by a side-slip, is known now to
represent no great risk for the airman, granted always that he has the
advantage of altitude. The machine, in such circumstances, falls a
certain distance. This is inevitable, and for the reason that it must
regain forward speed--which it has lost temporarily in its
side-slip--before its own inherent stability can become effective, or
its pilot regain influence over his controls. And it is this
unavoidable descent, this short period during which the machine is
recovering its momentum, and during which the pilot has no power of
control, that represents in a heavy wind the moments of peril, should
a pilot enter an area of disturbance just as he nears the ground.

An aeroplane, when it sets out to fly in bad weather, may be likened
to a boat that is being launched from a beach upon a rough and stormy
sea. It is the waves close inshore, which may raise his craft only to
dash it to destruction, that the boatman has chiefly to fear; and for
the aviator, when he leaves the land and embarks upon the aerial sea,
or when he returns again from this element and must make his contact
with the earth, there lurks a risk that, caught suddenly by an air
wave, and with insufficient space beneath his machine, he may be
forced into a damaging impact with the ground. But the skill of
designers and constructors, to say nothing of the growing experience
of aviators, is working constantly towards a greater safety.

Of the risk attached to engine failure, when he is piloting a craft
fitted with only one motor, an airman is reminded frequently, not only
from his own experience, but from that of other flyers. With the
aeroplane engine, even with types that have gained a high average of
reliability, there are many possibilities of a slight mishap--each of
them sufficient, for the moment, to put an engine out of action--that
the pilot who is flying across country must, all the time he is in the
air, have at the back of his mind the thought that at any moment, and
perhaps without any warning, he may find that his motive power has
gone. A magneto may fail temporarily; an ignition wire or a valve
spring break. The aeroplane engine of to-day is, of course, an
infinitely more reliable piece of apparatus than it was in those early
days when Henry Farman, working with extraordinary patience at
Issy-les-Moulineaux, was endeavouring--and for a long time without
success--to make the motor in his Voisin biplane run for five
c