turbine

The oldest and simplest form of turbine is the waterwheel, which is made to rotate by water falling across its blades and into buckets suspended from them. Hero of Alexandria invented the first steam-driven turbine in the 1st century A.D., but a commercially practical steam turbine wasn't developed until 1884; steam turbines are now the main elements of electric power stations. Jet engines are gas turbines. A turbojet engine uses a turbine to compress the incoming air that feeds the engine before being ejected to push the plane forward; a turboprop engine uses its exhaust to drive a turbine that spins a propeller. A wind turbine generates electricity by being turned by the wind; the largest now have vanes with a turning diameter of over 400 feet.