THE FIRST MAN-MADE OBJECTS IN THE SKY
Long before men learned how to fly, they sent objects soaring through the air.
The arrow dates from the Stone Age. The ancient Chinese flew kites. The early
inhabitants of Australia invented the boomerang, the blades of which they carved in
the shape of an airfoil.
As early as the Middle Ages, men of scientific mind prophesied human flight.
About 1250, Roger Bacon, an English friar, suggested the orthopter, a machine that
flaps its wings like a bird. He also conceived the balloon, proposing "a hollow globe
filled with ethereal air or liquid fire." Some 250 years later, the great Italian artist and
scientist Leonardo da Vinci studied the flight of birds. About 1490, he drew sketches
for flying machines, also of the orthopter type. Leonardo made drawings of a
propeller and a helicopter.
An Italian monk, Francesco de Lana, in 1670 proposed a vacuum balloon. Four
spheres, from which air had been exhausted, were to support a car equipped with
oars and a sail. He overlooked the phenomenon of atmospheric pressure, however,
which would have crushed the spheres.
Not until a hundred years later was the first balloon flown successfully in public.
In 1783, J. Etienne and Joseph M. Montgolfier inflated a big paper balloon with hot
which rose 6,000 feet.
Do'stlaringiz bilan baham: