Improvements in Insulating Electric Wires.
Year: 1890

page_text: Date of Application, 18th Feb., 1890
Complete Specification Left, 13th Nov., 1890-Accepted, 17th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Insulating Electric Wires.
I, JOHN EDWARD KINGSBURY of 79 Coleman Street in the City and County of
London Manager, (a communication to me from abroad by the Western Electric
Company of Chicago Illinois United States of America) do hereby declare the nature
of this invention to be as follows:-
This invention relates to insulating wires with fibrous material and its object
is to provide an insulation which shall be sufficiently high and at the same time of
comparatively low static capacity.
Heretofore various fibrous substances have been employed for insulating electrical
conductors; cotton, jute, silk, paper, hemp, and in fact almost every fibrous substance
capable of being wound thereon.
Jute has also been wound directly upon the wire in combination with an exterior
serving of cotton. Such an insulation has proved highly satisfactory as to insulating
properties, its static capacity, however, has not been so low as is desirable, especially
in telephone cables.
By the use of sisal wound directly upon the wires and bound thereon by an exterior
serving of cotton or other fine fibrous material which may be spun fine enough to
admit of being securely tied without unduly increasing the bulk by the size of the
knots the insulation of conductors of cables may be as high as is obtained by the use
of jute and cotton, while the static capacity thereof will be much lower than it is
possible to obtain when jute of the same thickness is used. The reduction in static
capacity thus obtained is found to be ten per cent, more or less according to the peculiar
conditions in each case.
The sisal is of such coarse fibre that it cannot be practically held in place without
an outside serving, the serving of cotton, is however, also of advantage on account of
its greater hydroscopic properties; several such insulated conductors may be twisted
together to form the core of a cable.
While it has been found that pure sisal is the best fibrous substance heretofore
employed for insulating purposes on account of its low static capacity, yet its fibre is
so short that in order to obtain yarn fine enough for certain classes of cable it has
yarn
been found necessary to mix manilla with the sisal and use instead of clear sisal
a yarn composed of a mixture of inanilla and sisal. The manilla in this case is used
simply for mechanical reasons; it is a substance of comparatively low static capacity
somewhat lower than cotton or jute but not so low as sisal.
The result which must be obtained mechanically is that the finished insulated wire
shall have as nearly as possible a circular section of the same diameter throughout its
entire length. This smooth and even exterior may be obtained notwithstanding the
use of hard and coarse fibre by simply using on the outside a serving of fine yarn like
cotton. The invention is therefore not limited to the use of pure sisal yarn when for
mechanical reasons it is necessary to have it spun finer than it is practicable to make
without mixing the sisal with some material having a longer fibre.
Dated this 19th day of February 1890.

page_text: Improvements in Insulating Electric Wires.
I, JOHN EDWARD KINGSBURY of 79 Coleman Street in the City and County of
London Manager, (a communication to me from abroad by the Western Electric
Company of Chicago Illinois United States of America) 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 :-
This invention relates to insulating wires with. fibrous material and its object is to
provide an insulation which shall be sufficiently high and at, the same time of com-
paratively low static capacity.
Heretofore various fibrous substances have been employed for insulating electrical
conductors, cotton, jute, silk, paper, hemp, and in fact almost every fibrous substanco
capable of being wound thereon.
Jute has also been wound directly upon the wire in combination with an exterior
serving of cotton. Such an insulation has proved highly satisfactory as to insulating
properties, its static capacity, however, has not been so low as is desirable, especially
in telephone cables.
By the use of sisal wound directly upon the wires and bound thereon by an exterior
serving of cotton or other fine fibrous material which may be spun fine enough to
admit of being securely tied without unduly increasing the bulk by the size of the
knots the insulation of conductors of cables may be as high as is obtained by the use of
jute and cotton, while the static capacity thereof will be much lower than it is possible
to obtain when jute of the same thickness is used. The reduction in static capacity
thus obtained is found to be ten per cent. more or less according to the peculiar con-
ditions in each case.
My invention is illustrated in the accompanying drawing, in which
Figure 1 is a perspective view of a single conductor covered with sisal, the sisal
being tied on by a serving of fine yarn.
Figure 2 is a sectional view of a cable consisting of several such insulated
conductors.
The conductor a is wound with sisal b and at the same operation the serving cof
cotton or like strong fine yarn is wound thereon so as to hold the sisal in place; the
sisal is of such coarse fibre that it cannot be practically held in place without such an
outside serving, the serving of cotton however, being of advantage, on account of its
greater hydroscopic properties; several such insulated conductors may be twisted
together to form the core of a cable as illustrated in Figure 1 and I have found that
such a cable is the most satisfactory, especially for telephonic purposes of any with
which I am familiar.
While it has been found that pure sisal is the best fibrous substance heretofore
employed for insulating purposes on account of its low static capacity, yet its fibre is
so short that in order to obtain yarn fine enough for certain classes of cable it has been
found necessary to mix manilla with the sisal and use instead of clear sisal yarn a
yarn composed of a mixture of manilla and sisal. The manilla in this case is used
simply for mechanical reasons; it is a substance of comparatively low static capacity
somewhat lower than cotton or jute but not so low as sisal.
The result which must be obtained mechanically is that the finished insulated wire
shall have as nearly as possible a circular section of the same diameter throughout its
entire length. This smooth and even exterior may be obtained notwithstanding the
use of hard and coarse fibre by simply using on the outside a serving of fine yarn
like cotton. The invention is therefore not limited to the use of pure sisal yarn when
for mechanical reasons it is necessary to have it spun finer than it is practicable to
make without mixing the sisal with some material having a longer fibre.

page_text: 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 [
claim is :-
1. The combination of a wire with sisal wound directly thereon, said sisal being
bound to the wire by a serving of cotton, or other fine fibrous yarn substantially as and
for the purpose specified.
2. The combination with an electric wire, of an insulating clothing therefor
consisting of sisal bound about the same, substantially as and for the purpose
specified.
3. A cable consisting of electric conductors, insulated one from another with sisal,
the sisal being held in place by an exterior serving of fine yarn, substantially as and
for the purpose specified.
J. E. KINGSBURY.