"When will man cease to crawl in the depths to live in the azure and
quiet of the sky?"

To this question of Camille Flammarion's the answer is easy. It will
be when the progress of mechanics has enabled us to solve the problem
of aviation. And in a few years--as we can foresee--a more
practical utilization of electricity will do much towards that
solution.

In 1783, before the Montgolfier brothers had built their
fire-balloon, and Charles, the physician, had devised his first
aerostat, a few adventurous spirits had dreamt of the conquest of
space by mechanical means. The first inventors did not think of
apparatus lighter than air, for that the science of their time did
not allow them to imagine. It was to contrivances heavier than air,
to flying machines in imitation of the birds, that they trusted to
realize aerial locomotion.

This was exactly what had been done by that madman Icarus, the son of
Daedalus, whose wings, fixed together with wax, had melted as they
approached the sun.

But without going back to mythological times, without dwelling on
Archytas of Tarentum, we find, in the works of Dante of Perugia, of
Leonardo da Vinci and Guidotti, the idea of machines made to move
through the air. Two centuries and a half afterwards inventors began