Air temperature alone is not an adequate indication of environmental warmth. Wind, sunshine and humidity are also important. The notion that all these factors might be combined into a single figure indicating warmth is attractive. In this 1972 monograph, the problem of constructing such an index of heat stress is examined from a theoretical point of view. The approach involves a step-by-step examination of the physical principles which govern heat exchange at the skin surface. Mathematical terms are carefully defined and the physical concepts explained and illustrated. A great deal of...