The boy is naturally inquisitive, and he is interested
in knowing WHY certain things are
necessary, and the reasons for making structures in
particular ways. That is the void into which
these pages are placed.

The author knows from practical experience,
while experimenting with and building aeroplanes,
how eagerly every boy inquires into details.
They want the reasons for things.

One such instance is related to evidence this
spirit of inquiry. Some boys were discussing the
curved plane structure. One of them ventured
the opinion that birds' wings were concaved on the
lower side. "But," retorted another, "why are
birds' wings hollowed?"

This was going back to first principles at one
leap. It was not satisfying enough to know that
man was copying nature. It was more important
to know why nature originated that type of formation,
because, it is obvious, that if such structures
are universal in the kingdom of flying creatures,
there must be some underlying principle
which accounted for it.

It is not the aim of the book to teach the art
of flying, but rather to show how and why the