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,
British and Creole intervention in the Sierra Leone hinterland in the 19th century British and Creole intervention in the Sierra Leone hinterland in the 19th century Sierra Leone assumed its present large geographical size only in 1896. Prior to that, it was only a small colony encompassing roughly the 30-km-long peninsula on which Freetown is located. Initially, the British and Creoles (freed slaves and their descendents) of the Freetown colony had only a very limited involvement in the affairs of the African kingdoms around them; such as it was, it consisted mostly of trading and missionary activity. Over the course of the 19th century this involvement gradually increased. The colonial government was, in