The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1903-01-03

Although 1t is more THAN AAIS
Gears since Geographic communication
was established between England and
France by a wire submerged beneath
the waters of the English Channel, the
general public still knows little about
the making and laying of submarine
cables. The writer has several times
been asked by fair inQuirers II divers
do not go down Wit, the cable to lay
IL in its proper place. Even members OF
the opposite sex, whom one would ex-
meet to be better informed on the sub
tect, have expressed a wish to know
how far the cable sinks, and whether
it is not necessary to attach weights
to it, in order to make it reach the
bottom. Others do not understand why
the bottom should be reached at all,
and approve of the plan once suggest
ed by a French engineer, that the cable
should be buoyed at a depth Of only
forty feet below the surface. They do
not like to see so valuable an asset
thrown overheard and left to take its
chance like a shovelful Of clinker, but
where they could pick it up in an or
dinary rowing boat and make sure that
1t was safe and sound.
MAKING THE CABLE.
In order to do away with such err
roneous impressions, it will be well to
begin at the beginning and describe the
component parts of the cable itself. The
essential portion is the small central
thread of copper, through which the
electric current passes. On account OF
the facility with which this metal con-
ducts electricity, the central copper
wire is called a conductor. The con-
ductor is drawn through a die together
with heated gutta percna, which is thus
laid on in a uniform covering. Gutta
percha is the best non-conductor Of
electricity available for the purpose,
and prevents the current leaking out
from the copper wire. Tarred jute pro-
tects the gutta percha from the steel
sheathing wires which form the arma- |
ture. AS the cable is made it is coiled !
into tanks and covered with water, |
which not only enables any incipient
faults in the insulator to be detected
more easily, but also forms the best
medium for preserving the essential
qualities of the gutta percha.
SHIPPING THE CABLE.
When the total amount of cable is
nearing completion, the ship which is to
convey it to it's destination, is moored
of the works. 1t is imperative that
cable works should be on the
banks of a river or close to docks where
a cable ship can lie, for it would be a
costly if not impossible undertaking to
transport cable by land in sections of
sufficient length for submarine pur-
poses. Temporary engines fitted up on
deck haul the cable out of the factory
on to the ship, where it Is coiled down
by hand into water-tight tanks. One
man receives it and carries it within
reach of his companions who are sta
toned round the tank. They take 1t
from him and lay it carefully and uni
one turn against another. The
man in the center Is frequently reliey-
ed, for the work is hard, especially in
the case of the larger shore-end types,
which sometimes weigh as much as
twenty tons per nautical mile. When (
all the cable is on board, final tests are
taken and the ship sails for the station
where the first end is to land.
SOUNDING FOR THE ROUTE.
soundings over the proposed route have
to be taken. This is usually done by
a smaller ship, before the arrival of the
one with the cable on board. 1t is very
important to know the contour of the
ocean bed on which the cable has to
lie. II no survey has been made, suf-
acient slack may not be paid out on
nearing a submarine hill, the cable will
hang in a festoon from the top OF it,
~
weight. Hemp lines used to be employ
ed for lowering the sounder, but as
these were found to be clumsy and I'M
reliable in great depths, Sir William
Thomson, now Lord Kelvin, substituted
for it in 1872, pianoforte steel wire. This
wire is twenty-five times less diameter
than hemp, whilst it's breaking strain,
bulk for bulk is eighteen times as great.
A sounder lowered with wire to depth :
Of 1000 fathoms or two and one-fourth
statute miles can be recovered in TWEEN
ty-two minutes, a hemp line occupying :
two and one-half hours under similar
conditions. e
There are several forms of saunders,
but the one in use by the Silvertowni
adaptation of Captain
U. &. N.-posSesses the essen
tial features of the others and may be
taken as a typical one. 1t consists OF
a central tube fitted with valves at top
and bottom, and three smaller tubes
fixed beneath the central one. AS the
sounder descends the valves of the CEN !
trail tube open upwards, and the water
rushes through. On reaching the bot
tom both valves close, and sample Of
the bottom water is brought up. The ]
three smaller tubes sink into the ooze,
and bring specimens of 1t to the sur s
face for chemical analysis. In order !
to increase the speed with which the :
sounder sinks, shot weighing from ]
thirty pounds to sixty pounds are slip
ped over it, becoming automatically de- ,
tached on reaching the bottom.
OF THE WATER :
In soundings taken for cable pur- +
poses, the temperature of the bottom {