In his work Pneumatica (B, 11) Heron describes a great invention, the steam whirl (or steam stele), thus putting the basis for the modern steam engine. The rotating steam whirl invented by Heron is known as Aeolosphere or Gate of Aeolos. Water is vaporised through a boiler and steam goes to a sphere with special valves by the means of two tubes bent at a right angle. This sphere has two outgrowths diametrically arranged and bent in such a way so as the steam pressure can make the sphere move in rotation, by escaping through them.
