Rudolf Clausius, German theoretical physicist, 19th century.
© Science Museum / Science & Society Picture Library
Portrait drawing from W Oechsli's 'Geschichte der Grundung des Eidgenossischen Polytechnikums mit einer Ubersicht Entwickelung, 1855-1905'. Rudolf Clausius (1822-1888), was the founder of the second law of thermodynamics. He outlined his theories in his 1850 paper 'Uber die bewegende Kraft der Warme', suggesting that Nicolas Carnot's earlier notions of thermodynamics was inconsitent with the mechanical theory of heat rapidly establishing itself. Clausius also introduced the term 'entropy' in 1865.