ylinder" is exact, for the inner
conformation of a submarine is necessarily rounded, so that relatively
thin partitions can successfully resist the greatest pressure of
water.

III

SUBMERSION AND TORPEDO FIRE

A new passenger, for the first time in a submarine, has often
professed to be unaware that he was fathoms deep under water and has
been quite unconscious that the boat had been diving. Of course his
astonishment indicates that he was not in the compartment where these
maneuvers take place, for it is in the commander's turret that the
whole apparatus is centralized for submersion, for steering to the
right depth, and also for emersion. At this juncture every man must be
at his post, and each one of the thirty members of the crew must feel
individually responsible for the safety of the whole in the difficult
and rapid maneuver of plunging, for the slightest mistake may endanger
the security of the boat.

The central control, situated in the commander's turret, is in reality
the brain of the boat. When the alarm signal is heard to change the
course from surface navigation to subsurface navigation, several
previously designated members of the crew take their post of duty in
the commander's turret. The commander, himself, is on duty during the
whole of the expedition in time of war, and he seldom gets a chance
for rest in his tiny little cabin. Day and night, if there is the
slightest suspicion of the approach of the enemy, he watches on the
exposed bridge on the top of the turret; for a few seconds' delay in
submerging might forfeit the taking of a much coveted prize. So he
learns to do without sleep, or to catch a few brief seconds of repose
by lying down in his wet clothes, and he is at once ready to respond
to the alarm signal of the officer of the watch.

In one bound he is once more surveying the horizon through the
periscope, or mounts to the bridge to determine with his powerful
field glass whether friend or foe is in sight. His observations must
be taken in the space of a few seconds, for the enemy is also
constantly on the lookout, and continual practice enables the sailor
in the crow's nest to detect the slender stem of a periscope, although
the hull of the boat is scarcely visible on the face of the waters.

The commander must come to a prompt decision as soon as he locates
the adversary's exact position. Not only may a retarded submersion
spoil our plan of attack, but we are exposed to bei