CHAPTER II
THE MILITARY USES of THE CAPTIVE BALLOON

Although the captive balloon is recognised as indispensable in
military operations, its uses are somewhat limited. It can be
employed only in comparatively still weather. The reason is
obvious. It is essential that the balloon should assume a
vertical line in relation to its winding plant upon the ground
beneath, so that it may attain the maximum elevation possible: in
other words, the balloon should be directly above the station
below, so that if 100 yards of cable are paid out the aerostat
may be 100 yards above the ground. If a wind is blowing, the
helpless craft is certain to be caught thereby and driven
forwards or backwards, so that it assumes an angle to its
station. If this become acute the vessel will be tilted,
rendering the position of the observers somewhat precarious, and
at the same time observing efficiency will be impaired.

This point may be appreciated more easily by reference to the
accompanying diagram. A represents the ground station and B
the position of the captive balloon when sent aloft in calm
weather, 300 feet of cable being paid out. A wind arises and
blows the vessel forward to the position C. At this point the
height of the craft in relation to the ground has been reduced,
and the reduction must increase proportionately as the strength
of the wind increases and forces the balloon still more towards
the ground. At the same time, owing to the tilt given to the
car, observation is rendered more difficult and eventually
becomes extremely dangerous.