Legendary characters used the power of mythology to fly through the heavens. About 200 BC, a Greek inventor known as Hero of Alexandria came up with a new invention that depended on the mechanical interaction of heat and water. He invented a rocket-like device called an aeolipile. It used steam for propulsion. Hero mounted a sphere on top of a water kettle. A fire below the kettle turned the water into steam, and the gas traveled through the pipes to the sphere. Two L-shaped tubes on opposite sides of the sphere allowed the gas to escape, and in doing so gave a thrust to the sphere that caused it to rotate.
