The Weekly Perrysburg journal. [volume] (Perrysburg, O. [Ohio]) 1861-1???, 1865-06-21
Selrtt StlistelIauv.
The Atlantic Cable c--Prcpnrn-
tlOns ON BOARD the Great East
crn Scientific Tests.

crn Scientific Tests.
Tho London Telegraph OF May %, has
tho following interesting account of tho
preparations on board tho Great Eastern
for laying tho ocean telegraph cable;
DIFFERENCES BgrwEES 1855 AND 1868.
a visit was paid TO tho Great Eastern
few days since 10y a largo party Of the hi.
| rcctols friends, aud il il may bo said that
all who understood tho preparations which
they saw, camo away with a greatly
strengthened confidence in tho future OF tho
new cable. Sit co 1858, whom tho first At
lantic line was laid tho advance that has
boon mado by the scientific world towards
oompTchonding electrical phenomena is
very great. II has been said, by man
well qualified TO speak on tho subject. that
electric science has passed. since that time,
from its childhood tu its maturity. So far
as tho phenomena connected with long
electric circuits are concerned, We lad in
1888 no knowledge whatever. Tho irstru-
monts IN common uso were unsuitod 20 re-
cciving signals througha a great lcngth OF
cable; the noooessity Of providing for the
conductor an insulation 30 perfect as TO
approach an absolute condition was inade-
quately appreciated. Tho best prelimin-
airy tost for long cable had not bocn do.
visod, and tho ul 1 Atlantic Telegraph was
laid without having been subjected to
to any searching test on shoro Every.
body had advice to givo concerning the
management of tho wire, but no Quo re.
commended tho precautions which subso,
qucnt experience had shown 10 DO neoces-
ary. When tho signals began to fail the
battery power was augmented, and electric
magnetic induction coils which rapidly
helped on tho destruction of the conductor,
were put in circuit. No ono thought of
nursing the cablo--of humoring its feo-
bic attempts at articulate uttoTanoo, and Of
finding out what il said rather hv listen.
ing acutely than by constantly calling on it
in tho language OF Victoria gallery, 10
"Speuk up" Tho old cablo however is
dead aud gone; part of il has beon picked
aud applied to ignoble uses, as race
horse past his work may bc put into the
shafts of "a Ilansom; part of II has been
abandoned, aud hes where il may rest ill
tho end of time, in tho "dark unfathomed
caves Of the deep soa. Lot us turn 70
tho practical present
SCENES ON BOARD THE GREAT EAsrERY.
| Tho Great Eastern looks just now more
like an engineers workshop than seago.
ing ship. Tho vast expanscs OF her dock
arc covered with wooden shods and piles
of timber. There are smiths forges below,
and between docks you might fancy your.
self in macbinists factory. Tho great
! engines of t,,o ship, II is true. have lost tho
4 bright loot of the machinery which is in
constant use; and the hugo dull masses of
iron seem asleep or in traneo, II you
descend tho ladders which load to The boil
ors and furnaces--Rn expedition which Il
moro like going down mine than any other
to which 1t can bo conn ared--yon iind
yourself in the midst of darknoss, solitude
and cold, but in those regions of tho vessel
whero the cablo ia being shipped and
watched, there is ovtry sign OF keen, vigil
liant intelligence. When you undor-
stand what is being done. you SEQ some
thing moro than this-that scientific fore.
sight OF the highest order directs every
stop; and that the thick, tarry rope, coar SC
and rough to appearance, which lies coilcd
away undor water in the tanks Of tho ship,
is manufactured, scanned and tested with
as much caro- as tho optical instrument in
an astronomers observatory, or tho most
delicate apparatus of fragile glass ever ap-
piled TO tho careful experiment Of chcmis.
| try.
THE SCIENTIFIC TEsTs.
| II secms impossible that thoro can be any
| fault IN tho Atlantic cable Whsn the CT eat
| Eastern goos 10 sea. To say rothing OF the
tests applied 10 Ii Mt the manufactory, il is
tosted not nlono aftor IL has bocn taken on
board, but during it's delivery into the shir.
As soon as length is brought alongside,
! ono eud is connected with tho coils already
| on board, and the other end with the instru.
| ments in the testing room record the small
est deviation from absolutely perfect insu.
lation. IL will be understood that pn insu.
lation which shall DO quite perfect, aa an
electrician undorstanda tho word, Is not ct
tainallo. A pip0p of metal, separated by
means Of tho puTost glass, and enclosed in
tho driest atmosphere that can be obtained,
will, ii charged with cleo u ity, lose that
electricity after q time. In speaking Of IN
suiation wo must therefore he mdoTstood
to mean an approximate condition; but tho
approximation ia the case Of the new Allan
tic cable comes Sd neaE 10 perfection, that
this rough tarry rope is a scientiiio wonder.
The last dying pulsation of the old At
lantic cable was forced through Il by means
of galyanic battery consisting Of two hun
dred and forty cells. Tho submarine tele-
graph from London to Amsterdam is habit
ually worked with battery Of lifty cells,
and such battery 10 commonly used for
the other submarine limos Of Europe. Sig
nals have boon repeatedly sent through
moro than thirteen hundred milee of the
cable now on board tho Great Eastern, BY
means Of one cell. Galvanic currenta so
feeble that they could not have heon felt
by the hand. and might have been passed.
harmlessly through circuit completed by
the operators tongue, can bp used TO convey
messages along a lengih Of cablo that
would very nearly stretch from London to
81. Petersburg. Over needle instruments,
such as these in ordinary use for ltnd tele-
graphy, a current from one cell would be
lpoweTless,
To record such faint pulsaiions Of elee-
tricity, it fs necessary 10 use Professor
ThoinpsoD's mirror galyanomoter. This
beautiful instrument consists Of mirror
about Tire size OF q fuur-I emmy piece, made
Of microscopic glass, and so thin that it
weighs only grain. On the back OF this
mirror minute magnet is fixed, and thus
supplemented il is suspended by a silken
fiber in tho heart Of coil Of wire, so that
any current passing through defects the
magnet and the mh roT along with il. A ray
OF light reflected by tho mirror falls on
scale, distant about eighteen OF twenty inch,
os, and reveals its faintest movement, Diff
lereut combinations Of these movements
represent the different letters Of the alpha
bet, aud thus the apparently eTratio wan
deriDgs of ray of light hro made 10 con-
vey intelligence. An instrument Of this
kind is constantly used 10 test the cable, rs
1 A =. A A A.. IL 4.