NO. II BODY RADIATIOX ALDRICH 7 



as shown in Figures 4 and 5, using thickness of diaphragm as abscissae 

 and calorimeter temperature minus thermoelement as ordinates. 



Partly from experimental error and partly because of differences 

 in conductivity of the various diaphragms, the individual points in 

 Figures 4 and 5 do not all lie on the curves. Smooth curves are drawn 

 however with fair certainty. In each case the extrapolation to zero 

 thickness yields a zero value of the dift'erence calorimeter temperature 

 minus thermoelement temperature. This result is gratifying since it 

 indicates that the thermoelement device measures correctly the surface 



Date 

 i92g 

 Sept. 



22 



26 



28 



30 

 Oct. 2 



Sept. 30 



Oct. 2 



5 



2 



5 



^ This velocity was intended to be 280 ft. but through an error was found to be 100 ft. 

 per minute too great. In Figures 4 and 5, the calorimeter minus thermoelement temperature 

 was adjusted to an air velocity of 280 ft. per minute. 



temperature. It confirms satisfactorily the substantial accuracy of the 

 skin temperature measurements reported in my previous paper cited 

 above. 



The following conclusions also are drawn from the surface tem- 

 perature measurements summarized in Tables i and 2 : 



(i) With the Smithsonian thermoelectric device, the flexibility of 

 the surface measured is an important factor as the air motion in- 

 creases. On a soft, flexible surface the instrument appears to give 

 nearly correct temperatures for all air motions. On a stiff surface it 

 probably reads nearly correctly for zero air motion but increasingly 

 too low as air motion increases. 



(2) In appreciable air motions, the device shows large, irregular 

 drift, making readings difficult. 



