The Sun.
London, England, 1858-08-02 00:00:00

THE ATL4XTIC TELEGRAPH.

The able correspondent of the Times, last week,
gave a full and practical exposé not only of the mis-
haps which have befallen the cable, but the cause
of these effects—the na'ure of the cable itself—the
structure of which, however suitable for shallow
waters, is entirely inapplicable, from its construc-
tion -and specific gravity, to the extreme depths
and span of the Atlantic. Ho states—r" That, for
the Atlantic, nothing but the comparative infancy
of the science of cable laying will ever excuse t e
attempt having been made withauch a description
of rope." And again—" Wire-covered ropes for
such deep seas as the At'antic are not only useless,
but literally almost render such an undertaking
impossible." Also, that ropes of light specific
gravity only are suitable, which would enable us to
dispense with "all the paying-out machines, buoys,
slip ropes,hauling-in apparatus, and all the worthless
awl expensive lumber which has been foisted into
what, under a different arrangement, should be one
of the simplest mechanical operation." We are glad
to revert to these remarks of an eye-witness, being,
front the test of experience, corroborative of the
principles we have ourselves so frequtntly pro-
pounded in reference to the inventions of Mr.
Allen, in Submarine Telegraphy.
We may here recapitulate the principles of
coesiruction, or rather the philosophy of the
submarine cable, the conditions of which are so
well maintained in the cables patented by him—
namely, that they combine with the necessary
conductibility for the distance, the . greatest
amount of relative strength possible Ito be at-
tained, and that, tco, in the form of an inexten-
sible core, so as to counteract tension and conse-
quent injury to the insulating medium ; and that
the specific gravity of a submarine cable should,
within certain limits, be inversely as the depths of
the sea on the intended route ; that is to say, the
shlaler the water, the heavier should the cable be,
and vice verse. There should, therefore, be three
several descriptions of cable ; viz., that which
within tideways will be subjected to the effects of
tides and waves, and, the chances of abrasion from
stun 39 and other disturbances, from anchors, &c.,
whose specific gravity should be about 4.5, or more;
a second part wh;ch might be affecgteradvbyy ofsli 3 slight
agitation of the bottom, of a specific gravity
and a third part for the deep sea, and which
should not have a specific gravity greater than
1.5, although less—say 1.3 (little more than
that of common tarred rope)—would be quite
enough ; the latter specific gravity taking consi-
derably over three hours to sink to a depth of 2,000
fathoms—a rate fast enough for any purpose of
submergence, and also insuring a straight and uni-
fo-m issue of the cable from the ship. A rope of
this specific gravity and weight could be handled
with great facility, and paid out with great rapidity,
dispensing entirely with friction-breaks andpaying-
out gear, which are necessitated only by heavy
ropes, the primary cause of all the mischief in such
undertakings.
It will thus be obvious that by such an arrange-
ment of parts, as to strength, conductibility,
weight, and specific gravity, in accordance with the
first principles of natural science, a submarine
telegraph may be established in any depths and to
any distance with comparative certainty; the
process being thus rendered at once simple, and to
all intents and purposes analogous to veering out
a log line.
With these objects in view, the peculiar feature
of Mr. Allen's cables is that of his putting the
metallic strength in the centre of the insulating
medium, thus forming an inextensible core in
place of a wire easing as heretofore. This, in the
specimens shown at the Institution of Civil Engi-
neers during the discussion on Mr. Longridge's
paper on the submergence of telegraphic cables, was
effected by a strand of iron wires, or of iron and
copper mixed, this latter being lighter and more
effective in many ways, as combining the conduc-
tibility of the copper with the strength of the iron.
It is then coated with gutta percha in the usal way,
and the whole enveloped in strands of hemp or boir
rope, with or without an outer serving of tarred
yarn.tr .on of
Contenting ourselves with this brief expos'
the principles maintained by Mr. Allen throughout,
the correctness of which has been so fully exem-
twoef whichtrust
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trheec elnatteo ccu
trialsrre ni
ec e st,h not thetlaniteie, as
now that the truth of science in regard to submarine
ropes may be said to be fairly ascertained, that no
fastidious or sinister influences
of hisntfluences will d
v
ill
seo preventeri
e
the
public from the benefit
Mechanics' Magazine.

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