New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1891-07-25
MORE TESTS OF ARMOR.
DEFECTIVE PLATES USED FOR THE FIRST
TIME.
McKEL-srEEL AGAIN PROVEN THE supEMon

''--SA1-N-H AIAlN PROVEN THE SUPERIOR
METAL-THE PRoJEcTILEs ALL BROKEN.
Washington, July "a (speeian-Another important
armor plate test has been concluded By the Navy
ordnance oncers at the Indian Head proving ground
the competition being, in all the recent trials be-
tween all steel and ncielsteel The novelty Of the
test rested In the fact that for the first time this
country oenecrve armor plate to be the subject.
The trial was to determine what kind of armor was the
best for the deck OF armored cruiser No (the New
YORK;, which Ia building at the Cramps shipyard.
Two firms, Cramps Sons and Carnegie, Phipps d Co..
submitted plates for test each concern sending
known construction steel plates The Cramp
plates were attacked first The two plates. each IA
inches thick and OF $4,000 pounds tensile strength.
were placed top OF the other bOted together and
Inclined twenty degrees to the plane of fire. The
plates were of all steel sx-inch gun was used,
throwing cast iron proectle of 100 pounds weight
the powder charge being 81 10 pounds For the
practical purposes Of the test cast iron proieces were
serviceable steel and more economical The pro
iectles had striking velocity Of 1918 feet per second
which represented the approximate striking velocity
Of battle range.
Five shots fired at each target one shot in each
corner and one in the centre as at the foreign
plates at the September tests last year The first shot
struck the Cramp target twenty inches from the top
and nineteen inches from the right hand edge AT
the point Of impact the plate dlshed three inches
below the plane Of its surface. The depression
elptca shaped with its longest axis in the direction
OF the line OF fire. The surface of the depression was
smooth and coated with copper from the rotating band
of tho shell. There cracks The second shot
was twenty-sx inches from the top and twenty two
inches from the left hand edge of the target and the
results similar 10 those of the previous shot The
third shot directed at the centre of the target but
owing a slight in sighting the gun which
magnifed by the angle of the target, the projecte
struck between and line with the first and second
D1AL ~, binh +Ia
target were cracked through the centre bolt hole at
the top the plate but the crack could not be followed
in the plate In the upper plate the crack curved
TO the rear of the first point of impact The bolt was
driven down through the bolt hole and the plate was
dished inches deep there This was by accident,
severe test for the target, and the result would not
have been disastrous TO vessel protected in actual
assault The fourth shot was twenty one inches from
the bottom and nineteen inches from the right hand
edge with results similar TO those of shots one and
two The fifth shot twenty-one inches from the
bottom and twenty-five inches from the left hand edge
of the target. and duplicate Of the preceding
shot The live oak backing beneath the target was
bruised but not broken.
The test of the Carnegie plates was under the same
conditions The Carnegie plates were l 1-2 inches
thick each and were Of nickel steel. The same gun
was used and the projectes were cast steel The
plates were placed the other as In the case OF
the Crsmp plates The first shot was twenty eight
hand edge of the target, which was dished at the
point of impact ! 40 inches. The ridges on the
plate. resulting from the mill scale, were slightly
smoothed by the blow. There were no cracks and no
bolts were broken. The second shot was thirty SIX
inches from the top and seventeen Inches from the
left side of the target dshing the plate Go lncheS
The third shot the centre Of the plate ana was
a duplicate of the first shot. The fourth shot was
tbirtv-two inches from the bottom Of and eighteen
inches from the right edge of the target and dshed
the plate / e-1o inches. The fifth shot was thirty
two inches from the bottom and fourteen inches from
the left edge and produced results similar to those OF
the fourth shot.
The Carnegie plates made longer than had been
expected and there was not under the structure
10 nut the nuts on the row Of bolts and the bolts
being merely driven down, allowed the bottom cage 10
curve up. This accounts for the deeper depression
made bv the lower shots than by the upper ones one
and fourtenths inches seemed 70 be about the normal
depression. The tensile strength of the Carnegie
plates was % 900 to 100000 pounds, and the elonga-
ton from IL to &c per cent. -
All Of the ten projectiles used were broken No
piece of shell detected than five degrees with
the plane OF the plate. The lateral dispersion was
e0Onf twenty degrees. The results OF this test
do not alter the position Of nickel steel which SILL
retains It's superiority the homogeneous metal
The ordnance authorities regard the Carnegie plates as
better than the Camp plates taking into considerations
of course the greater thickness of the former.