A NEW AND IMPROVED METHOD FOR INSULATING AND PROTECTING ELECTRIC TELEGRAPH WIRES FOR SUBMARINE, SUBTERRANEAN, AND OTHER LINES, WITH IMPROVEMENTS IN THE MACHINERY, AND IN THE PROCESS AND MATERIAL
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by William Alfred Marshall at the
Office of the Commissioners of Patents, with his Petition, on the
2nd August 1866.
I, WILLIAM ALFRED MARSHALL, of Leadenhall Street, in the City of
London, Telegraph Engineer, do hereby declare the nature of the said
Invention for "A NEW AND IMPROVED METHOD FOR INSULATING AND PROTECTING
ELECTRIC TELEGRAPH WIRES FOR SUBMARINE, SUBTERRANEAN, AND OTHER LINES,
WITH IMPROVEMENTS IN THE MACHINERY, AND IN THE PROCESS AND MATERIAL,"
to be as follows:-
Hitherto telegraphic wires for submarine and subterranean lines have been
insulated by means of a covering of gutta percha, india-rubber; or other
analagous substance; but it has always been desired to protect the insulating
material from the injurious effects of the various influences to which it is
subject, by enclosing it in a leaden or other metallic tubing; and several
methods have been suggested and adopted for applying the protective metal
without destroying the insulating substance; but no practical method has
hitherto been devised whereby an insulated wire may be enclosed in. a
metallic tubing while in course of formation; as the high temperature of the
metal when forced out of a machine destroys the insulating medium it
encloses.
Now my Invention relates to a new and improved method of insulating the
wire, and in the arrangement of machinery, and process, and material used,

page_text: whereby a leaden or other metallic tubing may be formed over and upon an
insulated wires or wires, that is to say, a leaden tubing is formed, and while in
course of formation is made to enclose one or more insulated wires without
injury to the insulating medium by the use and application of a material
known as "parafin wax" or other suitable insulating liquid or substance reduced
to a liquid state, which is introduced in and around the covered wire while
the same is being enclosed by the metal, so as to form a moist heat and
prevent the substance around the wire being burned or injured by the high
temperature of the metal.
The conducting wire of any suitable kind is covered with a fibrous substance,
such as silk, cotton, hemp, flax, or any other fibrous substance of a non-
conducting nature to a required thickness (whether the wire has been
previously covered with an insulating substance of a gummy or plastic nature
or not); it is then placed in a bath composed of the parafin wax or other
insulating substance reduced to a liquid state by heat, and after becoming
thoroughly saturated is allowed to cool. The tube may be made by an
ordinary tube-forcing machine, save and except that in order to pass the
covered wire through the interior of the machine so that it may come through
the die with and inside the metal tube, and to keep the liquid supplied round
the wire and into the tube, I have an inner chamber in the metal chamber
of the machine, one end of which is made with a small orifice, or to form a
hollow triblet in the die or nose of the machine where the tube is formed,
and the other end passing through an orifice in the plunger is fixed to the
framework beyond in such manner as to keep its proper position at the die,
and to allow the plunger to act freely along it; the outer end of this interior
chamber is then turned up or otherwise arranged so as to form a vessel to
contain the liquid.
When the metallic tube is being formed, the covered wire passing through
the inner chamber is kept saturated and surrounded by the insulating liquid,
and as. it passes through the small orifice or hollow triblet in the die, where
it is enclosed by the metal, sufficient of the liquid passes with it into the
tube to fill up the interstices in the fibrous material and any cavity between.
it and the metal, rendering the whole when cool a compact insulating body.
between the two metals.
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