Second law of thermodynamics
The second law of thermodynamics may be expressed in many specific ways, the most prominent classical statements being the statement by Rudolf Clausius (1854), the statement by Lord Kelvin (1851), and the statement in axiomatic thermodynamics by Constantin Carathéodory (1909). These statements cast the law in general physical terms citing the impossibility of certain processes. The Clausius and the Kelvin statements have been shown to be equivalent.
Reflections on the Motive Power of Fire
The "Reflections" contain a number of principles such as the Carnot cycle, the Carnot heat engine, Carnot's theorem, thermodynamic efficiency. Similar to how the "Reflections" was the precursor to the second law, English physicist James Joule's 1843 paper "Mechanical equivalent of heat" was the precursor to the first law of thermodynamics.