The rate of increase of the entropy of a simple viscous fluid, capable of conducting heat, is investigated in greater detail than has hitherto been customary. It is shown that, if Kelvin's hypothesis concerning the absolute temperature be adopted, and the usual law of viscosity be assumed, the requirements of the second law are satisfied.

• Received 19 April 1940

DOI:https://doi.org/10.1103/PhysRev.58.267