The Savannah morning news., 1903-03-06
PULLING A TON WITH A POUND.


From an English Newspaper.
A battleship of $1,000 tons swinging
in five or six knot tide-rip needs
a cable of enormous strength to hold
her. Considering that such a ship is
worth at least $1,000, 900, and has
aboard her seven to eight hundred val
liable lives, and that her safety de-
Ponds entirely upon the soundness of
her cables, it may be imagined how
necessary it is to test them thorough
ly before using them.
Gables are now made not of hemp, as
formerly, but of iron chain, for hemp
cables fit to hold large vessels are far
more bulky, expensive and perishable
than those made of iron. An ordinary
inch and a half iron chain is equal to
a hemp cable of sixteen inches circum-
ference.
In England, by an act passed in 1871,
certain bodies-such as LIoyds-are Ii
censed to erect machines for testing all
chain cables and anchors. There Is a
penalty of $3.50 for selling or purchas-
ing any chain cable or anchor weigh
ing over a hundred weight and a half
without the required previous official
testing.
The cable-testing houses are very i'm
portant parts of our dock yards. That
at Davenport is a long, shedlike build
ing of great strength and solidity.
Down its center runs an immense
wooden trough some eight feet in
length. At the end nearest the door
there is massive drum, over which
the cable about to be tested is fast
ened. At the other is a hauling ar
rangement, worked by hydraulic pow
err
chf y,fe- III t.
One of an inch and a half weighs 12l
pounds per fathom. So horses are en-
ployed to pull it into the testing shed.
and it is then lifted over the drum
and made fast by means of a stay
pin to the hydraulic ram.
When the cable is properly arranged
in the trough, and fastened at both
ends, the testing party retire into a
small room which opens from the left
of the shed. All the doors are closed,
and the ram is set in motion. In front
of the operator in the small room is an
ordinary pair of scales, and let into the
wall is a small chain, below which is
a scale marked with an index. The
chain is so arranged as to correspond
with the cable which is being tested
and the index shows how much the
latter stretches under the strain. Each
pound weight laid upon the scales is
NO. NtAlSiAh ~ a bOAl pun upOIl TIC Cd
BILE.
To test a cable whose links are of
lnch-and-a-half iron, sixty pounds are
put into the scales, and outside in the
testing shed the great cable may be
heard creaking and grooming under a
dead pull of sixty tons. The man in
charge then looks at the index, makes
note of the amount of stretch re-
corded, leases a lever, and the test
is thus completed.
The precaution of getting inside a
separate room and shutting the door
is a very necessary one, for now and
then a weak link fails, and, with a tire
mendous crash, the cable leaps in two.
and springs back whiplike across the
shed. Some little time ago a certain
admiral was most anxious to remain
and watch a cable being tested. But
when the risk was pointed out, he re-
luctantly consented to come into the
inner room. 1t was lucky he did so.
The chain broke, and this contributor
was shown great dent in the door
frame of the testing room by flying
end of it,
The iron from which ships cables. are
made must be of the very best, and
not too hard. Very hard iron will
snap at a sudden shock. The best ca
bic metal is extremely "ductile." At
the Davenport testing shed there is
shown a curiosity in the shape of a
piece of cable as stiff and straight as
an iron bar. This result was obtained
by putting a very heavy strain upon
piece of light chain. So excellent
was the material that, instead of snap
ping, its links heightened out until
they bit one another, and remained
rigid.
The standard test is by no means
the extreme limit which anchor chains
may have to bear at sea, so a few
links are usually cut at random from
cable and submitted to a second
test so per cent. greater than the first.
If this is withstood satisfactorily the
cable is passed for use.