An Improved Method of Duplex Telegraphy.
Year: 1894

page_text: Date of Application, 27th Sept., 1894
Complete Specification Left, 27th, June, 1895-Accepted, 27th Sept., 1895
PROVISIONAL SPECIFICATION.
An Improved Method of Duplex Telegraphy.
1, GEORGE EDWIN FLETCHER, of "The Homestead" Cale Green Stockport,
in the County of Chester, Electrical Engineer do hereby declare the nature of this
invention to be as follows -
An improved method of duplex telegraphy, whereby it is possible to place
duplex instruments intermediate on duplexed circuits, and at the same time be able
to work either duplex or simplex between any of the points, without having to resort
to any switching arrangements, and also to be able to place simplex instruments on
the same circuits to work with either the duplex or the simplex instruments. For
this, I preferably use double current double sounders, or needle instruments, together
with a double current polarised relay constructed in such a manner that the contact
pieces are held in a non-contact position by magnetic induction and upon a current
being sent either one or more tongues, as the case may be, produce the necessary signals
on the sounders. The coils are double-wound, and may be used either differentially
or otherwise, and are so placed that the poles of each pair are separated by small
air-spaces in which the contact tongues work. It will be seen that the tongues, if
so adjusted as to be nearer one core than the opposite core, and that the movement
allowed be so small that upon a current passing and the tongue moving nearer to
the opposite core but yet not so near as it is to the core in the presence of which
it rests, that when the current ceases it will fall back into its normal position.
The method of connection is as follows:-The line current going out from the
sending station splits through an artificial resistance and through the line:-the
artificial resistance, which is about equal to the line and one winding of the relay,
is so joined in as to form a local circnit across the commutator of the sending
instrument, and is short circuited when the commutator is at rest; the other part
of the current passing through the other winding of the relay, so that in sending
the relay is not affected, but upon a current being sent from another station at the
same time, if they are opposing currents the local circuits or artificial resistance
circuit records the signals required-if currents of the same direction the artificial
resistance circuit practically becomes useless and the line current gives the necessary
signals.
This method differs from all previous methods from the fact that the artificial
resistance is in no way connected with the earth, as in all other methods, and it is
owing to this that it is possible to work either duplex or simplex as before stated,―
at will.
Dated this 26th day of September 1804
improveu месной от Dupleд геторгарцу.
"
I, GEORGE EDWIN FLETCHER, of "The Homestead Cale Green Stockport
0 in the County of Chester, Electrical Engineer, 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 :-
An improved method of duplex telegraphy, whereby it is possible to place

page_text: duplex instruments intermediate on duplexed circuits, and at the same time be able
to work either duplex or simplex between any of the points without having to resort.
to any switching arrangements, and also to be able to place simplex instruments on
the same circuits to work with either the duplex or the simplex instruments. For
this, I preferably use double current double sounders or needle instruments, together
with a double current polarised relay, constructed in such a manner that the
contact pieces are held in a non-contact position by magnetic induction and upon a
current being sent either one or more tongues, as the case may be, produce the
necessary signals on the sounders...
"
The coils are double-wound, and may be used differentially or otherwise, and are
so placed that the poles of each pair are separated by small air-spaces in which the
contact tongues work. It will be seen that the tongues if so adjusted as to be
nearer one core than the opposite core and that the movement allowed be so
small that upon a current passing and the tongue moving nearer to the opposite
core but yet not so near as it is to the core in the presence of which it rests, it will
fall back into its normal position when the current ceases..
The method of connection is as follows: The line current going out from the
sending station splits through an artificial resistance and through the line: the
artificial resistance, which is about equal to the line and one winding of the relay,
is so joined in as 'to form a local circuit across the commutator of the sending
instrument, and is short-circuited when the commutator is at rest—the other part of
the current passing through the other winding of the relay, so that in sending the
relay is not affected, but upon a current being sent from another station at tlie
same time; if they are opposing currents the local circuit or "artificial resistance
circuit records the signals required, if currents of the same direction the artificial
resistance circuit practically becomes useless, and the line current gives the necessary
signals.
This method differs from all previous methods, from the fact that the artificial
resistance is in no way connected with the "earth" as in all other methods, and it
is owing to this that it is possible to work duplex or simplex, as before stated
at will
The arrangement specified, may be worked in connection with sounders or needle
instruments,,and with double current or single current apparatus, as may be deemed
desirable..
'
My invention also consists of a "translator" to be used in connection with the
duplex or simplex arrangements, on long circuits, and which may be employed with
either double or single current instruments. The action of the current passing
through the translator with the duplex arrangement is similar to that with the
double current polarised relay, in that it splits through the artificial resistance and
through the translator, and the necessary signals being transmitted south to north,
and north to south, instead of being merely recorded as with the double current relay.
The rheostat in this case not being connected to "earth" but forming a complete
shunt on the line.
Figures 1, 2 & 3 represent, plan, front elevation, and end elevation respectively of
the differentially wound relay used in connection with the double current duplex
telegraphy.
P, PP, P, are the electro-magnet cores, magnetised by the coils S1, S2, S³, S¹
respectively these are magnetised so that opposite poles act on the same armature.
M M² are the armatures which are inductively magnetised by the permanent
magnets R R2. On the same spindle as the armatures M² M² are the contact
tongues N N which make and break contact with the pillars 01 02 08 0"'as
hereafter described. The armatures being magnetised rest towards the pole of the
nearest electro-magnet, thus always falling back on to the stop, after a current has

page_text: ceased to flow. The contacts are so arranged that the armature cannot move far
enough to come under the attraction of the opposite pole piece. The 'action
of a current in one direction is to nove N¹ to make contact with O', and to more
strougly hold N2 against the stop 0%; whilst the action of a current in the other
direction is to move N to make contact with O and to hold N¹ more strongly
against its stop 01:
SHEET 2,
Figure 1 represents the diagram of the connections of the "translator" used in
connection with duplex double current telegraphy. The left shews the north
translator and the right hand the south instrument. I is the north line wire,
and 19 the south line. If north alone is sending a current to south, this same
arrangement works simplex.
V & V are two differentially wound galvanometers, which indicate when
current is received to work the relay coils L, L, Lor L, L L'.
If the circuits are correctly balanced there should be no deflection of the needle
by a sent current, & it is by this means that the rheostats T¹ & T' are adjusted.
T&T are adjustable rheostats by means of which the resistances of the
balancing circuits 2, 4, 5, 6, 7 L', L3, L³, 8, & 18, 16, 15, 14, 13 L, L, L 12 are
made equal to the resistances of their respective line circuits. A¹
to K8
represent the different working parts of the translator, & are lettered as in
Figs. 1, 2 & 3 of Sheet 3.
L, L, L&L, L, L' are the coils of the translator relays & the 2 portions of
each coil represent the differential winding of each.
42, 43 & 44, 45 represent the terminals of the local batteries which are
switched into circuit by the tongues B', BB, B2, B4, & E, E, E, E when the
armatures A, A, A, A' & D' D' D³, D₁ are attracted by the poles C1, C2, C³ or
F1 F2 F³.
If north only is sending a current to south, it would enter at 1 flow through 2, V₁,
3, E, K, E, K, K', E³, Kº, E2, 8, L³, L³, L', 9, 10 to earth.
The shunt circuit 2, V', 4, 5, T, 6; 7, L1, L2. L, 8 being of such high resistance
no current would flow through the coils L, L, L³ in this direction. The former
current passing through L, L, L, would move the armatures A¹ and A³ or
A and A according to its direction; with these would move the tongues B1 and B³
or Band B, which would switch in a new battery with poles 42 and 43.;' the
current from this would pass through J, B', 17; V2, 18 to line 19, and from the
other pole 43 through J B to 12, where it would split & part go to earth
through L L L 11 & 10, and the other part from 12 in the opposite direction
through L, L, L to 13, 14, T³, 15, 16, 18, thus forming a shunt across the
main circuit to line 19. This shunt circuit being made of equal resistance
to the complete line circuit by means of the rheostat T, the two currents
through L, L, & L would be equal, and of opposite direction, therefore would
produce no effect on the armatures D'D' D³ or D* of this relay.
Should however the the south be sending a current of the same direction as the
north, the current along line 19 would be doubled, & pass through 18, V2, 17,
B, J to 42 being pole of new battery, to 43, J, B8, 12, L, L, L, 11, 10 to earth,
thus connecting both batteries in series; as in the case of the north current through
the north translator, no part of the south current would pass through V2 to 16, 15,
T, 14, 13 L, L, L to 12 owing to its high resistance, therefore the south current
passing through L, L, L to earth as shewn would produce a movement of the
armatures D' and' D3; these would move the tongues E' and E3, which would join
in a new battery, whose poles are 44 and 45. This would send a
through J, E, K, E, 3, 2, 1, to north line, and from 45 through J', E, K³, D³.
splitting at 8, & part going through L, L, L', 9, 10 to earth, and the other par
through L, L, L', 7, 6, 1, 5, 4, 2, 3 here joining the line circuit, & so forming
shunt. This 'battery (44, 45) would by this means be put in series with the current
current.
il

page_text: from the north, & the two parts splitting through L³, L³, & L' at 8, would be.
equal & opposite (as their circuits would be of equal resistance), and therefore.
would not upset the working of the relay by the former north current.
If the current sent from the south were in opposite direction to the north,
it would neutralize all current in the south line by connecting the batteries in
opposition, instead of in series as before, so that the south relay would work by the
current from 42 through J¹, B', 17, 18, V2, 16, 15, 14, 13, L, L, L, 12, B³, J³, 43;
this current working the tongues D and D* would join in the battery 44, 45 in
opposition to the current in the north line thereby neutralizing it, but the north
translator would still work as before by the current from 44, 45 through J, E2, 8,
L³, L, L, 7, 6 T, 5, 4, 2 V, 3 Et, 18, 45. It will thus be seen that the currents
at the receiving stations would either be neutralized or doubled, & the signalling
would take place just as in the ordinary duplexing without translation.
Fig. 2, Sheet 2.
This represents the diagram of connections of one station working double current
duplex or double current simplex at will.
W & W' are ordinary sounders. 36 & 37 the terminals of a local battery to
work the sounders.
This local circuit is closed by means of the tongues N' & N', which close their
respective circuits 36, 40, W1, 41, O, N, 37 & 36, 38, W 39, O³, N³, 37, thus
working their respective sounders W¹ or W'. 27 & 28 are the terminals of the
line battery. 25 & 26 are the line & earth terminals. V³ is a differentially wound
galvanometer whose windings are in circuit with the balancing shunt & line circuits
respectively. The movement of its needle indicates when a current is working the
relay, but there is no movement of the needle due to a current sent out to line, if
the rheostat is adjusted correctly. It is by this means that the resistance of the
rheostat can be adjusted.
Ts is an adjustable rheostat, by means of which we adjust the resistance of the
balancing shunt circuit 21, 23, 24, 35, S2, S4, 33 to be equal to the resistance of line
circuit.
S1, S2, S³, S* represent the differential windings of the relay, and when there is
an excess of current in either S & S or S2 & S, they work the tongues N¹, N' by
means of armatures as shewn in Figs. 1, 2 & 3 Sheet 1; the letters refer to the
same part in both drawings.
29, 30, 31 & 32 represent the battery & line terminals of a commutator X¹ used
for reversing the currents sent to line from battery 27, 28.
If a current be sent by X' from 27 through 29, 32, 33, here dividing one part
going to earth through S³, S' 34 & 26; while the other part would pass from 33
through S', S2, 35, 24, T³, 23, 21, V³, 22, this being the balancing shunt circuit.
The other pole of the battery would be connected to line through 28, 30, 31,
22, 20, 25.
The resistance of the shunt being made equal to the resistance of line circuit by
means of the rheostat To, the current flowing in them would also be equal, & as
the currents flowing through S' S³ & S³ S would be in opposite directions & equal,
no effect would be produced on the tongues N' or N or on the needle of the
galvanometer Vº.
This current at the receiving end would enter as at 25 through 20, V³, 22, 21,
23 T3, 21, 35, S*, S, 33, S³, S, 34. 26 to earth. Here the current would be in the
same direction through both differential coils therefore adding the effects, and so
we should get both a movement of the needle of V³ & of one of the tongues N¹
or N according to the direction of the current. The tongues N' & N would close
their respective circuits thus working either sounder W₁ or W2. Should however
the south station send a current in the same direction as the north, and at the same
time, it will be seen that it would flow through the north instrument as follows.
From 26 to 34, S1, S³, 33, 32, 29, 27, thus connecting the batteries in series, & then
on through 28, 30, 31, 22, V³, 20, and 25. So we should double the strength of
the current flowing already through S¹ & S³, while the shunt between 22 & 33

page_text: through S & S being so high in resistance, no more current would flow through
these two coils. The current therefore in S & S³ would work one of the
tongues N' or N', as before at the south station, & so would work sounder W'
or W; and for the same reason would deflect the needle of V³.
Should however the south send a current opposite to the north one, it will be
seen that the batteries now would be joined in opposition through the line,, and
therefore the current through S¹ & S would cease, and leaving still a current
through S & S which would move the opposite tongue N¹ or N³, and work the
opposite sounder W' or W2 to the one which worked before; and also we should
have the needle of Va deflected in the opposite direction.
The same effects would take place at any intermediate stations in circuit.
SHEET 3.
ร
Figures 1, 2 & 3 represent respectively the plan, front elevation, & end
elevation of a translator relay, which may be used in connection with either duplex
or simplex double curreut telegraph, where the line is of extended mileage. The
two portions of the instrument are similar, one being used for signals from north
to south, and the other from south to worth. Their action is exactly identical.
CCC C C C are the poles of three electroimagnets, magnetised by the
coils L, L, & L in such a way that the opposite poles face each other, that is,-
C is of opposite polarity to C2, & C opposite to C. These poles move the
armatures A A A³ A', which are inductively magnetised by the permanent
magnets G' & G³, in such a way that A' & A³ move in one direction with á
certain current and A & A move in the opposite direction; tliese armatures being
magnetised causes them to be attracted to whichever pole they are set nearest to,
& by this means the contact tongues B B B & B, (which are held on the same
axles, & consequently move with them), are brought against the stops K, K², K³,
& K¹
The action of the current in the coils L, L & L is such that, when in one
direction B & B make contact against J and J, B & B are held more strongly
against their stops K' and K'; and when the current is in the other direction
B & B' make contact with J and J, while B & B are held more firmly against
their stops K and K³. I is an ebonite base on which the pair of relays are
mounted. The axles on which the armatures move are insulated from each
L
DHEET 4.
Figure 1 represents a diagram of connections of simplex double current
translator, where it is not required to work on the duplex system as well. In this
the same letters refer to similar parts as in the other drawings and diagrams,
but L, L, L, L, L, L, are not differentially wound, and V & Vs are only
simple galvanometers.
I is the north line and 12 the south line. 16 and 17, 18 and 19 are the
terminals of two local batteries switched in by the action of the currents in the
relays.
If north sends a current through line 1 through 2, V, 3, 4, 5, L', L², L³, 6, K³,
E K, E³, 7 to earth, it would work B¹ and B or B and B according to the
direction of the current; these would join in a new battery (16 and 17) & this
current would flow through 16, J¹, B', 8, 9, 10, V6, 11, 12 to south line and from
earth through 7, B2, K², B³, J³ to battery, if the current received had moved the
tongues B' and B; if B and B had been moved by the current received, the
current sent to south line would just be of opposite direction. So the current sent
south would be of the sume direction as that received from the north. South
would work north in exactly similar fashion.
i

page_text: It will be seen that current can only be received in the coils of one part of the
translator, when the tongues of the other part are at rest; and also that the two
tongues B & B or B2 and B cannot work together. This prevents any short
circuiting of the batteries.
Sheet 4 Figure 2.represents the diagram of single current duplex or simplex
telegraphy at will.
W is an ordinary sounder, 31 and 32 its terminals; 30 and 29 are the poles of a
local battery to work the sounder. The circuit from 30 and 29" through Ws is
closed by means of the tongue N₁ moving against the contact 0¹ & completing
circuit 30, 31, 32, N, O, 29. S1, S2, S3, S, represent the differential' windings of
the coils of a relay, and as before an excess of current in either pair of coils SS³
or S S works the tongue N' against its stop O'.
V is a differential galvanometer & T the adjustable rheostat, whose functions
are as described above for the double current duplex working.
Y is the sending key, 33 is the line battery, 20 the line wire & 28 the earth
connettion:
The balancing shunt circuit in this diagram is 22, 23, 24 T4, 25, 26 S3, S4, 27.
If the key Y be depressed; it would connect one pole of battery 33 to line
through Z2, Y, 22, V6, 21, '20 and the other pole to earth through 27, S³, S', 28.
The current however would split at 27 and part flow through S, S, 26, 25, T, 24,
23, V, & 22, thus forining a shunt across the line circuit. This shunt however
is of equal resistance to the line circuit by means of the rheostat T, therefore the
current 'flowing in it is equal to that of the line, and we get equal & opposite
currents flowing through S' S³ & S'S'. Therefore this relay would not be affected.
The current entering the line at the other station would flow through 20, 21, V6,
22, Y, Z, 27 S3, S1, 28 to earth. As in the double current working, uo current
would flow through the shunt circuit 22, 23, 24 T4, 25, 26, S2, S1, 27, being of such
high resistance. Therefore we should have N¹ moving by reason of the current
in S'S, & so we should work sounder W³.
If however a current be sent from this receiving station at the same time, & of
the same duration, there would be no alteration of the working of the relay at this
end' owing to the sont currents being as above shewn equal & opposite through the
relay but at the former sending station a current would flow as we shewed above
through the coils S3 and S4, thus we should upset the balance of current in these
coils and we should have a movement of N & consequently a signal from W³. at
both stations.
Should however this second current be kept on longer than the first one, we
should still have the tongue N' held over at the first sending station as described
at first.
The effects in single current working are as in the double current, except that
instead of the line currents being either doubled or neutralized as in double
currents, in the single currents they are either increased or one is taken off.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. An improved method of duplex telegraphy by means of which any number of
intermediate stations can be provided for, and duplex or simplex systems of
telegraphy resorted to at will without any switching arrangements, substantially as
herein set forth.
2. An improved method of single current duplex telegraphy, also admitting of
any number of intermediate stations and providing for duplex or simplex working
as may be desired substantially as herein set forth.
3. A means whereby each station can adjust its own shunt circuit, by the aid
of artificial resistances, without earth connections, substantially as herein set
forth

page_text: "
4. A method whereby either duplex or simplex systems of telegraphy may be
"translated on long circuits bringing into play a local battery by means of the
translating relays, substantially as herein set forth.
Dated this the 25th day of September 1895.
GEO. EDWIN FLETCHER,
The Homestead, Cale Green, Stockport.