Rudolf Clausius was a German theoretical physicist, born at Köslin in Pomerania, who was one of the founders of the science of thermodynamics, building upon the work of Sadi Carnot. He was the first to state a version of the second law of thermodynamics (1850) and he proposed the term entropy.

 

Clausius studied at Berlin, and afterwards lectured on natural philosophy as a privat-docent at Berlin, and as professor at the Zurich Polytechnic School. In 1869 he was appointed to the chair of Natural Philosophy at Bonn, a post he held until his death. He was elected a foreign member of the Royal Society in 1868, and in 1879 was given its highest honor, the Copley Medal. His scientific work covered parts of the fields of optics and electricity, but his essential work was his contribution to thermodynamics, a field that he effectively founded along with Carnot, Rankine, and Thomson. His mathematical methods he also applied to the theory of the steam engine, the kinetic theory of gases, and to electromagnetism.

 

His great work is his Abhandlungen über die mechanische Wärmetheorie (1864 and 1867), which in its second edition took a more systematic form as vol. i., Die mechanische Wärmetheorie (1876) and vol. ii., Die mechanische Behandlung der Electrizitat (1879). Other books are Ueber das Wesen der Wärme (1857), and Die Potentialfunction und das Potential (3d ed. 1877).