In science, Joseph Fourier (1768-1830) was a French mathematician and physicist notable for being one of the first instructors and later chair of the École Polytechnic and for his 1822 book Analytical Theory of Heat. [1]

Analytical Theory of Heat
In his Analytical Theory of Heat, basing logic on Newton's law of cooling, namely, that the flow of heat between two adjacent molecules is proportional to the extremely small difference of their temperatures, Fourier outlined a mathematical model of heat movement in various directions. He argues that any function of a variable, whether continuous or discontinuous, can be expanded in a series of sines of multiples of the variable.

Thermodynamics
In 1839, after listening to the praises of Fourier’s book by Royal Belfast Academical Institution of Northern Ireland astronomy professor John Nichol, a 15-year old William Thomson asked whether he should read the Théorie Analytique, to which Nochol’s replied “the mathematics is very difficult”. [2] William later got the book from the library. In his own words, “On the 1st of May … I took Fourier out of the University Library; and in a fortnight I had mastered it—gone right through it.” [3] This was one of Thomson's first seeds of interest on the topic of the nature of heat. Thomson would later go on to coin the term "thermo-dynamic" in his 1849 "An Account of Carnot's Theory of the Motive Power of Heat". [4]

References
1. Fourier, Joseph. (1822). Analytical Theory of Heat (Théorie Analytique de la Chaleur). Cambridge.
2. Lindley, David. (2004). Degrees Kelvin - a Tale of Genius, Invention, and Tragedy. Washington, D.C.: Joseph Henry Press.
3. Thomson, S.P. (1910). Life of Kelvin, (I: 14). London: MacMillan.
4. Thomson, William. (1849). “An Account of Carnot’s Theory of the Motive Power of Heat – with Numerical Results Deduced from Regnault’s Experiments on Steam”, (127-203) Transactions of the Edinburgh Royal Society, xiv.; Annales de Chime, xxxv. 1852.