IMPROVEMENTS IN TELEGRAPHIC CABLES
Year: 1861

page_text: LETTERS PATENT to Thomas William Evans, M.D., of No. 15, Rue de
la Paix, in the City of Paris, Empire of France, for the Invention of
"IMPROVEMENTS IN TELEGRAPHIC CABLES."
Sealed the 22nd August 1861, and dated the 7th March 1861.
PROVISIONAL SPECIFICATION left by the said Thomas William Evans
at the Office of the Commissioners of Patents, with his Petition, on the
7th March 1861.
I, THOMAS WILLIAM EVANS; M.D., of No. 15, Rue de la Paix, in the City.
of Paris, Empire of France, do hereby declare the nature of the Invention for
"IMPROVEMENTS IN TELEGRAPHIC CABLES," to be as follows:-
In constructing electric telegraph cables I employ a conductor composed of
several wires drawn from metal rendered absolutely pure by a process
analogous to that employed in the refining of the precious metals. As copper
possesses nearly seven times greater electrical conductability than iron I adopt
copper as the constituent metal of the wire conductor. By the increase of purity
the tenacity and consequently the conductability of the wire is largely augmented.
Recognizing the well-known electrical law that the capacity of condensation
is in exact ratio with the superficial surface of the conductor, and impressed
with the serious risk involved in the employment of a submarine electric con-
ductor composed of only a single wire, I combine seven copper wires (drawn

page_text: from perfectly pure metal) six of which surround the remaining one as a
centre. Having first placed these wires in parallel lines, in close contact with
each other, I draw them all together through a round holed draw plate. By
this means I reduce the volume and compel the wires to assume the form of
longitudinal sections of a prolonged cylinder, the exposed surface of which will
be, of course, exactly equal to that of a single wire of the same diameter,
while additional strength and additional safety from risk of total rupture are
effectually secured by the use of independent wires. Upon the cylindrical
conductor, thus prepared, I superimpose, to guard against the possibility of any
defects in the metal by means of a galvanic battery and a bath containing
either copper or gold in solution, a slight coating or plating of pure copper or
gold (the latter I prefer). By thus presenting a surface of absolutely pure
metal, the facility of electrical transmission is sensibly increased whilst the
danger of any chemical action upon the conductor from the contact of the
insulation is entirely avoided.
It is a well known fact that when caoutchouc vulcanized in the ordinary
manner with heat, is applied in direct contact with the copper, a chemical effect
is produced on the metal, which is rapidly corroded and rendered brittle. It
has been attempted to avoid this action by coating the wire with tin and silk or
cotton, but the tin is also corroded, and the silk or cotton by capillary attraction
absorbs the sulphur, thus communicating it to the wire. Now pure caoutchouc
over a gold surface has no such effect. For insulating the conductors of
electric telegraph cables I employ three distinct coats, an interior one of pure
caoutchouc, a second of gutta percha, and a third of caoutchouc.
Regarding the total exclusion of air as a matter of absolute necessity to the
effectual working of submarine cables in great sea depths, I effectually secure
this important result by a simple and beautiful adaptation of forces existing in
nature. For the interior coat: I employ pure caoutchouc unmixed with any
other material. From thin sheets of india-rubber. I cut. long. narrow bands,
which are then united together end to end, and stretched to, such a degree.as
to lose their elasticity. This inelastic gum cord is then wound upon bobbins,
and from these bobbins it is rolled off by simple machinery upon the metallic.
wire conductor, already prepared in the same manner that the large brass strings.
of musical instruments or ordinary insulated wire employed in electro-magnetic.
batteries are manufactured. Over this a second coating of gutta..percha in a.
semi-liquid state is imposed, and upon this is placed a third coating of
caoutchouc either pure or combined with pulverized. glass, feldspar, sand, or
other non-conducting substances: This is vulcanized by passing it. through a
bath cf sulphide of carbon on the cold process of vulcanizing. When these.

page_text: three insulating coats have been placed in the manner above mentioned the
conductor thus coated is passed through a chamber heated to a gentle heat,
and by this means the following results are determined:-The gutta percha
gradually softens and forms a complete solder between the two coats of
caoutchouc, whilst at the same moment the inner coating of spun caoutchouc
which, when cold, remains in its inelastic state, endeavours to assume its
normal contracted condition before being subjected to stretching; it conse-
quently, by the nature of its being, swells largely, and thus determines an
enormous and continued pressure upon the wire conductor. Thus two
important results are attained, namely, the solid union of all the coats of the
insulation and the total exclusion of air. A conductor thus insulated I cover
with an external envelope of hemp or other fibrous material wrought in the
usual fashion of ships' cordage.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said, Thomas William Evans in the Great Seal Patent Office
on the 5th September 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
WILLIAM EVANS, M.D., of No. 15, Rue de la Paix, in the City of Paris,
Empire of France; send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of March, in the year of our Lord One
thousand eight bundred and sixty-one, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give-and grant unto me, the said
Thomas William Evans, Her special licence that I, the said Thomas William
Evans, my executors, administrators, and assigns, or such others as I, the
said Thomas William Evans, my executors, administrators, and assigns; should
at any time agree with, and no others, from time to time and at all timės
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 "IM-
PROVEMENTS INTELEGRAPHIC CABLES;" upon the 'condition (amongst others)
that I, the said Thomas William Evans, 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

page_text: calendar months next and immediately after the date of the said Letters
Patent.
:
NOW KNOW YE, that I, the said Thomas William Evans, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
In constructing electric telegraph cables I employ a conductor composed
of several wires drawn from metal rendered absolutely pure by a process
analagous to that employed in the refining of the precious metals or by any
other process of refining. As copper possesses nearly seven times greater
electrical conductability. than iron I adopt copper as the constituent metal
of the wire conductor. By the increase of purity the tenacity and con-
sequently the conductability of the wire is largely augmented. Recognizing
the well known electrical law that the capacity of condensation is in
exact ratio with the superficial surface of the conductor, and impressed
with the serious risk involved in the employment of a submarine electric
conductor composed of only a single wire, I combine seven copper wires
(drawn from perfectly pure metal) six of which surround the remaining
one as a centre. Having first placed these wires in parallel lines in close
contact with each other I draw them all together through a round holed draw
plate. By this means I reduce the volume and compel the wires to assume
the form of longitudinal sections of a prolonged cylinder, the exposed surface
of which will be of course exactly equal to that of a single wire of the same
diameter, while additional strength and additional safety from risk of total
rupture are effectually secured by the use of independent wires. Upon the
cylindrical conductor thus prepared I superimpose, to guard against the
possibility of any defects in the metal, by means of a galvanic: battery, and
a bath containing either copper or gold in solution, a slight coating or plating
of pure copper or gold (the latter I prefer). By thus presenting a surface
of absolutely pure metal the facility of electrical transmission is sensibly
increased, whilst the danger of any chemical action upon the conductor from
the contact of the insulation is entirely avoided..
It is a well known fact that when caoutchouc, vulcanized in the ordinary
manner with heat, is applied in direct contact with the copper a chemical
effect is produced on the metal which is rapidly corroded and rendered brittle.
It has been attempted to avoid this action by coating the wire with tin
and silk or cotton, but the tin is also corroded and the silk or cotton by
capillary attraction absorbs the sulphur thus communicating it to the wire,

page_text: now pure caoutchouc over a gold surface has no such effect. For insulating
the conductors of electric telegraph cables, I employ three distinct coats,
an interior one of pure caoutchouc, a second of gutta percha, and a third
of caoutchouc.
Regarding the total exclusion of air as a matter of absolute necessity to
the effectual working of submarine cables in great sea depths I effectually
secure this important result by a simple and beautiful adaptation of forces
existing in nature. For the interior coat I employ pure caoutchouc unmixed
with any other material. From thin sheets of india-rubber I cut long
narrow bands which are then united together end to end and stretch
to such a degree as to lose their elasticity, this inelastic gum cord is then
wound upon bobbins, and from these bobbins it is rolled off by simple
machinery upon the metallic wire conductor already prepared in the same
manner that the large brass strings of musical instruments or ordinary
insulated wire employed in electro-magnetic batteries are manufactured. Over
this a second coating of gutta percha in a semi-liquid state is imposed, and
upon this is placed a third coating of caoutchouc either pure or combined
with pulverised glass, feldspar, sand, or other non-conducting substances.
This is vulcanised by passing it through a bath of sulphide of carbon, or the
cold process of vulcanising. When these three insulating coats have been
placed in the manner above mentioned, the conductor, thus coated, is passed
through a chamber heated to a gentle heat, and by this means the following
results are determined:-The gutta percha gradually softens and forms a
complete solder between the two coats of caoutchouc whilst at the same
moment the inner coating of spun caoutchouc, which when cold remains in
its inelastic state, endeavors to assume its normal contracted condition before
being subjected to stretching. It consequently by the nature of its being
swells largely and thus determines an enormous and continued pressure upon
the wire conductor. Thus two important results are attained, namely, the
solid union of all the coats of the insulation, and the total exclusion of air,
A conductor thus insulated I cover with an external envelope of hemp or
other fibrous material wrought in the usual fashion of ship's cordage.
By the combination 1 can let the wires run together in parallel lines to
save bulk, and then let one or more branch off to different stations, it is
especially useful for telegraph lines passing over the tops of houses. The
combined wires being so compact they make an economy of the outer covering,
be it what it may, as there is no loss of substance in the interstices between
the wires.
I claim the constructing the conductors of electric telegraph cables by

page_text: combining several wires together as herein described, not only for submarine,
but also for ordinary telegraphs.
I also claim the covering the wire conductors with gold both in constructing
submarine and ordinary telegraph cables.
And I also claim the insulating the conductors of electric telegraphic cables
as herein described.
In witness whereof, I, the said 'Thomas' William Evans, have hereunto
set my hand and seal, this Second day of September, in the year of
our Lord One thousand eight hundred and sixty-one.
Witness,
H. PAUL,
6, Rue Neuve, St. Augustin,
***Paris.
THOS. W. EVANS, M.D. (L.S.)