19th century in science Carnot captured some of the ideas of thermodynamics in his discussion of the efficiency of an idealized engine. Sadi Carnot's work provided a basis for the formulation of the first law of thermodynamics—a restatement of the law of conservation of energy—which was stated around 1850 by William Thomson, later known as Lord Kelvin, and Rudolf Clausius. Lord Kelvin, who had extended the concept of absolute zero from gases to all substances in 1848, drew upon the engineering theory of Lazare Carnot, Sadi Carnot, and Émile Clapeyron–as well as the experimentation of James Prescott Joule on the interchangeability of mechanical, chemical,
Baron Playfair Baron Playfair Baron Playfair, of St Andrews in the County of Fife, was a title in the Peerage of the United Kingdom. It was created on 3 September 1892 for the scientist and Liberal politician Sir Lyon Playfair. He was succeeded by his only son, the second Baron. He was a Brigadier-General in the British Army. His only son, the Hon. Lyon George Henry Lyon Playfair (1888-1915), was a Captain in the Royal Field Artillery and was killed in action in the First World War, unmarried. Consequently, the title became extinct on the death of the second Baron in 1939.