than bounce; it took the long, armor-piercing rifle
projectile to force the development of the tremendously thick plate of
modern times.

[Illustration: Figure 41--EIGHTEENTH CENTURY PROJECTILES. (Not to
scale.)]

Round shot was very useful for knocking out enemy batteries. The
gunner put his cannon on the flank of the hostile guns and used
ricochet firing so that the ball, just clearing the defense wall,
would bounce among the enemy guns, wound the crews, and break the gun
carriages. In the destruction of fort walls, shot was essential. After
dismounting the enemy pieces, the siege guns moved close enough to
batter down the walls. The procedure was not as haphazard as it
sounds. Cannon were brought as close as possible to the target, and
the gunner literally cut out a low section with gunfire so that the
wall above tumbled down into the moat and made a ramp right up to the
breach. Firing at the upper part of the wall defeated its own purpose,
for the rubble brought down only protected the foundation area, and
the breach was so high that assault troops had to use ladders.

The most effective bombardment of Castillo de San Marcos occurred
during the 1740 siege, and shot did the most damage. The heaviest
English siege cannon were 18-pounders, over 1,000 yards from the fort.
Spanish Engineer Pedro Ruiz de Olano reported that the balls did not
penetrate the massive main walls more than a foot and a half, but the
parapets, being only 3 feet thick, suffered considerable damage. Some
of the old parapets, Engineer Ruiz said, "have been demolished, and
the new ones have suffered very much owing to their recent
construction." (He meant that the new mortar had not sufficiently
hardened.) Ruiz was not deceived about what would happen if hostile
batteries were able to get closer; in such case, he thought, the enemy
"will no doubt succeed in destroying the parapets and dismounting the
guns."

Variations of round shot were bar shot and chain shot (fig. 41), two
or more projectiles linked together for simultaneous firing. Bar shot
appears in a Castillo inventory of 1706, and like chain shot, was for
specialized work like cutting a ship's rigging. There is one
apocryphal tale, however, about an experiment with chain shot as
anti-personnel missiles: instead of charging a single cannon with the
two balls, two guns were used, side by side. The ball in one gun was
chained to the ball in the other. The projectiles were to fly forth,
s