| Abstract: | Summary Clothed men at rest were exposed to two conditioning  indoor environments (British, coolmoist; American, warm dry) for 45 minutes, and then to a cold environment (36°F) at moderate and high relative humidity (50% and 85%). The following measurements were taken: Temperature—skin, rectum and clothing gradients; nude body weight change and metabolism; subjective data. An attempt was made to measure clothing humidity gradients. The results showed that warm conditioning kept the clothing and skin at a higher temperature for a matter of 1 1/2 hours or more during cold exposure. The physiological value of such conditioning may be less marked under field conditions. No physiological objective or subjective differences of practical importance were found between the effects of still air at 36°F at moderate or high humidity, except for the finding of a slightly warmer skin of the chest at the high humidity. These results agree fairly well with those of other workers for nude men.From the date obtained there is no clear evidence that sorption heat of wool is an important factor in keeping the body warm at resting conditions. Under field conditions, sorption heat might be of still less value. There is no basis for the supposition that moist air is either a better thermal conductor or a more efficient heat convector than dry air. The physiological difference between dry cold and damp cold is not due to properties of humid air, but to the associated weather or climatic differences (solar radiation, cloud cover, wind, barometric pressure, etc.) and, to some extent, to the mode of living indoors. Data from physical models and from physiological experiments in climatic chambers cannot be directly transposed into the realities of weather and climate out of doors.With statistical design and analysis by J. Draper |
