lf as strong as one 4-inch plate; and the English, at least, have
never subjected it to more than one valuable test. During the last year,
a 6-inch target, composed of 5/8-inch boiler-plates, with a 1-1/2-inch
plate in front, and held together by alternate rivets and screws 8
inches apart, was completely punched; and a 10-inch target, similarly
constructed, was greatly bulged and broken at the back by the 68-pounder
(8 inch) smooth-bore especially, and the 100-pounder rifle at 200
yards,--guns that do not greatly injure the best solid 4-1/2-inch plates
at the same range. On the contrary, a 124-pounder (10 inch) round-shot,
having about the same penetrating power, as calculated by the ordinary
rule, fired by Mr. Stevens in 1854, but slightly indented, and did not
break at the back, a 6-5/8-inch target similarly composed. All the
experiments of Mr. Stevens go to show the superiority of laminated
armor. Within a few months, official American experiments have confirmed
this theory, although the practice in the construction of ships is
divided. The Roanoke's plates are solid; those of the Monitor class are
laminated. Solid plates, generally 4-1/2 inches thick and backed by 18
inches of teak, are exclusively used in Europe. Now the resistance of
plates to punching _in a machine_ is directly as the sheared area, that
is to say, as the depth and the diameter of the hole. But, the argument
is, in this case, and in the case of laminated armor, the hole
is cylindrical, while in the case of a thick armor-plate it is
conical,--about the size of the shot, in front, and very much larger in
the rear,--so that the sheared or fractured area is much greater. Again,
forged plates, although made with innumerable welds from scrap which
cannot be homogeneous, are, as compared with rolled plates made with
few welds from equally good material, notoriously stronger, because the
laminae composing the latter are not thoroughly welded to each other,
and they are therefore a series of thin plates. On the whole, the facts
are not complete enough to warrant a conclusion. It is probable that the
heavy English machinery produces better-worked thick plates than have
been tested in America, and that American iron, which is well worked in
the _thin_ plate used for laminated armor, is better than English iron;
while the comparatively high velocities of shot used in England are more
trying to thin plates, and the comparatively heavy shot in America prove
most