In the 19th century the French physicist [[Nicolas Léonard Sadi Carnot]], who studied [[thermodynamics]], pioneered the development of the concept of a "system" in the [[natural science]]s. In 1824 he studied the system which he called the ''working substance'' (typically a body of water vapor) in [[steam engine]]s, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a boiler, a cold reservoir (a stream of cold water), or a piston (on which the working body could do work by pushing on it). In 1850, the German physicist [[Rudolf Clausius]] generalized this picture to include the concept of the [[environment (systems)|surroundings]] and began to use the term "working body" when referring to the system. | In the 19th century the French physicist [[Nicolas Léonard Sadi Carnot]], who studied [[thermodynamics]], pioneered the development of the concept of a "system" in the [[natural science]]s. In 1824 he studied the system which he called the ''working substance'' (typically a body of water vapor) in [[steam engine]]s, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a boiler, a cold reservoir (a stream of cold water), or a piston (on which the working body could do work by pushing on it). In 1850, the German physicist [[Rudolf Clausius]] generalized this picture to include the concept of the [[environment (systems)|surroundings]] and began to use the term "working body" when referring to the system. |