The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-07-26

| is over very regular SnOal water, so TO speak,
being at no part less than 100 fathoms, and
generally over 100 to its termination For
laying the deep-sea cable--that portion Of the
line between Brest and st. Pierre-the COM
pany wisely made selection of
THE GREAT EASTERN,
in which, to answer all requirements, num-
Der of iudicious changes were made, all look
! ing to the duty she was called upon to per
! form. She is now deeper by foot than she
! has ever been She is numbered by deck
! houses, and has, in other respects, been made
to resemble floating hotel. Great improve
ments have been made in her mechanism
Her rudder, formerly worked by twelve men,
now answers the bidding of steam machinery
A single helmsman turns the wheel. All that
he does is to act upon certain valves, and to
set in motion the power by which in reality
the vast hull is guided through the
sea. The paying-out machinery has also
been perfected, and there is less chance of
injury to the cable than there ever has been.
The cable having been coiled on board the
great ship, on the 18th of June, the day
before she left the Midway, where she was
lying, a short distance from London, to pro-
ceed on her work, a grand banquet was given
on her, atwhich some one hundred ladies and
gentlemen were present among whom were
Sir David Gooch. NJ p, Chairman of the
Telegraph Construction and Maintenance
Company Messrs. John Ponder, Ralph
Elliot, Thomas Brassey M. P; Captain
Sherard Osborne. Sir Samuel Canning, Mr..
julius Reuter-. Sir James Anderson, Mr..
Varley. Professor Jenlin, Baron d'Erlanger,
Lord Hay, Lord Houghton, MIR. Elliot Mr.. J,B.
Burke, Secretary of the glo-Mediteuanean
Compauy Mr.. b. Slater, Secretary French
Cable Company; Mr.. 7. Crompton, the layer
of the first successful submarine CABLE and
many others. The visitors examined the
various details of the arrangements for laying
the cable, and after having been seated at the
table Mr.. GOoch proposed the toast, 'Pros-
perity TO the French Cable Company This
was warmly responded to by Lord Hay, who
stated that the company had the highest
reason to be grateful to the Construction
Company for the manner in which they had
performed their work. The cable was excel
lent in its work, and had been completed
eighteen days under the stipulated time.
Baron d'Erlanger proposed the toast Of the
day, Success to the great work of laying
down the cable This was briefly responded
to by Nj, Bender and Lord Houghton.
THE INSTRUMENT
used on board the Great Eastern is that uni
versally adopted in working all submarine
lines--the rejecting galvanometer The
principle of this most delicate instrument was
discovered a few years ago by German cleo
trician named Weber. 1t consists Of a small
mirror with a magnet laid across its back and
that the two are very small indeed, may be
judged from the fact that both together weigh
less than three-eighths of grain. This small
reflector, which is intensely bright, is sus-
pended by a silk thread as fine as a hair,
in the midst Of a small circular coil
of insulated wires. Directly a current is
sent through this circular coil, no matter
how slight, it induces another electric
current within its circle, which acts in an OPP
posite 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 rejecting ray of light
with it. BY very simple arrangement, this
fine ray of light is thrown upon a horizontal
graduated scale. about three feet long and
three feet distant from the mirror. Thus,
when a current is sent through the little cir
cular coil round the mirror, the magnet is
acted upon, and turns the mirror with its ray
of ight-say on theleft of the scale in front 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 cir
cular 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 dot when it moves rapidly to the
right or left it means so many dashes, accord
ing to the distance it goes Thus the little
pencil of light makes dots or dashes on the
scale, Just as the old Morse instrument used
to make them in visible ink on paper, and any
combination of words or letters or figures can
be formed and read with the utmost ease
by the receiving clerk, who is watching
how the light moves and debating the
letters and words it sends When the
cable is at rest the light remains stationary
in the centre of the scale at zero. When q
fault occurs the loss of electricity is shown by
the currents, or the reverse currents, turning
the light more to the right OF left of the cen
tire of the scale than it should do. When
total fault occurs-that is, when the cable has
parted-the little ray Of light flies off the
scale altogether, and is never seen again till
the mischief is repaired. SO eXquisitely deli
cate is this instrument that most distinct
messages have been sent through the whole
length of the present French cable with
no greater battery power than that af-
forded by ladys thimble filled with weak
sulphuric acid and water 1t was by this re-
hecting galvanometer that the watchers
at Brest knew whether the Great Eastern at
the other end Of the long rope Of hemp and
! steel was steady or not. Each roll of the ship
| produced slight magnetic current in her
vast COILS which, transmitted through the
cable to the sensitive instrument, turned the
ray OF light to the right or to the left of the
scale, thus showing in a fraction of a second
of time the precise degree and rapidity at
which the vessel was rolling This unceasine
vibration follows the voyage of the ship.
marking its progress and Incidents to the
close. The same kind of instrument is also
made use OF on all the stations of the line.