Robert Summerhayes was born in England and migrated to Canada in his youth. He worked for the Notman photography studio between 1869 and 1880. In 1881, he opened his own studio in partnership with Alfred Walford. A decade later, Walford seemed to have left the partnership, and Summerhayes continued the business alone until 1894.

Sullivan was a Professor of mathematics at McGill University from 1908 to 1946. He became Emeritus Professor of Mathematics in 1947.