IMPROVEMENTS IN INSULATING AND PROTECTING ELECTRIC TELEGRAPH WIRES, AND IN THE MEANS OR APPARATUS EMPLOYED THEREIN
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by the said William Alfred Marshall
at the Office of the Commissioners of Patents, with his Petition, on
the 4th December 1866.
I, WILLIAM ALFRED MARSHALL, of Leadenball Street, in the City of London,
Telegraphic Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN INSULATING AND PROTECTING ELECTRIC TELEGRAPH WIRES,
AND IN THE MEANS OR APPARATUS EMPLOYED THEREIN," to be as follows:
My improvements in insulating and protecting electric telegraph wires
relates to introducing one or more insulated wires within a lead or other
similar soft metal tube at the same time that such tube is being formed, and
to causing an insulating substance in a liquid form to flow into such tube
around the insulated wires, thereby to prevent the insulating covering being
injured by the high temperature of the metal and to fill up the interstices
of and between the insulating covering and the space between the covered
wires and the metal tube. For this purpose each of such wires, whether
previously coated or not, is coiled with silk, cotton, hemp, flax, or other
suitable fibrous substance of a non-conducting character laid helically with an
interval between each coil, and then coated with the substance known as
paraffine wax whilst that substance is in a liquid-state so as to saturate the
fibrous coating therewith and fill up the intervals. There may be two or more
successive coils of the fibrous material laid one over the other, each succeeding
coil being laid in a direction opposite to that preceding; a wire or a series
of them so prepared is then surrounded by the tube of lead or other suitable

page_text: similar soft metal by that tube being formed thereon in a fluid or semi-fluid
state, and the metal tube so formed to enclose the wires is prevented from
coming into immediate contact with the paraffine wax at and for a short
time after the point of formation by the use of an intervening tube or triblet
whilst the paraffine wax is kept sufficiently liquid to flow into and fill up
the space between the wires and the metal tube.
The apparatus I employ in effecting the insulation and protection of the
wires is provided with a reservoir adapted to hold paraffine wax in a fluid
state. The wire or wires which have been coated with a non-conducting
fibrous substance and then immersed in a bath of the paraffine wax until such
fibrous substance has become fully saturated therewith are passed through
the reservoir out at or near the lower part thereof by an orifice sufficiently
large to admit of their passing freely and taking with them a sufficient quantity
of paraffine wax. About this point the molten or semi-fluid lead or such like
soft metal (as tin or pewter) is admitted to flow under pressure around the
wire or series of wires and their coatings, but by preference not in immediate
contact therewith. In order to prevent immediate contact of the fluid or
semi-fluid metal with the coating to the wire or wires, the outlet for the
passage of the wire or wires from the reservoir for the paraffine wax is
provided with a tubular triblet or mandril adapted to keep the wires and
their coating in correct relation, whilst the annular space formed between the
outside of the triblet or nozzle and the interior of another surrounding tube
serves as a guage for the size of the metal tube. The tubular triblet or
mandril is continued by preference until the metal tube is formed and
sufficiently cool to come in contact with the paraffine coating to the wire
or wires. A current or currents of water are admitted to surround the
annular space giving form to the metal tube to aid in cooling it. The soft
metal employed is either forced into the annular space to give form to the
tube by pressure applied to it or by being conveyed from a height adapted
to the pressure required.
The apparatus is also applicable when other insulating substance is employed
in place of paraffine wax to surround the wires.