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,
Italian Neoclassical and 19th-century art a desire to return to the perceived "purity" of the arts of Rome, the more vague perception ("ideal") of Ancient Greek arts, and, to a lesser extent, 16th-century Renaissance Classicism. Indoors, neoclassicism made a discovery of the genuine classic interior, inspired by the rediscoveries at Pompeii and Herculaneum, which had started in the late 1740s, but only achieved a wide audience in the 1760s, with the first luxurious volumes of tightly controlled distribution of "Le Antichità di Ercolano." Napoleon Bonaparte, who ruled most of Italy in the early 19th century hired Antonio Canova, one of the most influential Italian neoclassical