Year: 1872

The construction Of tolegraphic cable ls
very interesting process. The first step is
making what is termed the core, or conduct
ing agent, of copper WIRE The earlier cables
were generally made with one conductor of
thick wire, but it was found that-to use o
popular saying-this plan was the mistake of
putting all the eggs into one basket. If this
wire were to break, an accident to which it
was very liable in the act Of laying it, there
would have been breach Of continuity, the
tongue which talks under the ocean would
have been struck with paralysis In order to
avoid this, strong central wire Of the best
copper is used, and around this number Of
fine wires are twisted. By this method the
fracture of the central or base wire is no
longer of Importance, as the small wires, even
if there was strain upon the cable, would
carry the current. Indeed, we have seen ca
bles that have broken and dragged asunder
many inches, still geographically perfect, for
this reason. The twisting of the fine wires
round the central one is very similar to the
making of ordinary rope. In order to insu-
late the conductor thin slips of india-rubber
ribbon are carefully placed over it. 1t is Gu
rious to watch the machine at work at the
process, which must be done with the greatest
care, inasmuch as a small hole, by means Of
the eagerness of the electric fluid to pass
through it, speedily becomes big one. When
the whole length has become thus plated, in
order to secure the edges the cable is passed
through tank Of liquid india-rubber, which
cements them together. The core has now to
be armored, when protection is required for
deep or rough seas. This is done by laying
stout iron wires longitudinally and parallel
with the core, but these, again, have to be pro-
tected against the action Of the salt water,
which is done by plating Of hemp, coat
ing of tar completing the process. When ex-
cessively rough or rocky shores have to be
guarded against, the shore ends of the cable
have to be protected by several additional lay
ers of wire armor and hempen guards. When
accidents happen to cables after they have
been laid the cable has to be fished up, and
the fault found and spliced. The finding Of
fault in the deep ocean may appear to the
reader very difficult, nay, an impossible op-
Grafton. For instance, to have to pay in the
Atlantic cable, and examine it inch by inch,
in order to discover possibly mere pinhole,
would seem to be very labor Of Hercules.
But science is equal to the task; the electri-
clan, sitting in his room at his instrument, by
means of delicate appliances, can estimate to
within mile or two the distance at which the
fault rests. If in the Arabian Nights En-
tertainments the task were given to discover
the place of break in wire running under
1000 miles of ocean, it would appear more
wonderful of accomplishment than any other
feat mentioned, and some poor geni or witch
would have been called in to solve the diff
Guilty. But science is the wonderful geni OF
modern life, and it accomplishes more appa-
rently impossible tasks than any Of the ro-
mantle writer's of old could even imagine.
Nevertheless, as we have said before, every
precaution is taken to prevent these ultimate
appeals to science; for the lifting Of deep
sea cable is no child's play, and the cost is
great, consequently every precaution is taken
to secure the perfect insulation Of the cable
while it is being manufactured. Before one
of these marvellous talking wires is accepted
by purchasers, it is required to test up to a
certain given point; and in order to secure
this, there is an artisan rejoicing under the
name of the fault-fnder. We may mention
that this officer is employed in the portion OF
the factory where the insulation is made not
by india-rubber but by gutta-percha. When
this insulation is used, the liquid percha is
moulded on to the conducting wire as it is
passed through die, hydraulic pressure for
cling the material round it in hard, dense
pipe, which looks very much like chocolate.
The wire thus insulated, as it is wound off,
passes through the hands of the fault.fnder,
whose fingers, educated by practice, feel any
little air-hole that may have occurred in lay
ing on the gutta-percha. Directly after this
is found hot iron is applied to it, and it is
stopned