is. He modelled
his wings on those of a bat and worked them with ropes passing over
pulleys, the aviator lying prone, face downward, and kicking with
both arms and legs with the vigour of a frog. There is, unhappily,
no record that the proposition ever advanced beyond the literary
stage--certainly none that Da Vinci himself thus risked his life.
History records no one who kicked his way aloft with the Da Vinci
device. But the manuscript which the projector left shows that he
recognized the modern aviator's maxim, "There's safety in altitude."
He says, in somewhat confused diction:

The bird should with the aid of the wind raise itself to a great
height, and this will be its safety; because although the
revolutions mentioned may happen there is time for it to recover
its equilibrium, provided its various parts are capable of strong
resistance so that they may safely withstand the fury and impetus
of the descent.

[Illustration: _The Fall of the Boche._

_From the painting by Lieutenant Farre._

Photo by Peter A. Juley.]

The fallacy that a man could, by the rapid flapping of wings of any
sort, overcome the force of gravity persisted up to a very recent
day, despite the complete mathematical demonstration by von
Helmholtz in 1878 that man could not possibly by his own muscular
exertions raise his own weight into the air and keep it suspended.
Time after time the "flapping wings" were resorted to by ambitious
aviators with results akin to those attained by Darius Green. One of
the earliest was a French locksmith named Besnier, who had four
collapsible planes on two rods balanced across his shoulders. These
he vigorously moved up and down with his hands and feet, the planes
opening like covers of a book as they came down, and closing as they
came up. Besnier made no attempt to raise himself from the ground,
but believed that once launched in the air from an elevation he
could maintain himself, and glide gradually to earth at a
considerable distance. It is said that he and one or two of his
students did in a way accomplish this. Others, however,
experimenting with the same method came to sorry disaster. Among
these was an Italian friar whom King James IV. of Scotland had made
Prior of Tongland. Equipped with a pair of large feather wings
operated on the Besnier principle, he launched himself from the
battlements of Stirling Castle in the presence of King James and
his court. But gravity