McLennan, John Cunningham

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(b. Ingersoll, Ontario, 14 April 1867; d. near Abbeville, France, 9 October 1935)


McLennan’s father, David arrived in Canada from Scotland, in 1865, and was joined in 1866 by his wife, Barbara Cunningham, and their infant daughter. After having established himself as a miller and flour dealer, David McLennan relocated the family in Clinton, Ontario, in order to send his children to the local secondary school, the Collegiate Institute; when the family finally settled in Stratford, young John remained as a boarder in Clinton. In 1883, at age sixteen, he passed the Junior Matriculation Ex amination of the University of Toronto, which served as a secondary-school leaving certificate. McLennan then applied to work with the Grand Trunk Railway but failed to be hired. After a year living at home and working in his father’s office, he declared his intention to pursue a four-year arts degree at the University of Toronto. Since his father’s business was then foundering, McLennan had to earn money for his studies by teaching school.

At the end of a three-year pedagogical commit ment. McLennan decided on a career in exact sci ences. He took private lessons at home in preparation for the Senior Matriculation Examination at Toronto, the successful passing of which exempted a student from first-year studies. McLennan accomplished the task, and in 1889, at age twenty-two, he arrived in Toronto as a second-year student of mathematics and physics. Allowing himself few diversions, he received a B.A. degree in 1892, first in his class.

McLennan arrived at Toronto just when physics had become a separate institutional discipline. His physics professor. James Loudon, an undistinguished researcher who excelled at political maneuvering, had risen from classics tutor to physicist to, in 1892, president of the university. Since President Loudon retained his chair of physics, he required subordinates to carry out the routine tasks of teaching. Three men presented themselves for the posts; William James Loudon (who may have been related to James). Clarence Augustus Chant, and McLennan. The first two advanced up the academic ladder in mechanics and astrophysics while McLennan stayed on as President Loudon’s assistant. His progress, in scientific and professional terms, was painfully slow; his assistant demonstratorship of 1892 was converted into a demonstratorship only in 1899.

As assistant demonstrator. McLennan sensed that advancement in the world of physics depended on being initiated into its deeper mysteries in Europe, so he toured a number of laboratories in Great Britain and on the Continent during the summer of 1896.; The experience fired his interest for research, but he did not know where to begin. Like English speaking men the world over, he resolved to study with J. J. Thomson at Cambridge. But in 1897 his father died. He pleaded with his mother for the year in England; she consented, and he left in June 1898. He stayed at the Cavendish for a year, but funds were insufficient to allow him the second year of residence required for a Cambridge B. A.

Upon his return to Toronto, McLennan began research in radioactivity. A paper on electrical con ductivity in gases traversed by cathode rays appeared in the Philosophical Transactions of the Royal so ciety; Wilhelm Ostwald had it translated for his Zeitschrift für physikalische Chemie. Another minor piece was published in Canada. These articles were sufficient for the University of Toronto to award McLennan a Ph. D. —the doctorate then generally being reserved by Canadian universities as a reward for assiduous faculty members. A few more short publications followed until, in 1903, McLennan and Eli Franklin Burton observed radiation in the at mosphere. They, like other researchers who noticed the phenomenon, did not identify it as penetrating radiation—the cosmic rays of Viktor Hess and Jscob Clay.

McLennan came to direct physics at Canada’s premier twentieth-century university through the offices of his patron, President Loudon. Around 1900, at Loudon’s behest, McLennan took command of the university’s alumni association. The university was controlled by the provincial government; McLennan guided the alumni to pressure the government to take over the financing of four science departments and to construct new building, among them an impressive physics laboratory, during the next seven years. McLennan rode the crest of London’s wave; in 1902 he became associate professor, and in 1904 he advanced to direct the physics laboratory. When Loudon finally retired in 1906, his chair went, as expected, to McLennan, in 1907.

Once in charge of his own destiny, McLennan began to produce research articles on radioactivity spectroscopy, and cryogenics. His principal inves tigations concerned extracting helium from natural gas, low-temperature superconductivity, and dem onstrating that the auroral green line was due to excited oxygen. Most of his research was undertaken with students, some of whom later made their mark in the field : Gordon Merritt Shrum, who worked with McLennan on liquid helium and on the aurora; Charles Seymour Wright, who accompanied Robert Falcon Scott to the South Pole; physicist David Arnold Keys at McGill; and McLennan’s successor at Toronto, E. F. Burton, McLennan’s style did not endear him to his students—for instance, he cabled the first news of the auroral green line to Nature without indicating Shrum as a coauthor. It is questionable whether he had a hand in all the research that appeared under his name or, indeed, whether much of the research had permanent value. Nevertheless, the results propelled him to become, in the 1920’s the most visible and productive phys icist outside Europe and the United States.

Toronto was where McLennan felt at home. His family lived in Stratford, close at hand; in 1901 his sister Jean married William Arthur Parks, a geology instructor at Toronto. (He had no close relationship with his brother, an unsuccessful entrepreneur.) In 1910 McLennan married Elsie Monro Ramsay, the daughter of a wealthy merchant. By 1914 he was beginning to receive calls to British universities; Birmingham, Sheffield, Newcastle, Aberdeen. Glasgow, Belfast, and Bristol. He was tempted by John Henry Poynting’s chair at Birmingham and, later, by one at Bristol, but in the end he declined to leave Toronto, where his scientific reputation and his political position seemed unassailable, and his research facilities were all that he could ask for. The usual imperial honors came his way; fellow of the Royal Society in 1915; Order of the British Empire in 1917 for antisubmarine and dirigible re search during the war.

McLennan’s success was crowned in 1930 by his being named dean of the Graduate School at Toronto. He set out to invest his school with central authority for research and research funding. The various departments rebelled and forced his resignation as dean two years later. McLennan took the occasion to retire to private life in England the same year. He was suffering from heart trouble, and his wife’s health was not robust. He and his wife (they had no children) built a house in Surrey, and McLennan commuted to London, where he worked on cancer therapy at the Radium Institute. The pleasures of McLennan’s new life were cut short in 1933 with the death of his wife. In 1935 he was knighted—a distinction then conferred on Canadians if they re sided in England. Sir John savored his title for four months. He died on a train in France while returning from a meeting of the International Bureau of Weights and Measures, on whose council he sat as the rep resentative of the British Empire.


I. Original Works. A list of McLennan’s publications is in the biography by Langton (see below). Papers col lected by McLennan’s sister. Janet, are in the archives of the University of Toronto. Letters are in the Rutherford scientific correspondence (Cambridge and Montreal) and in the archives of McGill University, Montreal.

II. Secondary Literature. The standard biography is Hugh Hornby Langton, Sir John Cunningham McLennan: A Memoir (Toronto, 1939), by a former librarian at the University of Toronto; it includes a short discussion by E. F. Burton as well as the list of publications mentioned above. Obituaries are in publications of the Royal Societies of London and of Canada. See also Lewis Pyenson and Milan Singh, “Physics on the Periphery; A World Survey, 1920–1929,” in Scientometrics, 6 (1984), 279–306.

Lewis Pyenson

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McLennan, John Cunningham

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