The Sun.
London, England, 1851-09-12 00:00:00

12, 1851

THE SUBMARINE TELEGRAPH.
The preparations for making another attempt to lay
down a line of electrical communication at the bottom
of the sea between the English and French coasts are
rapidly progressing to completion. That it is possible
to transmit a current of galvanic electricity from one
shore to the other by means of an insulated wire
deposited in the bed of the Channel was fully demon-
strated by the experiment of last year, unsuccessful
as it was in permanently establishing the communi-
cation. The only question now remaining to be solved
is, whether sufficient measures can be adopted to
insure the connecting chain against the casualties
which proved fatal to the project as originally designed,
and according to the plan now finally determined
upon there is every prospect of attaining the desired
end. The essential conditions upon which the success
of the undertaking have been shown to depend are, in
the first place, that the conducting medium should be
so securely isolated as to resist the pressure of the
immense mass of water to which it will be subjected,
a❑d should unite the flexibility requisite to allow of its
being easily coiled and uncoiled with a strength and
weight sufficient to enable it to retain its position at
the bottom of the sea and to resist any ordinary
violence from the natural action of the waves ;
and, secondly, that the points on either coast to be
connected should be so chosen that the line be-
tween them present no other causes of accident than
have been foreseen and guarded against in the prepa-
ration of the connecting line, and that the effect of
these be reduced to the least passible amount. The
line of communication which is now being manu-
factured at Wapping will, it is expected, entirely ful-
fil the required conditions. It consists of four
copper wires the thickness of an ordinary bellwire,
cased in gutta percha, and twined with a correspond-
ing number of hempen strands steeped in a mixture
of tar and tallow into a rope of about an inch
diameter. Anotherstrand similarly prepared is wound
transversely round this, and finally ten wires of gal-
vanised iron, about a third of an inch thick, are
twined round this central core and form a solid and
at the same time flexible casing. The whole, when
thus completed, has the appearance of an ordinary
4i-inch metallic cable. The machinery by which this
is effected is extremely simple, and the work proceeds,
night and day, with the utmost regularity. A huge
coil is thus being formed in one continuous piece at
the rate of about 1 mile a day, and will finally at-
tain the length of 24 miles. Tne weight of the
entire rope when finished, it is estimated, will be from
170 to 180 tons. From time to time, as the work
proceeds, a gavanic current is passed through the
wires and their conducting power is tested by a
galvanometer. The results thus obtained have been
hitherto highly satisfactory, and as the whole length
is now nearly completed there is every reason to
anticipate that the same success will attend the work
to the end.
Messrs. Crampton and Wollaston, the engineers
who have undertaken to carry out the necessary mea-
sures for establishing the submarine telegraph, have
recently been engaged in exploring the coast in the
neighbourhood of Calais, for the purpose of selecting
the most advantageous point towards which to direct
the line of communication. In performing this task
they have had the advantage of the experience of
Captain Bullock, who is engaged in a survey of the
Channel, and whose steam-vessel, the Fearless, has
been placed at their disposal. The starting point on
the English coast which has been fixed upon as the
most advantageous, on account of the nature of the
beach and the comparative freedom from the danger of
ships anchoring in the immediate vicinity, is the South
Foreland. The line will be conducted down a shaft
practised perpendicularly in the cliff and along ashort
tunnel, communicating with it at right angles, to the
beach, where it is proposed to bury it at some consi-
derable depth beneath the shingle, to the lowest level
of ebb tide. The spot selected on the French coast
for similar reasons is situated about four miles to the
south of Calais, near the village of Sanngate.
The beach at this point consists entirely
of sand, and a ridge of sandhills called dunes
extends for a considerable distance along the coast,
protecting the adjacent country from the inroads of
the sea. The line will here be buried again to some
depth beneath the sand, and on reaching the dunes the
communicating wires will be continued underground
to the telegraphic station at Calais, and brought into
immediate communication with the network of tele-
graphic lines radiating from that point, and embracing
the principal towns of the continent. The line from
the South Foreland to Sanngate, although not the
shortest that could be drawn between the two coasts,
is that which presents the fewest chances of accident.
The point at the two extremes are those were the low-
water mark is nearest the high, and the character of
the bed of the Channel 13 ing between, as far as can be
ascertained by careful soundings, offers no peculiari-
ties likely to affect the integrity of the conducting
line.

Every facility that could be given for establishing
the connexion of the sub-marine wire with the tele-
graphic station at Calais has been granted with the
greatest alacrity by the French Government, as well
as by those persons whose local rights had to be con-
sulted before the line could be laid down, and, should
the experiment prove successful as far as regards the
transmission of the galvanic fluid across the Channel,
the communication with Paris will be almost immedi-
ately established.