IMPROVE- MENTS IN COATING OR COVERING ELECTRIC CONDUCTORS
Year: 1868

page_text: LETTERS PATENT to Matthew Gray, of Highbury Hill, in the County
of Middlesex, Engineer, and Lemuel Gibson, of Silvertown, in
the County of Essex, Foreman, for the Invention of "IMPROVE-
MENTS IN COATING OR COVERING ELECTRIC CONDUCTORS."
Scaled the 24th November 1868, and dated the 22nd June 1868.
PROVISIONAL SPECIFICATION left by the said Matthew Gray and
Lemuel Gibson at the Office of the Commissioners of Patents, with
their Petition, on the 22nd June 1868.
We, MATTHEW GRAY, of Highbury Hill, in the County of Middlesex,
Engineer, and Lemuel Gibson, of Silvertown, in the County of Essex,
Foreman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN COATING OR COVERING ELECTRIC CONDUCTORS," to be as
follows:-
Electric conductors for telegraphic purposes are usually coated or:
covered with gutta percha or other insulating material for the purpose
of insulating them. In this operation as hitherto conducted there is.
great liability of the coating or covering being of unequal thickness,:

page_text: especially when two or more wires are being simultaneously coated in
the same apparatus. This inequality in the thickness of the gutta
percha or other insulating material arises in great measure from the
difference in temperature of different parts of the mass of gutta percha
which is softened by heat in order to bring it into a plastic state, so
that it may be forced out through dies or openings, from which the wire
conductor is made to issue. We have found that when the gum is
very soft and plastic it will issue from the dies with much greater
facility than when it is harder or less soft; it will be evident then that
if one part of the mass be softer than the other the wires will not all be
evenly or equally coated, in fact some will have a thicker coating than
others. This irregularity may be modified by bringing the dies nearer
to or further from the nozzles of the tubes through which the wires pass
until they are adjusted so as to deliver the exact quantity of gutta
percha required.. As, however, when several wires are being coated
simultaneously in the same apparatus some may be found with the
proper thickness of covering while others may have too thin or too thick
a covering, it will be evident that if all the dies or nozzles are fixed in
or form part of the same plate there will be considerable difficulty in
adjusting the apparatus to suit all the wires, and moreover no adjust-
ment can take place without stopping the coating or covering operation.
It is the object of our Invention to so arrange and construct the dies or
nozzles as to be able to effect the required adjustment of any particular
die with facility and while the covering operation is proceeding. To
this end either the dies may be screwed up separately in a fixed common
plate, so that the position of each may be adjusted by itself so as to
approach to or recede from the nozzles of the wire conducting tubes, or
the latter may be mounted in the same manner in a plate in which
each is capable of separate longitudinal motion. This adjustment may
be effected by simply screwing up the dies or tubes in their seats, but
unless the apparatus be made with great accuracy this may give rise to
another inconvenience, and we have found it more convenient to adjust
the dies or nozzles longitudinally without giving them an axial motion.
To this end the conducting tubes are screwed externally at their upper
ends and pass through and work in female screws in pinions, which are
separately actuated by other pinions on counter spindles or shafts
provided with square heads, so that they may be turned by means of a
key. If the dies are made adjustable instead of the conducting tubes
and nozzles they may he actuated in an analogous manner.

page_text: In carrying out another part of our Invention the wires to be covered.
with gutta percha are first coated with a compound composed of gun
balata, rosin, oil, and pitch, made by dissolving 12 lbs. of rosin and 5 lbs.
of pitch in 5 lbs. of oil of tar, and then adding, say, 30 lbs. of gum balata.
The mass should be mixed warm and all the ingredients thoroughly.
incorporated, so as to form a homogeneous mass. When the wires have
been covered with one coating of gutta percha they may receive a second
one in the same manner, but they must previously be a second time
paid over with the gum balata compound, which will cause the second
covering of gutta percha to adhere firmly to the first.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Matthew Gray and Lemuel Gibson in the Great
Seal Patent Office on the 22nd December 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, MATTHEW.
GRAY, of Highbury Hill, in the County of Middlesex, Engineer, and
LEMUEL GIBSON, of Silvertown, in the County of Essex, Foreman, send.
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of June, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Matthew Gray and Lemuel Gibson, Her
special licence that we, the said Matthew Gray and Lemuel Gibson,
our executors, administrators, and assigns, or such others as we, the
said Matthew Gray and Lemuel Gibson, our executors, administrators,
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 "IMPROVEMENTS IN COATING OR COVERING
ELECTRIC CONDUCTORS," upon the condition (amongst others) that we,
the said Matthew Gray and Lemuel Gibson, our executors or adminis-
trators, by an instrument in writing under our, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,

page_text: 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 Matthew Gray, on behalf of myself
and of the said Lemuel Gibson, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement,
reference being had to the Drawing hereunto annexed, and to the letters
and figures marked thereon (that is to say) :-
:-
Electric conductors for telegraphic purposes are usually coated or covered
with gutta percha or other plastic non-conducting material for the
purpose of insulating them. In this operation as hitherto conducted there
is great liability of the coating or covering being of unequal thickness,
especially when two or more wires are being simultaneously coated in the
same apparatus. This inequality in the thickness of the gutta percha or
other insulating material arises in great measure from the difference in
temperature at the moment of the application of the gutta percha to the
wires of different parts of the plastic mass of gutta percha, which is
softened by heat in order to allow of its being forced out through dies
or openings, from which the wire conductor is also caused to issue.
We have found that when the gum is very soft and plastic it will issue
from the dies with much greater facility than when it is harder or less
soft; it will be evident then that if one part of the mass be softer than
the other the wires will not all be uniformly coated, in fact some will have
a thicker coating than others. This irregularity may be modified by
bringing the dies or die plate nearer to or further from the nozzles of
the tubes, through which the wires pass until an adjustment is effected
that will allow of the delivery of the exact quantity of gutta percha
required. As, however, when several wires are being coated simul-
taneously in the same apparatus some may be found with the proper
thickness of covering while others may have too thin or too thick a
covering, it will be evident that if the dies being fixed all the nozzles
form part of, one and the same plate, or vice versa, there will be con-
siderable difficulty in adjusting the apparatus to suit all the wires, and
moreover no re-adjustment can take place without stopping the coating
or covering operation.
Now the object of the first part of our Invention is so to arrange and
construct the dies or die plate with respect to the nozzles as to be able

page_text: to effect the required adjustment of any particular nozzle or die with
facility and while the covering operation is proceeding. To this end
cither the dies may be screwed up separately in a fixed common plate,
so that the position of each may be adjusted by itself so as to approach
to or recede from the nozzles of the wire conducting tubes, or the.
latter may be mounted in the same manner in a plate, in which each
is capable of separate longitudinal motion. This adjustment may be
effected by simply screwing up the dies or tubes in their seats, but
unless the apparatus be made with great accuracy this may give rise to
another inconvenience, and we have found it more convenient to use a
die plate and adjust the nozzles longitudinally without giving them an
axial motion.
This arrangement is shewn in several views in the accompanying
Drawing, where Fig. 1 represents in longitudinal section so much of the
machine used for coating electric telegraph wires as will serve to explain
our improvements therein; Fig. 2 is a back end view of the same; Fig. 3
is a view of the front end; and Fig. 4 is an end view with the die plate
removed.
The diagram Fig. 5 illustrates the mode of fitting this instrument in
the press which feeds it with the plastic gutta percha at such a pressure
as will ensure its discharge readily through the die plate. The press
consists of two cylinders fitted with plungers, which by means of cut-off
valves are enabled alternately to propel forward the gutta percha, and
connected with these and midway between them is a conical seating
for receiving the shaping or moulding instrument, shewn at Fig. 1.
This instrument takes externally the shape of a conical plug, the outer
part or case A being a hollow conical casting with side openings. When
placed in its seat it is held securely therein by clamps or any other
suitable contrivance. Fitted to the front end and rebated edge of this
case A is the die plate A'; it is provided with steady pins which enter
holes in a hollow core B fitted within the case A; this core consists.
of a flattened broad stem cast with two end plates B', B',. which fit
tightly in the case A. Parallel holes are bored through the solid part
of the core to receive tubes C, C, C, (in this instance five in number)
carrying at the outer extremities nozzles c, c, c, which are screwed
therein, and smaller holes b are made through the plate B. The tubes C
are at their rear ends screwed externally, and they are each fitted with
a spur pinion c¹, the boss of which is tapped to work on the screw of

page_text: its tube. Into this pinion gears a pinion d, the spindle of which turns
in bearings formed for it in the plate B² and in a cap plate D which is
made fast to the core plate B by clamping screws d' and covers in the
gearing. The ends of the spindles of the pinions d project through the
cap plate D, and are squared to allow of their receiving a key for giving
them an axial motion for the purpose to be presently explained.
Immediately opposite the nozzles c, c, are the dies a, a, a, which may
be simply holes in the die plate, or may be screwed gauging tubes fitted
to tapped holes in the die plate. The conducting wires it will be
understood are led into the tubes C through their nozzles c and out at
the dies a, and one of the cut-off valves of the press being opened and
motive power applied to the piston the heated gutta percha will be
forced into the case A. Having filled the hollow core the gutta percha
will pass through the holes b, and reaching the die plate will find its
way out at the dies, coating the wires which at the same time are being
drawn out through the dies. If now it is found that one of the dies is
supplying a thicker or thinner coating than is desired to the conducting
wires, the nozzle that is opposite that die will require adjustment
to decrease or increase (as may be required) the discharge of the plastic
non-conducting material. To this end a key is applied to the spindle
of the pinion d which commands the tube that lies opposite the die in
question, and by the pinion on the tube being turned an endway motion
will be given to the tube, and the nozzle which it carries will be
advanced to or withdrawn from the die according to the necessities of
the case. In this way the delivery of any of the dies may be adjusted
without interrupting the action of the apparatus. If the dies are made
adjustable instead of the conducting tubes and nozzles (an arrangement
which we do not prefer) they may be actuated in an analogous manner
to that described.
A further improvement in coating electric conductors consists in
treating the wires which are to be covered with gutta percha with a
preparatory coating for facilitating the adhesion of the gutta percha to the
wire. This coating consists of a compound composed of gum balata,
rosin, oil, and pitch, made by dissolving twelve pounds of rosin and
five pounds of pitch in five pounds of oil of tar, and then adding, say,
thirty pounds of gum balata. The mass should be mixed warm and all
the ingredients thoroughly incorporated so as to form a homogeneous mass.
When the wires have been covered with one coating of gutta percha

page_text: they may receive a second one in the same manner, but they must
previously be a second time paid over with the gum balata compound,
which will cause the second covering of gutta percha to adhere firmly to
the first.
Having now set forth the nature of our Invention of improvements
in coating or covering electric conductors, and explained the manner
of carrying the same into effect, we wish it to be understood that under
the above in part recited Letters Patent we claim,―
First. Equalizing the thickness of the covering applied to clectrical
conducting wires by the means above described.
Secondly. Applying to electric conductors the preparatory coating for
the purpose above set forth.
In witness whereof, I, the said Matthew Gray, have hereunto
set my hand and seal, the Twenty-second day of December,
in the year of our Lord One thousand eight hundred and sixty-
eight.