This feature of aeronautics is particularly important, because any
device which will give automatic stability when turning corners will go
far toward making aviation a safe amusement. Inequalities of velocity
exist not only on curves, but also when the wind is blowing at anything
but uniform velocity across the whole front of the machine. The
slightest "flaw" in the wind means an at least temporary variation in
lifting force of the two arms. Here is a pregnant source of danger, and
one which cannot be left for the aviator to meet by conscious thought
and action. It is this, then, that blindfolds him: he cannot see the
wind conditions in advance. The conditions are upon him, and may have
done their destructive work, before he can prepare to control them. We
must now study what these conditions are and what their influence may
be on various forms of aerial navigation: after which, a return to our
present subject will be possible.