IMPROVEMENTS IN THE MANUFACTURE OF ELECTRIC TELEGRAPH CABLES, AND IN APPARATUS EMPLOYED THEREIN
Year: 1869

page_text: LETTERS PATENT to William Alfred Marshall, of Canonbury, in the
County of Middlesex, Telegraphic Engineer, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF ELECTRIC TELEGRAPH CABLES, AND
IN APPARATUS EMPLOYED THEREIN."
Sealed the 3rd June 1870, and dated the 11th December 1869.
PROVISIONAL SPECIFICATION left by the said William Alfred Marshall
at the Office of the Commissioners of Patents, with his Petition,
on the 11th December 1869.
I, WILLIAM ALFRED MARSHALL, of Canonbury, in the County of
Middlesex, Telegraphic Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ELECTRIC TELEGRAPH
CABLES, AND IN APPARATUS EMPLOYED THEREIN," to be as follows:-
In carrying out my Invention, which relates to improvements in the
process of insulating and protecting the wires of subterranean, submarine,
and other telegraph cables, I employ one or more conducting wires on
which I wind spirally two or more cords or strands at a time of cotton
or other non-conducting fibrous substance, leaving intervals or spaces

page_text: between each spiral, and then apply another layer composed of a similar
number of cords or strands, which are laid in the contrary direction to
the first layer, but in a similar manner, and so on until the desired
thickness is obtained. The wire or wires thus covered are then dried
and steeped in the substance known as paraffin wax in a liquid state.
This being done I proceed to enclose and complete the insulation of the
wires in the following manner:-A lead or other soft metal tube of
convenient length is laid horizontally in a straight line, through which
I next
the conducting wire or wires are passed in any suitable manner.
wind the soft metal tube containing the wire or wires on a skeleton
drum furnished with a hollow spindle, with which one end of said tube
is placed in communication. The drum is then placed in bearings in a
tank, and the hollow axis of said drum connected to a supply pipe by
means of a stuffing box or joint constructed to allow of the free rotation
of the drum. This pipe communicates with a tank containing paraffin
wax in a liquid state, and is provided with a suitable stop-cock. I now
fill the tank containing the drum on which the cable is wound with
melted paraffin wax, which serves to heat the tube to a suitable degree,
the heat being supplied and maintained from any convenient source or
in other suitable manner. An air pump is now attached to the free end
of the lead tube (which is not immersed in the bath of paraffin wax), by
the aid of which pump I exhaust the air from the tube, and as soon as
the necessary vacuum has been obtained I open the stop-cock to admit
the paraffin wax from the supply tank, which by the atmospheric
pressure and if necessary by the force of gravitation also is forced into
and through the whole length of the tube, so as to completely fill the
space between it and the wire or wires which it encloses, and all
interstices formed by the fibrous covering of the same. By first creating
a vacuum in the tube I prevent the formation of air bubbles therein,
which would impair the insulating properties of the paraffin wax. In
order to provide for the contraction of the paraffin wax on cooling I
proceed to cool the cable gradually in the direction of its length,
commencing at the disengaged end, which I first close, and then
pass
over one or more friction rollers at the edge of the tank in a vertical
downward direction to a cold water tank. Tension is now applied to
this suspended end so as to rotate the drum and unwind the cable
therefrom, the latter being drawn gradually through the cooling tank at
a speed slow enough to allow the paraffin wax time to be completely
solidified on leaving the tank, after which it may be coiled on a drum
it

page_text: for disposal. By thus cooling the cable gradually in a longitudinal
direction any spaces left by the contraction of the wax at the part cooled
are immediately filled up by the liquid wax forced in by the pressure
above that point, the temperature of the cable being maintained
throughout until it has passed into the cooling tank. In this manner
the tube will be entirely filled by the covered wire or wires, and the
paraffin wax enclosing the same, thus forming a perfectly solid body.
By putting each section of the cable in tension in a vertical direction
while cooling a vibratory motion is imparted to the conducting wire or
wires which bear the chief part of the strain while the solidification of
the paraffin wax is taking place, whereby they are caused to assume a
more concentric position in the tube, and so obtain a more equal
distribution of the paraffin wax forming the insulating medium around
the covered wire or wires. The lengths or sections of cable are afterwards
united either by means of short tubes or couplings of soft metal enclosing
the ends, and soldered thereto (fresh paraffin wax being added to fill up
any spaces and complete the insulation), or the sections may be otherwise
united.
I would observe that I make no claim to the use of lead or other soft
metal tubes or of paraffin wax as means of protecting and insulating
telegraph wires
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Alfred Marshall in the Great Seal Patent
Office on the 11th June 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALFRED MARSHALL, of Canonbury, in the County of Middlesex,
Telegraphic Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of December, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Alfred Marshall, Her special licence
that I, the said William Alfred Marshall, my executors, administrators,
and assigns, or such others as I, the said William Alfred Marshall, my
executors, administrators, and assigns, should at any time agree with, and

page_text: 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
THE MANUFACTURE OF ELECTRIC TELEGRAPH CABLES, AND IN APPARATUS EMPLOYED
THEREIN," upon the condition (amongst others) that I, the said William
Alfred Marshall, my executors or administrators, by an instrument in
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 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 William Alfred Marshall, 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, reference being had to the Sheet of Drawings
hereunto annexed, and to the letters and figures marked thereon (that is
to say) :-
My Invention relates to improvements in the process of insulating and
protecting the wires of subterranean, submarine, and other electric
telegraph cables, and I will proceed to describe the same with reference
to the accompanying Drawings, Figure 1 of which shows a general view
of the arrangement and construction of the apparatus employed in
carrying out my improvements, whilst Figures 2 and 3 are partial
longitudinal and transverse sections of the cable on an enlarged scale
showing the manner in which the serving of cotton is applied on the
conducting wire.
The process of insulating and protecting the wires is as follows:-
The cotton or other fibrous non-conducting material with which the
conducting wire or wires is to be covered is first dried and wound
loosely on bobbins, and then boiled in a vessel containing paraffin wax
until the whole of the cotton or other fibres are thoroughly permeated
by the wax. The waxed cords or strands are then preferably rewound
on other bobbins, previous to which they are made to pass over the flame
of a spirit lamp or lamps or gas jet or jets with the object of singeing
off any loose fibres and smoothing the surface of the strands. Two or
more bobbins containing the cotton or other fibrous material so treated
are mounted together on an ordinary serving machine, by which the

page_text: two or more waxed cords are laid or wound at one time on the wire in
a regular and even manner, with a space between each coil or strand,, as.
shown in Figure 2. On the wire thus covered another and similar
serving of (preferably) finer cord (previously steeped in liquid paraffin
wax, as above described) is then applied two or more strands at a time,.
as before, but laid in the contrary direction, the wire and its double-
covering presenting the appearance shown in Figure 2, in which a is the.
wire, and b and c the first and second servings of cotton or other fibrous
material, the insulating paraffin wax; and A, the lead or other
soft metal protecting tube. The wire thus covered may if necessary
be coiled on a drum and steeped in liquid paraffin wax to coat
and fix the double serving of cotton, and replace any of the wax
removed by the serving operation, and if to be a compound cable
the covered wires are formed into a cable in the ordinary way. I
then proceed to enclose the wires and complete their insulation and
protection in the following manner :-The wire or wires thus: covered
or prepared are introduced in a lead or other soft metal tube A of con-
venient length, laid or stretched horizontally in a straight line. One
mode of introducing the wires is to first draw a pith ball through
the tube by the aid of an air pump, to which ball is attached a light line
of increasing strength, by which the wire (or wires) is finally drawn
through the tube, the wax with which the fibrous covering is permeated
serving as a lubricant to facilitate the passage of the wire or wires.
through the tube. I then wind the tube A, enclosing the insulated wire.
or wires on a skeleton drum B, Figure 4, in order that the heat applied
as herein-after described may the more readily be communicated to the
inner coils of the cable. The drum B is carried on an axis, one of the
journals d of which is made hollow, and with which hollow journal
the end of tube A is put in communication (before winding said tube on
the drum) by means of a pipe C attached to the hollow journal, and
preferably coiled, as shown in Figure 1, for facilitating the connection
and disconnection of the tube A therewith by means of a union or other.
suitable joint. The drum B when filled with the tube or cable A is.
carried to a tank D containing paraffin wax in a liquid state (or it may.
be a hot air chamber) in which it is mounted in standards E, as seen..
The hollow journal d of the drum spindle is then connected, as shown,
to a supply pipe e communicating with a tank F containing paraffin
wax in a liquid state forming a source of supply. The pipe e is provided
with a suitable stop-cock, the lower end of said pipe which descends

page_text: into the tank D terminating in a universal connection g to permit of
the liquid paraffin wax passing freely to the hollow spindle of the drum
whilst the latter is rotated. The paraffin wax in tanks D and F and
pipe e is maintained at the requisite temperature by means of gas jets or
by enclosing the said tanks in suitable steam jackets. The heat of the
bath of paraffin wax in tank D, (in which the drum B carrying the
tube A is immersed, as before mentioned) is communicated to the wax
with which the cotton or other fibrous covering of the conducting wire
or wires is imbued, and the wax thereby becomes liquefied and collects at
the lower part of each coil of tube A, whence it requires to be removed.
To effect this I connect a force pump to any part of tube e below the stop-
cock f, as at point e³, and force sufficient air through the tube A to expel
all the melted paraffin wax collected therein, as above mentioned. The
force pump having been disconnected and the tube e closed, an air
pump is now attached to the free end of the tube A, which being
uncoiled for a short distance from the drum is not immersed in the
bath of wax. By the aid of this pump I exhaust the air from the
tube A, and when the necessary vacuum is created communication with
the pump is cut off; I then open the stop-cock f to admit the paraffin
wax from the supply tank F, which by the atmospheric. pressure, and if
necessary by the action of gravitation also, or preferably by the aid of
a force pump is quickly forced into and through the whole length of
tube A, so as to completely fill the space between it and the wire or wires
which it encloses, and all interstices formed by the fibrous covering of
the same. By introducing the paraffin wax into the tube A in which a
vacuum is created as above explained 1 prevent the formation of air
bubbles therein, which would impair the insulating properties of the
paraffin wax. A glass tube closed at one end may be connected at or
near to the end of tube A before filling the latter, in order to ascertain
by observation when the wax has passed completely through and filled
said tube A.
°
In order to provide for the contraction of the paraffin wax on cooling
I proceed to cool the cable gradually in the direction of its length, com-
mencing at the disengaged end. For this purpose I pass the cable over
one or more roller h at the edge of the tank D in a vertical downward
direction into a cold water tank or well G, through which the cable A
is drawnn radually at a speed slow enough to allow of the complete
solidification of the paraffin wax. The cable may either be drawn

page_text: through a stuffing box or gland in the bottom of the tank G, or when
a deep tank or well is employed I prefer to pass it under grooved
wheel H at the bottom of such well and up again to the surface for the
purpose of prolonging the cooling operation, whence it is withdrawn, as
shown in Figure 1, and coiled on a drum I for disposal. The wheel H
should be of large diameter to avoid any sudden bend in the cable
before the paraffin wax is completely solidified, and is mounted to rotate
freely in bearings in a suitable framing working in guides at the sides
of the well, provided with suitable rack and pinion or other gearing
operated from above for raising said wheel (and framework) to the
surface when required, as, for instance, for the purpose of passing the
cable end thereunder. Adjustable grooved rollers i are mounted near
the edge of tank D, said rollers being placed the one above the other
and on opposite sides of the descending portion of the cable. By
regulating the pressure of one or other of these rollers on the tube A
the conducting wire or wires may be brought as nearly as possible to a
central position therein, as shown by the red line at x, Figure 1. Power
being applied to rotate drum I the cable A is gradually unwound
from the drum B and passed downwards through the cooling tank
or well G, as above described, where being cooled gradually in a
longitudinal direction any spaces left by the contraction of the wax
on solidification are immediately filled up by the liquid wax in the
tube, the temperature of which is maintained throughout by the
heated bath of wax D in which it is immersed, and which is con-
tinually supplied under pressure from the tank F during the whole
process of cooling. When the whole length of tube has been
unwound from drum B the supply of paraffin wax is cut off and the
cable disconnected. In this manner the tube A will be entirely filled
by the covered wire or wires and the paraffin wax enclosing the same,
thus forming a perfectly solid cable. The tension to which the cable is
subjected when passing downwards in a vertical direction through the
cooling tank imparts a slight vibratory motion to the conducting wire or
wires (which bear the greater part of the strain) while the solidification
of the paraffin wax is taking place, whereby said wire or wires tend to
assume a central position within the tube at all parts. A more equal
distribution of the paraffin wax forming the insulating medium around
the covered wire or wires is thus ensured. The whole length or section
of cable having been passed entirely through the cooling well G and
wound on drum I the process is complete, the sections or lengths of cable

page_text: being afterwards united in the following or other suitable manner:
The ends of the conducting wires of the different sections having been
spliced or connected and covered with the prepared cotton or other
fibrous material before referred to are enclosed in a short length of tube
of slightly larger diameter which has been previously passed over one
end of cable A, and is then brought over the connected wires and
soldered to the ends of the sections of cable which it connects, an
opening (which is afterwards closed) being left in the junction tube
for the introduction of fresh paraffin wax in a liquid state to entirely
fill the same and complete the insulation. It may, however, be found
desirable to unite the lengths of cable (tube and wire) at the time of
filling instead of by a subsequent operation as above. In this case when
the end of the cable A is entirely unwound from drum B. and dis-
connected as before the motion of the cable through the cooling tank
is arrested for a short period, during which time the empty drum B is
replaced by another carrying a fresh section of tube A containing a
conducting wire or wires. This drum is to be previously heated, and
the melted wax collecting in the coils of the cable removed by the aid
of a force pump, as before. The section of cable which it carries. is
then in readiness to be connected to the end of the section previously
operated on. The junction is made by connecting the wire or wires and
enveloping such connection in an outer tube soldered to and uniting the
ends of tubes A, as in the previous case. The fresh length of tube to be
filled with paraffin wax is now exhausted by the aid of an air pump
placed in connection with the length of tube, and the wax is again
introduced from tank F, and the process continued as before, provision
being made for removing any air which may remain in the tube. In
this manner the entire cable is wound on drum I in a continuous
length.
Having described the nature of my Invention and the manner of
performing the same, I would observe that I make no claim to the use
of any of the materials mentioned for insulating and protecting the
conducting wire or wires of electric telegraph cables; but what I do
claim as my Invention to be protected by the herein-before in part
recited Letters Patent is,-
1st. The improved process of insulating and protecting the conducting
wire or wires of submarine, subterranean, and other electric telegraph
cables, as herein-before described.

page_text: 2ndly. I claim the skeleton drum B for carrying the length of cable in
combination with the heating tank D (or hot-air chamber), substantially
as shown and for the purpose specified.
3rdly. I claim the combination with drum B of hollow journal d,
coil C, and tube e, for the supply of paraffin wax from tank F to cable A
during the rotation of the drum B, substantially as shown and described.
In witness whereof, I, the said William Alfred Marshall, have
hereunto set my hand and seal, this Ninth day of June, in the
year of our Lord One thousand eight hundred and seventy.
W. A. MARSHALL. (L.S.)