The Sun.
London, England, 1867-05-24 00:00:00

The Chalmers Target at Vincennes.

Some important experiments were made on Mon-
day at Vincennes in the presence of various distin-
guished officers of the Artillery and Marines in the

French and English services. One of the main ob-
jects was to test the Chalmers system of backing

armour-plates. Two targets were erected—one on
the Chalmers plan, and the other representing a
section of an ordinary French ironclad ship of war.
The superficial dimensions of the targets were the
same—about 17ft. by Bft ; and they were placed
side by side in a nearly vertical position. The French
target was protected by two wrought-iron plates of
71 inches, but the plates on this as well as the other
covered a portion of the surface only, about 14ft.
by 6ft. The Chalmers target had a front plate of
51- inches; behind which was the compound back-
ing of alternate layers of iron and timber ; the
laminae of iron being a foot wide and over i-inch

►ick, the timber being of the same width, and 6

ucheS in thickness. These layers were, before be-
!ore being attached to the target, riveted together
,n blocks of three plates of iron and two planks of

timber ; the whole backing finally resting against a
second plate of finch iron covering the upright
timbers of the target. The vertical timbers and
inner planking of both targets were alike, and both
were supported in the rear by iron knees and a
strong diagonal frame of timber. The two were, it
would seem, intended to have been fired at alter-
nately, hut the actual practice made was against
the Chalmers target only. The rounds were fired
from a 9-inch 12-ton Armstrong gun, throwing 250
pound steel shot with Palliser ogival form of head ;
some were with full charges of 431 b. of English
powder, and some with reduced charges. Two
shots penetrated, one stuck, and three failed
to get through the out plating.
These experiments seem to deserve attentive con-
sideration. Strict comparison with those recently
made against combined steel and iron plates at Shoe-
buryness is hardly possible, because the plates there
were unsupported, and the effects of the Palliser
missiles upon them was more of a simple punching
nature. Still when we regard the fact that in our
experiments a 7in. gun was used againstth 7in
two best
,
and just penetrated, or rather stuck,
in e
pllsalbte.sef(Aplenswsrdse.r,Cwaemmlneulsl'ts)a,
eewehrednsopmroepevlelerdy
ewointh_
siderable value to Mr. Chahate cner's backi
madesin. to keep
ewnitthoites assistance,largeran
d heavier shot fromgun.
The rule for punching plates is well known—
namely, a diameter of shot slightly larger than the
thickness of the plate, and the greater the margin
between the diameter of the shot and the thickness
ei tblm.ultil:laeinloly:vtzltlbrieciertoautaistelia)late has
of plate the more the difference tells in favour of
the penetrative action of the shot. We have the
, siaoh
to 5t
:);
impression that
tlohgesieelorst°P stopped
comparisons the7ct
de-
tails of the French experiments, which have reached
us from private sources, are not sufficiently
ample. We know that in these last Vincennes
trials the effect of two or three of the stringers .
the backing brought into resisting in
simulta-
neously by the impact of the n • action
pene-
tration even when fully charged,lissile prevented
the distance at which the
know that when the shotgun was placed. We also
where the plating was • got through the armour
the shot was turned supported by only one stringer,
in the backing. This
aside and became jammed
the number of iron 18- would' seem to indicate that
increased and the anunz in the backing might be
diminished, or, in thickness of the wood planking
frequent. other words, that the more
would be alternationsbeneficial
of wood. and iron planking
, to resistance offered by the
Chalmers target. These particulars would also
seem to extend the proofs of the
value of Mr.
Chalmers's system,