The Sun.
London, England, 1857-07-22 00:00:00

THE ATLANTIC TELEGRAPH.

The operations of making the insulated wire rope
that is intendtd to transmit telegraphic signals
from Ireland to Newfoundland, and of transferring
it on board the Agamemnon at East Greenwich,
we have already described ; together with the ap-
paratus by which it is proposed to transmit cur-
rents of electricity through the wire. Similar
operations have b:en going on at the same time at
Birlielbead, and it was expected that the last
lenAlt of the c able would be taken on beard the
Niagara on Monday night. The nature of the
work has been somewhat different in the port
of Liverpool from that at Eat Greenwich,
because the Niagara was obliged to lie in the
Mersey, at some distance from the shore, and as
sistant steam-boats were required. The fallowing
account of the important undertaking, taken from
a Liverpool paper of Saturday last, presents i s as-
pect as seen on the Mersey:—
" The cable I-as been conveyed to the Niagara in
three vessels of about 500 tons each, viz , the Wal-
lace, the Eden, and the Perthshire, the last-named
having finished her delivery on Thursday night,
was replaced by the Wall-Lce, containing the last
280 miles of the cable. The process of delivering
this portion was c )mmenced. yesterday (Friday)
morning, and it will be completed, it is expected,
on Monday. The weight of the cable is, as nearly
as can be estimated, one ton per mile, so that the
portion conveyed by the Niagara will be 1,225
tons in addition to which there will be about 60
miles, viz., 50 miles at one end, and ten at the
other, of about six tons weight to the mile. Great
numbe►s of people aro convoyed on board the Nita,-
gar), by the Rock Ferry steamers, and with great
liberality they are allowed by Captain Hudson to
impect the process of coiling the cable, and to per-
arubula'e the deck.

" The cable is tested from time to time as it is
stowed away, and the coiling on board the Niagara
isundtr the superintendence of Mr. Woodhouse,
C.E., who took part in laying down the Varna and
Balaklava telegraph, and this gentleman will ac-
company Mr. C. Bright in the Niagara, to assist in
laying down the h 11f of the cable stretching from
the middle of the Alintic to the American
shore. These two gentlemen will have to take
alternate watch in the Niagara of the paying
out of the cable during the progress of the
work, The machinery for paying out the cable
has been made with great promptitude by Messrs.
includes
paying de Berge and Co., Manchester. It
paying out sheaves or drums, of five feet in diame-
ter, having grooves corresponding to the thickness
of the cable, with a friction drum attached to them,
revolving three times as fast as they do, and with
breakage power to check or ret Ird. the motion of
the sheaves at pleasure. From tie hold of each
ship, the cable, passing over four of these sheaves
to a, fe,lv feet above the deck, will be dropped into
the sea over a fifth sheave, placed above the stern.
The exact amount of strain will be constantly indi-
cated by an instrument for the purpose, under the
eye of the breakmar. At the sides of the vessel
will hang down into the water new electrical logs,
principally due to the ingenuity of Mr. Cnarles
Bright, the Atlantic Company's chief engineer.
These immersed logs have vanes and wheels revolv-
ing at a rata proportioned to the passage of the
ship through the water, and making an electric cir-
cuit which is broken at each revolution. An elec-

trio wire, from the log to the deck, records there
every revolution of the log, and consequently the
exact speed of the ship. it must not be supposed,
when the ships part company, tat communication
will be lost between those on board the vessels.
The electricians have hold of either extremity of
the coils of the cable, and will interchange signa's
constantly, so that each vessel will be in know-
ledge of the other's fate, and of every incident
that may help or retard the progress of sub-
mersion, unless some unfortunate emergency
should snap the link. When the topmasts of the
ships have sunk beneath the horizon, and they are
lost to view by the look-out men, the interoceanic
current of elec.ricity will give instant record of all
passes, until the lengthening line of cable has been
spun out from shore to shore. A bell on board
each vessel will sound every second as each portion
of the cable is payed out, and its silence will pro-
bably be the first indication of any mishap arising
from friction or over-tension of the cable, and the
vessels will have apparatus on board, worked by
a stationary steam-engine of 28 horse power ; "so
that, in any such emergencies, they can be backed,
the cable recoiled until the faulty place is found,
when a piece will be cut out and the perfect por-
tions reunited with as little delay as possible. In.
case of a storm, apparatus has been provided to
allow for any extraordinary strain that may occur,
and if necessary, for cutting the cable without let-
ting the outer end of it slip to the bottom of the
ocean, whence it might never be recovered. In
such an emergency there are large reels of auxiliary
cable, of great strength, which could be attached
to the end ; and these auxiliary cables can be sus-
pended from huge float-shaped buoys on the sur-
face of thea_. very
alln°dn are to be
con-
siderable stra.e till all danger has passed
and
"The two theN7Bse's'
water, capable of resisting
e power,
Niagara, sail about.'
-mehanna These
thef2ris,tAahtg
ins
te.
e Leopold and the
joined by her Majest.rb •
am.: assist tLe
are
United States' frigate Sub., •
• bl
paddle-wheel steamers of co,,"id
The four stearnerd
and -- are. intended to pilot
other vessels when necessary, •