IMPROVEMENTS IN ELECTRIC TELEGRAPH CABLES
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Charles Sylvester Rostaing at
the Office of the Commissioners of Patents, with his Petition, on
the 2nd December 1868.
I, CHARLES SYLVESTER ROSTAING, Citizen of the United States of
America, but now residing at Paris, in the Empire of France, Gentleman,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN ELECTRIC TELEGRAPH CABLES," to be as follows:-
The principle upon which electric cables have hitherto been
constructed has always been very inimical to their strength. The want
of elasticity inherent to their vicious construction admits of no great
strain or bending without effecting a re-hardening of the metallic.
wires conductors of the electric current. This hardening of the metallic
wires causing crystallization of the metal, a breakage of the wire takes
place whenever the cable is submitted to a powerful strain, to com-
pression, bending, or rolling.
The hitherto adopted constructions of cables being based upon false
mechanical principles, there remained but one means of remedying their

page_text: defects, namely, by giving to the electricity conducting wire a
completely different position in relation to the centre, or that which I
will term the core of the cable.
Having since the year 1852 greatly occupied myself in seeking the
most suitable form to be given to the conducting wire in the con-
struction of insulated wires to be submitted to repeated tractions and
bendings, I have ascertained that the form of spirals more or less close
rolled around a cord or core of isolating material possessing clasticity,
would best fulfil this purpose. Starting from this principle I have
contrived the construction of electric cables possessed of various degrees
of elasticity and which may be submitted to the most powerful tractions,
to a bending at right angles, or to a powerful compression without in
any degree losing their electricity conducting properties.
To construct these elastic cables commence by taking a cord or
rope of variable diameter and made of semi-vulcanized india-rubber, of
unalterable gutta percha, of hemp or flax impregnated with a solution of
caoutchouc or of gutta percha, or even made of other materials more or
less elastic. This cord or core must be placed in any suitable machine
which will give it such a rotary motion that one or more copper wires
may be wound spirally upon it (as shewn on the annexed Sheet of
Drawing, forming part of this my Provisional Specification), care being
had to leave between each spiral a space of at least half an inch. The
use of several electricity conducting wires requires their previous
twisting into the shape of thread or cord, (see annexed Drawing Fig. 4)
to prevent the electric current from producing induction or secondary
currents when it passes along these wires. When the elastic cord or
core is furnished with the spirals of copper or other metal they are
covered with thin bands or ribbons of india-rubber, or of fabrics
prepared with india-rubber freed from efflorences of sulphur, by passing
sulphuret of carbon or other solvent over their surface, taking care to
wind the first band following the direction of the copper spirals and
that the second layer be wound in reverse direction to the first. The
object of winding the isolating and wire protecting coverings in contrary
or alternate directions as above set forth is to preserve the elasticity of
every part of the cable in order that neither traction nor compression may
effect any deterioration of the wire. All the succeeding isolating coats
or layers must be applied on the same principle even should metal wires
be inserted to still further increase the strength of the cable. In this

page_text: latter case the double layer of metallic wire may be covered with several
layers of clastic isolating materials, which should be coated with
solutions of india-rubber or of gutta percha rendered unalterable or
even with solutions of other resinous matters. The last layer but one
of isolating material should form a ground for the covering intended to
protect the cable against very great compression, the friction of the
shingle on sea coasts, and other dangers. This layer should be composed
of very enduring materials in the shape of thin cords of hemp, or of flax,
impregnated with solutions of caoutchouc or of other resinous matters or
of collodion. The two last protecting layers may be composed of iron
or steel wire, and must also be laid round the cable in contrary or
alternate directions.
It is unquestionable that a cable constructed on the principles which
I have above developed must be endowed with a greater degree of
conductibility for the electric fluid than cables as hitherto constructed,
the spirally twisted wire offering a greater body of conducting metal.
These cables may be submitted to compression of the most formidable
kind without fear of breaking the electricity conducting spirals, as
these spirals can only open away from each other, sliding between the
core and the covering of india-rubber band. When the compression
ceases the spirals are compelled to resume their original position by
reason of the powerful pressure which the elastic core brings against
them as well as upon the other layers of the cable. Again a bending
at right angles or a powerful traction upon the cable can only produce
a widening of the spirals of the conducting wire without ever hardening
or breaking it. These properties will doubtless prove sufficient to meet
every requirement in connection with electric telegraph cables whether
submarine, subterranean, aerial, or other, and as regards military
telegraphs, my principles of construction permit the production of a
cable which while very light and strong may be trodden under the feet
of horses and rolled over by artillery on the field of battle without the
possibility of intersecting the conducting wires, and the cable need no
longer be laid in the ground, a method greatly objected to by military
authorities.
The main and essential characteristic of my Invention is winding the
conducting wire spirally around an elastic core, but I will now concisely
enumerate the various improvements concurring in producing my
improved electric telegraph cables, they are,-

page_text: Firstly. The use of materials or fabrics impregnated with solutions
of gum resins, or resinous gums, such as cotton, aloes, or felt applied as
previously described.
Secondly. The application of a second electricity conducting wire
wound in the interstices which the first layer of isolating ribbon leaves
free between the spirals surrounding the central clastic cord or core of
the cable, so as to telegraph by one wire and receive the reply by the
other or to despatch several telegrams at once.
Thirdly. The application of a perfectly unalterable and very plastic
compound composed of gutta percha melted with from five to ten per
cent of tannin, or of catechu, or of a combination of gutta percha and
caoutchouc melted and thoroughly worked together, also combined with
tannin or catechu, whether they be used for impregnating textile
fabrics_serving for the construction of my electric cables, or for coating
them, or for giving the electric fluid conducting wires, for their better
insulation, a coating or varnish more or less thick before winding them
round the central cord or core.
Fourthly. The use of spirals of metal wire more or less wide apart
covered or coated with several layers of resinous and elastic solutions,
or of melted gum resin, whether for completely insulating them or as
a protective substance against all the chances of injury to which they
may be exposed.
On the annexed Sheet of Drawing I have given illustrations of
various cables constructed according to my Invention, shewing the
elastic core, conducting wires, and inner coverings, the exterior coverings
may be varied according to requirement so that they be always wound
as herein-before set forth.
Fig. 1 represents a portion of that part of a submarine cable which
is to lic on the bottom under water, and may be of less diameter than
the shore ends. A, construction of the inner part (ordinary size) with
two conducting wires unimpregnated with resinous solutions in order
that it may be more readily taken to pieces for inspection of its make;
B, median part composed of textile fibres impregnated with solutions of
gum resins, of gutta percha, or other analogous materials, to which
additional strength may be given by the insertion of metal wires; C,
outer part of the cable composed of alternate layers of hempen cord
combined with thin metal wires impregnated with insulating materials;
and Fig. 1 section of greatest diameter of said cable, that is to say, of

page_text: the part issuing from the water and resting on shingly or other shore;
A and F centre more or less elastic, and surrounded with two metal
spirals conductors of the electric fluid; G, india-rubber or impregnated
textile materials; H, first layer of cords plaited with textile materials;
I, first coating of metal wire plaited or wound in two alternate layers; K,
space composed of alternate layers of textile materials impregnated with
gum resins; C, outer part of cable composed of two alternate layers of
hempen cord, furnished with thin iron or stell wire, and impregnated
with insulating materials. Figs. 2 and 2, cables of small diameter for
deep water and for underground cables with but one conducting wire;
A, centre or core of the cable shewn full size, but the size of which may
be decreased as at Fig. 2 for the addition of a second conducting wire;
C, median part composed of textile fibres impregnated with solutions of
gum resins such as caoutchouc, gutta percha, or other analagous matter;
B, exterior of the cable composed of two alternate layers of hempen
cord interwoven with thin metal wire, and thoroughly insulated with
resinous matter. A double layer of metal wire may be wound in
alternate directions in the median part C to give additional strength to
the cable. Fig. 3 inner part or core of an electric telegraph cable with
two conducting wires well adapted for military and aerial telegraphs; A,
elastic core surrounded with the first conducting wire; B, first band or
ribbon of india-rubber or impregnated textile materials surrounded
with the second conducting wire; O, second band or ribbon of india-
rubber or impregnated textile material, insulating the core and the two
connecting wires; D insulating covering composed of textile isolating
materials impregnated with collodion, with caoutchouc, or with gutta
percha, or even with fat siccative oils. Fig. 3º section of Fig. 3, and
Fig. 3b aerial telegraph wire with a but slightly clastic core or central
cord surrounded with spirals and covered with gutta percha or textile
materials impregnated with gum resins. Fig. 4 shews spirals of twisted
wire with core removed.