IMPROVE- MENTS IN THE CONSTRUCTION OF TELEGRAPHIC CABLES OR CONDUCTORS
Year: 1865

page_text: LETTERS PATENT to Cromwell Fleetwood Varley, of Fleetwood House,
Beckenham, in the County of Kent, for the Invention of " IMPROVE-
MENTS IN THE CONSTRUCTION OF TELEGRAPHIC CABLES OR CONDUCTORS."
Sealed the 15th June 1866, and dated the 28th December 1865.
PROVISIONAL SPECIFICATION left by the said Cromwell Fleetwood
Varley at the Office of the Commissioners of Patents, with his
Petition, on the 28th December 1865.
I, CROMWELL FLEETWOOD VARLEY, of Fleetwood House, Beckenham, in
the County of Kent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE CONSTRUCTION OF TELEGRAPHIC CABLES OR CON-
DUCTORS," to be as follows:--
This Invention has for its object improvements in the construction of
telegraphic cables or conductors. In telegraphic cables as at present con-
structed a minute fault in the insulator when the cable is laid will ultimately
render the cable useless, as the copper of the conductor where it is exposed
becomes eaten away by electrolitic action. To obviate this danger I make
one or more of the wires of the strand forming the conductor either entirely
or in part of platinum, and then should the copper be thus eaten away the
platinum remains and is sufficient to carry a current. At the present time
in joining the conductor it is usual to solder the two ends of the conductor
together and to coil fine copper wires around the joint spirally, in such
manner that should the joint break the spirals stretch out, and the tine wires
are sufficient to carry a current over. Now I make one or more of the
spirals of each joint of platinum, so that should water penetrate to the

page_text: wires they may not be entirely eaten away. In place of platinum gold and
some other metals may be employed. Also in constructing long telegraphic
cables, in place of making the conductor and the insulator of the same
thickness from end to end of the cable, as is most usual, I make the con-
ductor smaller and smaller in passing from shore ends towards the centre
of the cable, and at the same time, that is to say, in passing from the shore
towards the centre, I make tlie thickness of. the insulator to bear a con-
tinually increasing ratio to the diameter of the conductor. One of the
advantages of this arrangement is, that the protection of the cable from
injury from earth currents is rendered more efficient as the danger increases.
It will be desirable to select the gutta percha and employ the highest
quality. near the centre of the cable. These improvements admit of
tlie copper and gutta percha of the cable being combined in cheaper
proportions to obtain the same speed of working, and the thickness
of the gutta percha may be decreased, when the consequences of a fault
are not so fatal as they have been heretofore. In order to render the
insulated conductor less liable to injury from abrasion and otherwise, I
employ in the insulation, either in part or entirety, strips or bands of
woollen fabric saturated or filled with Chatterton's compound gutta
percha or other insulating compound or material, and these strips are
lapped over the conductor, either previously covered or otherwise. In
place of woollen fabrics woollen yarns or cords may be employed.
I am aware that it has been proposed to use other fabrics and fibres in
the manner above described, but wool being an insulating material and
comparatively inexpensive is much superior to the fibres heretofore
employed or suggested for use for this purpose. :
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Cromwell Fleetwood, Varley in the Great Seal Patent
Office on the 28th June 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CROMWELL
FLEETWOOD VARLEY, of Fleetwood House, Beckenham, in the County of
Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of December, in the year of
our Lord One thousand eight hundred and sixty-five, in the twenty-ninth
vear of Her reign, did, for Herself, Her heirs and successors, give and

page_text: grant unto me, the said Cromwell Fleetwood Varley, Her special licence
that I, the said Cromwell Fleetwood Varley, my executors, administrators,
and assigns, or such others as I, the said Cromwell Fleetwood Varley, 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
THE CONSTRUCTION OF TELEGRAPHIC CABLES OR CONDUCTORS," upon the condition
(amongst others) that I, the said Cromwell Fleetwood Varley, 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 Cromwell Fleetwood Varley, do hereby
declare the nature of the 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 :-
This Invention has for its object improvements in the construction of
telegraphic cables or conductors. In telegraphic cables as at present
constructed a fault in the insulator when the cable is laid will ultimately
render the cable useless, as the copper of the conductor where it is exposed
becomes eaten away by electrolitic action. To obviate this danger I make
one or more of the wires of the strand forming the conductor either
entirely or in part of platinum, and then should the copper be thus eaten
away the platinum remains and is sufficient to carry the electric current.
One of the methods I have adopted for this purpose consists of inserting
a platinum rod inside a hollow copper cylinder, and then drawing them
down together into wire. In this way copper wire is formed containing a
fine platinum interior. Another plan consists of making the centre wire
of the conductor a strand of fine wires, one, two, or more of which
are platinum wires. A third plan consists of making the copper
conductor wholly of fine wires, one or more of them being platinum.
I prefer giving the strand a much more rapid lay than that usually
adopted, so as to allow it to go and come with the cable when the latter
is sprung by the operation of laying or picking up. At the present.
time in joining the conductor it is usual to solder the two ends of the

page_text: conductor together and to coil fine copper wires around the joint spirally, in
such manner that should the joint break the spiral wires stretch out, and the
fine wires, are sufficient to carry a current over. Now I make one or
more of the spirals of each joint of platinum, so that should water penetrate
to the wires they may not be entirely eaten away. In place of platinum
gold and some other metals may be employed. Also in constructing long
telegraphic cables, in place of making the conductor and the insulator of
the same thickness from end to end of the cable, as is most usual, I make
the conductor smaller and smaller in passing from the shore ends towards
the centre of the cable, and at the same time, that is to say, in passing
from the shore towards the centre, I make the thickness of the insulator
to bear a continually increasing ratio to the diameter of the conductor:
It is impossible here to lay down the best dimensions to be used, because
they vary with the price of the materials, and must be calculated for each
circuit by a competent electrician, who must also take into account the
resistance of the particular kinds of instruments and batteries at each end
of the circuit. I prefer that in a cable not joined to a land line the shore
end should have not less than four times as inuch copper as the centre
portion. One of the advantages of this arrangement is; that the protection of
the cable from injury from earth currents is rendered more efficient, as the
danger of the electricity breaking through the insulator increases towards the
middle of the cable. It will be desirable to select the gutta percha and
employ the highest quality near the centre of the cable. The above improve-
ments admit of the copper and gutta percha of the cable being combined in
cheaper proportions to obtain the same speed of working, and in consequence
of the platinum wire the thickness of the gutta percha compared to the
conductor may be decreased, when the consequences of a fault are not
fatal as they have been heretofore. In this way considerable economy can
be effected; for instance, a cable containing 300 lbs. of copper and 400 lbs.
of gutta percha will work no faster than one containing 330 lbs. copper
and 330 lbs. gutta percha; the latter being an expensive article the gain is
obvious; hitherto an excess of gutta percha has been used to leave a
large margin of surplus insulation. In order to render the insulated
conductor less liable to injury from abrasion and otherwise, I employ in the
insulation, either in part or entirely, strips or bands of woollen fabric
saturated or filled with Chatterton's compound gutta percha or other insu-
lating compound or material, and these strips are lapped over the conductor,
either previously covered or otherwise.
woollen yarns or cords may be employed.
In place of woollen fabrics
I am aware that it has been

page_text: proposed to use other fabrics and fibres in the manner above described, but
wool being an insulating material and comparatively inexpensive is much
superior to the fibres heretofore employed or suggested for use for this
purpose. The wool used for these purposes must be cleansed from grease.
When the conductor of a cable is constructed as above described, should a
fault in the insulation show itself it is desirable to preserve the copper
of the cunductor as long as possible. To effect this I employ condensers,
as described in my Patent of 1862, No. 3453, with the addition of a
battery consisting of a large number of cells of small dimensions and of
great resistance, so as to keep the cable always, negative to the earth,
namely, insert between the cable and the telegraph instruments at each end
a condenser of large capacity, say equal to one-eighth part or one-quarter
the capacity of the cable; secondly, connect at one or both ends of
the cable a battery of 500 (more or fewer) cells through a large resistance,
say one million ohmads, the positive pole to earth, the negative to the cable.
This will keep the copper at the exposed part of the cable always electro-
negative, and the condensers, while they cut off nearly the whole disturb-
ance arising from earth currents, still permit the signals to pass freely from
end to end. If the condensers alone be used, the copper wire exposed at
the fault becomes alternately positive and negative; when positive it dis-
solves, when negative it is deposited not in a compact but in a spongy form,
and in one case which came under my experience ultimately connected the
copper conductor through the yarn with the outer iron covering. The
battery must have so many cells that it will always overpower any earth
current; should, however, the earth current on any exceptional occasion
exceed that of the battery the latter should be immediately disconnected,
and the cable left to the partial protection afforded by the condensers. The
platinum wire, however, will never eat away when the copper is all gone;
it is obviously best to preserve the copper as long as possible. It will be
advisable to insert a galvanometer in the battery circuit to give notice
should the earth current overpower it.
In witness whereof, I, the said Cromwell Fleetwood Varley, have
hereunto set my hand and seal, this Twenty-sixth day of June,
One thousand eight hundred and sixty-six.
CROMWELL FLEETWOOD VARLEY. (L.S.)