Letter from Louis Vessot King, McGill University, Macdonald Physics Building, Montreal, to Sir Joseph Larmor, St John's College, Cambridge He thanks Larmor for his criticisms of the paper 'On the disturbed motion of fluids', helpful in working out the rationale of his experiments. He discusses at length further developments which have resulted from that, beginning with a brief history of his work on the Boussinesq problem and historical sources. His solution of the problem for a boundary condition at constant temperature was not backed by orthodox analysis and therefore he delayed publication. He describes some published works of others, including Lord Rayleigh, and King describes experiments with platinum wires. He discusses 'curious velocity distributions in the flow of air through a two dimensional channel', his interpretation of experiments, and his inability to account for some aspects of these. 16 August 1915