bmarine, there is an answer. The answer was not
ready when the war began, but it was not long delayed. We are apt to
think of the submarine as if it always operated under water, and
completely under water. But when it is completely under water, it is
completely blind and as helpless as other blind things are. To see
objects at a distance, it must be on the surface, and to see them
even close at hand it must at least expose its periscope. Having
definitely located an object within easy range, it may wholly
submerge and deliver its torpedo without seeing the target. But the
chance of a hit under these conditions is remote. Normally the
submarine remains on the surface until it sights an enemy. Having
approached as close as seems practicable without danger of being
seen itself, it submerges, _except for the periscope_, and
approaches within range, directing its course and its aim, _by
sight_--not by some occult instinct such as is often attributed to
it. When within a zone where imminent danger threatens, it may
remain wholly submerged for a long period of time, but when so
submerged, it is not in any degree a threat to other craft.

In other words, the submarine is dangerous only when it can see. And
when it can see, it can be seen--not easily perhaps, but certainly
by an observer reasonably close at hand and on the lookout. It is
especially liable to detection from an airship. Moreover, the noise
of its propellers can be heard at a considerable distance, and a
very sensitive microphone has been developed as a submarine
detector. The waters about Great Britain are now patrolled by
hundreds of small, fast craft--destroyers, trawlers, motor
boats--always on the lookout for a periscope or other indication of
the proximity of a submarine. If one is actually seen, its capture
or destruction follows as a matter of course. If the presence of one
is indicated by the microphone or other evidence, such as oil
floating on the water, or bubbles rising to the surface, nets are
lowered and the water dragged for miles around. It is not known how
many submarines have been destroyed by these tactics, but the number
is unquestionably large. Thus the submarine is being robbed of much
of its mystery and much of its terror, and while it remains, and
will always remain, a danger, the lesson of the war is that it must
take its place beside other dangers with which modern war is filled,
as something to be respected and feared, but not as having