An Improvement in Telegraph Cables and their Connections.
Year: 1896

page_text: Date of Application, 10th Oct., 1896
Complete Specification Left, 9th July, 1897-Accepted, 14th Aug., 1897
An Improvement in Telegraph Cables and their Connections.
We, JAMES MARK BARR, and CHARLES EDMUND STANLEY PHILLIPS, Electrical Engineers,
both of Castle House, Shooters. Hill, in the County of Kent, do hereby declare the
nature of this invention to be as follows:-
Our invention relates to such an arrangement of the conductors in a telegraph cable
and their connections to the metallic sheath as to render the self induction nil, to
diminish capacity, and thus to increase the speed of signalling and render the signals
transmitted more definite.
For this purpose we insulate the metal wires or strands of the cable by material of
low specific inductive capacity and of comparatively low conductivity such as paper,
and we divide the wires or strands into two groups selecting for each
group wires or strands which are intermediate to wires or strands of the
other group. At each end of the cable we connect each group through a key and
battery to the metallic sheath, this key being so arranged as to keep the
one group in circuit, the other group being out of circuit.
On moving the key for the purpose of signalling, the group that was in circuit is
cut out and at the same moment the other group is brought into circuit. In both
cases the metallic sheath is in circuit, and the fall of energy in the one
group as it is cut out is completely balanced by the rise of energy in the other
group as it is brought into circuit, so that there is no self induction."
Dated this 10th day of October 1896,
ABEL & IMRAY,
Agents for the Applicants..
An improvement in Telegraph Cables and their Connections.
We, JAMES MARK BARR, and CHARLES EDMUND STANLEY PHILLIPS, Electrical Engineers,
both of Castle House, Shooters Hill, in the County of Kent, do hereby declare the
nature of this inventiou and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
Our invention relates to an arrangement of the conductors in a telegraph cable and
their connections to the metallic sheath or armour of the cable, in such a manner that
self induction and capacity are diminished, and signalling can be carried on at greatly
increased speed, the signals transmitted being also more clear and definite than with
cables arranged and operating in the usual way.
For this purpose, we separate from each other the metal wires or strands of the
cable by covering them with material of comparatively low conductivity and low
031

page_text: specific inductive capacity, such as paper, and we divide the wires or strands into
two equal groups, preferably selecting for each group wires or strands intermediate
to those of the other group.
Assuming for instance that there are 8 wires or strands insulated from each other
by paper, wrapping, and arranged around a core of hemp, paper or the like, then one
of the groups which we may term the odd group would consist of the
wires or strands, 1, 3, 5, and 7, the other or even group consisting of the
intermediate wires or strands 2, 4, 6, and 8.
Both groups being surrounded by a thick layer of impervious material of high
specific, resistance such as gutta percha protected by armour in the usual way, at
each end of the cable we connect each of the two groups to the armour through a
battery and key, the key being so arranged that, when it is employed for signalling,
the one group is brought into circuit with the armour, and the other group is cut out
of circuit.
By this arrangement the armour is always in circuit with the one or the other of
the two groups, but in the act of signalling the energy in the one group, as it is cut
out of circuit, falls while the energy in the other group as it is brought into circuit
rises, the rise of the one compensating for the fall in the other so that there is little
or no self induction, and consequently there is no appreciable retardation except
that which is due to the insulating material which separates the wires; this, however,
being of lower specific inductive capacity, canses very little retardation to the
signalling waves. Owing to the absence of self induction, resulting from the grouping
of the wires as described, and to the low capacity of the insulating material,
.signalling can be carried on much more rapidly than with cables as they are usually
constructed and operated, and the signals, such, for instance, as those formed by the
syphon-recorder, are much more sharp and well defined.
The cable having its conductors arranged in two groups as described can be used
for telegraphing by connecting the two groups of wires and the annour as shewn
diagrammatically in Figure 1.
A the armour of the cable is connected directly to the one terminal of a battery B
the other terminal of which is connected to a spring key K which normally makes
contact with C for the one group W of the cable wires, or can be pressed so as to break
contact with C and to make contact with C for the other group W1; the
contact slides C Care urged by springs S S¹ as far as permitted by
adjustable collars D D. At the distant end of the cable the wire group W is
connected to the armour A, the other group being connected to the armour A
through any suitable receiving instrument I. On depressing the key K for the
purpose of sending a signal, the circuit from B, through C, W and A back to B
remains closed until just after the key has come in contact with C¹, at which moment
the circuit from B through C¹ W₁ I and A back to B is also closed, but on farther
depressing the key, the circuit through W is opened, that through Wi being alone
closed. During the instant of change of circuits the wave of energy in W is falling
while that in W₁ is rising so that there is no self induction in the cable and
consequently no loss of time due to self induction.
The movements of the diaphragm of a telephone transmitter may be used to
operate somewhat like the key K, increasing energy in the one group of wires while
it diminishes that in the other group.
For duplex telegraphy the instruments and connections may be arranged as shewn
diagrammatically in Figure 2.
At each terminal station there is a receiving instrument or relay I oppositely
coiled, the one coil connecting the contact C¹ with the one wire group W, and the other
coil connecting the contact C¹ with the armour A. The contact C connects to the
wire group W. The two contacts C and C¹ are arranged as described with reference
to Figure 1, having between them a spring key K which opens the one circuit while
it is closing the other. The key K is rigidly connected to another key K' which
moves with K either making or breaking contact with C2, which, like C, connects to
he wire group W. The key K is connected through the battery B to the

page_text: armour A and K¹ is also connected to the armour A. The circuits are all provided
with suitable resistances or rheostats for purposes of adjustment. From this
arrangement it will be seen that signals can be transmitted to and received by both
terminal stations at the same time, each signalling movement of either key K
increasing energy in the W group of wires and lessening energy in the W group.
The armour also is always in circuit with the one or the other group of wires the
current flowing through it being practically constant.
Although we have described the groups of conducting wires or strands as being
connected at the ends of the cable to the armour, obviously the operation and results
would be the same if, instead of the armour, a special wire were employed, or
earth return, as equivalent to the armour.
Also although we have described our invention as applicable for telegraphing, it
may obviously be employed for telephoning.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is
1. A telegraph cable having its conducting wires or strands separated by paper or
other material of comparatively low conductivity and low specific inductive capacity
and the wires or strands arranged to be connected at the terminal ends of the cable
in two equal groups to the armour of the cable or equivalent return conductor by keys
so arranged that, while the one group is cut out of circuit, the other group is
brought into the circuit with the armour or return conductor, substantially as and for
the purposes set forth.
2. The herein described method of arranging and operating a telegraph cable by
dividing its suitably insulated conducting wires or strands into two equal groups,
connected to the metallic armour of the cable or equivalent return conductor by
signalling keys so arranged as to cut the one group out of circuit while the other
group including suitable signalling instruments is brought into circuit, for the
purposes set forth.
Dated this Oth day of July 1807
ABEL & IMRAY,
Agents for the Applicants.