Mathematician and physicist best known for discovering radiation pressure exerted by light in 1903. He is the author of both Survey of Modern Physics and Elementary Modern Physics.
He taught math and science at Hamilton Collegiate Institute in Ontario.
He conducted the experiment with Ernest Fox Nichols, the invention is known as the Nichols radiometer.
He married Wilhelmine Brandt on September 5, 1911.
He was a contemporary of fellow mathematician and physicist Max Born.