ft. I shall deal
with this question in a later chapter.

During the early days of the war anti-aircraft artillery appeared to
be a much overrated arm. The successes placed to its credit were
insignificant. This was due to the artillerymen being unfamiliar with
the new arm, and the conditions which prevail when firing into space.
Since actual practice became possible great advances in marksmanship
have been recorded, and the accuracy of such fire to-day is striking.
Fortunately the airman possesses the advantage. He can manoeuvre beyond
the range of the hostile weapons. At the moment 10,000 feet represents
the extreme altitude to which projectiles can be hurled from the arms
of this character which are now in use, and they lack destructiveness at
that range, for their velocity is virtually expended.

Picking up the range is still as difficult as ever. The practice
followed by the Germans serves to indicate the Teuton thoroughness of
method in attacking such problems even if success does not ensue. The
favourite German principle of disposing anti-aircraft artillery is to
divide the territory to be protected into equilateral triangles, the
sides of which have a length of about six miles or less, according to
the maximum effective range of the pieces at an elevation of 23 1/2
degrees.

The guns are disposed at the corners of the triangles as indicated
in Figs. 13-14. Taking the one triangle as an example, the method of
picking up the range may be explained as follows. The several guns at
the comers of the triangle, each of which can be trained through the
360 degrees in the horizontal plane, are in telephonic touch with an
observer O stationed some distance away. The airman A enters the area
of the triangle. The observer takes the range and communicates with the
gunner B, who fires his weapon. The shell bursts at 1 emitting a red
flame and smoke. The observer notes the altitude and relative position
of the explosion in regard to the aircraft, while gunner B himself
observes whether the shell has burst to the right or to the left of the
objective and corrects accordingly. The observer commands C to fire,
and another shell is launched which emits a yellow flame and smoke. It
bursts at 2 according to the observer, while gunner C also notes
whether it is to the right or to the left of the target and corrects
accordingly. Now gunner D receives the command to fire and the shell
which explodes at 3 throws off a white flame and