J. J. Thomson (1856-1940), British physicist and Nobel laureate. Sir Joseph John Thomson was born near Manchester, England, and educated at Owens College (now part of Victoria University of Manchester) and Trinity College, University of Cambridge. At Cambridge he taught mathematics and physics, served as Cavendish Professor of Experimental Physics, and was (1918-40) master of Trinity College. He was also president of the Royal Society (1915-20) and professor of natural philosophy at the Royal Institute of Great Britain (1905-18).

Thomson was awarded the 1906 Nobel Prize in physics for his work on the conduction of electricity through gases. He is considered the discoverer of the electron through his experiments on the stream of particles (electrons) emitted by cathode rays. A theorist as well as an experimenter, Thomson advanced in 1898 the “plum-pudding” theory of atomic structure, holding that negative electrons were like plums embedded in a pudding of positive matter. Thomson was knighted in 1908.