Improvements in Electric Cables.
Year: 1892

page_text: Date of Application, 20th June, 1892
Complete Specification Left, 23rd Feb., 1893-Accepted, 25th Mar., 1893
"
PROVISIONAL SPECIFICATION.
Improvements in Electric Cables.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the
City of London, Civil Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention (a communication to me from the firm of Felten &
Guilleaume, of Mülheim on the Rhine, in the German Empire, Cable Manu-
facturers,) to be as follows:-
This invention relates to electric cables the conductors of which are partially
enclosed within and insulated by air-spaces, with the object of reducing the
capacity."
In such cables it is of importance that the air-spaces should be protected
throughout against humidity or moisture, and that any sheathing with which the
cable may be provided for protection against physical injury should not, by pressing
on the core, deform the air-spaces.
In carrying out this invention, the cable is preferably constructed as follows:-
The twisted strip or core containing the air-spaces or channels is provided with a
coating of lead, which may be applied by means of a lead press. Outside the lead,
one coating or more of gutta-percha is or are put on by a gutta-percha covering
machine; the lead coating preventing the gutta-percha in the soft state in which it
is used in the covering machine from penetrating into the air-spaces or channels.
A serving of textile material, such as hemp yarn, is then applied. Over the
serving of textile material is put a sheathing of interlocked wires, which form a
flexible tube. The interlocked wires do not effect any pressure upon the core, but
they preserve the latter from injury resulting from rough usage and thus preserve
the air-spaces or channels from being crushed or distorted.
In cases where the cable contains more than one core or group of conductors,
each may be provided with the sheathings of lead and gutta-percha before they are
twisted together to form a strand. Or, the several cores or groups may be first
twisted together and the sheathings of lead and gutta-percha afterwards applied.
In either case, the serving of textile material and the sheathing of interlocked
wires are applied to the strand or cable as a whole.
Dated the 20th day of June 1899
G. G. M. HARDINGHAM.
COMPLETE SPECIFICATION.
Improvements in Electric Cables.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the
City of London, Civil Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention (a communication to me from the firm of Felten &
Guilleaume, of Mülheim on the Rhine, in the German Empire, Cable Manu-
facturers,) 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 electric cables the conductors of which are partially
enclosed within and insulated by air-spaces, with the object of reducing the
"capacity."
In such cables, it is of importance that the air-spaces should be protected
throughout against humidity or moisture, and that any sheathing with which the
cable may be provided for protection against physical injury should not, by pressing
on the core, deform the air-spaces.

page_text: The accompanying drawings represent a cable constructed according to my
improved method, Fig. 1 being an elevation showing the several constituent parts,
and Fig. 2 being a transverse section.
In carrying out this invention, the cable is preferably constructed as follows:-
a is a twisted strip of non-conducting material formed in such a manner as to present
channels or air-spaces b. c c¹² care conducting wires, each insulated from the
others by the non-conducting material a, and about which is wrapped a covering d
of paper or other non-conducting material. e is a lead sheathing which supports
gutta-percha coverings ffl. g is a serving of soft material, such as hemp yarn,
about which is applied a metal sheathing consisting of wires h h¹² &c. formed and
arranged in such a manner as to interlock with one another and to afford to the
parts enclosed by the sheathing protection from external pressure. k is an external
serving of tarred hemp or the like for the protection of the metallic sheathing last
referred to. By these means, the air-spaces in which the conductors lie are
preserved from being crushed or distorted as the result of rough usage. Although
in the present illustration four conducting wires are shown, it will be obvious that
six or other number desired may be employed, the strip of non-conducting material a
being formed with a corresponding number of air-channels b.
In cases where the cable contains more than one core or group of conductors,
each may be provided with the sheathings of lead and gutta-percha before they are
twisted together to form a strand. Or, the several cores or groups may be first
twisted together, and the sheathings of lead and gutta-percha afterwards applied.
In either case, the serving of textile material and the sheathing of interlocked wires
are applied to the strand or cable as a whole.
I am aware that lead sheathings have been employed in the manufacture of
cables wherein the conductors are arranged in air-spaces; but in those construc-
tions the lead sheathing is employed for the purpose of protecting the cable from
moisture, whilst according to my invention the function of the lead sheathing is to
support a waterproofing material, such as gutta-percha, which is applied in a plastic
state and which, except for the presence of the lead sheathing, would fill the said
air-spaces.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. An electric cable consisting of a series of naked conductors c c² c² &c.,
respectively occupying air-spaces bbb &c. in a spirally grooved strip of non-
conducting material a, a lead sheathing c, gutta-percha or like waterproof coating f
and a metallic sheathing composed of interlocked wires such as h h h² &c., substan-
tially as herein described.
2. In an electric cable of the kind herein referred to and in which the several
naked conductors are respectively arranged in separate air-spaces, sheathing such
core with lead for the purpose of supporting a gutta-percha or like waterproof
coating, substantially as herein described.
3. In an electric cable, the combination, with a series of naked conductors c c¹ c²
&c., respectively occupying air-spaces 61 62 &c. in a spirally grooved strip of non-
conducting material a, of a metallic sheathing composed of interlocked wires such
as h h h &c. insulated from the aforesaid central group of parts, and serving to
protect the same from distortion, substantially as herein set forth.
Dated the 17th day of February 1893.
G. G. M. HARDINGHAM.