IMPROVE- MENTS IN COVERING WIRE OR OTHER SUITABLE CONDUCTORS WITH INSULATING PROVISIONAL SPECIFICATIONINERYOY IN
Year: 1872

page_text: LETTERS PATENT to Edwin Thomas Truman, of Old Burlington
Street, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN COVERING WIRE OR OTHER SUITABLE CONDUCTORS WITH INSULATING
PROVISIONAL SPECIFICATION left by the said Edwin Thomas Truman
at the Office of the Commissioners of Patents, with his Petition,
on the 15th February 1872.
I, EDWIN THOMAS TRUMAN, of Old Burlington Street, in the County
5 of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN COVERING WIRE OR OTHER SUITABLE CONDUCTORS WITH
INSULATING MATERIALS, AND IN MACHINERY EMPLOYED IN THE COVERING PROCESS,"
to be as follows:-
-
My Invention relates to an improved process of covering wires or
strands intended for use as conductors of electric currents with insulating

page_text: materials, in which process improved machinery, such as is herein-after
described, is to be employed.
It has been usual heretofore to cover the conducting wires used for
submarine or subterranean telegraphs, or analogous purposes, with several
coatings of insulating materials, and in the case of gutta percha being
employed as the covering material, to which I am about more particu-
larly to refer, it is usual to allow one coating to become cold before a
second is added. This has been necessary because this material when
rendered plastic by the usual processes and applied to the wire allows
the wire to bend or sag, and the insulating material being left un-
touched is liable to fall away from the wire in parts, or the wire is apt to
shift from its central position relatively to the surrounding insulating
material, and to cut into the upper portion of that material as it leaves
the covering apparatus before it has had time to cool and set by passing
as is now usual into cold water.
Gutta percha being a very bad conductor of heat cools very slowly,
and therefore unless the quantity put on the wire at one time is very
small, so as to place a very thin covering, the cooling process is not
sufficiently completed before the wire loses its central position. These
thin layers of gutta percha require to be dried or set. before a second is
superadded, and as gutta percha will not properly adhere if one surface
of the material is cold, except under strong pressure, it is usual to pass
the wire, after each comparatively thin coating of gutta percha has set,
through a hot adhesive compound, which forming a thin adhesive layer
over the gutta percha cements the outer coating to the preceding inner
one, and they are again cooled together. It is usual in this way to
build up as it were the gutta percha and apply the thin coating layer
upon layer, and thereby give the wire a more or less central position;
but with the greatest care and most skillful management this is not
always possible, and as the thinnest point of the covering may be said to
govern the insulation of the entire cable, defective insulation at some
part where the wire has shifted from its central position, or where the
successive coatings may not have been properly applied, has been a
common cause of failure in long lengths of cable, as the adhesive
cementing compound applied between the coatings in a heated state is
found to have small bubbles of gases or air mixed with it, and is in
parts applied in unequal thicknesses.

page_text: The object of my Invention is to remedy these defects by covering the
wire in a solid homogeneous layer concentrically with the wire, the layer
being applied of any requisite thickness, so as to cover an ordinary
telegraph wire or strand of wires, and enable a sufficient body of insu-
lating material to be applied to it in one covering operation, thereby
dispensing with the necessity of repeating successive covering operations
and of using the adhesive cementing materials.
In the covering machine at present in ordinary use, the wire is caused
to pass from a carrying drum through a die, into which the gutta percha
is forced by a piston working in a cylinder; the covered wire passes out
into a tank of cooled water where it is allowed to set and cool, and is
then wound upon a receiving drum, the delivering and receiving drums
being fixed one at each end of the trough and rotating each in one
direction; thus the wire travels from one drum to the other but does not
rotate on its own axis.
In my improved covering machinery I employ delivering and receiving
drums which rotate on their axes in the direction in which the wire
travels, as in the ordinary covering machinery, and at the same time I
cause the drums, which are carried in suitable frames or by other
suitable means, to revolve in planes at right angles to the line of
travel of the wire, which double motion being well understood, the
means employed to provide for it need not be described in detail. It
will be obvious that where it is not intended that any twist or extra
twist should be put upon the wire or strand of wires, care must be
taken that the drums should be carried round at uniform velocities,
so as to give the wire and its applied coating an even and regular
rotation round its line of travel, and in that case the wire will have two
motions, the one from drum to drum, the other rotatory, the rotation
of all points in the wire being synchronous. If it is desired to give a
twist or additional twist to the wire or strand of wires, by regulating
the relative speeds at which the respective drums are made to rotate
round the transverse axes the object may be readily effected.
In order to conduct the wire or strand intended to be covered properly
into the covering machine, I employ a fixed guide through which the
wire or strand passes into a tube, which I make about two inches long,
and which nearly fits the wire or strand, which can rotate freely in it.
This tube leads the wire into a receptacle or chamber supplied with

page_text: gutta percha from a machine which I prefer to construct in the manner
described by me in the Specification of Letters Patent granted to me on
the 25th day of March 1870, No. 878, because by the use of such a
machine I can give an even supply which is of great consequence in
producing a uniform covering; but any suitable means of filling this
chamber may be adopted so long as the supply is constant and even in
force and quantity. The tube leads the wire to about one inch from the
opening of a second tube forming the exit of the chamber, and placed in
such a manner as to allow the wire to pass through it centrally, or if at
all out of the central line, a little above the centre; this second tube,
which is an important feature in my improved machinery, I form of glass
or glazed earthenware, or other suitable materials having, or having
applied to them, analogous surfaces in which the gutta percha will rotate
when hot without adhering to them. While the wire is passing through
the glass or glazed or enamelled tube, the insulating material is placed.
around it and begins to travel with it in both directions, that is, in the
direction of the line of travel of wire as it is drawn on by the receiving
drum, and in a circumferential direction as the wire with the drums is
made to revolve round that line. I employ a tube of about 8 or 10 inches
in length for my improved covering machinery when used with ordinary
gutta percha for covering ordinary wire, but it will be well understood
that the length should be regulated as experience will shew to be
necessary, according to the quality of material used for covering, and the
heat also. It must be very strong as the pressure on it is very great, and
it must be very solidly fixed to prevent vibration which would mark the
wire, causing inequalities. The inlet and outlet of this tube I chamfer
out or otherwise shape so as to form cups or bell mouths; the first, to
facilitate the filling operation; the second, to prevent the inner edge from
cutting or marking the covering material at its exit. In some cases the
glass or glazed tube may be fitted in such a position that the lowest parts
of the interior surfaces of this tube and the copper tube herein-after
described may be in the same straight line. In some cases instead of
using a copper tube the requisite support may be afforded by employing
a grooved or other table. The internal diameter of the glass tube
regulates the thickness of the covering. At the exit end of the said
glass tube I fit on a metal tube made by preference of copper, which is
especially suitable on account of its conducting capacity. This copper
tube I fit to the external diameter of the said glass tube, and for a space
of two or three feet I remove about one-third of its upper part, and open

page_text: the overlapping portion into straight sides, thus forming about 3 feet of
open trough for the covered wire to rotate in after it leaves the glass; and
in order to prevent adhesion and to facilitate motion forwards whilst the
insulating material is yet soft, it may be lubricated with water, or water
in which saponified matter or other suitable matter is dissolved. This
copper tube must be placed evenly with the run of the wire, and be
refrigerated externally by the application of suitable refrigerating liquids
or materials, as is well understood. The conducting copper will carry off
the heat from the gutta percha very rapidly, and the process being com-
pleted in this cold tube, the covered wire will be rendered hard and ready
for use, and pass out at the end (which should be opened into a bell
mouthed shape) and through a guide which is very solidly fixed, and
if necessary may be lined with felt before passing on to the receiving
drum.
The point of inlet of the tube leading into the chamber should be also
preceded by a guide also fixed firmly; and between these two guide
points the wire will be stretched in a straight line, and kept taut by a
break on the delivering drum and the pull caused by the motion of the
receiving drum. Thus in my improved covering machine the wire is
made to travel in a straight line from point of entrance to point of exit,
and to rotate at the same time round its line of travel, whilst the requisite
portion of insulating material is placed around it, and so forms a
homogeneous insulating coat of a sufficient thickness, the insulating
coat being circumferentially and evenly pressed upon the wire while
it is rotating inside the tube, and being kept under control until the
insulating coat is set and cooled, and the covering is thus completed at
one operation.
The concentricity of the wire relatively to its insulating coat is secured
by causing the wire while being held sufficiently tightly to be in a straight
line to rotate with its applied covering inside the tubes in the manner
above mentioned. All parts of the machine must be solidly and evenly
worked, and the speed of rotation of the wire round its line of travel
according to the speed at which experience may enable the operator to
find it advisable to move and deliver the covered wire.
Although in covering ordinary wire or strand I find it beneficial to
cover it at one operation, it is not imperative to do so, as by my improved
machinery a layer of any thickness can be put on, and repeated layers
may be in some cases superadded; also adhesive compounds may be used

page_text: in cases where they are preferred to be employed, but as great pressure is
exerted on the wire by the superimposed gutta percha, it will be found
that two layers may be perfectly united by slightly warming the surface
of the first before adding the second. When using some qualities of
insulating material it will be found that the first covering is to a
sufficient extent heated in its passage through the chamber of hot

page_text: The rapidity of covering will depend on the power of the filling
machine and the rapidity of cooling in the copper tube, as the wire
cannot be wound on to the receiving drum till it is quite cold; and, as
before stated, the wire must not leave the glass tube faster than the filling
machine can easily deliver insulating material sufficient to keep it full.
The supply drum and the receiving drum I have said should work
synchronously, that is, if the wire or conductor is already laid to the
required strand, but if it is required to twist the wires more than they
are at starting, then one drum may rotate faster than the other; but these
are points well understood, and may to some extent be adopted without
destroying the action.
Office on the 15th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWIN
THOMAS TRUMAN, of Old Burlington Street, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of February, in the year of our
Lord One thousand eight hundred and seventy-two, in the thirty-fifth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Edwin Thomas Truman, Her special licence that I,
the said Edwin Thomas Truman, my executors, administrators, and
assigns, or such others as I, the said Edwin Thomas Truman, my
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 COVERING WIRE OR OTHER SUITABLE CONDUCTORS WITH
INSULATING MATERIALS, AND IN MACHINERY EMPLOYED IN THE COVERING
PROCESS," upon the condition (amongst others) that I, the said Edwin
Thomas Truman, my executors or administrators, by an instrument in

page_text: writing under my, 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, and cause
the same to be filed in the Great Scal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Edwin Thomas Truman, 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 thereof, that, is to say :-
My Invention relates to an improved process of covering wires or
strands intended for use as conductors of electric currents with insulating
materials, in which process improved machinery, such as is herein-after
described, is to be employed.
It has been usual heretofore to cover the conducting wires used for
submarine or subterranean telegraphs, or analogous purposes, with several
coatings of insulating materials, and in the case of gutta percha being
employed as the covering material, to which I am about more particularly
to refer, it is usual to allow one coating to become cold before a second
is added. This has been necessary because the present process of
covering allows the wire to bend or sag, and the insulating material
being left uncontrolled is liable to fall away from the wire in parts, or
the wire is apt to shift from its central position relatively to the sur-
rounding insulating materials; the wire in consequence cuts into the
material as it leaves the covering apparatus before it has had time to
cool and set by passing as is now usual into cold water.
Gutta percha being a very bad conductor of heat cools very slowly,
and therefore unless the quantity put on the wire at one time is very
small, so as to place a very thin covering, the cooling process is not
sufficiently completed before the wire loses its central position. These
thin layers of gutta percha require to be dried or set before a second is
superadded, and the layers of gutta percha will not properly adhere if
one surface of the material is cold, except under strong pressure; it is
usual to pass the wire, after each comparatively thin coating of gutta
percha has set, through a hot adhesive compound, which forming a thin
adhesive layer over the gutta percha cements the outer coating to the
preceding inner one, and they are again cooled together. It is usual in

page_text: this way to build up as it were the gutta percha and apply the thin
coatings layer upon layer, and thereby give the wire a more or less
central position, but with the greatest care and most skilful management
this is not always possible, and as the thinnest point of the covering may
be said to govern the insulation of the entire cable, defective insulation
at some part where the wire has shifted from its central position, or
where the successive coatings may not have been properly applied, has
been a common cause of failure in long lengths of cable, as the adhesive
cementing compound applied between the coatings in a heated state is
found to have small bubbles of gases or air mixed with it, and is in parts
applied in unequal thicknesses.
The object of my Invention is to remedy these defects by covering
the wire in a solid homogeneous layer concentrically with the wire, the
layer being applied of any requisite thickness, so as to cover an ordinary
telegraph wire or strand of wires or bands, and enable a sufficient body
of insulating material to be applied to it in one covering operation,
thereby dispensing with the necessity of repeating successive covering
operations and of using the adhesive cementing materials.
In the covering machine at present in ordinary use, the wire is caused
to pass from a carrying drum through a die, into which the gutta percha
is forced by a piston working in a cylinder; the covered wire passes out
into a tank of cooled water where it is allowed to set and cool, and is
then wound upon a receiving drum, the delivering and receiving drums
being fixed one at each end of the trough, and rotating each in one
direction; thus the wire travels from one drum to the other, but does not
rotate on its own axis.
In my improved covering machinery I employ delivering and receiv-
ing drums which rotate on their axes in the direction in which the
wire travels, as in the ordinary covering machines, and at the same time
I cause the drums which are carried in suitable frames or by other
suitable means to revolve in planes at right angles to the line of travel
of the wire, which double motion being of well-known character and
well understood, the mechanism which may be employed to provide for
it need not be described in detail. It will be obvious that where it is
not intended that any twist or extra twist should be put upon the wire
or strand of wires, care must be taken that the drums should be carried
round at uniform velocities, so as to give the wire and its applied coating

page_text: an even and regular rotation round its line of travel, and in that case
the wire will have two motions, the one from drum to drum, the other
rotary, the rotation of all points in the wire being synchronous.
If it is in some cases desired to give a twist or additional twist to the
wire or strand of wires, by regulating the relative speeds at which the
respective drums are made to rotate round their transverse axes the
object may be readily effected.
In order to conduct the wire or strand intended to be covered properly
into the covering machine, I employ a fixed guide through which the
wire or strand passes into a tube, which I make about 2 inches long,
and which nearly fits the wire or strand, which can rotate freely in it.
This tube leads the wire into a receptacle or chamber supplied with
gutta percha from a machine which I prefer to construct in the manner
described by me in the Specification of Letters Patent granted to me on
the 25th day of March 1870, No. 878, because by the use of such a
machine I can give an even supply of covering material, which is of great
consequence in producing a uniform covering; but any suitable means
of filling this chamber may be adopted so long as the supply is constant
and even in force and in quantity. The tube leads the wire to about one
inch from the opening of a second tube, forming the exit of the chamber,
and placed in such a manner as to allow the wire to pass through it
centrally, or if at all out of the central line, a little above the centre;
this second tube, which is an important feature in my improved
machinery, I form of glass or glazed earthenware, or other suitable
materials having, or having applied to them, analogous surfaces in
which the gutta percha will rotate when hot without adhering to them.
While the wire is passing through the glass or glazed or enamelled tube,
the insulating material is placed around it and begins to travel with it in
both directions, that is, in the direction of the line of travel of wire as it
is drawn on by the receiving drum, and in a circumferential direction as ;
the wire with the drums is made to revolve round that line. I employ
a tube of about 8 or 10 inches in length for my improved covering
machinery when used with ordinary gutta percha for covering ordinary
wire, but it will be well understood that the length should be regulated,
as experience will shew to be necessary, according to the quality of
material used for covering, and its heat. The tube must be very strong,
as the pressure on it is very great, and it must be very solidly fixed to

page_text: prevent vibration, which would mark the wire, causing inequalities.
The inlet and outlet of this tube I chamfer out or otherwise shape so
as to form cups or bell mouths; the first, to facilitate the filling ope-
ration; the second, to prevent the inner edge from cutting or marking
the covering material at its exit. In some cases the glass or glazed tube
may be fitted in such a position that the lowest parts of the interior sur-
faces of this tube and the copper tube herein-after described may be in
the same straight line. In some cases instead of using a copper tube
the requisite support may be afforded by employing a grooved or other
table. The internal diameter of the glass tube regulates the thickness
of the covering. At the exit end of the said glass tube I fit on a metal
tube made by preference of copper, which is especially suitable on
account of its conducting capacity. This copper tube I fit to the
external diameter of the said glass tube, and for a space of two or three
feet I remove about one-third of its upper part, and open the over-
lapping portion into straight sides, thus forming about 3 feet of open
trough for the covered wire to rotate in after it leaves the glass; and in
order to prevent adhesion, and to facilitate motion forwards whilst the
insulating material is yet soft, it may be lubricated with water or water
in which saponified matter or other suitable matter is dissolved. This
copper tube must be placed evenly with the run of the wire, and be
refrigerated externally by the application of suitable refrigerating liquids
or materials, as is well understood. The conducting copper will carry
off the heat from the gutta percha very rapidly; and the process being
completed in this cold tube, the covered wire will be rendered hard and
ready for use, and pass out at the end (which should be opened into
a bell-mouthed shape) and through a guide which is very solidly
fixed, and if necessary may be lined with felt before passing on to
the receiving drum.
The point of inlet of the tube leading into the chamber should be also
preceded by a guide also fixed firmly; and between these two guide
points the wire will be stretched in a straight line, and kept taut by a
break on the delivering drum, and the pull caused by the motion of the
receiving drum. Thus in my improved covering machine the wire is
made to travel in a straight line from the point of entrance to point of
exit, and to rotate at the same time round its line of travel, whilst the
requisite portion of insulating material is placed around it, and so forms
a homogeneous insulating coat of a sufficient thickness, the insulating

page_text: coat being circumferentially and evenly pressed upon the wire while it
is rotating inside the tube, and being kept under control until the insu-
lating coat is set and cooled, and the covering is thus completed at one
operation.
The concentricity of the wire relatively to its insulating coat is secured
by causing the wire while being held sufficiently tightly to be in a
straight line to rotate with its applied covering inside the tubes in
the manner above mentioned. All parts of the machine must be
solidly and evenly worked, and the speed of rotation of the wire round
its line of travel according to the speed at which experience may
enable the operator to find it advisable to move and deliver the covered
wire.
Although in covering ordinary wire or strand I find it beneficial to
.cover it at one operation, it is not imperative to do so, as by my improved
machinery a layer of any thickness can be put on, and repeated layers
may be superadded in some cases; also adhesive compounds may be
used in cases where they are preferred to be employed, but as great
•pressure is exerted on the wire by the superposed gutta percha, it will be
found that two layers may be perfectly united by slightly warming the
surface of the first before adding the second. When using some
qualities of insulating material it will be found that the first covering is
to a sufficient extent heated in its passage through the chamber of hot
material.
The heat of the material and the previous treatment are of the greatest
consequence to the perfect uniformity of the covered wire, but these
points being well understood by persons working in these materials,
require only to be mentioned.
For lubricating the wire in the copper tube water is quite sufficient,
but other matters may be used if preferred.
Any of the plastic insulating materials ordinarily employed for
covering telegraph wires may be employed with my improved covering
machinery. I have referred particularly to gutta percha to prevent con-
fusion in describing my improvements. In practice I find that great
latitude in regard to the solidity of the insulating materials or compounds
may be allowed when my improved machinery is used; thus the lowest
quality of gutta percha almost semi-fluid may be used, whilst the
highest qualities, which are very hard, may also be employed with the

page_text: same good results, it being understood that the parts of the machinery:
and the temperature employed must be modified accordingly, as will be
well understood by persons accustomed to work in these materials in the
manner contemplated.
The copper tube above referred to must be of sufficient length to allow
the covering material to become set before it passes out. The length
will be governed, first, by the power of refrigeration used; and
secondly, by the quality of the material and speed of covering required.
The length of the glass tube must be regulated according to the
pressure required, and it may be tapered for some purposes; but the
supply of covering material must be quite equal to keep it perfectly
filled or the wire will pull out the centre material and leave the tube
minus part of its required covering; also it should be long enough to
allow the covering material to be thoroughly attached to the wire,
and to consolidate the gutta percha to some extent before it passes
away.
The rapidity of covering will depend on the power of the filling
machine and the rapidity of cooling in the copper tube, as the wire
cannot be wound on to the receiving drum till it is quite cold; and, as
before stated, the wire must not leave the glass tube faster than the
filling machine can easily deliver insulating material sufficient to keep it
full.
The supply drum and the receiving drum I have said should work
synchronously, that is, if the wire or conductor is already laid to the
required strand, but if it is required to twist the wires more than they
are at starting, then one drum may rotate faster than the other; but
these are points well understood, and may to some extent be adopted
without destroying the action.
Having now described my Invention, and the manner in which it is
to be performed, I claim, the process of covering wires or strands by
placing round the wire or strand a plastic coating of insulating material,
the wire or strand being held concentrically in its coating and made to
travel forward, and also rotate on its line of travel, and the coating
material being circumferentially compressed, and afterwards cooled and
set, substantially as herein described.
Also I claim the use for covering wires or strands in the manner
herein-before set forth of a tube of glass, or a tube having a glazed or

page_text: analogous smooth surface, applied as and for the purpose above
described.
Also I claim the combination of parts forming the improved wire
covering machinery constructed and employed substantially as above
described.
In witness whereof, I, the said Edwin Thomas Truman, have here-
unto set my hand and seal, this Fifteenth day of August One
thousand eight hundred and seventy-two.
EDWIN THO³. TRUMAN. (L.S.)