uspicious
position; the movement through the air interferes with close continuous
observation. On the other hand, the dirigible can maintain a stationary
position aloft for hours on end. Then the issue is resolved into a
contest of patience, with the advantage to the airman. The soldiers in
the trenches fret and fume under cover; confined concealment is irksome
and is a supreme test of the nerves. Unless the soldiers are made of
very stern stuff, physical endurance succumbs. Some rash act--apparently
very trivial--may be committed; it suffices for the vigilant
sentinel overhead. He detects the slender sign of life, forms his own
conclusions, and returns to his headquarters with the intelligence that
the enemy is playing "Brer Rabbit."

It has also become increasingly difficult for the airman to gather
absolutely trustworthy data concerning the disposition and movement of
troops. Small columns are now strung out along the highways to convey
the impression that the moving troops are in far greater force than is
actually the case, while the main body is under the cover offered by
a friendly wood and is safe from detection. The rapidity with which
thousands of men are able to disappear when the word "Airman" is passed
round is astonishing. They vanish as completely and suddenly as
if swallowed by the earth or dissolved into thin air. They conceal
themselves under bushes, in ditches, lie prone under hedgerows, dart into
houses and outbuildings--in short, take every cover which is available,
no matter how slender it may seem, with baffling alacrity. The
attenuated column, however, is kept moving along the highway for the
express purpose of deceiving the airman.

Advancing troops also are now urged to move forward under the shelter
of trees, even if the task entails marching in single or double file, to
escape the prying eyes of the man above. By keeping close to the line
of trunks, thus taking full advantage of the overhanging branches, and
marching in such a manner as to create little dust, it is possible to
escape the aerial scout.

The concealment of cavalry, however, is somewhat difficult. An animal,
especially if he be unaccustomed to the noise of the aeroplane,
is likely to become startled, and to give vent to a frightened and
vociferous neighing which invariably provokes a hearty response from
his equine comrades. The sharp ear of the airman does not fail to
distinguish this sound above the music of his motor. Again