Kennelly, Arthur Edwin (kĕnˈəlē) [key], 1861–1939, American electrical engineer, b. Bombay (now Mumbai), India, educated at University College School, London. He was Edison's chief electrical assistant (1887–94) and was later professor at Harvard (1902–30) and at the Massachusetts Institute of Technology (1913–24). Much of his research was on electromagnetism and alternating currents. In 1902 he advanced the theory, also proposed by Oliver Heaviside, that a layer of ionized air in the upper atmosphere might deflect downward electromagnetic waves. The theory was demonstrated as fact, and the deflecting layer is known as the Heaviside-Kennelly layer (see ionosphere).