Physicist (cathode rays, atomic structure, electrons) and administrator. On the faculty at University of Cambridge, 1884-1940: director, Cavendish Laboratory at Cambridge, 1884-1918; master of Trinity College, 1918-1940; and on the natural philosopy faculty at the Royal Institution of Great Britain from 1905. He won the Nobel Prize for Physics in 1906 for his theoretical and experimental investigations on the conduction of electricity by gases.