Classified List of Publications of the Carnegie Institution of Washington Volume 42 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ...a thermal gradient extending from the high temperature of the alcohol flame down to the temperature of the incoming water of the heat-absorbing system. In this case great heat is concentrated at one point, while the cooling area, i. e., the area of the absorbers, is quite extensive. In the case of experiments with man we have a body temperature, which on the surface is not far from 330, affecting a relatively large area, and a cooling area similar to that during the alcohol check experiments. In severe work experiments we have the body more or less exposed and the temperature of the absorbing system cooled nearly to zero. It is therefore difficult to see how the electrical resistance thermometers, distributed as shown in figure 33, can in any way assume accurately the average temperature of the air in the whole chamber. During rest experiments and alcohol check experiments the discrepancies are not so great as during work experiments with men, but it is clear that slight disturbances in either the heat-radiating surface or in the heat-absorbing surface will make considerable differences in the average temperature of the total volume of air. With alcohol check experiments this factor is practically a constant one, and while the electrical resistance thermometers may not represent the average temperature in the system, at the same time, owing to the constancy of the thermal gradient, they probably record accurately any differences in temperature, and it is these alone which affect the volume of air. In experiments with man the temperature factor could be eliminated were it possible to have the heat-radiating surface constant throughout the whole period. With variations in position, muscular activity, changes in clothing, bedding, etc., however, it is very dif...