British physicist. After working under J. J. Thomson at Cambridge he was professor of physics at McGill Univ. (1898-1907), professor and director of the physical laboratory at the Univ. of Manchester (1907-19), and in 1919 succeeded Thomson as professor and director of the Cavendish Laboratory at Cambridge. He is known for his studies of radioactivity and for his discovery of the atomic nucleus. He discovered and named alpha and beta radiation and with Frederick Soddy proposed a theory of radioactive transformation of atoms; for this work he was awarded the 1908 Nobel Prize in Chemistry. On the basis of experiments with alpha rays carried out under his direction by H. Geiger and E. Marsden he was led (1911) to a description of the atom as a small, heavy nucleus surrounded by orbital electrons; this nuclear model of the atom was taken by Niels Bohr (1913) and combined with the new quantum theory to provide the basic description of the atom still accepted today. In the course of his researches, he produced hydrogen by bombarding atoms of various elements, e.g., nitrogen, with helium nuclei (alpha rays); these results, published in 1919, were the first evidence of artificially produced splitting of atomic nuclei. In addition to his own work, Rutherford was known for his outstanding leadership in directing the research of others. Rutherford was knighted in 1914 and elevated to the peerage in 1931. His works include Radioactive Transformations (1906), The Electrical Structure of Matter (1926), The Artificial Transmutation of the Elements (1933), and The Newer Alchemy (1937). The first volume of his collected papers appeared in 1962.