The Cleveland leader. [volume] (Cleveland [Ohio]) 1865-1865, 1865-06-10
THE ATLANTIC GABLE.
Preparations on Board the Greai
Easterm--Scfentt6c Tests.

the following interesting account OF the
preparations on board the Crest Eastern
for laying the ocean TELEGRAM cable:
DTFEREScEs BETWEEN 1858 AND 1865.
A visit was paid TO the Great Eastern a
few days since by g large party of the Di.
rectors' friends, and it may be said that all
who understood the preparations which
they saw came away with q greatly
Strengthened confidence in the future of
the new cable. Since 1858, when the first
Atlantic line was laid, the advance that
has been made by the scientific world to-
wards comprehending electrical phenome-
ma is very great. It has been said, by q
man well qualified 70 speak on the subject,
that electric science has passed, since that
time, from Its childhood to its msturity.-
SO far as the phenomena connected with
long electric circuits were concerned, we
had in 1858 nc knowledge wbstever. The
instruments in common use were uDsuited
to receiving the signals through a great
length of cable; the necessity of providing
for the conductor an insulation so perfect
as to approach an absolute condition was
i~nadequAtely appreciated. The best pre-
liminsry test for = long cable had not been
devised, and the old Atlantic telegraph
was laid without having been subjected to
any searching test on shore. Every body
had advice to give concerning the man
agement Of the wire, but no n recon-
mended the precautions which subsequent
experiences has shown to be necessary
When the signals began to fail the battery
power was augmented and electro magnetic
induction coils, which rapidly helped on
the destruction of the conductor, were put
= .- NJ k--Le Il I--s--fT
the csble-of humoring its feeble attempts
81 s~rticulste utterance, and Uf finding out
what it said rather by listening acutely
than by constantly calling on it in the
language of the Victoria gallery, to "Speak
up" The old cable, however, is dead and
gone; part Of 1t has been picked up and
applied TO ignoble uses, IS 8 rscehorse past
his work msy be put into the shafts Of a
HAnsomj psrt7 of it has been abandoned,
and lies whore it may rest till the end of
time, in the Hdark, ~unfsthomsd caves of
the deep sea. Let us turn to the practical
present.
SCENES ON THE GREAT EAsTERN
The Great Eastern looks Just now more
like an engineers workshop than a sea-
| going ship. The vast expsnse of her deck
are covered with wooden sheds snd piles
OF timber. There are smiths FORCES below,
and between the docks you might fancy
yourself in q mschinIst's factory. The
great engines of the shop, it is true, AVE
lost the bright look of machinery which is
in constant use; and the huge dull masses
of iron seem asleep, or ina trance. If you
descend the ladders which lead to the
boilers and furnsces-sn expedition which
is more like going down a mine than any
other to which it can be compared-you
Hnd yourself in the midst of darkness,
solitude and cold; but in those regions OF
the vessel where the cable is being shipped
and watched there is every sign of keen,
vigilant intelligence. When you under
stand what is being done, you see some
thing more than this-thst scientific fore
sight of the highest order directs every
step and that the thick tsrry rope, coarse
and rough to appearance, which lies coiled
away under water in the tanks of the ship,
is manufactured, scanned and tested with
as much care rs the incest optical instru-
ment in an astronomers conservatory, or
the most delicate apparatus or fragile glass
ever applied to the careful experiments of
chemistry.
q SCIENTIFIC TESTS.
It seems impossible that there can be
any fault in the Atlsntie cable when the
Great Eastern goes so sea. To say moth
ing of the tests applied TO it at the manu-
factory, it is tested not alone after it has
been taken on board, but during its delivery
into the ship. As soon as q len 9Th is
brought alongside, one end is connected
with the coils already on board, and the
other end with the instruments in the
testing room. The circuit is thus made
through the whole extent of the coil, tie
portion on board and the portion along
side. The Process of hauling in then com.
mences, and the insulation Is continuously
over. The instruments in the testing
room record the smallest deviation from
absolutely perfect insulation. 1t will be
understood that an insulation which shall
be quite perfect, as an electrician IN
derstands the word, Is not attsinRble A
piece Of metal separated by means of the
pureet glass, and enclosed IN the driest at
atmosphere that can be obtsined, will, if
charged with electricity, lose that %electri-
city after q time. In speaking of insuls-
tion we must therefore be understood TO
mean an approximate condition, but the
approximation In the case Of the new
Atlantic cable comes so near to perfection
that his rough tArry rope is g scientific
wonder.
The last dying pulsstion of the old At
lsntic cable was forced through it BY means
of q galvRnic battery consisting of 24O
cells. Thu submarine telegraph from Lon
pom to Amsterdam is habitualIy worked
with 8 battery of fifteen cells, and such a
battery is commsnly used for the other SUBJ
marine lines Of Europe. Signals have
been repeatedly sent through more than
thirteen hundred miles of the cable D w op
board the Crest Eastern by means of ona
cell. GalvAnic currents so feeble that thew |
could not have beenf felt by the hand. and
might have been passed hsrmlesslv tbrou0b
q circuit completed by the Operators
tongue, can be used to convey messages
along 8 length of cable that would veTv
nearly stretch from London to ST. Peters.
burg. over needle instruments. such As
those in ordinary use for hand telegrapbv
q current from one cell would be power.
less. J
To record such faint pulsstions of cleo
tricity it Is necessary to use Professor
Thompson's mirror gslvsnometer. This
beautiful instrument consists of q mirror
about the size Of q fourPenny piece, made
Of microscope glass, and so thin that it
Welghs only q grain On the back OF this
mirror q minute magnet is fixed, and
thus supplemental is suspended by asiIk-
en- fore in the heart OF q coil of wire, so
that any current passing through tie col.
defects the msgnet and the mirror along
with it. A ray Of light reflected by the
mirror falls on a scale, distant about eigh-
teen or twenty inches, and reveals its
f4intest movements. Different combins-
tons Of these movements represent the
different letters of the slphsbet, and thus
the apparently erratic wanderings of q
ray Of light are made to convey intelli-
gence. An instrument of this kind is con
stsntly used TO test the cable, as it is haul
ed on board; and if any fault had existed
it could not nave passed without detec-
ton. Up to this time, when there are on
board the ship and along side 1870 miles
Of cable, no fault has been discovered.
THE IMMERSION.
The machinery for paying out is not yet
on board, but is being put together st the
Greenwich works. The process of INNER
sion viii take about q fortnight. The be-
ginning Of the shore end will be laid bya
small vessel, which will meet the Great
Eastern shout twenty miles from the Irish
The cable will then be passed on