Little Masterpieces of Science: Invention and Discovery — John Shaqi
Little Masterpieces of Science: Invention and Discovery
History
Little Masterpieces of Science: Invention and Discovery
Inventions
In 1866 a new company was organized, for two objects: first, to recover
the cable lost the previous year and complete it to the American shore;
second, to lay another beside it in a parallel course. The _Great
Eastern_ was again put in commission, and remodelled in accordance with
the experience of her preceding voyage. This time the exterior wires of
the cable were of galvanized iron, the better to resist corrosion. The
paying-out machinery was reconstructed and greatly improved. On July 13,
1866, the huge steamer began running out her cable twenty-five miles
north of the line struck out during the expedition of 1865; she arrived
without mishap in Newfoundland on July 27, and electrical communication
was re-established between America and Europe. The steamer now returned
to the spot where she had lost the cable a few months before; after
eighteen days' search it was brought to the deck in good order. Union
was effected with the cable stowed in the tanks below, and the prow of
the vessel was once more turned to Newfoundland. On September 8th this
second cable was safely landed at Trinity Bay. Misfortunes now were at
an end; the courage of Mr. Field knew victory at last; the highest
honors of two continents were showered upon him.
'Tis not the grapes of Canaan that repay,
But the high faith that failed not by the way.
[Illustration: Fig. 59.--Commercial cable, 1894]
What at first was as much a daring adventure as a business enterprise
has now taken its place as a task no more out of the common than
building a steamship, or rearing a cantilever bridge. Given its price,
which will include too moderate a profit to betray any expectation of
failure, and a responsible firm will contract to lay a cable across the
Pacific itself. In the Atlantic lines the uniformly low temperature of
the ocean floor (about 4 deg. C.), and the great pressure of the
superincumbent sea, co-operate in effecting an enormous enhancement both
in the insulation and in the carrying capacity of the wire. As an
example of recent work in ocean telegraphy let us glance at the cable
laid in 1894, by the Commercial Cable Company of New York. It unites
Cape Canso, on the northeastern coast of Nova Scotia, to Waterville, on
the southwestern coast of Ireland. The central portion of this cable
much resembles that of its predecessor in 1866. Its exterior armour of
steel wires is much more elaborate. The first part of Fig. 59 shows the
details of manufacture: the central copper core is covered with
gutta-percha, then with jute, upon which the steel wires are spirally
wound, followed by a strong outer covering. For the greatest depths at
sea, type _A_ is employed for a total length of 1,420 miles; the
diameter of this part of the cable is seven-eighths of an inch. As the
water lessens in depth the sheathing increases in size until the
diameter of the cable becomes one and one-sixteenth inches for 152
miles, as type _B_. The cable now undergoes a third enlargement, and
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