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,
19th century in ichnology 19th century in ichnology The 19th century in ichnology refers to advances made between the years 1800 and 1899 in the scientific study of trace fossils, the preserved record of the behavior and physiological processes of ancient life forms, especially fossil footprints. The 19th century was notably the first century in which fossil footprints received scholarly attention. British paleontologist William Buckland performed the first true scientific research on the subject during the early . A slab of Permian-aged sandstone had been discovered in Scotland which preserved a series of unusual footprints. After acquiring the specimen, Buckland experimented with modern animals