Improvements in the Operation of Telegraph Circuits and in Apparatus therefor.
Year: 1889

page_text: Date of Application, 9th Nov., 1889-Accepted, 11th Oct., 1890
COMPLETE DIBUITICATION,
Improvements in the Operation of Telegraph Circuits and in
Apparatus therefor.
I, CHARLES ADOLPH GISBORNE, of 7, St. Paul's Churchyard, in the City of
London, Gentleman, do hereby declaro the nature of this invention (a communication
to me from abroad by David Herbert Keeley, of Ottawa, in the County of Carleton,
Province of Ontario, Dominion of Canada, Electrical Expert), and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
This invention consists in a new arrangement of signalling apparatus whereby the
interference from statical electricity in a circuit is entirely eliminated.
It has long been recognised that the transmission of signals in a telegraph circuit
is greatly interfered with by the phenomenon of static charge and discharge due to
the electrification of the conductor; and so well have the conditions occasioning this
phenomenon been studied, that well defined laws are laid down in the text books,
whereby the signalling capacity of any given conductor can be mathematically deter-
mined, and it has become an accepted fact that the economical operation of a simple
Morse telegraph line is limited to a certain mileage of circuit wire. In duplex and
other multiplex systems of telegraphy the practicable length of line for efficient
operation has been limited to a very marked degree; and in the operation of long
submarine cables the speed of signalling is far below the practicable rate of
an ordinary operator's manipulation despite the use of specially designed and delicate
apparatus.
The object of this invention is to remove the impediment above defined, and to
render the transmission of signals both in single and duplex circuits on aerial or
submarine wires of the greatest length easily practicable at the highest rates of
speed.
1
I accomplish this by the simple expedient of providing a rapidly reversing current
at the receiving end of the line, and at the sending end a double current transmitter..
The receiving instruments are polarized. If the sending key is depressed a current
of one polarity say +, goes to line and charges the conductor. If the current reverser
at the distant end presents a current to line, that current combines with the
current transmitted, and affects the polarized receiver in one direction, say, closes it ;
when the current reverser presents a + current to line, it is opposed by the + current
transmitted, hence no effect is produced in the receiver, which remains closed. If the
key at the sending station is upraised, a current goes to line. When the current
reverser at the receiving end presents + to line, it combines with the transmitted,
and affects the polarized receiver in the direction opposite to that imparted before,
and opens it; and when the current reverser presents to line, it is opposed by
the transmitted, therefore no effect is produced and the receiver remains open.
Hence the distant receiver is actuated by the distant battery under the operation
of the sending key.
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Single Morse circuits of great length have not heretofore been practicable, for
the reason that in makes and breaks affected by movements of the key at the
sending end, the duration of the breaks does not allow sufficient time for the charge
emanating from the battery at the distant end to withdraw from the circuit; the
receiving instrument consequently remains closed where makes and breaks rapidly
occur. In duplex and other multiplex circuits, and in submarine cables, the
difficulty is that heretofore in every such circuit the receiving instrument is
actuated by currents emanating from the sending end alone. When the line is
charged and the battery then withdrawn, the charge flows out at both ends; to
earth at the sending end and through the receiver to earth at the distant end.

page_text: The discharge current renders the receivers sluggish in action; and the sending
currents must be heavy in order to be effectual in the circuits of land lines operated
in this way.
In long cable circuits heavy currents are inadmissible; a weak
current is employed, and it is so attenuated after coursing through the great
resistance of the conductor, that receiving instruments of great sensitiveness are
Decessarily employed, these are therefore rendered correspondingly sluggish by the
action of the discharge currents despite the application of special devices to
accelerate their movements and the speed attainable in signalling is consequently
very low.
From what has been hereinbefore set forth, it will be seen that all the above
explained defects are obviated by the device constituting the principal element of
this invention.
The principle and function of this invention having now been clearly set forth,
the methods of its application will be readily perceived by reference to the
accompanying drawings.
Figure 1 shews the plan of equipment of a single circuit.
Figure 2 shows the same with details of the current reverser and receiving
instruments.
Figure 3 shews how the invention is applied to duplex circuits in land lines
or cables.
.
Figure 4 shows how it is applied to cable circuits arranged as heretofore for
operation by the double key system.
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In Figure 1 at station A, R is a polarized relay of any suitable description :
Ma Mbare main line batteries, connected to the back and front stops respectively
of a sonding key K. The batteries M M are also connected to the opposite
halves of a two-part commutator C, which is rotated under the brush Bi and con-
sequently presents to it, the currents from Ma and Malternately. The
+pole of Ma, and the pole of Mb are connected to earth. S, is a three-point
switch to the arm of which the main line wire, through the relay R, is connected.
When the switch S is closed on the point a, the main line is connected with the
key K and when S is closed on the point e, the main line is connected with the
brush B v. The parts at station B are precisely similar, and correspondingly
lettered. Station A is represented as sending to station B. The switch S at A
is closed on the point a; and the switch ST at B is closed on the point c¹. At
station B, the rotating commutator C₁ alternately presents + and
· currents from
the batteries ma¹ m¹ to the main line; these alternations are made at a rate not
less than 24 per second, or twice as fast as the rate of practicable manipulation
of a key in Morse transmission (thus during the formation of a dot by the
sending key, at least two phases, + and -, of current are presented to line by
the commutator at the receiving end).
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At station A, the key K is open and resting on its back stop, and its position
presents the current of the battery ma, to the main line; the circuit is traced
from Eat A through the battery Ma, key K, point a, switch S through relay R,
to line, thence through relay R¹, at B, switch $¹, point c¹, wire 4, to brush B
on the commutator ; thence by wiros 5' and M to earth at E¹, or by..
wire 61 and + Ma¹ to E¹. There is therefore a current traversing the line
from station A. When the commutator (, at B presents a current to line,
the one neutralizes the other and no effect is produced in the relays R R¹; but
when the commutator O, at B, presents a + current to line, the one current
combines with the other, and the combined current operates to actuate the
relays R. R. With the current from A therefore, the + current at B operates
to actuate the relays; and at B has no effect. As the relays are polarized the
+ current at B operates to actuate them and move the levers in a certain
direction say to their back stops 66 as shewn in the drawing. Now
when the key K at station A is closed, and rests on its front stop, the + current
from the battery M 6 goes to line; this obviously has the reverse effect of the
former current; the + current at station at B is now neutralized, and the current
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page_text: at B operates to actuates the relays R R in the opposite direction and moves their
levers to the front stops ff. The opening and closing of the key K at station A
therefore, causes the relays to be actuated in one direction and the other;
consequently the movements of the key are reproduced by the relays, and signals are
transmitted in the usual way.
In very long lines or where the discharge or return current due to the
emissions of the batteries at the receiving station are very considerable, the
connections of the commutator with the batteries are made at a certain point in each
battery so as not to include the whole; whereas the whole of the battery in each case
is included in the connections with the key. This is shewn in the drawing where the
whole of the battery Ma is connected with the back stop of the key K, and the
commutator is connected at a certain point in Ma not including the entire
series; the same with respect to the connections of the battery Mb. The object of
this arrangement is to make the current transmitted from the sending station
paramount in the circuit; when this condition exists, a given inclination imparted to
the relay at the distant station is maintained despite the contrawise discharge current
thero occurring.
In the practical application of the idea involved in the arrangement of apparatus
described in Fig. 1, any suitable means for producing the requisite alternations of
current at the receiving end of the circuit may be used; preferably the special device
shown in Fig. 2 at station B. is employed. It consists in a pole changing transmitter Pc
such as is used in duplex and quadruplex systems, which is operated by the electro-
magnet M, local battery Land Morse key K, in the asual way, for sending when the
switch S is open; and by the automatic circuit breaker C, with its contacts 2, s, to
effect the current reversals for receiving, when the switch S is closed.
1
The arrangement and operation of the automatic circuit breaker C is as follows:
Pm, Pm, are polarized electro-magnets so connected with the batteries X, XI, that
when the lever of Pm is against the stop -, it closes a circuit (from X + wire 11,
lever h, wire 9, through Pm by wires 5, 4, to - X) whereby the lever h³ of P m³ is
moved to its stop The latter contact closes a circuit (from X +, wires 11, 10,
lever, wire 7 through Pm, by wires 6, 4, to X) whereby the lever h of P m
is moved to its stop + and this latter contact, in turn, closos a circuit (from
X+, 4, 5, Pm², 9, 7, 8, to -X') whereby the lever of P m² is moved to its
stop + Then this latter contact (by the circuit X¹ +, 4, 6, P m, 7, h¹, 12, — X¹)
causes the lever of Pm to again return to its stop ; the action is then repeated
over again, and goes on continually.
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The levers of Pm P m' are therefore continually oscillated, the rapidity of move-
iment being determined by the strength of the batteries X, X', and the distance
apart of the rest points of the respective levers. An extension, &s, with a spring
contact can therefore be provided on one of them, Pm³, whereby the circuit
of the pole changer magnet, M, may be opened and closed regularly at any desired
rate of operation.
At station B in Figure 2 an arrangement of the receiving instruments is also shown,
in which the relay R is associated with an induction coil I.
The primary wire pp, of the induction coil is included in the inain line circuit.
The relay R is included in the circuit of the secondary wire Sc and the friction
jaws g, k moved by the lever of the pole changer Pc operate to close the circuit
of the relay to receive the induced currents due to the introduction of a current
into the primary pp and to open the circuit of the relay before the withdrawal
of a current from the primary.
The circuit of the relay is traced from the secondary, Sc, by wire 3, lever 1,
jaw gor k, wire 1, relay R, wire 2, to Sc. The action of the lever and jaws gk is
that, by friction, the jaws remain in whichever position moved by the lever 1.
When the lever is drawn down it leaves g, thereby opening the circuit of the
relay R before the contact y (connected to MB) leaves the spring (connected
to earth); and closes on the jaw k, before the spring u (connected to line) is lifted
off (connected to + MB) and is in contact with y. Thus the lever 7, leaves the
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page_text: -
jaws before the current is withdrawn, and closes on the jaw & before the
current is put to line. When the lever 7 is upraised, the reverse action takes
place. The relay R is, in consequence of this device, only influenced by the
polarity of the currents introduced into the primary wire p p of the induction
coil.
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The object of this is to accelerate the movements of the relay on circuits where
extraordinarily rapid transmission of signals is to be effected, in which case a
single + or phase of the correspondingly rapid reversals of current required at the
receiving end of the circuit would be too brief to affect the relay directly.
With the explanations given it will have been seen that the arrangements in Fig. 2
are substantially the same as in Fig. 1.
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->
In Fig 2 station A is represented as sending to B; the switch Sat A is open;
the pole changer Pc is operated by the key K', the latter is open and a current is
sent to line. The circuit is from E at A by wire 8' spring u', contact y¹, to + of
tho battery M B¹, from M 13 to contact ', spring u', wire w¹, through the relay R'
to line, thence through primary pp of the induction coil I at station B, by wire w,
spring u, contact to + M B, froin MB to contact y, spring v, wire s¹ to earth at E.
The switch S at station B is closed, but the contacts s 9 of the automatic circuit
breaker, C are open, consequently the lever of the pole changer Pe is unattracted and
upraised and the + of the battery MB is presented to line. A + current at station B
therefore combines with the curront from station A and operates to put the levers
of the relays on their back stops b¹ b. A current at station B would neutralize
the from A, and the relays would remain undisturbed; while, as before explained,
if the key Kat station A were closed, and a + current transmitted therefrom, the
current at B, when presented to line, would combine with it and operate to put the
relays on their front stops f¹, f. The position of the key at the sending station
therefore determines the position of the levers of the relays, whose actuation however
is referable to the allied or the opposing forces alternately presented to line at the
receiving end of the circuit.
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Fig. 3 shows the arrangement of a duplex on the Bridge system, adaptable with my
improvement to a long land line or submarine cable circuit.
The current alternator, which may be arranged in any suitable way, or according to
that specified in connection with Fig. 2, is represented at (, station A, and is included
in a derived circuit from the main line wire. The arrangement and operation of the
duplex system being well known and understood, it will be sufficient to point out that
the existence of the derived circuit affords two paths for the current sent out to line.
One part goes to earth by the derived circuit and the other part through the line
wire to earth at the distant station. According to my arrangement of the apparatus
the resistance of the derived circuit is made, by an adjustable resistance, com-
paratively low with reference to that of the line circuit, consequently only a small
portion of the current emanating from the sending battery goes to line; this small
current, however, of whatever polarity is supplemented by a current emanating from a
similar derived circuit at the distant end embracing a current alternator (, and the
combined currents operate to actuate the receiving instruments. When the transmitted
current is withdrawn from the line, the latter concurrently discharges by way of the
low resistance circuits in derivation at either end, consequently there is no lagging
effect in the receiving instruments and speedy signalling is accomplished with the
greatest facility. The operation of the apparatus and circuits is as follows: At
station AR is the polarized receiving instrument or relay, included in the neutral wire
of the bridge; R Rare the short arm resistances; ✗ is the balancing resistance,
made equal to the joint resistances beyond the point 5 of the bridge connections; (n is
a condenser of small capacity to compensate for whatever small amount of return
current escapes past the derived circuit (5, C, X³, E), and passes through the relay.
As arranged, it is well understood, the outgoing currents emanating from the
battery MB, have no effect on the receiver R, while incoming currents actuate it.
The currents emanating from the current alternator C, in the derived current, therefore
flow in as it were from the line, and affect the relay, + in one direction and—in the other.

page_text: -
The joint resistance of the circuits from the point 5 to earth being very low compared
to the resistance of the main line circuit very little current from C will pass over the
line. To produce the proper effect on the relay R therefore, the currents emanating
from C are not necessarily very strong. Supposing no current i to line at the distant
end; and
from Coperates to open the relay R, while + from C operates to close it.
If the key at the distant end is closed, and + sent to line, part of it will pass by way
of 5 CX to earth at E, and part through the relay R, in the same direction as the +
from C. The relay will therefore close; and so long as + continues to flow from
station B, the relay R will remain closed, since its presence in R will neutralize the
effect of the current from C which would otherwise operate to open it. The reverse
effect takes place when is sent from station B. The relay k at A is therefore
actuated by the currents from the alternator Cat A under the control of the key at the
distant end of the circuit. The arrangements being precisely the same at both ends of
the line, the relay at B is in like manner operated by the key at A the line being
thus duplexed.
It is obvious that my improvement may be applied to any other system of duplex
telegraphy in substantially the same way, viz.: by placing a current alternator in
derivation to the main line at either end of the circuit.
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Figure 4 shows how my device may be applied to cable circuits for operation by the
double key system. The principal of this system as is well understood, is that signals
are effected by right and left deflections of a galvanometer needle, produced by current
impulses of dot length uniformly; + impulses representing Jols and impulses
representing dashes. The object is to obviate the increased charge of the cable that
would attend the more lengthy depression of the key in signalling a dash by the
American Morse single key system. In order to effect a partial neutralization of the
residual current which gradually discharges from the cable after the signalling current
is withdrawn, the receiving instruments have heretofore been placed, through the
medium of a condenser in circuits secondary to that in which the transmitters operate.
The defect of the system as thus arranged consists in that the employment of the
condenser involves the introduction of a very large resistance between the cable and
the earth at one end of the circuit, and the presence of this resistance precludes the
rapid discharge of the cable. The consequence is, the slowly discharging current has
a sluggish effect on the receiving instruments and rapid signalling is rendered
impossible. It is well known that in circuits operated by this system the effect of the
residual current can be in a degree neutralized by the presentation of a reverse current
to line at the transmitting end immediately on the withdrawal of the signalling
impulse, but no means has heretofore been found to produce this result efficiently in
practice.
In the arrangement of the circuit Figure 4 for the operation by the double key
system according to my invention the above defined defects are obviated. The con-
denser, and therefore the secondary circuit, are dispensed with, and the double keys
are arranged to automatically transmit the alternate impulses in their transition
from the under to the upper contacts after a signalling impulse has been sent into the
cable.
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J
In the figure S at station A is a three point switch to whose arm the cable conductor
is directly connected. When S is on the point a, the cable is connected with the
transmitting keys: and when S is on the point c, the cable is connected with the
receiving instrument. The keys K+K when depressed, send currents from
the batteries B and B a respectively. The key K + plays between jaws d, e, from
whose arbor a spring extension p presses against flat contact plates w; the friction
contact thus created holds the jaws de in whatever position moved by the rear arm of
the key; the contact on the jaw d is insulated from the jaw e and extension p. The
jaw e and extension p are in electrical continuity. The key K is likewise associated
with jaws f. g. extension y. and contact plates y. z. R is the receiving galvanometer or
syphon recorder whose deflections to right and left represent dots and dashes C is the
commutator or current alternator hereinbefore described. The arrangements at
station B are precisely similar, and the parts are correspondingly lettered.
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page_text: -
Suppose the switch S at station A is put on the point a and the switch S¹at B is put
on the point C; then A will be in position to send to B and in the normal condition,
both keys being upraised at A, the circuit will be from E. at A by wire 7 plate y,
extension 9, jaw g, key K wire 2 plate w, extension p, jaw e, key K +, wire 1,
point a, arm S, to cable, thence by switch St, at B point O', wire 8', through receiver R¹,
brush Br, alternator C, to earth at E. There is in this case no battery in circuit at
the sending station A, while at the receiving end B, the commutator is alternately
presenting + and currents to line through the receiver R'. These currents rapidly
succeeding one another have the effect of oscillating the recording needle of the
receiver R within narrow limits.
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Now if the key K + at station A is depressed, the following action occurs.
The rear
arm of K + leaves the jaw e, and striking the jawd, moves it to its limiting stop. By
this movement the extension p is shifted from the plate w to x. While the key K +
is in contact with the jaw d, tho + current from the battery B, goes to line; the
circuit is from E to B, from B+, by wire 3, to jaw d, key K +, to line, thence
through the receiver R', at station B, alternator O, to earth at E. The + current
now proceeding from A combined with the trom the alternator C¹ at B and deflects
the recording needle to one side, say the right, signallizing a dot. The + current
from A opposes the + from the alternator C at B hence this latter current is
neutralized in its normal effect in the receiving instrument. Meanwhile the key K +
at station A is upraised; the rear armn leaves the jaw d, withdrawing the + current
from the line, and passes down towards the jawe; a discharge from the line follows.
The part that goes to earth at station B is opposed and neutralized by the first
+current emanating from the commutator ( at that end; this neutralization of the
discharge is further facilitated by the transmission of a momentary reverse current
from the distant end, as will presently be explained and the needle of the receiver
promptly returns to its normal limit of oscillation. Meanwhile the rear arm of the
key at station A strikes the jaw e, and moves it down to its limiting stop; during
this operation however a current is momentarily presented to line. When the rear
arm of K+ touches the jaw e, the extension p is still on the plate a which is connected
to a point low down in the series of the battery - Ba. In this condition the circuit is
traced from E through part of battery + Ba-, hy wire 5, to plate x, extension p,
jaw e, key K + to line. A weak current is therefore presented to lino; it is however
only momentary; the movement of the rear arm of K + carries the jaw e down to its
limiting stop and shifts the extension p from the plate a to w, whence the circuit is
traced as in the normal condition, to earth.
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It will be seen by the drawing that the key Kis in the same way connected with
the batteries Ba
and B+; so that the depression of K - sends the full current
of Ba
to line, and in its uprisal a weaker current emanating from a portion of B +
is sent to line.
The object of this device has already been very well explained; the presentation of
the weak alternate current which combines with the return current following the
withdrawal of the previous signalling one, contributes to the neutralization of the
discharge from the distant end as it occasions a concurrent flow of electricity in
the opposite direction in the circuit. The consequence is that the movements of the
recording needle to the right and left at the distant end can be more rapidly produced
and more sharply defined for each successive signal than has been possible with the
circuit arrangements and devices heretofore employed in double key transmission.
The nature and scope of my invention has now been fully explained.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent I declare that what I claim is :-
First. The device consisting in a rapidly reversing current at the receiving end of a
telegraph line or cable, and at the sending end a double current or pole changing
transmitter to operate in conjunction therewith as, and for the purpose described.
Second. The arrangement in circuit of an induction coil and a polarized relay in

page_text: combination with a device consisting in the friction jaws g k (Fig. 2) operated by the
opening and closing of the electro-magnet, m, for the purpose explained.
Third. The device comprising an adjustable automatic circuit breaker with two
polarized electro-magnets Pm Pm³ (Figure 2) and batteries X, XI, all arranged and
connected substantially as described.
Fourth. The application of these devices to systems of duplex telegraphy in the
manner described.
Fifth. The application of these devices to circuits operated on the double-key
system (Figure 4) substantially as described and the arrangement and connections of
the transmitting keys K +, K- in combination with the jaws d, e and f, g, extension
spring levers pand'
and contact plates to x and y = respectively substantially as and
for the purpose set forth.
Dated this 9th day of Now 1 1000
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.