An engine, or motor, is a machine designed to transform one form of power into power. Warmth engines, consisting of interior combustion engines and external combustion engines (such as steam engines) burn a fuel to add heat, which then produces a pressure. Electric motors convert electrical energy into mechanical movement, pneumatic motors use pressed air and others-- such as clockwork motors in wind-up toys-- utilize elastic power. In organic systems, molecular motors, like myosins in muscles, use chemical energy to add pressures and ultimately activity. "Engine" was initially a term for any type of mechanical gadget that transforms force right into activity. For this reason, pre-industrial tools such as launches, trebuchets and damageding rams were called "siege engines". The word "gin," as in "cotton gin", is short for "engine." The word obtains from Old French engin, from the Latin ingenium, which is additionally the origin of words innovative. Most mechanical gadgets designed during the industrial revolution were described as engines-- the vapor engine being a notable example.