The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1895-03-22
TAXING AN OCEAN GABLE.
fast Amount OF Work Bctoro 1t Can
BE Laid in tho Ocean.

BE Laid in tho Ocean.
Ehc making ofGfn ocean cable is a
tatlS involving no small, amount of skill
and mechanical ingenuity, and it is
something to thc'Jrcdit of the first cable
makers that their pattern has not
greatly changed in thirty years. When
the Commercial Cable company decided
TO lay IL new Atlantic cable last year.
the work was intrustcd 10 the firm of
Siemens Brothers, of Woolwich, Lon
don. AS this firm has constructed no
less than eight out OF the eleven cables
now linking Great Britain and the
United States, says the new Science Re
view, its method Of manufacture may
be watched us typical of the best The
first care of 4 cable manufacturer is to
secure tho very best materials The
copper wire, which forms the heart and
essential part of the cable, must be of the
purest metal, since the purer the metal
the higher it's standard of conductivity
Wilde. Every strand and every coil Of
wire TINT goes into tho cable is ex-
pectcd to reach n certain standard; and
to such O degree of excellence Is the
making OF copper wire for electrical
purposes brought nowadays that the
material submitted is more frequently
above that standard than below.
Tho single wires having passed tho
test for purity and conducting power,
eloven similar strands arc taken and
spun into a slender ropc in lengths of
ono mile. Gutta-percha insulation is
then applied in sheets prepared from
the raw material as it comes to hand
from Singapore and other Malay ports.
These sheets IRE wrapped by OK
pcrienccd hands so firmly and smoothly
round the wire that not an air bubble
can remain between the copper and it's
insulator. The "core" is then ready to
be submitted TO galvonomcter test, TO
ascertain whether tho insulation is per
feet, or as nearly perfect as that very
elusive agent, electricity, will permit.
That test having been satisfactorily
passed. q workman, whose sole bust
ness is to attend to the joining of the
lengths Of cable, spices the ends of the
mile lengths. Again tho insulation
test is applied. The galvanomcter in
dicatng no very apprcciablc loss of
electricity, even under tho strain of m
alternating current OF 5000 volts, tho
core is passed into the hands of the
sheathers, whose caro- it is to surround
tho copper and gutta-pcrcha with
moro substantial protective covering
before they are submitted TO the rough
action of the sea. And now the weight
and stze of the cable become appreci-
able. Already each milo length has In
it some 500 pounds OF puro copper and
$40 pounds Of pure gutta-pcrcha. Over
this is spun Of cost Of jute yarn
weighing nearly 600 pounds to the mile.
Then the cable is made the center of o
twisted sheath of steel wires of the
stoutest kind, averaging moro than
1000 pounds to the mile. And finally a
compound Of tar is laid over tho whole,
which brings it's own weight of 500
pounds to the mile. After tho tar is
applied the cable is coilcd and left to
soak in tanks of water until such time
as the cable ship shall be ready to lay
1t in it's last resting place. Such cable
as this is made at the rate of fifty to
fifty-fivc miles per twenty hours.