The Sun.
London, England, 1865-07-15 00:00:00

THE ATLANTIC TELEGRAPH EXPEDI•

(From the Special Correspondent of the Timas)
GREAT EASTERN, July 14.
By the time this notice reaches the public the
Great Eastern will probably have begun her event-
ful voyage. At daybreak to-morrow the single
Trotman's anchor, which has held her safely against
wind and tide during the late severe weather, will
be raised, and under easy steam the monstrous ves-
sel, with her ponderous freight, will be carefully
navigated through Bullock's Channel to the open
water, and thence make the best of her way to
Valentia. It seems like mere iteration to explain
again all the almost endless precautions which have
on this occasion been taken to secure success.
Hull, engines, stowage, and fittings of every kind
have been carefully revised, adapted, or improved.
All that the experience of previous attempts could
suggest, all that the most earnest and painstaking
foresight could anticipate, has been done ; every-
thing now rests with the weather. In the four
great divisions on which the success of the under-
taking
may be said to turn—namely, the cable it-
self, its stowage, the ship, and its engines, nothing
apparently has been overlooked. As regards the
cable, it still reitains in the same perfect state as
when it was tested at the works, and, in fact, its
whole electrical condition is such as the largest
shareholder in the undertaking would desire for it.
Its various lengths are now and have been for some
days past joined up, and twice every day, morning
and evening, messages are sent through. The time
which these occupy in transmission shows its con-
dition to be as nearly invariable as possible. Last
week experiments were tried with a variety of in-
struments to ascertain the highest rate of working
speed with a low battery power. The best of these
instruments was, it is said, one invented by Mr.
Varley, with which it was found easy to work
through the whole length of 2,500 miles at an ave-
rage of about four words a minute. At this speed
the signals were remarkably clear and distinct, and
it is still claimed that it is possible to devise instru-
ments which can raise the rate from four words a
minute to as high as eight or even ten. This, how-
ever, remains to be proved. Yet, even in the absence
of such instruments, there can be no doubt but that
the gradually improving skill of the signalling
clerks, as they become more accustomed to work
through the wire, will, with the bettered electrical
condition of the cable when at the bottom of the
Atlantic, soon make four words a minute the mini-
mum of what can be accomplished by this telegraph.
The insulating properties of the gutta percha are
always increased by external compression. When
sunk in the tremendous depths beneath which the
cable is to be submerged it is calculated that the
weight of water above it will give a pressure of about
two and three-quarter tons to the circular inch.
Under this enormous weight the bulk of the in-
sulating core will probably be reduced one-third,
and, in fact, so compressed on all sides as to most
materially improve both " conductivity" and in-
sulation. Such aids to signalling excellence,
when coupled with the benefit which the cable
is certain to derive from the unvarying tem-
perature at the bottom of the ocean, are likely
to do more towards increasing the rate at
which messages can be sent than any instrument
which has yet been brought forward. During the
time of paying out, signals will be sent to Valentia
for every 50 miles of cable sunk, and for every 50
miles the Great Eastern runs. Thus it will be per-
fectly easy for the public to follow her course on any
map, and know precisely by the diffecrence between
the distance traversed and the length of cable sunk
the amount of slack that is being paid out. This
slack, as it is called, will afford the best index to
the state of the weather and the way in which the
Great Eastern is doing her work. No less than 33
per cent. of the entire length of the cable has been
allowed for slack, or waste, as we may better call it.
If all goes well, not more than 10 per cent. of this
will be used ; but, on the other hand, with bad
weather or irregular going of the Great Eastern
every coil will go over the stern to the very last
mile. So far as regards the cable.
As concerns the Great Eastern herself, Captain
Anderson and his officers have taken every possible
precaution as to her stowage and general equipment.
From outside she seems at the first glance to be
almost alarmingly deep in the water. It is, however,
less her actual depth which creates this unpleasant
impression than the appearance which she presents
of " sagging" amidships. Of course, this awkward
and most unpleasant appearance is merely an optical
delusion, no doubt created by her deep trim astern.
There is a difference of nearly sft between her trim
fare and aft. Astern she draws 35ft of water, while
under the bows it is only 30. Levels have been care-
fully taken to ascertain if any deflection was per-
ceptible under the ponderous weight she bears. No
sign of change, however, has been observable. Before
any of the cable was coiled on board 1,400 tons of
water were pumped into the aftermost compartments
of the ship, and 1,100 tons into the compartments
most forward. Underthese weights at her extremities
the Great Eastern deflected nearly an inch and a
half, recovering herself directly the water was
pumped out. This proof of strength is, of course,
very satisfactory. It would have been more so, how-
ever, if the test strains employed bore a closer rela-
tion to the enormous weights which she has now on
board. All told, the Great Eastern will leave the
Thames with rather more than 25,000 tons in her, a
burden almost as great as the whole fleet with which
Nelson fought the battle of Trafalgar could have
carried. All the weights are stowed as high as
possible to counteract to the utmost the Great
Eastern's most unpleasant tendency to roll. It is
popularly supposed that this ship is almost immov-
able
in any sea. Against a bead wind she is cer-
tainly very steady, though she can pitch as well as
other vessels, and has, in the Atlantic, aye, and even
in the Channel, taken in heavy seas over her bows.
Nevertheless, in a beam sea she is particularly
44lively," and rolls just in proportion to her size—
that is to say, she rolls very much indeed. Her
motion is easy, slow, and deep, occupying about 15
seconds. To make her do this, however, a beam

sea of 15 seconds interval between the waves is
necessary, and such a sea is rare even in the Atlantic.
Of course, all her system of stowage proceeds on

the theory that high-placed weights will prevent

her rolling. The Agamemnon was stowed after

the same fashion on the occasion of the last Atlan-

tic expedition, and our readers will probably re

collect that on that occasion the great
battle ship rolled as if she was never coming up
_ .

again. All the compasses now on board were at
first considerably affected by the magnetic in-
fluence of the cable. Some deviated as much as

32 points, while others, strange to say, though
ahnost similarly situated with regard to the tanks of
wire, varied as little as six. Every one of them has
now been carefully adjusted, and everyone will again
need readjustment when the cable is out of the
Great Eastern at Newfoundland. All the running-
gear has been removed from the rigging, so as to
obviate the possibility of anything falling from aloft
into the paying-outmachinery. Some
the yards
have been lowered, and scarcely a spar has
sang.
The village of huts and workshops has disappeared
from her decks, but their places have been more

than occupied by shanty coverings of various kiwis,
leading troughs, buoy rope wheels, gigantic buoys

for floating the cable at various depths from 600 to

3,000 fathoms, and, above all, the whole space of
what other vessels would be the quarterdeck is oc-

cupied by th© paying-out apparatus. The praise
which was at first bestowed up3n the simple effi-

ciency of this machinery has been amply vindicated
by its everyday working. As far as can be known

from mere preliminary trials it is absolutely perfect.
Both screw and paddle engines are reported to be
in very good condition. Every part of each, of
course, has been carefully overhauled and examined.
From the great depth of the vessel it has been

necessary to considerably reduce, or rather reef in,
the paddle floats. One-third has been taken off each
float, and the two remaining thirds brought as close
to the inner ring as possible. On the voyage round
to Valentia both screw and paddle will be used,
while during the submergence of the cable the Great
_ _

Eastern will depend mainly on her screw. The pad-
dles, however, will be kept under steam, turning
easily to save the screw the labour of driving them