There are men so strong and outstanding in character and appearance that even death is unable to efface their personality. Lord Rutherford, who. was a personal friend of Sir John McLennan for many years, justly wrote: “If the details only could be obtained, an epic story could be written of the rise of McLennan from a demonstrator in a small and badly equipped laboratory in Toronto to the Directorship of a great research laboratory in Physics in that University and the acknowledged leader of Science in Canada.” The debt of Canada to Scotland can never be adequately expressed. John Cunningham McLennan was born on April 14, 1867, at Ingersoll in Ontario. His father, David, sprang from a race of farmers in the County of Aberdeen, while his mother, Barbara Cunningham, came from an Ayrshire family which from time to time “included an occasional minister.” It would, however, be a mistake to consider McLennan as purely a Scot, because from his earliest days Canada had impressed upon him her mark. His education began at Clinton High School in Huron County, whence he passed in 1883 the matriculation for his provincial university. He did not, however, enter the University of Toronto until 1888, and the five intervening years were passed at teaching at schools in the County of Perth and in studying mathematics at the Stratford Collegiate Institute under Dr. A. H. McDougall, afterwards Principal of the Ottawa Collegiate Institute. There were great teachers in those days and this period of teaching, of study, of contact with a powerful personality exercised “the greatest formative influence on his early intellectual life.” McLennan was older than most undergraduates when he entered the University of Toronto (1888), and he was twenty-five years old when he graduated (1892), with first class honours and head of his class, in the Physics division of the Mathematical and Physics Honours course.