Joseph John Thomson was born in Cheetham Hill, a suburb of Manchester on December 18, 1856. He enrolled at Owens College, Manchester, in 1870, and in 1876 entered Trinity College, Cambridge as a minor scholar. He became a Fellow of Trinity College in 1880, when he was Second Wrangler and Second Smith's Prizeman, and he remained a member of the College for the rest of his life, becoming Lecturer in 1883 and Master in 1918. He was Cavendish Professor of Experimental Physics at Cambridge, where he succeeded Lord Rayleigh, from 1884 to 1918 and Honorary Professor of Physics, Cambridge and Royal Institution, London.

Thomson's early interest in atomic structure was reflected in his Treatise on the Motion of Vortex Rings which won him the Adams Prize in 1884. His Application of Dynamics to Physics and Chemistry appeared in 1886, and in 1892 he had his Notes on Recent Researches in Electricity and Magnetism published. This latter work covered results obtained subsequent to the appearance of James Clerk Maxwell's famous "Treatise" and it is often referred to as "the third volume of Maxwell". Thomson co-operated with Professor J. H. Poynting in a four-volume textbook of physics, Properties of Matter and in 1895 he produced Elements of the Mathematical Theory of Electricity and Magnetism, the 5th edition of which appeared in 1921.

In 1896, Thomson visited America to give a course of four lectures, which summarised his current researches, at Princeton. These lectures were subsequently published as Discharge of Electricity through Gases (1897). On his return from America, he achieved the most brilliant work of his life - an original study of cathode rays culminating in the discovery of the electron, which was announced during the course of his evening lecture to the Royal Institution on Friday, April 30, 1897. His book, Conduction of Electricity through Gases, published in 1903 was described by Lord Rayleigh as a review of "Thomson's great days at the Cavendish Laboratory". A later edition, written in collaboration with his son, George, appeared in two volumes (1928 and 1933).

Thomson returned to America in 1904 to deliver six lectures on electricity and matter at Yale University. They contained some important suggestions as to the structure of the atom. He discovered a method for separating different kinds of atoms and molecules by the use of positive rays, an idea developed by Aston, Dempster and others towards the discovery of many isotopes. In addition to those just mentioned, he wrote the books, The Structure of Light (1907), The Corpuscular Theory of Matter (1907), Rays of Positive Electricity (1913), The Electron in Chemistry (1923) and his autobiography, Recollections and Reflections (1936), among many other publications.

Thomson, a recipient of the Order of Merit, was knighted in 1908. He was elected Fellow of the Royal Society in 1884 and was President during 1916-1920; he received the Royal and Hughes Medals in 1894 and 1902, and the Copley Medal in 1914. He was awarded the Hodgkins Medal (Smithsonian Institute, Washington) in 1902; the Franklin Medal and Scott Medal (Philadelphia), 1923; the Mascart Medal (Paris), 1927; the Dalton Medal (Manchester), 1931; and the Faraday Medal (Institute of Civil Engineers) in 1938. He was President of the British Association in 1909 (and of Section A in 1896 and 1931) and he held honorary doctorate degrees from the Universities of Oxford, Dublin, London, Victoria, Columbia, Cambridge, Durham, Birmingham, Göttingen, Leeds, Oslo, Sorbonne, Edinburgh, Reading, Princeton, Glasgow, Johns Hopkins, Aberdeen, Athens, Cracow and Philadelphia.

In 1890, he married Rose Elisabeth, daughter of Sir George E. Paget, K.C.B. They had one son, now Sir George Paget Thomson, Emeritus Professor of Physics at London University, who was awarded the Nobel Prize for Physics in 1937, and one daughter.

From Nobel Lectures, Physics 1901-1921, Elsevier Publishing Company, Amsterdam, 1967

This autobiography/biography was first published in the book series Les Prix Nobel. It was later edited and republished in Nobel Lectures. To cite this document, always state the source as shown above.

Sir Joseph John Thomson, b. Dec. 18, 1856, d. Aug. 30, 1940, is universally recognized as the British scientist who discovered and identified the electron. At the age of 27 he succeeded (1884) Lord Rayleigh as professor of physics at Trinity College, Cambridge, and was named director of its Cavendish Laboratory in the same year, continuing in that position until 1919. Thomson demonstrated (1897) that cathode rays were actually units of electrical current made up of negatively charged particles of subatomic size. He believed them to be an integral part of all matter and theorized a model of atomic structure in which a quantity of negatively charged electrons was embedded in a sphere of positive electricity, the two charges neutralizing each other. For these investigations he won (1906) the Nobel Prize for physics; in 1908 he was knighted.
Subsequently, Thomson turned his attention to positively charged ions. His research showed that neon gas was made up of a combination of two different types of ions, each with a different charge, or mass, or both. He did this by using magnetic and electric fields to deflect the stream of positive ions of neon gas onto two different parts of a photographic plate. This demonstration clearly pointed to the possibility that ordinary elements might exist as isotopes (varieties of atoms of the same element, which have the same atomic number but differ in mass).

Thomson was a highly gifted teacher--seven of his research assistants as well as his son, George, won Nobel Prizes for physics--and he led Great Britain to dominance in the field of subatomic particles in the early decades of the 20th century. He was accorded the honor of burial in Westminster Abbey.