3585 THE TWENTIETH CENTURY-THE GREAT WAR.
greeted by thousands of rifle bullets; if
further off, by bursting shells from anti-aircraft guns especially designed for that purpose. Enemy aircraft, too, were likely to
endeavor to destroy or drive away the spy.
The exigencies of real warfare quickly
revealed needs in the air not unlike those
upon the water. Some aircraft were built
purely for observation purposes. These
corresponded to the scout cruisers of the
watery main. Others were built primarily
for fighting purposes and corresponded to
battleships. Still others were designed to
carry heavy loads of bombs. Incredible as
it would have seemed fifteen years before,
some types of aeroplanes were actually
armored, to protect both the crew and
also the more vital parts of the machines.
Offensive weapons were at first confined to
automatic pistols and rifles; then machine
guns were installed; and finally some of the
battle planes carried small cannon.
On the sea both sides made considerable
use of hydro-aeroplanes for scouting purposes, and the Allies found these machines
helpful in locating and destroying submarines.
A few instances were reported in which
dirigibles or aeroplanes were able to damage
or destroy merchant vessels or small
warships, but not a single instance occurred
of a battleship being sunk by such an
attack. Certain peculiar properties of
high explosives, in fact, unfit them for
destroying vessels in this manner. The
force of a high explosive, when merely
placed or dropped upon an object is mostly
exerted upward, and only a bomb of
enormous size would be likely to sink a
battleship unless, by rare chance, it should
happen to fall down a smokestack. Furthermore, many of the battleships were
provided with nets designed to intercept
bombs dropped from the air.