Evening star. [volume] (Washington, D.C.) 1854-1972, 1865-06-13
THE ATLANTIC CABLE.
Preparations on Beard the ..areat East.
efnS-Scienttfic TeSt

ern"-Scientific Test.
The London Telegraph, Of May %, has tho
tions on board the Great Eastern for laying th.
ocean telegraph cable:
Differences Between 1 SIS and 1855.
A visit was paid to the Great Eastern 8 few
uays since oy large party Of the directors
friends, and 1t may be said that all who UNDER
stood the preparations which they saw came
away with greatly strengthened condolences
In the future OF the new cable Since 1852
when the first Atlantic line was laid, the ad-
vance that has been made by the scientific
@ woria .owaras comprehending electrical phe-
1t has been said, by a man well qualified to
speak on the subject, that electric science has
Its maturity. So far as the phenomena con-
nected with long electric circuits were CON.
cerned, we had in 1855 no knowledge what
ever. The instruments In common use were
unsuited to receiving signals through great
the conductor an insulation 50 perfect as 10
quately appreciated. The best preliminary
test for long cable had not been devised, and
the old Atlantic telegraph was laid without
shore. Everybody had advice to give con-
cerning the management OF the wire, but no
one recommended the precautions which sub
sequent experience has shown to be necessa-
When the signals began to fail the battery
Induction coils, which rapidly helped on the
destruction OF the conductor, were put in cir
cult No one thought of "nursIng" the cable,
of humoring its feeble attempts at articulate
utterance, and Of finding out what it said
rather by listening acutely than by constantly
calling on it, in the language Of the Victoria
ever, is dead and gone. Part of 1t has been
picked up and applied to ignoble uses, as 8
race horse past his work may be put into the
doned, and lies where 1t may rest till the end
of time, in the "dark, unfathomed caves" Of
the deep sea. Let us turn to the practical
present.
Scenes on Board the ssGreat Eastern,
The Great Eastern looks just now more like
an engineers workship than sea going ship
with wooden sheds and piles Of timber. There
are smiths forges below, and between the
decks you might fsnsy yourself in q, ma.
ship, it is true, have lost the bright look OF
machinery which is in constant use; and the
huge dull masses OF iron seem asleep, or In q
trance. Ii You descend the ladders which
lead to the boilers and furnaces, an expedl-
ton which Is more like going down mine
than any other to which IT can can be compares
solitude and cold; but In those regions OF tha
vessel where the cable is being shipped and
nsn YOU SIGN Ss
thas scientific foresight OF the highest order
directs every step, and that the thick, tarry
robe, coarse to appearance, which lies coiled
away under water in the tanks Of the ship, is
manufactured scanned and tested with as
an astronomers observatory, or the most deli
cate apparatus of Fragile glass ever applied TO
the careful experiments OF chemistry.
The Scientific Tests.
1t seems impossible that there can be any
fault in the Atlantic cable when the Great
Eastern goes TO sea. To say nothing OF the
ed not alone after it has been taken on boards
but during its delivery into the ship. As SOON
as q length is brought alongside, one end is
and the other end with the instruments IN the
testing room. The circuit is thus made through
the whole extent Of the coil, the portion on
board and the portion alongside. The process
Of hauling in then commences, and the insula-
ton continuously observed. The instruments
in the testing room record the smallest devia.
ton from absolutely perfect insulation. ltwiH
be understood that an insulation which SHAH
be quite perfect, as an electrician understands
the word, is not attainable. a piece Of metal
separated by means of the purest glass and In.
closed in the driest atmosphere that can be OBJ
tsined, will, ii charged with electricity, lose
that electricity after time. In speaking OF
INSULATION we must therefore be understood to
mean an approximate condition. But the ap-
proclamation IN the case Of the new Atlantic
rough tarry rope is scientific wonder.
The last dying pulsation of the old Atlantic
cable was forced through it by means OF q GAL
forty cells The submarine telegraph from
London to Amsterdam is habitually worried
with battery of fifty cells, and such battery
is commonly used for the other submarine llnes
| of Europe. Signals have been repeatedly sent
through more than thirteen hundred miles OF
the cable now on board the Great Eastern oy
| that they could not have been felt by the hands
| and might have been passed harmlessly
| through a circuit completed by the operator
| tongue, can be used to convey messages along g
| length of cable that would very nearly sretcn
| from London to St. Petersburg. over needle
| instruments, such as those in ordinary use ZOE =
land telegraphy, q current from one cell Woul0
| 70 record such faint pulsations Of electricity
it Is necessary to use P5oiessor nG%pser
| ment consists Of mirror about the size o&-a
| fourpenny piece, made OF microscope glass
| and SO thin that 1t weighs only grain. On
| the back of this mirror minute magnet l.
fixed, and thus supplemented 1t Ii s"~spelded
by a silken fibre in the heart Of coil OF wire
| 80 that any current passing through the coli
defiests the magnet !. and the mirror along with
on scale, distant about Is or 20 inches, and
| reveals its faintest movements Different com.
6iaa.0ns tUn , OF these M IN movements represent the
| apparently erratlc wanderings Of q ray Of light
are made to convey Intelligence. An instfu-
msnt Of this hind is constantly used to test the
cable as IL is hauled on board; and If anv fault
had existed II could not have passed without
detection: Up to this time, when they are on
CABLE no fault has been discovered.
The Immersion.
The machinery for paying out is not yet on
board, but Is being put together at the Green :
l wien WorKs. Inc process OF immersion Will
take about q fortnight. The beginning of the
| shore end will be laid by q small vessel, which
will meet the Great Eastern about twenty miles
| from the Irish coast. The cable will then be
| passed on board, connected with that in the
| great tanks, and the big ship will begin her
voyage. To the uninitiated this process Of cut
| ting and joining the cable appears very mys-
tericur, bat the engineers who are used to the
| work face 1t without hesitation. The joints DC
not really endanger either the insulation or the
strength OF the cable, as wherever they are
imade the external and conducting wires are
spliced along considerable length-some-
times not less than thirty yards-and the quits
percha carefully put on in separate layers,
FIRMLY pressed together by means Of warm
| rons. The completeness OF the joints is tested
| by laying ii in an insulated metallic vessel
| containing water, and ascertaining, by means
| Of tests applied TO this vessel, whether any
| electricity escapes from the Joint as current
| Is passed along the cable.