New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1894-05-31
ARNOR TESTS AT INDIAN HEAD.
DO FLAWS DEVELOPED IN MANUFACTURE
GREATLY IMPAIR THE RESISTANCE
OF PLATES?

OF PLATES?
WASHINGTON. May % (SpeciaD-An official report
relating 10 recent armor tests at Indian Head re-
celvel at the Navy Department to-day. raises the
question as whether or not flaws in the surface
~ plates developed In manufacture. seriously i'm
pair the powers OF resistance OF such plates. The
remarks Of Lieutenant Mason. the commanding Off
Ger at Indian Head. on the results OF experiments
with a plate which contained five perceptibe
vertical surface cracks the upper edge and
less conspicuous crack running nearly the whole
length OF the plate, would seem to show that the
presence OF such defects In a plate did not affect
its efficiency The plate referred to was one OF the
six-inch curved Harveylzed nickel steel type. which
had been sent to Indian Head from the Carnegie
Works for experimental purposes. The cracks were
TO the right Of the central vertical line. None OF
them extended through the hardened surface. The
plate was 81 feet inches long and 1914 feet wide.
and weighed 22a tons. II was unbacked, and its
power 10 resist penetration was consequently les
sened. Three rounds were fired A six-inch rifle
and Carpenter armor-plercng shells were employed
In each round. The plate was 81 feet from the gun.
In the first round the charge OF powder was 1876
pounds. giving a striking velocity OF 1000 foot Sec
onds and a striking energy Of 22iS foot tons.
The shell struck the plate two inches TO the left OF
the centre about fifteen inches from the nearest
crack and eight and one-haf inches from the edge.
The she'll broke up. the ogive welding into the
plate, and the remaining fragments scattering and
treton was about 80 inches The effect OF the i'm
pact on the cracks, was to open them out little
and deepen them slightly None of the cracks was
heightened. nor were any new ones developed on
being struck the plate sprang like bow the edges
going out one inch at each edge and springng back
into place again.
In the second round when the same striking
loclty and striking energy developed in the
first discharge. the plate was struck about six inches
from the ends OF the cracks and midway between
them. The shell was broken up, the osive again
partly welding into the plate, and the fragments
lying the front for considerable distance. The
existing cracks once more opened out slightly, and
were Ieepened a little without being heightened.
Three face cracks from eight to twelve inches long
opened about four 10 eight inches from the right
edge Of the plate. The plate sprung out somewhat,
In the former round. and 10 about the same ex-
tent In the third round the charge or powder was
increased 10 as pounds, which developed striking
velocity OF 1000 foot seconds and striking energy
OF 9 7I6 foot tons. The shot struck at an angle OF
about 10 degrees about two Inches from the second
impact The penetration was four inches The plate
I'm the original cracks observed
An examination after the firing by experts pres
emf showed that the plates hard surface contained
very fine grains having clear ring wnen STRUCK