20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Unlike the first series of experiments on lo subjects (see table B), 

 this second series was carried out in midsummer. Fortunately the 

 room was equipped with refrigerating pipes so that the room tem- 

 peratures were kept fairly normal and comfortable. These pipes were 

 entirely outside of the curtained room where experiments were made. 



Attention is called to the summaries of table E data contained in 

 tables H, J and K. Table H divides the air velocities into four groups 

 and shows how, with the room and wall temperatures remaining 

 nearly constant, the calories of radiation loss progressively decrease 

 as the air motion mcreases. Table J gives for each subject, in calories 

 per sq. m. of body surface, the basal meiabolism and the loss of heat 

 by radiation ; also the ratios between these two cjuantities. These 

 ratios are also arranged according to increasing room temperatures. 

 A marked decrease in the ratio occurs with increasing room (and 

 with it the wall) temperatures. Table K is a summary showing the 

 changes in skin and clothing temperatures with varying air velocities, 

 dividing the changes into three groups, namely, temperature changes 

 on the side of the subject toward the fan, perpendicular to it, and 

 away from it. A drop in temperature occurs in all three groups, with 

 the greatest drop on the side toward the fan. In the other two groups 

 the drop is only about one half as great. On the side towards the fan 

 the clothing temperature drop is about one third greater than the skin 

 temperature drop. 



GENERAL DISCUSSION 



We have presented the results of three series of experiments on the 

 radiation loss of human subjects, and a fourth series on the radiation 

 loss from specially prepared calorimeters. The first series gave the 

 results of Drs. Abbot and Benedict on the radiation and skin tempera- 

 tures of a nude subject when the room temperature was held at 15° 

 and again when it was held at 26°. It is interesting to note the change 

 in radiation loss in these two different cases. On March 31, when the 

 room temperature was 15°, the thermoelement skin temperature 

 (mean of 87 values, many of which are not included in table A) was 

 27^2, and on April i, when the room temperature was 26°o (mean of 

 40 values), was 30°8. The black body temperatures, computed from 

 the melikeron values and the Stefan formula, were March 31 (mean 

 of 20 values) 28'^2, and on April i (mean of 12 values) 33°4. 

 Dr. Benedict estimated the wall temperature on April i to be 26°, and 

 it is probable that on Alarch 31 the wall temperature was at least as 

 low as 15°. (Outside temperature was 8°6.) Assuming these wall 



