VI. THE AGE OF THE GIANTS

Until the Wright Brothers definitely solved the problem of
flight and virtually gave the aeroplane its present place in
aeronautics, there were three definite schools of experiment.
The first of these was that which sought to imitate nature by
means of the ornithopter or flapping-wing machines directly
imitative of bird flight; the second school was that which
believed in the helicopter or lifting screw; the third and
eventually successful school is that which followed up the
principle enunciated by Cayley, that of opposing a plane surface
to the resistance of the air by supplying suitable motive power
to drive it at the requisite angle for support.

Engineering problems generally go to prove that too close an
imitation of nature in her forms of recipro-cating motion is not
advantageous; it is impossible to copy the minutiae of a bird's
wing effectively, and the bird in flight depends on the tiniest
details of its feathers just as much as on the general principle
on which the whole wing is constructed. Bird flight, however,
has attracted many experimenters, including even Lilienthal;
among others may be mentioned F. W. Brearey, who invented what
he called the 'Pectoral cord,' which stored energy on each
upstroke of the artificial wing; E. P. Frost; Major R. Moore,
and especially Hureau de Villeneuve, a most enthusiastic student
of this form of flight, who began his experiments about 1865,
and altogether designed and made nearly 300 artificial birds.
one of his later constructions was a machine in bird form with a