The Sun.
London, England, 1869-06-29 00:00:00

THE SUN, LONDON; ----TUESDA.Y EVENING, JUNE 29, 1869.

THE ATLANTIC CABLE.

The Atlantic Cable happily seems all right again, and
the Great Eastern is steaming away successfully doing her
work. She must now be passing over some of the shallowest
water on her deep sea course, less than 1,700 fathoms,
and on the 3rd or 4th of next month she will pass over the
deepest water of all, 2,760 fathoms. The deepest water in
which the present Atlantic cables are laid is only 2,424
fathoms,but in a depth of nearly 17,000 feet of water, a
couple of thcusand feet, more or less,makes verylittle differ-
ence. Supposing all to have gone well, the Great Eastern
ought to have run a little over 800 miles from Brest, and
paid out about 900 miles of cable, and her fore tank must
just now be empty. Fourteen per cent. on the whole
distance was allowed for slack of cable in paying-
out, but up to the present the Great Eastern
has only used 10 per cent. This saving has
arisen from the fact that for nearly 300 miles of her course
at first she was never in very deep water. In greater depths
she will have to use more slack, which will bring up her
percentage to the same as that of both the existing cables,
which was at the rate of 14 per cent. Submarine cables
sink very slowly, and it is calculated that at great depths
the Great Eastern will have a curve of line from her stern
of not less than twenty-one miles long before it rests on
the bed of the ocean.

The method of signalling used between the ship and the
laud is that now universally adopted in working all long
submarine lines—the reflecting galvanometer. The prin-
ciple of this most delicate instrument was discovered a
few years since by a German electrician, named Weber.
It was then, however, a large machine, and the con-
densation of all its powers into the smallest and
lightest form is due to the scientific research and skill
of Sir William Thompson. This instrument consists
of a small mirror with a magnet laid across its back. That
the two are very small indeed may be judged by the fact
that both together weigh less than three•eighths of a
grain. This infinitesimally small reflector, which is
intensely bright, is suspended by a silk thread as fine as a
hair in the midst of a small circular coil of insulated
copper wires. Directly a current is sent through
this circular coil, no matter how slight, it induces
mother electric current within its circle, which
acts in an opposite direction, and this causes
the little magnet at the back of the mirror to
turn to the right or left, and, of course, to turn the
little mirror with its reflecting ray of light with it.
By a very simple arrangement this fine ray of light is
thrown upon a horizontal graduated scale, about 3ft.
long, and 3ft. distant from the mirror. Thus, when a
current is sent, through the little circular coil round the
iirror the magnet is acted upon, and turns the mirror
with its ray of light—say on the left of the scale in
'rout of it. When the current is reversed, and that
is instantly done by pressing a little key in the
speaking instrument, the current in the circular coil
is reversed and sent in the opposite direction, and this in
turn sends the ray of light from the mirror on to the
opposite side of the scale to the right. When the ray of
light rests stationary on any part of the scale it means a
dot ; when it moves rapidly to the right or left it means
so many dashes, according to the distance it goes. This
reflecting galvanometer tells with unerring certainty
whether or not the Great Eastern is steady. The
vessel now at the end of the cable is, with its coils
of insulated wire and iron hull, a mere electro-magnet, so
to speak. The course of the Great Eastern is east and west,
and therefore at right angles with the course of the magnetic
current, which is north and south. Thus, every time the
ship rolls, either to port or starboard, a slight current but
still a current, is induced in her vast coils, and thence
transmitted through the cable to the shore end at Minou,
where it acts upon the reflecting galvanometer, and turns
its ray of light a little to the right or left of the centre of
the scale, and thus shews in a fraction of a second of time
the precise degree and rapidity at which the vessel is
rolling.

It is reported that Mr. M. W. Ridley, M.P., is about
to be married to Miss Hardy, a daughter of the Eight Hon.
Gathorne Hardy.

It is stated that her Majesty will probably visit the
camp at Aldorsbct on Thursday and stay till Saturday.
There is to bo a grand review on Friday, at which the Prince
and Princess of Wales and the Viceroy will probably be
present.
A betting case prosecution of a minor character
has Leen decided at Hull. henry Hare, a butcher, for
causing an obstructio❑ in tie Market Place, has boon
brought before Mr. Travis, the stipendiary magistrate,
tnd fined ltls. and costs. The magistrate warned the de-
fendant that if be was again convicted of a like offence ho
would be sentenced to the longest term of imprisonment
which ac law allow( d.

A sr d accident occurred at the Rocket Colliery, the
property of the Earl of Dudley, on Saturday. Two mon were
engaged in blasting a piece of rock at the bottom of the shaft,
and aft( r two mis-tires they ha I set the third and signalled
to the engi❑eman to draw them up, using a water bow•k for
a skip. They had miscalculated how long the fuse would
burn, and before they were drawn up the explosion took
place, and they were terribly shattered. Both men are in a
Fecarious state.

CANADIAN FISHERIES.—It is gratifying to hear
that the fishing season has this year opened most promis-
ingly in Canadian waters. Both from Newfoundland and
Nova Scotia we learn that it is many years since the
fishermen met with such success as they are now enjoying.
They are making exceedingly heavy catches, . and the
indications are that they will have_an unusually succeesfu
geom.—Toronto Tclegraph.