Existing comment:
First Flights
Humankind first took to the sky using the principle of buoyancy. As the Greek philosopher Archimedes explained, when an object weighs less than the amount of fluid it displaces, it will rise until it reaches an equilibrium point. A balloon can become buoyant when filled with hot air or a gas that is lighter than air, such as hydrogen. While small hot air balloons were flown centuries ago in Asia, and a small balloon may have been flown in Lisbon as early as 1704, the first people did not venture aloft until the fall and winter of 1783. |