ken without doing serious
damage to 10-1/2-inch laminated armor backed with 18 inches of oak.
The comparative test of solid and laminated armor has already been
mentioned. The best 4-1/2-inch solid plates, well backed, are
practically proof against the guns of English iron-clads, namely,
68-pounder smooth-bores and Armstrong 110-pounder rifles, the service
charge of each being 16 pounds.

_Rifling and Projectiles_. The spherical shot, presenting a larger area
to the action of the powder, for a given weight, than the elongated
rifle-shot, has a higher initial velocity with a given charge; and all
the power applied to it is converted into velocity, while a part of the
power applied to the rifle-shot is employed in spinning it on its axis.
But, as compared with the rifle-shot, at long ranges, it quickly loses,
1st, velocity, because it presents a larger area to the resisting air;
2d, penetration, because it has to force a larger hole through the
armor; and 3d, accuracy, because the spinning of the rifle-shot
constantly shifts from side to side any inaccuracy of weight it may
have on either side of its centre, so that it has no time to deviate in
either direction. Practically, however, iron-clad warfare must be
at close quarters, because it is almost impossible to _aim_ any gun
situated on a movable ship's deck so that it will hit a rapidly moving
object at a distance. It is believed by some authorities that elongated
shot can be sufficiently well balanced to be projected accurately
from smooth-bores; still, it is stated by Whitworth and others that a
spinning motion is necessary to keep an elongated shot on end while
passing through armor. On the whole, so far as penetrating armor is
concerned, the theory and practice favor the spherical shot. But a more
destructive effect than mere penetration has been alluded to,--the
bursting of a shell within the backing of an iron-clad vessel. This
can be accomplished only by an elongated missile with a solid head for
making the hole and a hollow rear for holding the bursting charge. The
rifle-shot used in America, and the Armstrong and some other European
shot, are covered with soft metal, which in muzzle-loaders is expanded
by the explosion so as to fill the grooves of the gun, and in
breech-loaders is planed by the lands of the gun to fit the
rifling,--all of which is wasteful of power. Whitworth employs a solid
iron or steel projectile dressed by machinery beforehand to fit the
r