IMPROVEMENTS IN ELECTRIC CABLES
Year: 1886

page_text: I SIDNEY FORTESCUE SHELBOURNE of 11 Gold Street in the city of New York,
State of New York, United States of America, Counsellor at Law, do hereby declare
the nature of my invention for IMPROVEMENTS IN ELECTRIC CABLES to be as follows:-
Electric cables as generally used heretofore have been constructed of single insu-
lated conductors, either simply bunched together or laid up in spiral layers about a
central wire or strengthening core, by means of an ordinary cabling machine.
In patent No. 6644 granted to me and dated the twenty second day of April 1884,
there is illustrated a cable made up of strands of insulated conductors each strand
being composed of several conductors twisted about each other and any two adjacent
strands of the cable having the spirals of their conductors of opposite direction. The
conductors in the cable there shown were designed to be used in single lines of
ground circuits.
The present invention relates, firstly, to an arrangement of the insulated conductors
in strands of four wires each, spiralled about each other, and six of these strands
spiralled about another one which forms the core or central support for the six in
spiral about it.
Secondly, the combination of the strands thus disposed in cable form with additional
single insulated wires of identical size and insulation with those of the strands, and
which оссиру the depressions or spaces upon the outer contour of the cable between
the converging circles of the strands so as to fill up the general circular form of the
cable and at the same time constitute additional metallic circuits within the same
economized space, which may be arranged or connected anti-inductively with each
other, and thus also act in harmony with the circuits composing the strands, and on
similar principles, the whole forming together a compact round cable, which when
covered with lead, will retain that form and leave no considerable vacant air spaces
within the enclosure.
The particular object of the invention is to prevent the effects of dynamic induc-
tion in telephone service. To accomplish this the conductors of the strands are con-
nected together in pairs as metallic circuits, each pair composing a circuit being the

page_text: two conductors diametrically opposite to each other in each of the strands; and when
the separate wires occupying the depressions upon the outer contour of the cable are
considered, these also are connected together in pairs, each pair forming a circuit
being the two conductors diametrically opposite to each other across the cable.
Such a cable is intended in the telephone service to constitute a trunk line under-
ground between the exchanges, and to be operated in connection with induction
repeaters at the exchanges and by means of such repeaters with the single local
ground circuits of the subscribers associated with the exchanges respectively. When
constituting such a trunk line the cable will usually be extended through considerable
distances and therefore be composed of many sections of regular length connected
with each other. In making such connections between the sections the conductors of
the strands are connected directly across the hand or test boxes, those of each strand
with those of a similar strand of the next section whether of the core in the central
position or of the contour strands, while the single insulated conductors occupying
the contour depressions are connected with each other as follows:-The two conductors
of each pair are connected in the general line so as to cross each other at each connec-
tion or test box and occupy, each the position of the other, alternately, first on the one
side of the cable and then on the side diametrically opposite. It will be seen there-
fore that when the two are connected in metallic circuit at the extreme ends entering
the two exchanges associated with each other the electric current will flow, in such a
circuit, alternately for the sections of the cable, and on the same side of it, in opposite
directions and thus balance or neutralize the inductive action produced for the length
of one section, by that produced for the length of the succeeding section, provided
the precaution has been observed to have the sections of equal length and the cable
composed of an even number of sections.
The anti-inductive arrangement of the metallic circuits composing the strands will
be readily understood by electricians of ordinary experience without further expla-
nation.
Dated the 10th day of June 1886
Dated the 10th day of June 1886.
COMPLETE SPECIFICATION.
Improvements in Electric Cables.
I SIDNEY FORTESCUE SHELBOURNE of 11 Gold Street in the City of New York
and State of New York United States of America counsellor at law, do hereby declare
the nature of my invention for IMPROVEMENTS IN ELECTRIC CABLES and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
Electric cables as generally used heretofore have been constructed of single insu-
lated conductors either simply bunched together or loosely twisted together and used
in separate strands, or laid up in spiral layers about a central strand or strengthening
core by means of an ordinary cabling machine.
In Patent No. 6644, dated the 22nd day of April 1884, I have shown a cable made
up of strands of insulated conductors, cach strand being composed of conductors
twisted about each other and any two adjacent strands of the cable having the spirals

page_text: of their conductors of opposite direction, the conductors as there shown being designed
for use as single lines of ground circuit.
The present invention relates; firstly, to an arrangement of the insulated conduc-
tors in strands of four wires each, spiralled compactly about each other, and six of
these strands laid compactly about a seventh one which forms the core or central
support for the six laid upon or around it; secondly, to the combination of the strands
thus disposed in cable form with additional single insulated wires of identical size
and insulation with those of the strands and which occupy the depressions or spaces
upon the outer contour of the cable, between the converging circles of the strands so
as to fill up the general circular form of the cable and at the same time constitute
additional metallic circuits within the same circle of space as the strands will occupy
and which single conductors may be arranged or connected anti-inductively with each
other and at the same time act in inductive harmony with the circuits composing the
strands, the whole forming together a compact round cable, which when covered with-
lead will retain its round form and leave no considerable vacant air spaces within the
lead inclosure.
The particular object of the invention is to prevent the effects of dynamic induction
in telephone service. To accomplish this the conductors of the strands are connected
together in pairs as metallic circuits through telephonic transmitters and receivers at
or very near the ends of the cable, or through telephonic repeaters at the central
stations, in inductive relation with ground circuit subscriber's lines converging at said
stations or exchanges, each pair, composing a circuit and thus connected, being the
two conductors diametrically opposite to each other in each of the strands. When
the separate wires occupying the depressions upon the outer contour of the cable are
in like manner considered, these also are connected together in pairs, each pair
forming a circuit being the two conductors diametrically opposite to each other across
the cable.
This construction of cable is intended to constitute in telephone service an under-
ground trunk line between the several exchanges, and to be operated from either end
in connection with induction repeaters at the exchanges where the trunk metallic
circuits are related inductively through such repeaters with local subscriber's ground
circuit lines.
As constituting a trunk line as indicated, the cable will usually be extended through
considerable distances and thus composed of many sections of uniform length con-
nected with each other at hand or test boxes, at intervals along the line. In making
such connections between the sections of the cable, the conductors of the strands are
connected directly across the hand or test boxes, those of each strand with those of
a similar strand of the next section, whether of the core in the central position or of.
the contour strands, while the single insulated conductors occupying the contour
depressions are connected with each other as follows: The two opposite conductors
across the cable, forming each pair, are connected together in completed line so as to
cross each other at each hand or test box, and each limb of the outgoing and
returning metallic circuit, occupying, the one the position of the other alternately,
first on the one side of the cable and then on the side diametrically opposite.
The relation and connection of the conductors of both the strands and the separate
added circuits of the cable are shown in Figs. 1 and 2 of the drawing herewith and
forming part of this specification. In the sectional view of the cable, Fig. 1, the
conductors of each strand are numbered for convenience 1, 2, 3, and 4, respectively
while the separate conductors in the contour spaces are numbered from 1+ to 6+,
respectively. While at the hand or test boxes along the line the wires of each of the
strands are connected with those of a similar strand directly across the box by identical
number of the conductors, at the ends of the cable or at the exchanges the conductors
of each strand are connected across the strand; as for instance number 1 with num-
ber 3 and number 2 with number 4, as indicated by the crossing lines in Fig. 1.
In Fig. 2 the connections of the separate single conductors are shown. The four
sections of the cable in the figure present three intermediate hand or test boxes.
Conductor 1+ along the top of the cable is seen to cross downward and become
.

page_text: connected with 4+ at every alternate hand box, while conductor 4+ passes upward and is
connected with 1+ at the appropriate hand box alternately. The direction of the
current and its neutralizing inductive effect upon the strands of the cable, being in
opposite direction for equal distances along cach of the strands, and at equal average
distances from each of the conductors thereof, is indicated by the direction of the
arrows in Fig. 2. A short length of the completed cable, with fibre wrapping or
braiding, and provided with a snug jacket of lead by means of a hydraulic lead press,
is shown in Fig. 3, partly in section and in perspective. It is to be observed that in
furnishing the cable with its lead covering, durability by freedom from corrosion for
a long time will be secured by slightly adulterating the lead with arsenic antimony
or tin.
To secure the best anti-inductive arrangement of the separate single conductors, it
will be observed that a number of sections of cable connected together at the hand
boxes will be essential, and when the sections of the cable are of equal length and
their number divisible by two the most perfect security against dynamic induction
from the separate crossing circuits will be provided.
The conductors in the strands being connected in pairs across their strand and thus
forming two metallic circuits for each strand will necessarily have no dynamic inductive
effect upon each other because each limb of each metallic circuit passing spirally around
the centre of its strand will act inductively as though it was located in the straight line of
that centre; and again because each metallic circuit presents equal and opposite
currents acting inductively from the same general line of space, the inductive ton-
dencies of such currents aro observed to neutralize each other.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. A series of strands forming a lead enclosed electric cable, each strand being
composed of four separately insulated conductors arranged in a close helix about each
other and combined in each of the strands electrically by the connection, at or near
the ends of the cable, of the two conductors diametrically opposite to each other in
said strand as herein described.
2. A lead enclosed electric cable formed of strands of four conductors each, said
strands arranged helically about one of their number constituting the core of the
cable, and each strand connected with its successor in progression between the
sections in the length of the cable by the electrical union of wires of identical
position and number in the same strand or lincal succession of strands, as set forth.
3. In an electric cable, the combination of strands of four insulated conductors
.helixed about each other, with separate single conductors arranged in the converging
spaces between the strands in the contour of the cable, as described.
4. The combination with the strands, and in their converging spaces, as herein
described, of the separate single conductors 1+ to 6+ each in pair with its opposite
diametrically across the cable, the limb of each member of the pair forming a circuit,
being interchanged with that of the other at the junctions of the sections of the cable
made at the hand boxes.
5. Quadruplex strands of insulated conductors and separate single conductors in
combination with each other in such relative position that the single conductors
occupy the converging spaces between the strands on their outer contour when
assembled, the whole forming together an approximately cylindrical cable, said single
conductors being crossed and recrossed each to an opposite side of the cable in its
several sections alternately at the test or hand boxes, as herein described.
Dated this 4th day of March 1887.