IMPROVE IN THE CONSTRUCTION OF SUBMARINE TELEGRAPHIC CABLES, AND IN THE MEANS OF PROTECTING THE SAME FROM UNDUE STRAIN OR WEAR AND TEAR
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by David Ker at the Office of the
Commissioners of Patents, with his Petition, on the 9th February
1861.
I, DAVID KER, of Plymouth, in the County of Devon, Superintendant of
Works, do hereby declare the nature of the said Invention for "IMPROVE
IN THE CONSTRUCTION OF SUBMARINE TELEGRAPHIC CABLES, AND IN THE
MEANS OF PROTECTING THE SAME FROM UNDUE STRAIN OR WEAR AND TEAR,"
to be as follows:-
My Invention of improvements in the construction of submarine telegraphic
cables, and in the means of protecting the same from undue strain or wear
and tear, relates, first, to a novel mode of constructing the cable, so that the
electric conductor may be more effectually insulated and protected from
damage than heretofore; and second, to a novel mode of protecting telegraphic
cables from abrasion or injury in cases where from its position and other
circumstances it may be exposed or liable to injury.
The core of the cable, and which constitutes the electric conductor, is
formed of copper wire, either single or two or more twisted together in the
usual manner. This conductor is covered or coated with a composition com-
posed principally of gutta percha, with a small admixture of vegetable or
other wax, by the addition of which tho insulating properties of the gutta
percha or composition are materially improved. The conductor thus pro-
tected is enclosed within a tube made of copper, zinc, tin, composition, or other

page_text: metal for the purpose of preventing the insulating compound from being
squeezed out or detached from the conductor. The metal tube is coated or
painted over with a waterproof composition, such as marine glue or gutta
percha and tar melted together, and made thin enough to be applied with
facility. A covering of whalebone, sliced cane, or tough wood of any sort,
suitably prepared, is then laid round the cable, and another coating of marine
glue or composition is applied, and a spiral covering of zinc or other metal cut
into strips of suitable width is then laid round, so that the flat part of the
metal lies upon the cable, thus presenting a wide surface, which is not liable
to cut into the composition.
I would observe that three or more layers of whalebone, cane, or prepared
wood, and also of helical metal coverings, may be employed if desired. The
number of these protecting coverings and their disposition in the cable must,
of course, depend upon the particular circumstances under which the cable is
to be used. The external metal covering may also be secured by an outer
covering of twine or string coated with tar or other suitable material or
composition.
Telegraph cables of this kind will be lighter and stronger that those usually
constructed, and may be frequently used without further means of protection;
but under some circumstances it will be found absolutely necessary to afford
additional protection not only against abrasion or wear and tear, but also
against undue strain.
To this end I propose to employ the second head of my Invention, which
consists in adapting or attaching the above or other submarine telegraphic
cables to a chain cable of suitable strength and dimensions. Although the
desired object may be attained by securing the telegraphic cable to a single
chain cable of the ordinary kind, or by enclosing it between two or more cables
of the same kind, I prefer to construct chain cables expressly for the purpose,
and in so doing I prefer to make the links long, and with holes through their
ends, through which the telegraphic cable may be passed, so that it will lie
between the side pieces of the links, whereby it will be protected from abrasion,
and any undue strain that may be put upon the cable will be resisted by the chain.
A convenient form of link for the above purpose is one resembling an elongated
shackle, but other forms of link may be employed as above mentioned, if
desired.