or on speed
combined with rapid twisting and turning, or erratic undulating flight,
rendering it extremely difficult for the gun-layer to follow his path
with sufficient celerity to ensure accurate firing.

At altitudes ranging between 4,000 and 6,000 feet the aeroplane comes
within the range of rifle and machine-gun firing. The former, however,
unless discharged in volleys with the shots covering a wide area, is not
particularly dangerous, inasmuch as the odds are overwhelmingly against
the rifleman. He is not accustomed to following and firing upon a
rapidly moving objective, the result being that ninety-nine times out
of a hundred he fails to register a hit. On the other hand the advantage
accruing from machine-gun fire is, that owing to the continuous stream
of bullets projected, there is a greater possibility of the gun being
trained upon the objective and putting it hors de combat.

But, taking all things into consideration, and notwithstanding the
achievements of the artillerist, the advantages are overwhelmingly
on the side of the aviator. When one reflects upon the total sum of
aircraft which have been brought to earth during the present campaign,
it will be realised that the number of prizes is insignificant in
comparison with the quantity of ammunition expended.

CHAPTER XVI. MINING THE AIR

While the anti-aircraft gun represents the only force which has
been brought to the practical stage for repelling aerial attack, and
incidentally is the sole offensive weapon which has established its
effectiveness, many other schemes have been devised and suggested to
consummate these ends. While some of these schemes are wildly fantastic,
others are feasible within certain limitations, as for instance when
directed against dirigibles.

It has been argued that the atmosphere is akin to the salt seas; that
an aerial vessel in its particular element is confronted with dangers
identical with those prevailing among the waters of the earth. But such
an analogy is fallacious: there is no more similarity between the air
and the ocean than there is between an airship and a man-of-war. The
waters of the earth conceal from sight innumerable obstructions, such as
rocks, shoals, sandbanks, and other dangers which cannot by any means be
readily detected.

But no such impediments are encountered in the ether. The craft of the
air is virtually a free age in the three dimensions. It can go whither
it will without let or hind