St. Paul daily globe., 1893-07-12
ARM0R PLATE TESTS.
THIRD SERIES TAKES PLACE AT THE
NAVAL PROVING GROUNDS.
GOOD RESULTS OBTAINED.

Whole Contract Accepted, but No
Premium Was Earned by the
Makers-Even More Satisfac-
tory Showing Made by the Pro-
Jectiles Used.
July ia third series
of armOr plate tests of worldwide in
tereSt and Importance took place today
at the naval proving grounds twenty
miles south of the city or the Potomac
river. There were two plates tested,
which were attacked by three projec-
tiles each. The tests were for
acceptance and premium. it hav-
ing been stipulated that if the
plates resisted penetration under GER
tain prescribed velocity, the makers
should receive premium of $50 ton
in addition to the contract price of
S575 ton. The first test was nine
inch plate six feet and four inches wide
and nine feet and seven inches long,
Monadnock. 1t was nickel steel,
weighed ten tons and was made by the
Carnegie-Frick company, of Pittsburg.
Three Holitzers projectiles, weighing
$50 pounds each, were fired against it
from an eight-inch rifle, the muzZle
being fifty-eight feet from the face OF
the target. The first projectile had
velocity of 1,400 feet second at the
moment of impact, and penetrated the
plate and oak backing to depth of LII
inches.
The Second Proiectile,
with striking velocity of 1,6S3 feet,
went through the plate, three feet of
oak backing, and lost itself in the earth
against which the butt was built. The
third projectile had velocity of 1886
feet. and penetrated plate and backing
to a depth of fourteen and half
inches. The plate we'll wthstood
the strain of the attack, no cracks being
perceptible, and it fully met every re-
quirement for acceptance. But the re-
suit of the second shot deprived the
makers of any chance for the premium.
Depending upon this test were about $50
tons of plate, involving nearly $3.50. 900.
The test of the second plates was an
exact duplicate of the first in its results.
1t was sample of the curved plates for
the barbette on the Indiana, made by
the Bethlehem company, and. like the
first, of nickel steel. Its dimensions
were eight feet four inches in
height, twelve feet one inch in
length and seventeen inches thick,
forming a mass weighing thirty-one
and a half tons. 1t was the heaviest
plate yet tested, and its thickness will
probably not be surpassed to any great
extent until there is change in the
method of naval warfare and ship
building. 1t was subjected to attack
from
A Twelve-Inch Rifle
which threw monster Carpenter she'll
weighing $50 pounds. Its muzzle was
3l9 feet from the face of the plate. The
striking velocity of the first shot was
1922 feet a second, and it penetrated to
depth of 1876 inches. lacking less than
half of an inch of going through.
The second shot was fired
with velocity of 1,495 feet
second and went three inches into the
oak backing. The third and last shot
was to determine whether or not the
premium was to be paid. and the veloc-
ity was raised to 1858 feet second.
When the smoke and dust following
the discharge had lifted it was found
that the shell had gone clear through
the plate and thirty-siX inches of oak
backing and then, finding the embank-
ment rather thin, was DETECTED into
the air and plulged into the
river some hundreds of yards away. or
was lost in the woods on tine hillside
Expert opinion on this point differed,
but that it had ploughed its way through
all distractions aud disappeared from
view was obvious. The plaed secure
for its makers the acceptance the
whole contract, amounting to from 500
to 700 tons, but
Earned No Premium.
Like the Monadnock plate il. t.showed
no cracks under the terrific strain to
which it had been subjected.
Even more satisfactory than the show
ing made by the plates was that of the
projectiles. The eight-lnch shells were
VI tHe hOllLcT COuCldl pattern anu the
| twelve-inch of the Carpenter conceal
pattern. All four of the shells
that were recovered appeared
wholly unchanged to the unprac-
ticed eye of the layman, and the
| gauge showed that they were disturbed
to such small degree that they might
| again be fired with the attachment of a
new strip for rifling. Some idea of the
force with which the shells struck the
face of the plates may be gained
from the fact that the energy
of the last shot fired was equivalent
to the force necessary to move a
mass of 21,6OO tons through one foot of
space. The cost of the tests today was
no small item, and as they compelled
acceptance of the plates represented it
falls upon the government. In round
numbers the barbette plate cost S15, 900,
the armor plate $1,000, and the firing of
the rifles $1,000. After the tests had
been concluded all the officials and ex-
! pertS expressed unbounded qualification