Improvements in Electric Cables.
Year: 1898

page_text: Date of Application, 23rd May, 1898
Complete Specification Left, 22nd Feb., 1899-Accepted, 6th May, 1899
PROVISIONAL SPECIFICATION.
Improvements in Electric Cables.
I, WILLOUGHBY STATHAM SMITH, of 13, Courtfield Road, South Kensington,
in the County of Middlesex, Electrical Engineer, do hereby declare the nature
of this invention to be as follows:-
This invention has for its object improvements in conductors for electric
cables more particularly submarine cables-whereby the inductive capacity of
such cables is considerably reduced.
In order to obtain the lowest inductive capacity the surface area of the con-
ductor should be as small as possible in proportion to its sectional area, and
were it not for the danger of any single wire breaking, it would be best to use
a solid conductor of cylindrical form.
In practice a strand of seven or more wires of equal diameter or a central wire
surrounded with any number of wires of a smaller diameter is used but by these
methods the surface area is considerably increased.
According to my invention I take a cylindrical wire and lay around it a
thin metal tape or two or more such tapes can be laid around parallel to one
another or two or more layers of such tapes can be superimposed with or with-
out reversed lays to any desired thickness.
A cable thus constructed approaches a solid in regard to surface area whilst
the danger of failure of continuity is avoided.
Whenever necessary, such as for submarine cables, the qylindrical wire is first
coated with an adhesive compound before receiving the metal tape, or if layers
of tapes are superimposed it is advisable to use compound between each layer.
Dated this 23rd day of May 1898.
WILLOUGHBY S. SMITH.
Improvements in Electric Cables.
I, WILLOUGHBY STATHAM SMITH, of 13, Courtfield Road, South Kensington,
in the County of Middlesex, Electrical Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed to be parti-
cularly described and ascertained in and by the following statement:-
This invention has for its object improvements in conductors for electric
cables-more particularly submarine cables-whereby the inductive capacity of
such cables is considerably reduced.
In order to obtain the lowest inductive capacity the surface area of the con-
ductor should be as small as possible in proportion to its sectional area, and
were it not for the danger of any single wire breaking it would be best to use
a solid conductor of cylindrical form.

page_text: In practice a strand of seven or more wires of equal diameter or a central wire
surrounded with any number of wires of a smaller diameter is used but by these
methods the surface area is considerably increased.
According to my invention I take a cylindrical wire and lay around it a
metal tape or strip or preferably as shown in Figure 1 two or more such tapes
or strips are laid around parallel to one another or two or more layers of such
tapes or strips can be superimposed with or without reversed lays to any desired
thickness as shown respectively in Figures 2 and 3.
It is essential that the tapes or strips should be of the same metal as the
cylindrical conductor and practically copper is the only suitable metal for silver
is too expensive.
The tapes or strips may have any desired form and thickness but usually it is
desirable to employ thin tapes as otherwise there is considerable difficulty in
making them lie close to each other and to the central conductor and if thick
strips are employed their edges must be bevelled which is difficult and costly.
A cable thus constructed approaches a solid in regard to surface area whilst
the danger of failure of continuity is avoided.
Whenever necessary, the cylindrical wire is first coated with an adhesive com-
pound before receiving the metal strip or tape, or if layers of strips or tapes are
superimposed it is advisable to use compound between each layer but the various
layers must not be insulated from each other. Such compound may consist of
a mixture of Stockholm tar, resin and gutta percha.
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. The combination of a central cylindrical metallic conductor and a tape or
strip of the same metal as the conductor helically wound on it and in electrical
connection with it.
2. Electric cables substantially as described and illustrated in the drawings.
Dated this 3rd day of February 1800
WILLOUGHBY S. SMITH.