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

THE ATLANTIC TEI EGRAPH.

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 effec's—the na' tire of the cable itself—the
sttucture of which, however suitable fur shallow
waters, is entirely inapplicable, from its construe.
tiou and spocitha gravity, to :he v' trnme deptlia.
and span of the Atlantic. Ho gates*" That, for
the Atlantic, nothing but the comparative infancy
of the science of cable laying will ever excuse t e
attempt having been made with such a de;cription
of rope." Aed again—" Wire-covered ropes for
such deep seas RI the Atlantic 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 al I the worthless
and expenFive lumber which ha; la, en foisted into
what, under a differsnt arrangement, shouldbe,ode
of the simplest mechanical operation." We are glad.
te revert to these remarks of au eye-witnese, being,
from the test of experience, corroborative of the
principles we have ourselves so treqeently pro-
pounded in reference to the inventions of Mr.
Allen, in Submarine Telegraphy.
We may here recapitulate the principles of
cons'ruction, or rather the philosophy of the
submarine cable, the conditions of which are so
well maintained iu the cables patented by him—
namely, that they combine with the necessary
conductibility for the distance, the greatest
amount of relative strength possible Lto be at-
tained, and the, too, 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
shealer the water, the heavier should the cable be,
and vice versa. 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
ston3s and other disturbances, from anchors, dm,
whose specific gravity
mshotifigdhthebaebao.A4tesd,
bo
y slight
r more;
aagisteactoioundoftahre ot
part
hvrillotn, of a sepeeperistceag,raavniatywohfi3ch
should
ud a;
and
not have
pa a srt forp
e
c
i
fi
thc
gravity greater thin
e d
although less—say I'3 (little more than
l
th it of common tarred rope)—would be quits
enough ; the letter specific gravity taking consi-
derably over three hours to sink to a depth ofl,ooo
lathoms—a ra'e fast enough for any purpose of ,
submergence, and also insuring a straight and mil-
k) m issue of the cable from the ship. A rdpe of •
this specific gravity and weight could be handled
withgreat facility, and paid out with great rapidity,
dispensing entirely with friction-breaks andpayinge
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 BUIL 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 vtcring 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 casing as het etofore. This, in the
specimens shown at the Institution of Civil Engi-
neers during the discussion ou Mr. Lon,vidge's
paper on the submergence of telegraphic cables, waus
effected by a strand of iron wires, cr of iron arid
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 coir
rope, with or without au outer serving of tarred
yarn.
Contenting ourselves with this brief exposition of
the principles maintained by Mr. Allen throughout,
the correc!ness of which has been so fully °zeal-
phw trusthic
hlaisfiebde
cbmy
trieleceLit,moctertii,rinnc est,hne o
At tthi3e,ilteiac,s t
woof
now that the truth of science in regard to submarine
ropes may ba said to he fairly asascertained,vtelniatttnheo
fastidious or sinister influences will
public from the benefit of his discoveries.-
Mechanics' Magazine.

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