An Improvement in Electric Cables and Insulating and Protecting the same.
Year: 1887

page_text: Date of Application, 5th Apr., 1887.
Specification Accepted, 6th May, 1887.
COMPLETE SPECIFICATION.
An Improvement in Electric Cables and Insulating and Protecting
the same.
I, THOMAS HARRISON DUNHAM, of Boston, in the County of Suffolk, Massachusetts,
United States of America, Ropemaker, 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:-
:~
I illustrate my invention by the accompanying drawing in which Figure 1 is a
side elevation in detail of my invention. Figure 2 is a transverse section of the same.
Similar letters refer to similar parts in both figures. In Figure 1 for the purpose of
illustration the inner core is represented with ten wires and the outer covering with
four wires.
:
In Figure 2 for the purpose of illustration the inner core is represented with forty
wires and the outer covering with thirteen wires. Heretofore electric cables have
been covered with lead and also with other metals as an outer covering which are
liable to corrosion and are very heavy and also with gutta-percha or similar
substances which do not allow a bend or turn in any cable in any easy or ready
manner twisted silk and similar substances have been used but these do not protect
the wires from exposure. The object of my invention is to insulate wire or wires
with a light and flexible covering, and to make a cable which is easily handled,
durable, flexible and waterproof and which at the same time secures perfect insulation.
To carry my invention into effect I take a sheet of untwisted raw cotton or raw
silk, the one being an equivalent of the other, and form it into a tube shape E.
wire or wires F to be insulated are then placed in said tube E before said tube is
closed as shown in Figure 1 and the same is then closed around the wire or wires F
and pressed thereon as shown in Figure 2 by the use of any suitable device. Said
wire or wires F thus covered are then put into a core as shown in Figure 2. I then
cover this core with an oakum D of cotton filled with resin, pitch and tar, which
oakum D serves as a waterproof protection and a soft pad or cushion for the covered
wire or wires F. I then take iron wires C, O, and cover them with cotton B which
I saturate with resin, pitch and tar, not necessarily but preferably in the proportion
The

page_text: one third each. These iron wires C, C; which may be one or more in the same
strand, when covered thus I put on over the inner strand under solid heavy pressure
by any suitable device twisting them as strands as shown in Figure 1 each covered
wire or wires C, C having a distinct place and formed with each and all the others in
regular manner making à compact cable A.
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. In an electric cable the combination of the core of the electric wires thereof with
untwisted raw cotton or raw silk, said cotton or silk being saturated with a solution
of resin, pitch and tar, substantially in the manner and for the purpose described.
2. In an Electric Cable, the covering and protecting the core of electric wires
thereof by one or more iron wires covered with untwisted raw cotton or raw silk
saturated with a solution of resin, pitch and tar and twisted around the core
substantially in the manner described and for the purpose set forth..
3. An electric cable with each of the electric wires thereof covered with untwisted
raw cotton or raw silk; the entire core of said wires being covered with said raw
cotton or raw silk saturated with a solution of resin, pitch and tar, and the whole core
covered and protected by a shield composed of one or more iron wires covered with
said raw cotton or silk saturated with said solution of resin, pitch and tar, and
twisted around said core substantially in the inanner described and for the purpose
set forth.
Dotal thin Twont sichth day of Tab 1987
THOMAS HARRISON DUNHAM.