After attending secondary school in Montreal, he entered in 1889 McGill University, where he received in 1893 his bachelor's degree in physics and, after working there as a demonstrator in chemistry, an M.S.
In 1898, Ernest Rutherford succeeded to Callendar's professorial chair and supervised Barnes, among others.
In 1899 Barnes went to the U.K. on a scholarship from the Royal Society; he returned to McGill in 1900 as a lecturer in physics.
In 1907 he succeeded Ernest Rutherford as Macdonald Professor of Physician, but resigned his chair in 1919.
[3] Barnes worked with Callendar on extremely precise measurements in constant-flow calorimetry, in which a given amount of electrical energy is added to a given mass of flowing liquid whose consequent increase in temperature is precisely measured.