Abstract: This chapter reviews the early works of William Thomson. Thomson began to publish exceptionally early, in 1841, while still in his late teens; and a steady stream of papers came from him thereafter. Most of them in the 1840s concerned heat diffusion, electricity, or magnetism, and related mathematical methods such as the Fourier series and potential theory. These papers manifest a procedure of working by analogy in which methods were taken from one topic and adapted for use in another one.

Keywords: publications, heat theory, electricity, magnetism, Fourier series,