Mineral Point weekly tribune. (Mineral Point, Wis.) 1859-1868, 1859-01-18
The Atlantic Telegraph h---Why il Failed How TO
Succeed.

M. B. Severson, a Baltimore archi-
tect, who Is principally engaged in the
construction Of iron roofs and bridges, III
a lucid communication in the Baltimore
Patriot, endeavors to explain the causes
of the failure of the Atlantic Telegraph,
and TO describe the kind Of cable which
would insure success. On the first point
he says:
The core of the Atlantic cable in sur
rounded with eighteen strands, each con-
slstlng of seven wires twisted together.
/ The strands thus formed are wound spir-
ally around the core, and form spiral
| lay of twisted strands. And the relation
existing between this spiral-lay and the
twist IN the strands Is such that straight
ening the strands by unwinding them will
tighten their twist, and this may be car
rled 10 such an extent as 10 destroy them
! by tors:on. The cable is, in this respect,
similar 10 a twisted rope.
. Now, the strain upon the Atlantic
Cable while paying it out, was quite unlike
what would occur IN testing a short piece
In the uusal way for, while the part at
and near the bottom of the ocean was near
ly free from strain, the strain in the upper
part (when no. under Way was equal to
the specific gravity Of the suspended part,
the strain gradually Increased III intensity
from the bottom upward, so that in depths
of TWO miles the strain at the point of sus-
pension was about 5000 pounds. The
effect OF this concentrated strain was TO
straighlen the spiral-lay, by unwinding
the strands Of this part, and, II doing SO,
tightening the twist ia the strands, SO as TO
impair their strength by torsior to such
an extent as to cause the cable 10 part ui-
der less than half the strain It could bear
safely under circumstances of uniform ten
slon-such as would take place in a short
length when both ends are held secure
and, the lower part being but slightly
strained, and consequently free to revolve,
The unwindlng of the upper part is thrown
into this lower slack part, 50 that the wind
ing of this part becomes tightened, and
the twists ia the strands reduced, in the
same proportion that the winding of the
upper part is reduced and the twist in the
strands IS nghtened.
q" Consequ uentlly, the lower slack part
Will be thrown into qulrls, folds or festoons,
such as are liable 10 change 50 as to form
sharp kinks, disiorting and separating the
loose and uutWIsled strands from the core.
leaving this vital part naked and exposed
the fuii force OF the pressure Of the water.
And, considering how the part of the core
must have been strained Is extension ana
twisting while passing from the ship, caus-
ing the tai to o0ze from 1t like sweat, as
some have expressed il, It can surely not
tie expected, after such abuse to be able
. TO resist the enormous pressur of the wa
ter at depths Of two miles and more
This IS withou: doubt the reason why the
present cable will not work, and why il
did not work better ct first. The posi-
blLty Of rapid communication has, there
+ fore, not been fairly tested in this cable,
4 for The reason that the core has probably
been defective from the first Had it been
whole The result would, without doubt, have
been far more satisfactory.
Mr.. Severson suggests
:" That the conductor be made Of single
copper wire, spIiced strong and compact,
TO make the requisite length, making the
splice slightly stronger than the plain wire,
as can be done. / would have il single,
/ because II Will then have much less exter-
nal surface TO BE acted upon by external
and retarding influence the same a.
mount of conducting material will have
when divided into several small wires
! The difference of surface when in one or
IL seven wires is about as one is 10 two
and five-eights. This | regard as very
important--not new except so far as 10
show how It can be made practical in sub
marine cables. | would cover such con-
ductor by winding around 1t several thick
nesses of hbrous guia percha material,
such as fLe cloth perfectly saturated and
distinctly coated, SO that the fbrons part
of each layer as wound around the wire
be separated from each other by the coat
ing, and thus make It impervious and IN
sulatinr. Over this | would apply per-
feet coating of gura percha or elastic gum.
By forming the core thus IF fibrous ma
terial, the strong fbres will be sure TO hold
the conductor safe IN the center OF the
core-lhe furtheSt possible from external
influence, such as have acted so msichivi-
ously on the conducting wire of the pres
ent A.iaatic Gable.
" Around this core l would place wire
straight and parallel 10 each other. and
Of such size as Will give sufficient strength
to the cable, and Will, when closely press
tu NE ttkes uSt COY cf lt> SuftdCe- AtTe
| would hold firm BY closely wrapping or
serving them with anuealed wire, and
thus cover the whole we'll with tar. By
means of thus serving the cable, the main
wires and the core can be so comparess-
ed as 10 remove all danger from leaking.
The longitudinal wires can be splIced
neatly and 50 strong as TO make the splice
the strongest part, and they may thus be
made continuous through The entire length
Of the cable.
And as they win be straigtand paral-
lei, there wii. be no danger of twisting.
Nor will such cable stretch perceptibIy
IL the operation Of laying il In deep water
consequently the conductor and It's sur.
-.-.LL - ..-..----L