Improvements in Telegraphy.
Year: 1893

page_text: Date of Application, 24th Aug., 1893-Accepted, 23rd Dec., 1893
]
Improvements in Telegraphy.
I, CHARLES ARTHUR ALLISON, of 52 Chancery Lane, London, in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Pierson J. Wicks, of Brooklyn, New
York, U.S.A., Electrician), and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
This invention is particularly applicable to those systems requiring means for
avoiding false signals in a neutral relay during current reversals employed in the
transmission of a second message or signal over the main line.
In the quadruplex or duplex telegraph which has come into general use, one
message is transmitted by current reversals and a second message by changes in
current strength, the reversals being received upon a polar relay, while those due
to changes in strength are produced upon a neutral magnet. The neutral relay,
however, is found to respond to current reversals and to this extent there is
a mutilation of signals, for not only is it necessary that the polar relay should be
responsive to reversals only, but the neutral relay should be equally independent of
reversals. At each reversal there is either a period of no current, or at least, a
period of diminished current on the main line, and a correspondingly weakened
magnetism in the neutral relay, and, as a consequence, if the armature of the
neutral relay were held in an attracted or signalling position by an increased
current, it would often be so far withdrawn by its retracting device as to produce
false signals.
The invention is intended to overcome such difficulty, and to this end I avoid
reversals of magnetism in the core of the neutral relay; and this I accomplish by
instrumentalities controlled by the to-and-fro currents themselves, the mean's
employed serving to so direct the alternating pulses as to create or maintain one
direction of magnetic effect, or to avoid reversals of magnetism in the relay core
or cores.
Fig. 1, is a diagram showing a quadruplex transmitting and receiving apparatus,
used at each end of the line, in which my invention is employed.
Fig. 2, shows a like telegraph arrangement, in which a modified form of neutral
relay and arrangement of circuits are used.
Figs. 3, 4, 5 and 6, each show quadruplex receiving apparatus and further
modifications of the neutral relay and circuit connections.
Figs. 7 and 8, show further modifications in which the same direction of magnetic
effect is produced or maintained by two magnets.
Where two magnets are used, either one or two armatures are employed. As
shown in Fig. 7, two independent armatures are placed upon a single lever, while
in Fig. 8, one magnetic bar is common to the two magnets.
Referring to Fig. 1, K is a pole changer for alternately connecting dynamos a, b,
to' the main line in the transmission of current reversals, while K¹, is a transmitter
for sending signals by changes in current strength, whatever the polarity, these
devices' being actuated by local electro-magnets and their respective keys k', k".
By opening and closing key k¹, lever K, is rocked to alternately rest on stops r, s,
thus alternately joining the dynamo to line. If key k", be open, as shown in
Figs. 1 and 2, the circuit from K, is closed to line by way of point u, resistance m,
point
and thence to to; and at the same time a portion of the current is diverted
from, to spring o, hook p, rheostat n, to earth. Thus the current from either
generator is weakened by the insertion of resistance' m, and partly diverted and

page_text: wasted through the earth branch containing rheostat n, and, as a consequence, the
flow to line is of minor strength. When, however, key ", is depressed to transmit
a signal, the armature of lever K³, is attracted until spring o, is arrested against
stop g, and hook P is raised above the point of spring o, thereby breaking contact
between o and ; at the same time that connection is established between o and q.
And by this action the branch circuit to earth through rheostat n, is broken, and a
circuit from u to v, is formed by way of q, and spring o, thereby short circuiting
resistance m, when a maximum current will flow to line and actuate at the distant
station the neutral relay to form a signal. The receiving relays R, P, are
differentially wound and are therefore irresponsive to outgoing signals, and to this
end the usual form of artificial line, A L, having a rheostat A R, and condenser,
is employed. Relay P, is of the polar type and is responsive to reversals for the
production of messages sent from a distance by alternations of current, and its
armature tongue, o¹, vibrates between stops, m', n', to open and close the circuit of
sounder I. Relay R, is also of the polarized type, but it is employed wholly for
the recording of messages due to changes of current strength, although in itself it
is not capable of accomplishing this result, and is, in fact, only an auxiliary to the
neutral relay which is preferably placed in a bridge between the main and
artificial lines. The armature h, of the relay R, is electrically joined at point y,
with the main line, while the free end of the armature at each reversal of current
from the distant station is vibrated between stops f, g, to which, respectively, the
differential coils d, e, of relay D, are connected, said coils being united at a point c,
and thence joined with the artificial line at point x. It is now seen that a current
flowing from the distant station over the main line divides at point y, a large part
passing by way of armature h, stop f, and thence through coil d, and, owing to the
direction of flow and the winding of coil d, a south magnetic pole is produced in
the relay core facing the armature. If now the current on the main line, from
the distant station, be reversed, the tongue of armature h, will almost immediately
and before any considerable amount of current can find its way through coil d, be
thrown from stop f, to stop g, the flow now taking place from point x, through
coil e, stop g, and armature lever h, to y. Thus while the current is now flowing in
au opposite direction on the main line, it is nevertheless, so passed around the
relay core by coil e, as to produce the same polarity of magnetism in relay D, as
before, and the magnetism of the relay is therefore not reversed. While the
weaker currents are flowing over the main line and through either coil d, or e, the
core of D, will not be sufficiently magnetized to attract armature ; but upon
increasing the main line current, the magnetism developed in the core of magnet D,
will attract armature l', from back stop ;, to its front contact k, thereby breaking
the circuit of the repeating relay E, and releasing its armature so that the latter
may be withdrawn from its front contact I, and the circuit of sounder F, closed to
produce a signal.
In Fig. 2, I have shown galvanic batteries a, b, in Fig. 1, while upon relay D,
only one coil is employed. The relay tongue h, as before, is connected at its
pivoted end with the main line at point y, but the artificial line in this case is
connected from point x, to the anvil z, of a pole changer against which springs f, g,
are alternately brought into contact and removed therefrom by the free end of
tongue. In this arrangement, a current flowing from the distant station passes
from point y, to tongue h, spring g, and thence through the coil of D, to spring /
stop, and point; but upon a reversal of current, owing to the quick movement
of tongue h, little or no current of the reverse order will pass through the coil of D,
before tongue, and spring 9, are separated, and as h, is almost immediately brought
into contact with spring, the flow will retain its direction in relay D, and will
still pass from spring g, through coil d', e', to spring f, though the flow will now be
from the artificial to the main line.
In Fig. 3, I have shown in place of the two polarized relays P, R, in Figs. 1, 2, 5:
and 6, a compound relay having two tongues, the tongue o', vibrating between
stops m³, n³, to record messages due to current reversals, while the lower tongue

page_text: plays between fand g, as an auxiliary of relay D, the latter still being employed
to record signals due to changes in current strength. With this arrangement, as
before, obviously, the two tongues of the compound relay are unaffected by
outgoing currents, and although both are responsive to reversals from distant
stations, relay D, is only brought into action when main line currents are sufficiently
increased to enable the core of D, to attract armature l'. The compound relay R,
however, is virtually two relays, as is relay R, of Fig. 4.
In Figs. 1, 2 and 3, I have shown armature l', as of the polarized type, and this
form, for quickness of action, possesses many advantages, though I find it entirely
feasible, as indicated in Figs. 4 and 6, to make said armature of soft iron.
In Fig. 4, is shown a modification of apparatus contained in Fig. 3, in which
relay R, by means of a single armature, effects a record of the message due to
reversals upon a sounder, I, which is actuated as armature lever o', is brought into
contact with stop n', while at the same time a spring, connected to but insulated
from lever o', is vibrated between points f, g, thus connecting point. of the main
line alternately to the differential coils, d, e, of relay D. Obviously in this
arrangement, as in other forms already described, relay D, is responsive to increased
currents.
Fig. 5, is a modification of the receiving apparatus shown in Fig. 1, in that a
different order of currents must be employed to actuate the tongue of relay D, in
forming signals. One end of a soft iron core is fixed to a permanent magnet, N, in
the construction of relay D, and the magnetism of the core which is developed
from magnet N, is only overcome or neutralized when a maximum current is flowing
from the distant station. In the operation of such arrangement when the neutral
transmitting key is open the strongest current is sent to line and the armature lever,
is permitted to fall against back stop, but no signal is produced; if, however, the
neutral transmitting key be depressed, as is necessary in this instance, and only a
weakened current transmitted to line, enough magnetism in the core of relay D,
will not be developed to neutralize the opposing magnetism derived from N, and,
as a consequence, , will be attracted to point k. It is apparent that if the current
were removed entirely from the line, armature l', would still be attracted and more
strongly than before.
Fig. 6, represents an arrangement in which the bridge containing relay D, does
not join the main and artificial lines at points of equal potential as a and Y, shown
in the other figures of the drawings. In this instance armature lever h, of relay R,
is joined to a point w, and thence through one or the other of coils f¹, e', according
to the position of armature h. In this case, therefore, the bridge in which relay D,
is placed is merely a shunt around rheostat R", but with this arrangement it is
necessary to duplicate the coils of relay D, in order that outgoing currents may be
differentialized. If the coils of relay D, through which signalling currents from a
distant station flow, could have their opposite extremities connected to points of
equal potential on the main and artificial lines, such coils would constitute bridges
in which outgoing currents would not flow; but if the coils be joined with the main
line at points w and a, their extremities are at different potentials, and relay D, if
unprovided with differential coils, is responsive to outgoing signals. To obviate
this difficulty two additional coils c, d, are so wound on the core as to neutralize
the effect of outgoing currents in those coils f', e', through which signalling currents
from a distant station arrive. Currents from the home station passing through
differential coils f', d', produce no signals at the home station; and in like manner
when h, is attracted against stop g, currents flowing through c', e', neutralize each
other in relay D; thus in respect to outgoing currents, as shown in Fig. 6, there is
a flow of current through two differential coils in both positions of the relay
tongue h, but in either position of h, incoming currents flow through only one of the
two coils e¹, f¹.
In Fig. 7, is shown a further modification of relay D, in which are employed
two iron cores with separate coils acting respectively and alternately upon two
independent armatures, both being mounted upon a lever l', but obviously even

page_text: where two separate magnets are employed I need not be limited to separate
armatures, as the cores of both magnets may, as shown in Fig. 8, act upon an
armature common to both. In these arrangements, however, it is preferable to
permanently polarize the cores of both magnets and to so direct signalling currents
through their coils as to reinforce the permanent magnetism. It will also be seen
that in the organization shown in Fig. 7, both magnets may present the same poles
to their respective armatures, as said armatures in this case are magnetically
independent. Where, however, as in Fig. 8, the armature is an iron bar common
to both magnets, one magnet should present a north and the other a south pole
thereto. At the moment of reversal, if the action of relay R, were slow in moving
armature lever 1, a reverse current would flow through that coil of relay D, last
in action, and the object of the invention would be defeated. I find, however, that
under ordinary conditions no such reversals in the coils of relay D, occur, although
it might well be assumed that before tongue h, could be moved away from either/
or g, enough current of opposite polarity would flow through the coil to reverse
the magnetic polarity of its core. The action of h, is so quick, however, that the
mechanical effect of the reverse flow could be but slight, but if the tendency were
greater it would ordinarily be dissipated by the self induction of the relay itself.
And in some cases it may be desirable to so construct relay D, that it shall have
considerable self-inductive capacity or lag, but such remedy should be sparingly
applied, as the effect of self-induction is to render relays slow and inefficient as
telegraphic receiving instruments.
Many other arrangements will be suggested by those already described in which
alternating currents transmitted over a main line may so direct themselves that
they shall not reverse the magnetic polarity of a neutral relay or one designed to
receive only signals in response to changes in current strength, and I, therefore,
wish to broadly claim all equivalent means and methods for accomplishing this
desirable result.
Having now particularly described and ascertained the nature of my
invention and in what manner the same is to be performed, I declare that what
I claim is:
:-
1. In a telegraph system for simultaneously transmitting two messages in the
same direction on one line, the combination of a receiving instrument which is
responsive to current reversals for recording signals due to such currents, a main
line relay for recording signals due to changes in current strength, and means for
maintaining the same direction of magnetic effect upon the armature of said second
relay by main line currents, irrespective of their direction.
2. In a quadruplex or duplex telegraph, a relay at a receiving station, a second
relay for recording signals due to changes in current strength, and a relay for
directing main line currents to said second relay in either of two directions,
according to the direction of main line current.
3. In a telegraph system for simultaneously transmitting two messages in the
same direction over one wire, two relays both of which are responsive to current
reversals, one being employed to record signals due to such currents, and the other
to actuate a commutator or switch, and a relay for recording signals due to changes
in current strength, the arrangement being such that main line currents shall be
directed through said relay in either of two ways, according to the direction of
main line current during reversals.
4. In a quadruplex telegraph, a main and an artificial line at each station, two
relays which are responsive to alternating currents received from a distant station,
a third relay placed in a bridge joining the main and artificial lines, and controlling
devices actuated by one of said relays for maintaining the same direction of
magnetic effect in said bridge relay, irrespective of the direction of main
line flow.
5. In a quadruplex telegraph, the combination at one station of two polarized
relays which are differentially wound, a bridge conductor joining the main aud

page_text: artificial lines of said system, a relay placed in said bridge having two coils d, e,
and an armature lever h, for alternately connecting said coils in circuit whereby
the same direction of magnetic effect may be maintained in relay D, irrespective of
the direction of main line flow.
Dated thin 24th day of A
1000
ALLISON BROS.,
Agents for the Applicant.