-
When the first impulse reaches the receiving end of the first section, the tongue
of the "dot" relay moves on to its "marking" stop and remains on it during the
period corresponding with the first three dots of the symbol, joining, say, the
positive pole of the line battery with the "live" stop of the repeater.
Simultaneously with the movement of the relay tongue the contact lever moves
onto its "live" stop and transmits a positive impulse to line the lever is then
moved against the "earth" stop, back again to the "live" stop and so on. When
three positive current impulses have been sent to line and the end of the line has
been three times "put to earth," as required, the
19
dash relay comes into
action and connects the "live" stop of the repeater with the negative pole of
the line battery so that a negative impulse is sent by the contact lever into
the line.
Finally the last "dot" of the symbol is sent in the same manner as the first,
and the live stop of the repeater is then put to earth or insulated by the relays so
that the contact lever may continue to oscillate without sending any impulses into
the line until the arrival of the next signal on the relay.
Dated this 11th day of June 1895.
H. A. TAYLOR.
J. A. L. DEARLOVE.
Improvements in Automatic Repetition on Telegraph Cable and
other Lines.
We, HERBERT ARNAUD TAYLOR, M.I.C.E., and JOSEPH ARTHUR LOVEL
DEARLOVE, Electrical Engineer, both of 4 Great Winchester Street, in the City
of London, 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 :-
"
On a submarine telegraph line consisting of two or more sections of cable, it has
up to the present time been found impracticable, when the sections exceed a few
hundred miles in length to "repeat or "translate" the signals from one section
to another by means of relays on account of the low speed of transmission
attainable by this method.
By the usual practice the signals received by means of the syphon recorder on
one section are retransmitted on the next by a clerk, such re-transmission
obviously increasing the chance of error and limiting the speed to that of hand
sending.
The unsuitability of relays arises from the character of the arrival current on a
cable circuit worked at syphon recorder speed, for if a succession of impulses of

page_text: the contact lever may continue to oscillate without sending any impulses into the
line until the arrival of the next signal on the relay.
In order that our invention may be fully understood and readily carried into
effect we will proceed to describe the drawings annexed.
Figures 1 and 2 have been already explained.
Figure is a diagram illustrating the general arrangement of apparatus in
accordance with our invention.
Figure 4 is an end elevation of a portion of this apparatus and Figure 4ª shows
some of the parts separately.
Figure 5 illustrates another method for carrying out our invention.
On the left hand side of Figure 3 T shows an automatic transmitter at the
originating station. Such au instrument as is shown in our Specification 20807**
is suitable. This transmitter sends electrical impulses at a uniform speed into one
end of the cable line L₁.
These impulses are governed so as to correspond with the message required to
be sent by means of a punched paper tape.
At the receiving end of the line L₁ are two sensitive polarized relays, one,
say R, brought into action by negative currents and the other, say R₁ by positive
currents.
The local circuits of these relays may be joined up, as shown, so that a movement
of the tongue of R₁ onto its contact stop C, causes a negative impulse to be
transmitted from the relay-battery to the wire W the positive pole of the battery
being to earth at E, and, similarly, a movement of the tongue of R, on to its
contact stop C, transmits a positive impulse to the wire W.
Between the pole of the battery and the contact stops C, C, is placed an
additional relay R, preferably of low resistance not exceeding 20 ohms. This
relay works with every current that flows from the relay battery into the
wire W.
The function of the relay R, is explained later on.
The electric impulses are not allowed to pass directly from the wire W into the
cable line La for as already explained the relay tongues R, and R, will not be able
to follow every movement of the contact levers of the transmitter T but whilst
several successive contacts are made by one of these levers the corresponding relay
tongue will hang against its contact stop C₂ and will continue to do so until it is
thrown off by a reversal of the current in L. During each of these dwells of the
relay tongues separate electrical impulses have to be sent into the second cable
line L, in order that the condition at the sending end of this cable may correspond
to that at the sending end of the cable L₁. To do this the following apparatus is
employed:
Two cams n and n₁, are mounted on an arbor s caused to revolve by means of a
train of clockwork or by an electro motor at a uniform speed which should be the
same as that at which the corresponding part of the transmitter at the originating
station revolves.
These cams control the movements of the lever 1, which once in every revolution
of the cam axle is caused by the intermediate levers ii, and their springs and
pushing needles jji to pass from the stop d₁ to d and back to d. The lever is
made to press, by means of the jockey roller and spring, upon the stop against
which it is placed by the pushing needles.
The relative duration of the contact on either contact stop is regulated by the
relative position of the cams n, n'.
The automatically repeating lever is connected with the cable line L, the
upper contact stop d is connected with the wire W and the lower contact stop d₁
with earth which is indicated by the letter E.

page_text: equal strength and duration and of the same polarity is applied to one end of a
cable, the first impulse may be quite competent to carry the tongue of the relay
at the other end against its "marking stop " but instead of breaking contact
between the impulses as it should do to simulate the original sending, the tongue
remains against the stop because the variation in the strength of the received
current is too small to allow the tongue to fall away during the interval of time
between the impulses.
On the other hand when the polarity of the current sent to line is reversed the
tongue of the relay responds readily and is carried by the current against the
opposite stop.
Thus if the current impulses sent into the cable and corresponding with the
symbol for "understand" are represented by Figure 1 of the drawing annexed
the current at the receiving end of the line would, under the conditions supposed,
be represented nearly by Figure 2 from which it is obvious that the relay at the
intermediate station could only send into the second section of the line, three
impulses of unequal duration, instead of five impulses of equal duration.
receiving end of the second section the signals would be hopelessly distorted.
We proposed to counteract this failure on the part of the relay to respond to
repeated current impulses of like polarity and to take advantage of its greater
sensitiveness to reversals as follows:-
At the
The signals at the originating station are sent into the line by means of an
automatic transmitter working at a constant speed.
The receiving instrument at the intermediate station consists of a compound
polarized relay, or of a pair of single polarized relays, in circuit with a device we
shall call a synchronous repeater by means of which the missing beats or impulses
are reproduced and the correct sequence of impulses applied to the second section
of the line.
We shall assume that a pair of relays are used. The synchronous repeater
consists in effect of an insulated contact lever which by a suitable train of
clockwork is caused to oscillate between a pair of contact stops one of which is
spoken of as the "earth" stop and the other as the "live" stop.
The speed of the clockwork is adjustable so as to oscillate the contact lever at
the same rate as the contact levers of the automatic transmitter at the originating
station and the lever of the repeater is also kept "in step" with the movements
of the tongues of the relays by means of an electromagnetic governor controlled
by the relays.
The said contact lever is in electrical connection with the second section of the
line, the "earth" stop is of course connected with earth, and the "live"
stop is
joined up in such a manner with the local circuits of the receiving relays and with
the line battery that its polarity is positive, negative or neutral according to the
positions of the relay tongues.
Thus to retransmit the symbol " understand " the action of the relays and of the
synchronous repeater would be as follows:-
When the first impulse reaches the receiving end of the first section, the tongue
of the "dot" relay moves on to its "marking" stop and remains on it during the
period corresponding with the first three dots of the symbol, joining, say, the
positive pole of the line battery with the "live" stop of the repeater.
Simultaneously with the movement of the relay tongue the contact lever moves
onto its "live" stop and transmits a positive impulse to line the lever is then
When
moved against the "earth" stop, back again to the "live" stop and so on.
three positive current impulses have been sent to line and the end of the line has
been three times "put to earth," as required, the "dash" relay comes into
action and connects the "live" stop of the repeater with the negative pole of
the line battery so that a negative impulse is sent by the contact lever into
the line.
Finally the last "dot" of the symbol is sent in the same manner as the first, and
the live stop of the repeater is then put to earth or insulated by the relays so that

page_text: It is evident that so long as either pole of the relay battery is joined by means
of the relays R, R, through the wire W with the upper contact d, a succession of
charges and discharges will enter and leave the cable L, as the lever l oscillates
between its stops. The polarity of the charge of course depends upon the position
of the relay tongues as explained.
Thus the oscillating lever intermits or interrupts the current supplied to the
wire W in its passage onwards towards the second cable.
To the wire W is also connected one pole of a large condenser (20 or 30 micro-
farads) the other pole of which is to "earth" through an adjustable resistance.
The use of this condenser and resistance will be explained later on.
In order that the lever may properly perform its function of as it were
breaking up the long dwell of the tongues of the relays R₁ R₂ into a series of
separate contacts, it is necessary that the lever should come to its stop d at the
same instant that either of the relay tongues comes to its stop c₂. This synchronism
is obtained by the aid of an electro-magnetic governor in the following way :-
(seen both in Figures 3 and 4) is a straight bar of soft iron with curved ends
somewhat of an S shape, it is fixed on the axles of the cams n, n₁.
ee are the two
limbs of an electro magnet with pole pieces p and p₁ just clearing the curved ends
of the bar as the latter revolves. k is a light wheel attached to the axis and
partly surrounded by the strap o hinged at t and having an iron armature which
may be attracted by the electro-magnet e2. The hinged bar or strap acts on the
light wheel as a "brake" when the electro magnet e, is excited. b and b₁ are two
cams also mounted on the axis s, the cams respectively governing the movements
of contact levers a and a, which once in each revolution is put in contact with its
stop for f, and is separated therefrom.
These cams b, b₁ are for convenience of illustration drawn in Figure 4* side by
side instead of on the same axle. The cams are here shown in their proper relative
positions both as regards themselves and the bar h in Figure 4; at this instant also
the cams n n will be thrusting the lever on to the contact stop d.
The circuit of the governing apparatus is diagrammatically shown in Figure 3,
the relay R, before referred to is brought into action every time a signal from the
originating station is received on either relay (R₁ R₂).
•
The local circuit of the relay R, includes the contact levers a and a₁ their contact
stops and also a local battery B and the electro magnets e e₁ e, as shewn. It
may therefore happen that when the tongue of relay R, is moved, that the circuit
may be completed through a f-through a f₁, or may be broken, according to the
position of the cams b and b, at the instant the signal is received."
If for instance when the relay tongue of R, acts, contact through a fis made the
circuit through the electro magnets e e, is established, and this happens before the
straight part of the bar h has reached the pole pieces of the electro magnets e, ei
which causes the motion of the bar together with the axle s carrying the cams n. n₁
to be accelerated by the attraction on the curved extensions of the bar h.
In this way the motor, being then slow, is corrected.
If on the other hand when the relay tongue of R, acts the contact through a fi
is made the bar h will be in advance of its proper position and the electro magnet e
will be energized thus bringing into action the brake o and retarding the motion of
the cam axis.
The condenser y and resistance rare inserted so as to ensure that a sufficient
current may be sent along the wire W to actuate the relay R, even when owing to
the position of the contact lever the contact stop d₁ happens to be insulated.
The resistance r is added so as to slightly prolong the time of charging of the
condenser.
It is assumed that the lines will as is usual be worked with condensers, so that
in any case the local circuit of the governor can only be established for a short
time.
Figure 5 illustrates another method, in which exact synchronism is dispensed

page_text: with and the movements of the tongue of the relay R, each time that they occur
determine the start of the lever at the proper instant.
The three relays R₁ R₁ R, are arranged as in Figure 3. The wire W is
connected with a lever d and through this lever the current reaches the automatic
repeating lever ? which is permanently connected with the cable liue L, as before.
A cam when it rotates moves the lever / so that its lower end leaves the lever d
and makes contact with the lever d' which is connected to earth. Suitable stops
and springs are provided in connection with these levers as the drawings
illustrate.
The three levers Id d₁ are carried upon a slide which can be adjusted by a screw
so as to set the upper end of the lever nearer to or further from the cam axis.
Thus the relative durations of the contacts with d and d₂ can be varied at will.
The cam is not continuously driven but is connected intermittently with a driven
axle by a clutch apparatus. The driven axis is set to run almost synchronously
with the transmitter. The clutch apparatus which we employ we need not
describe in detail, for it is well known in connection with Professor Hughes'
printing telegraph; moreover it is described in my (Dearlove) Specification
No. 916795.
e
is an electro magnet forming part of the clutch apparatus, its soft iron core is
magnetised by a permanent magnet beneath so that it holds its armature until a
current from the relay R, passes in the magnet coils. The armature is then
thrown up by a spring and strikes the end of the lever Y, this causes the clutch
to engage, the cam makes one or more complete revolutions opening and closing
the cable circuit as described. At each revolution the armature is replaced on the
magnet and when it is retained a stoppage of the cam and an accurately timed
restart of the cam takes place.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim,is-
1. The improvement in automatic repetition, by a relay or relays, of a message
.automatically transmitted through a cable line, which consists in intermitting the
.currents passing from the relay or relays by mechanism running synchronously or
nearly so with the automatic transmitter.
2. The combination of apparatus substantially as described consisting of an
automatic transmitter, a cable line, a receiving relay or relays, a current
interrupter, an electro magnetic governor or synchroniser and a second or
forwarding telegraph line.
Dated this 10th day of February 1896.
H. A. TAYLOR.
J. A. L. DEARLOVE.