French mathematician and physicist Jean Baptiste Joseph Fourier published Théorie analytique de la chaleur in 1822. Fourier’s application of new methods of mathematical analysis to the study of heat extended rational mechanics to fields outside of those defined in Newton’s Principia, enabling the systematization of a wide range of phenomena. To further his study of heat, Fourier introduced the Fourier series and Fourier integrals.
Hook & Norman, The Haskell F. Norman Library of Science and Medicine (1991) no. 824.