Improvements in Telephone Cables.
Year: 1892

page_text: Date of Application, 5th Apr., 1892-Accepted, 7th May, 1892
COMPLETE SPECIFICATION.
Improvements in Telephone Cables.
I, JOHN EDWARD KINGSBURY, of 79 Coleman Street, in the City of London,
Manager, (a communication to me from abroad by The Western Electric Company
of Chicago, Illinois, U.S.A.,) do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
This invention has reference to the making of telephonic cables and its objects
are to so cover the wires that air spaces may be left between them and also to so
dispose the wires of the cable that "cross-talk" between the different circuits
may be prevented.
Heretofore paper tape has been used as an insulator or clothing for the different
wires of cables, but the tape having been of uniform consistency and wound on
of uniform thickness no air spaces have been left between the wires.
In this invention paper tape is employed which is corrugated transversely at
the centre, the edges being left unbroken so that the tape may have sufficient
strength to permit it to be wound upon the wire; a cable is also formed, the
separate wires of which are insulated by paper tape corrugated transversely at
the centre; said tape when wound upon the wires becomes contracted or puckered
at the centre on account of such softening or partial cutting away of the centre so
that the thickness of the covering composed of the central or corrugated portion of
the tape will be greater than at other portions thereof. In this manner a spiral ridge
of loose texture or consistency is formed about each wire. As many layers of
such paper tape may he wound about each wire as may be desired. It has been
found that two layers of sixty pound paper in strips five eighths of an inch wide
are sufficient to cover a No. 18 B. and S. gauge conductor to a diameter of an
eighth of an inch.
Heretofore it has been usual to twist the wires together in pairs with a regular
and uniform twist and make use of the different pairs for metallic circuits. The
object of twisting the wires in pairs, as heretofore employed, is to provide that the
two limbs or sides of the same circuit may be placed as nearly as possible in the
same position with respect to the other wires of the cable, in order that the currents
induced in the two sides of the same pair may neutralize one another.
It is evident that if the two wires constituting a pair are not in the same relative
position with respect to the circuit from which the induced currents are received,
that the current in one wire of a pair will not be equal to the current in the other
wire of the same pair, and hence there will be resulting cross talk. In cables laid
up as heretofore such want of harmony as between the wires of a pair and the
circuit from which the induced currents are received, may be occasioned by two
adjacent pairs starting at the same relative positions of their twists, so that there
will be a parallelism of the four wires constituting the two pairs throughout the
entire length of the cable, the case being the same as using the two adjacent wires
of a strand of four, instead of the two diagonally opposite wires of the same strand
for the two branches of the circuit. It is evident that if the twist of one of the
strands constituting a pair of wires was of a different pitch from that of the other
parallel strand, there would not be that harmful parallelism, as between the two
strands which results in objectionable cross talk.
According to this invention the wires of the strands or pairs are twisted together
at a different pitch, or at different degrees at alternate sections, and two or more of

page_text: such strands are combined into a cable so that parallelism between the two wires of
any two different strands may be avoided.
Telephone cables are also laid up in pairs, with the strands constituting the
different pairs having a different amount of twisting at alternate sections.
The invention is illustrated in the accompanying drawing, in which-
Figure 1 is an enlarged edge view of a strip of paper embodying the invention.
Figure 2 is a plan view of the same.
Figure 3 is an elevation of a single wire insulated with the paper tape.
Figure 4 is a plan view of a piece of paper tape in which the central portion is
perforated or partially cut away.
Figure 5 is an end view of a cable composed of seven wires embodying the
invention, the air spaces being shown between the different wires.
Figure 6 is a view of a portion of a strand having its wires at different sections.
twisted to a different pitch or degree;
Figure 7 is an enlarged view, showing two such strands thus twisted together
and placed side by side, so that sections having different degrees of twisting will
be opposite one another.
Like parts are indicated by similar letters of reference throughout the different
figures.
The tape a may be corrugated and cut in the centre b as indicated in Figures 1,
2 and 3 by running the same through cogged wheels, the cogs being of the required
width. In this manner the central portion of the tape is torn and stretched and
thereby softened so that when wound upon a wire as shown in Figure 3 this
central portion 6 will take the form of a spiral ridge. Any desired number of
thicknesses of tape may be wound about the different wires; when formed into a
cable as shown in Figure 5 there will be air spaces between the wires, thus
making the electrostatic capacity of the cable much less than that of cable wound
with ordinary tape.
In Figure 4 I have shown perforations d at the centre of the tape. When tape
thus partially cut away at the centre is wound upon the wire it is evident that air
spaces will be formed where the paper has been removed. Thus the desired result
will be accomplished.
The manner of making these perforations or of corrugating the tape at the centre
is immaterial so long as the tape when wound upon the wire will leave air spaces
between the wires.
It has been found that the tape corrugated at the centre as shown in Figures 1
and 2 is preferable to the form shown in Figure 4, since the corrugation and
cutting may be made at the same time the tape is being wound on to the bobbins,
while cutting in the manner shown in Figure 4 requires special machinery.
The invention admits of other modifications which would readily suggest
themselves to those skilled in the art, and I therefore do not limit myself to the
precise details of construction illustrated and described herein.
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. As an article of new manufacture a paper tape for insulating purposes cut at
the centre transversely, substantially as and for the purpose specified.
2. As an article of new manufacture a cable composed of wires insulated with
paper tape, said paper tape being cut centrally, and wound upon the wires, whereby
air spaces are formed between the wires to reduce the electrostatic capacity of the
cable, substantially as and for the purpose specified.
3. The combination with electric wires, of paper tape separately wound upon
said wires, said paper being cut centrally to form transverse corrugations and
thereby spiral ridges about the wires, said wires being formed into a cable, sub-
stantially as and for the purpose specified. .

page_text: 4. The combination of two or more pairs of wire, the wires constituting the
different pairs being twisted together with an undulating or varying degree of
twisting, said strands being laid in the same cable to "break joints" with respect
to the different undulations of twisting, whereby cross talk is prevented, substan-
5 tially as and for the purpose specified.
Dated this 2nd der of A1 1900
J. E. KINGSBURY.