The results of experiments designed to determine the threshold values for various thermal stimuli have been reported. The threshold increments in the intensity of radiation in ‘still’ air were determined first for several areas of exposure. In further experiments the effects of simultaneous changes in both the speed and temperature of the air, and the air speed and radiation intensity, were examined.
The data from these experiments were then used to estimate the relation between the temperature and speed of the air on the rate of heat loss by convection. The findings were shown to be in good accord with previously published data.