Mathematics was taught at McGill as early as 1848 when it was a discipline of Natural Philosophy. Mathematics at McGill was initially divided into two largely independent departments, one under the Faculty of Arts and Science and another under the Faculty of Engineering; the two departments merged in 1924 under the chairmanship of Daniel Murray. Still, mathematics remained subsidiary to other programs, owing to McGill's emphasis on engineering and British-style applied mathematics. Until 1945, Mathematics was almost wholly a service department with only seven faculty members. Though a small graduate program was shared with the Physics Department, most of the students in the program were headed for further graduate work in physics. In 1945, Department members Lloyd Williams and Gordon Pall founded the Canadian Mathematical Congress, which took the lead in persuading the National Research Council to make funds available for the support of pure mathematics. Meanwhile, as chairman of the Department, A. H. S. Gillon initiated in 1945 an Applied Mathematics program and in 1948 recommended for appointment to a professorship Hans Zassenhaus, a pure mathematician who began to attract a number of strong graduate students into his program. Zassenhaus, along with Professors Wacław Kozakiewicz, Charles Fox, Edward Rosenthall, and Phil Wallace, was instrumental in developing the Department's Graduate School. McGill's first mathematics Ph.D. was awarded to Joachim Lambek, who obtained his doctorate in 1950 under Zassenhaus's supervision. In 1963, as public funds came to the university and a larger budget became available, the newly appointment chairman, Edward Rosenthall, concentrated on building a balanced and well-qualified academic team, which could sustain a vigorous graduate program along with the demands made upon the Department in a service capacity. Analysis and algebra became strong elements in the Department's program in the late 1960s and the early 1970s, and there was also a lively interest in statistics and in applied mathematics. Research in category theory began in 1966, when Lambek decided to promote the subject at McGill. The number of full-time staff in the Department had grown to 36 by 1960, and to 56 by 1970. The Departmental library was established in 1971, and dedicated in 1987 in honour of Edward Rosenthall. At the time of its closure in 2015, the Rosenthall Library held over 14,000 mathematics journals dating from the nineteenth century, more than 10,000 monographs, as well as a collection of rare mathematics books.
