Generating Steam by heating water above its boiling point and using the resulting pressure was to the basis of the first engines to replace wind-, water-, and muscle-power. In the 1st Century AD, the Greek geometer and inventor Hero (Heron) of Alexandria built an engine that converted the velocity of a steam jet into rotational movement: The Hero Engine - the first steam driven engine. The basic idea of the Steam Engine was born. Thomas Newcomen's invention of the first practical steam engine in 1705 and its improvement by James Watt sixty years later mark the beginning of the Industrial Revolution and the basis for energy supply in modern society. It's a real mystery why it took the best part of two millennia before significant progress on Hero's approach was made. Today the optimized Clausius Rankine cycle is the most common thermodynamic steam process in the conventional power plants that supply the immense demand for electrical power for modern society. The basic concept of the Steam Engine, but using alternative working fluids instead of water, will probably play a significant role in future energy systems powered by solar and geothermal heat. The engines on this page are reminiscent of early steam technology and an exciting introduction to the thermodynamics of heat engines.