British-born US electrical engineer, who proposed the existence of the ionosphere in 1902. Born in Bombay, the son of an Irish naval officer in the employ of the East India Company, Kennelly was educated in Britain. He left school at thirteen and worked for some years with a variety of telegraph companies. In 1887 he emigrated to the USA, where he worked until 1894 as an assistant to Thomas Edison. Kennelly left Edison to set up as a consulting engineer on his own. However, in 1902 he began an academic career as professor of electrical engineering at Harvard, a post he occupied until his retirement in 1930.
Although Kennelly made many contributions to the theory of alternating currents and worked extensively on the accurate measurement and standardization of electrical units, he is best known for his suggestion in 1902 that a layer of electrically charged particles in the upper atmosphere is capable of reflecting back to earth radio waves broadcast from the surface of the earth. This would explain how radio waves were first transmitted across the Atlantic by Marconi in 1901. The layer was initially known as the Heaviside–Kennelly layer after Kennelly and Oliver Heaviside, who independently proposed its existence at the same time. Its existence was confirmed in 1924 by Sir Edward Appleton, after which it became known as the ionosphere, although the E region of the ionosphere is still sometimes known as the Heaviside–Kennelly layer.
From Who's Who in the Twentieth Century in Oxford Reference.
Subjects: Contemporary History (Post 1945).