The Story of the Atlantic TelegraphField, Henry M. (Henry Martyn)
History
The Story of the Atlantic Telegraph
Field, Henry M. (Henry Martyn)
Transatlantic cables
"No particular connected with this great project has been the subject of
so much comment through the press as the form and structure of the
telegraph cable. It may be well believed that the Directors have not
decided upon a matter so all-important to success, without availing
themselves of the most eminent talent and experience which could be
commanded. The practical history of submarine telegraphs dates from the
successful submersion of the cable between Dover and Calais in 1851, and
advantage has been taken of whatever instruction this history could
furnish or suggest. Of the submarine cables heretofore laid down,
without enumerating others, the one between Dover and Calais weighs six
tons to the mile; that between Spezzia and Corsica, eight tons to the
mile; that laid from Varna to Balaklava, and used during the war in the
Crimea, less than three hundred pounds to the mile; while the weight of
the cable for the Atlantic Telegraph is between nineteen hundred pounds
and one ton to the mile. This cable, to use the words of Dr. Whitehouse,
'is the result of many months thought, experiment, and trial. Hundreds
of specimens have been made, comprising every variety of form, size, and
structure, and most severely tested as to their powers and capabilities;
and the result has been the adoption of this, which we know to possess
all the properties required, and in a far higher degree than any cable
that has yet been laid. Its flexibility is such as to make it as
manageable as a small line, and its strength such that it will bear, in
water, over six miles of its own weight suspended vertically.' The
conducting medium consists not of one single straight copper-wire, but
of seven wires of copper of the best quality, twisted round each other
spirally, and capable of undergoing great tension without injury. This
conductor is then enveloped in three separate coverings of gutta-percha,
of the best quality, forming the core of the cable, round which tarred
hemp is wrapped, and over this, the outside covering, consisting of
eighteen strands of the best quality of iron-wire; each strand composed
of seven distinct wires, twisted spirally, in the most approved manner,
by machinery specially adapted to the purpose. The attempt to insulate
more than one conducting-wire or medium would not only have increased
the chances of failure of all of them, but would have necessitated the
adoption of a proportionably heavier and more cumbrous cable. The
tensile power of the outer or wire covering of the cable, being very
much less than that of the conductor within it, the latter is protected
from any such strain as can possibly rupture it or endanger its
insulation without an entire fracture of the cable."
CHAPTER VII.
SEEKING AID FROM CONGRESS.
Public-domain text, read in full here on John Shaqi.
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