AN IMPROVEMENT IN THE MANUFACTURE OF COVERED ELECTRICAL CONDUCTORS
Year: 1869

page_text: LETTERS PATENT to Matthew Gray, of Highbury Hill, in the County
of Middlesex, Engineer, for the Invention of "AN IMPROVEMENT
IN THE MANUFACTURE OF COVERED ELECTRICAL CONDUCTORS."
Sealed the 13th April 1869, and dated the 20th February 1869.
PROVISIONAL SPECIFICATION left by the said Matthew Gray at the
Office of the Commissioners of Patents, with his Petition, on the
20th February 1869.
I, MATTHEW GRAY, of Highbury Hill, in the County of Middlesex,
Engineer, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN THE MANUFACTURE OF COVERED ELECTRICAL CONDUCTORS," to he
as follows:-
The object of this Invention is to improve the manufacture of covered
electrical conductors by removing or reducing the liability which the
conducting strands or wires have to lose their central position in the
india-rubber covering during the vulcanizing process, and so far
increasing the strength of the covering that the electric conductor may,
if desired, be safely used without the addition thereto of a hempen or

page_text: metallic covering The conducting wire or strands of copper I enclose,
first, in pure india-rubber, and then overlay this covering with a plastic
compound of india-rubber and sulphur; I then lap or coil helically
around this compound (while still in a green or uncured state) a tape
or strip of cotton or other suitable fabric. This cloth covering I pay
over with a solution of the rubber compound, and I prepare the face of
a second tape or strip of cloth with the like solution; I then lap this
coated cloth or tape (the prepared surface inwards) around the coated
wire, coiling it however in the opposite direction to that of the first cloth
covering, and I am thus enabled effectually to close all the joints of
the inner cloth covering.
The electrical conductor thus prepared I submit to heat to produce
the "change" in the india-rubber compound, whereby it is converted
into vulcanized rubber, and as the joints in the cloth covering are
effectually closed no oozing out of the compound through the joints will
take place, and consequently the tendency of the wires or strands to
lose their central position will be avoided. Moreover the cloth strips
or tapes will become firmly united to the rubber compound and will
enable the electrical conductor to bear a considerable longitudinal strain
without injury. Wires thus coated may be used as cores for submarine
telegraph cables or be used without any additional protection both on
land and in the water.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Matthew Gray in the Great Seal Patent Office on
the 20th August 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MATTHEW
GRAY, of Highbury Hill, in the County of Middlesex, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of February, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Matthew Gray, Her special licence that I,
the said Matthew Gray, my executors, administrators, and assigns, or
such others as I, the said Matthew Gray, my executors, administrators,

page_text: and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "AN IMPROVEMENT IN THE MANUFACTURE OF
COVERED ELECTRICAL CONDUCTORS," upon the condition (amongst others) that
I, the said Matthew Gray, my executors or administrators, by an
instrument in writing under or their, or one of their hands and
scals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters.
Patent.
NOW KNOW YE, that I, the said Mathew Gray, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement (that is to say) :-
The object of this Invention is to improve the manufacture of covered
electrical conductors by removing or reducing the liability which the
conducting strands or wires have to lose their central position in the
india-rubber envelope in which they are enclosed while the vulcanizing
of the insulating compound forming the envelope is proceeding. In
carrying out this improvement I so far increase the strength of the
electric conductor as to admit (when desired) of the conductor being
safely used without the addition thercto of a hempen or metallic
covering. The conducting copper wire, or it may be strands of fine
copper slightly twisted to cause them to hold together, I enclose first
in pure india-rubber in the ordinary way of insulating conducting wires.
This insulated core I overlay with a plastic compound of india-rubber
and sulphur of any required thickness, applying the same by means of
the machine shewn and described in the Specification of the Patent
granted to me in conjunction with Frederick Hawkins, and bearing date
the Eleventh August One thousand eight hundred and sixty-eight, or
I may employ any other suitable machinery for the purpose; I next lap
or coil helically around this coating of india-rubber and sulphur
compound (while still in a green or uncured state) a tape or strip of
cotton or other suitable fabric measuring, say, an inch (or more or less)
in breadth. This cloth covering I pay over with a solution of the

page_text: rubber compound, and I prepare the face of a second tape or strip of
cloth of similar quality and breadth with the like solution; I then lap
this coated cloth or tape (the prepared surface inwards) around the
coated wire, laying it however in the opposite direction to that of the
first cloth covering. By this means I am enabled effectually to close
all the joints of the inner cloth covering, and I thereby obtain an
important result. Or instead of coiling the first cotton tape helically
around the coating of india-rubber and sulphur compound, I sometimes
put on this cotton coating longitudinally at the same time and in the
same manner as the compound by means of rollers, such as those
described in the Specification above referred to, that is to say, I lead
two tapes or strips of cloth to a pair of grooved compressing rollers, into
the grooves of which the coated wires are led as they pass from the
rollers which have covered the wires with the compound. The width
of the tapes or cloth employed will depend upon the diameter and
number of the covered strands under manufacture, and the compressing
rollers as they rotate will shear the cloth into strips of suitable width
for covering the strands and at the same time press the strips around
the coated wires; over this covering the second cotton covering or
tape is then to be laid helically as above described.
The electrical conductor prepared as above explained I next submit to
heat to produce the well-known "change" in the india-rubber compound,
whereby it is converted into vulcanized rubber. As the joints in the
cloth covering are by the mode of applying the cloth effectually closed
no oozing out of the heated compound through the joints will take place
as heretofore, and consequently the tendency of the wires or strands to
lose from this cause their central position in the insulating compound
will be avoided. Moreover the cloth strips or tapes will become firmly
united to the rubber compound and will enable the electrical conductor
to bear a considerable longitudinal strain without injury.
The usual mode of vulcanizing covered electrical conductors is to
make them up into loose coils like a coil of rope and to put them in this
form into the heat to be vulcanized. This mode has the disadvantage of
putting twists or turns into the conducting wires, which causes them at
certain points to press through the rubber whilst in the process. of
vulcanization and destroy or deteriorate the insulation. To prevent this
I take a large hollow iron cylinder or drum covered on the outside with
a soft substance, such as cotton, and on this I wind the covered con-

page_text: ductor in a regular and uniformn manner by causing the drum to rotate,
and thereby prevent any twists from being put into the conductor or
any unequal pressure on its surface. I then put this drum into the
heated or vulcanizing chamber and vulcanize the rubber in the usual
way. The drum being hollow and open at the ends will allow of a
smaller drum similarly laden with a covered electrical conductor being
placed therein, and this second drum may contain a third, and so on,
whereby the space in the vulcanizing chamber will be economized to its
fullest extent.
Electrical conductors manufactured as above described may be used
as cores for submarine telegraph cables, or they may without any
additional protection be used both on land and in the water. In the
latter case I may find it desirable to increase the thickness of the
coating.
Having now set forth the nature of the Invention of "An Improve-
ment in the Manufacture of Covered Electrical Conductors, and
explained the manner of carrying the same into effect, I wish it to be
understood that under the above in part recited Letters Patent I lay no
claim to the covering of wire strands with india-rubber compound or to
the use of binding tapes irrespective of their special use and the stage
(in the manufacture) of their application; but what I claim is, the
means described for ensuring the central position of the conducting
wire or strands in the insulating compound.
In witness whereof, I, the said Matthew Gray, have hereunto set
my hand and seal, the Twentieth day of August, in the year of
our Lord One thousand eight hundred and sixty-nine.
MATTHEW GRAY. (L.S.)