STEPHEN PROKOFIEVITCH TIMOSHENKO 1878-1972 Elected For.Mem.R.S.1944 BY E.H.MANSFIELD,F.R.S.AND D.H.YOUNG INTRODUCTION STEPHEN PROKOFIEVITCH TIMOSHENKO will long be remembered as an out- standing scientist,distinguished engineer,and a great and inspiring teacher. His long and active career extended from Czarist Russia,across Europe,and finally to America.The events of his interesting and often exciting life can be read in his most delightfully written autobiography,As I remember. Throughout his career,Timoshenko held steadfastly to one goal.This was to further the advancement of mechanics as a science and to promote its application to practical engineering problems.He strove always to bring mathematical theory and engineering practice into closer harmony.In attaining this goal he had singular success.His scientific papers,which taken collectively represent a monumental contribution to applied mechanics,were always aimed at solving real problems.His world-famous engineering textbooks put the most recent theoretical results into usable form for practising engineers.As a teacher,he was able to pass on to his students not only knowledge but much of his enthusiasm for mechanics.He was much loved and admired by all of his students and can never be forgotten by those who were fortunate enough to come under his influence. Stephen Timoshenko really had two careers:one in Russia before the Revolution and one in America after the first world war.Each of these careers divides itself rather naturally into three periods.The first period in Russia, representing his early childhood and formal education,begins with his birth in 1878 and ends with his graduation from the Institute of Engineers of Ways of Communication in St Petersburg in 1901.The second,representing his early years as a professor,his graduate study in Germany and the beginnings of his creative scientific work,ended abruptly with dismissal from his university post for political reasons in 1911.The third,covering the years from 1911 to 1922, represent the impact of the Revolution on his life.They represented for him and his family a period of great uncertainty and danger during which they wandered all over Russia,then into Western Europe,and finally to America. 679