The National tribune. [volume] (Washington, D.C.) 1877-1917, 1903-09-03
SUBMARINE TELEGRAPHY.
How cables are Made, Laid, Worked and Mended.
By J. W. DAVIS.

weighing from 80 pounds to GO pounds are
slipped over it, becoming automatically de-
tached on reaching the bottom.
THE IMPORTANCE OF SEA TEMPERATURE.
| In soundings for cable purposes, the
temperature of the bottom water is re-
quired for temperatures play an import
ant part in submarine telegraphy. a low
| temperature increases at the same time
! the conductivity of the copper wire and the
| insulation of the gutta percha covering,
| and is therefore the most suitable for ca
bles. Faults are usually located by the
electrical resistance of the conductor. 1t
is known that the particular conductor in
question gives. when in normal condition, n
certain resistance per nautical mile at n
| given temperature. If the cable is broken
so as to expose the conductor, one has only
| to divide the resistance obtained from the
| tests by the resistance per nautical mile
| in terms of the same temperature in order
to arrive at the approximate distance Of
| the fault from the testing station. A
knowledge of the bottom temperature is
therefore indispensable for accurate re-
suits. and in taking soundings a thermom-
eter is always attached to the wire a short
distance above the sOunder.
/ The temperature of the sea bottom be-
tween San Francisco and Honolulu aver
ages 81 degrees T.. The light rays of the
sun penetrate only a short distance be-
meath the surface of the sea, and as far
as extraneous illumination is concerned,
the ocean abysses remain in absolute dark
ness.
Some deep sea fish. however. have.
strange to say, two parallel rows of small
circular phosphOrescent organs running
down the whole length of their bodies. so
that they resemble ships at night, with
double rows of shining portfolios. 1t is
thought possible by certain naturalists
that portions of the sea bottom may be as
brilliantly Illuminated by this kind of light
as the streets of a large city after sun
set.
LAYING THE CABLE.
On reaching the place selected for the
landing of the cable, the ship approaches
as close to the shore as possible, and. let
ting go anchor, prepares to land the shore
end. In some companies this is done by
means of RATS; in others, couple of
spider sheaves, or large V-shaped wheels
in light iron frames, are sent ashore and
fixed by sand-anchOrs some 60 yards
apart. Hauling lines are paid out from
the ship, reayed through the sheayes and
brought back on board again. One end
of this continuous line is attached to the
cable and the other to the picking-up gear.
The engines are then set in motion, and
the cable is dragged slowly out of the
ship toward the shore. As it goes large
India rubber buoys inflated with air are
dashed to it every 30 or 60 feet, to keep
it afioat and to prevent the damage which
would result from its being dragged along
the bottom.
When sufficient cable has been landed,
the piece on shore is laid in a trench
which runs from low water mark to the
cable hut, and the end inserted through
a hole in the floor.
| Testing and speaking instruments are
set up in the hut, which is occupied day
and night during the laying by the cleo
trician in charge. and his assistants.
When satisfactory test has been taken
the ship gets slowly under way.
The scene on the deck of n cable ship
during the commencement of paying-out
| is full of interest to one who has not wit
messed it before. The cable. being fast
on shore, drags itself out as the ship
moves forward. At first it rises slowly
from the tank, passing along a series of
guiding troughs to the paying-out ma
chine, round the drum of which it runs
three times. Between this drum and the
sheave at the stern by which the cable
leaves the ship, stands the dynameter. This
machine shows the strain to which the
cable is subjected, and is an important
factor in cable-aying As the water
deepens, the weight of cable in suspen-
| sion tends to make it run out more quick
ly. This tendency is contracted by in
creasing the weights on the brake arms
of the paying-0ut r,Gchine. If the water
| shoals suddenly, the weight of the cable
outboard is considerably reduced the
strain lessons and the brakes have to be
eased, in order to allow ii to run out at
the same speed as before. The amount
of cable in suspension varies according to
the depth and of rate of paying-out. In
$500 fathoms, with the ship steaming at
eight knots per hour, no less than %
miles of cable are in suspension under the
water. Two and half hours are occu-
pied in this case by any particular point
| in the cable. from the time of leaving the
ship to touching the bottom.
THE TEsTING-RooM ON BOARD A SHIP.
One of the most interesting spots OH
board a cable-ship during laying, is the
testing room. Here, in front of a table
glistening softly with the polished ebonite
and bright terminals of various testing
Instruments, sits an electrician, watching
q round disc of light, as it sways to and
fro on graduated scale. This disc is
q reflection from the mirror of the gal
vanOmeter, and the swaying movement is
caused by the induced currents set up in
the coiled cable by the rolling of the ship
At the end of every fifth minute the spot
gives a vigorous leap upward OH the
scale, and the electrician duly notes its
magnitude. The leap is caused by sig
nal from the shore and proves that the
continuity of the conductor is still pre-
served. AS the cable leaves the heated
ship and sinks into the almost freezing
temperature of the ocean bed, the insua-
ton improves and the spot of light grad
ually works down toward zero. When,
on the other hand, the de1ector grows
larger, and the spot shows an inclination
to steal off the upper end of the scale,
something is wrong, and . careful test
must be taken. Should this prove that
a fault exists, the ship is stopped, the ca
Bile cut, and if the fault is near, picking
up commences. If the fault is some dis
lance away, the cable is buOyed and the
ship steams to the locality of the faulty
portion.
Supposing. however, all goes well. the
whole section is paid out and buOyed and
the ship steams to the second landing
place. Here the shore-end is landed in
the same manner as before, and cable is
paid out up to the buoy.