f the steam
engine is another case in point. Sometimes however the application
of the hints of nature to the needs of man is rather ludicrously
indirect. Charles Lamb gravely averred that because an early
Chinaman discovered that the flesh of a pet pig, accidentally
roasted in the destruction by fire of his owner's house, proved
delicious to the palate, the Chinese for years made a practice of
burning down their houses to get roast pig with "crackling." Early
experimenters in aviation observed that birds flapped their wings
and flew. Accordingly they believed that man to fly must have wings
and flap them likewise. Not for hundreds of years did they observe
that most birds flapped their wings only to get headway, or
altitude, thereafter soaring to great heights and distances merely
by adjusting the angle of their wings to the various currents of air
they encountered.

In a similar way the earliest experimenters with balloons observed
that smoke always ascended. "Let us fill a light envelope with
smoke," said they, "and it will rise into the air bearing a burden
with it." All of which was true enough, and some of the first
balloonists cast upon their fires substances like sulphur and pitch
in order to produce a thicker smoke, which they believed had greater
lifting power than ordinary hot air.

In the race for actual accomplishment the balloonists, the advocates
of lighter-than-air machines, took the lead at first. It is
customary and reasonable to discard as fanciful the various devices
and theories put forward by the experimenters in the Middle Ages and
fix the beginning of practical aeronautical devices with the
invention of hot-air balloons by the Montgolfiers, of Paris, in
1783.

The Montgolfier brothers, Joseph and Jacques, were paper-makers of
Paris. The family had long been famous for its development of the
paper trade, and the many ingenious uses to which they put its
staple. Just as the tanners of the fabled town in the Middle Ages
thought there was "nothing like leather" with which to build its
walls and gates, thereby giving a useful phrase to literature, so
the Montgolfiers thought of everything in terms of paper. Sitting by
their big open fireplace one night, so runs the story, they noticed
the smoke rushing up the chimney. "Why not fill a big paper bag with
smoke and make it lift objects into the air?" cried one. The
experiment was tried next day with a small bag and proved a complete
success. A neigh