PROF. HAROLD SIMPSON retires from the chair of mathematics at Bedford College, University of London, at the end of the present session. After a distinguished career at Oxford and, a short period at Bangor, North Wales, he became head of the Mathematics Department at Bedford College in 1907 and was appointed professor there in 1912. Prof. Simpson has contributed many important articles on various topics to mathematical and scientific periodicals; in addition, he has written four valuable books. (These have appeared under the name Hilton, which Prof. Simpson gave up in 1939.) The first of these, on "Mathematical Crystallography", appeared in 1903, and his interest in this application of mathematics continues; he has served on the council of the Mineralogical Society on various occasions since 1908 and often attended the meetings of the Geology Section of the British Association. His next books, on "Finite Groups" (1907) and "Homogeneous Linear Substitutions" (1914), are in certain respects an almost essential complement to his first, having regard to the state of algebraic knowledge in Britain at the time. His other book, "Algebraic Plane Curves" (1920, 1932), is well known both to teachers and to students. Prof. Simpson has served on the council of the London Mathematical Society since 1915 and has been librarian since 1925.