NO. 6 BODY RADIATION ALDRICH 5 



lated. The diaphragms helped to prevent convection currents from 

 reaching the honeycomb and also limited the radiation received to a 

 known solid angle. A water circulating shutter completed the mount- 

 ing. The side of the shutter exposed to the melikeron consisted of a 

 large number of projecting metallic points and resembled a "pin- 

 cushion." This made the shutter as well as the melikeron an approxi- 

 mately " black body " by virtue of its form. The vestibule and shut- 

 ter are shown in cross-section in figure i. 



The melikeron and mounting were securely clamped to the round 

 of a chair back. Observations were made upon the nude subject 

 standing or sitting before the instrument so that the skin was about 

 15 mm. from the shutter. Direct skin temperature measurements 

 were made at the same positions and as nearly as possible at the same 

 time by Dr. Benedict, using his rubber-backed thermoelement device 

 described in his paper. " The temperature of the human skin " (Asher- 

 Spiro's Ergebnisse der Physiologic. Supplement-Band, 1925). 



To abstract from Dr. Abbot's notes — 



Suppose the temperature of the " pin-cushion " shutter is 

 To = 273-Ffo- Its radiation is o-ro* = 8.20X IQ-^^X (2734-/0)* in small 

 calories per sq. cm. per minute (Stefan-Boltzmann formula, see 

 Smithsonian Physical Tables, p. 247). This applies to radiation to a 

 whole hemisphere. The jacket surrounding the melikeron limits the 

 radiation to a circular opening 3.66 cm. in diameter and 7.03 cm. 

 from the absorbing surface of the melikeron. It is necessary to deter- 

 mine what part of the total radiation from a whole hemisphere enters 

 through this opening. See figure 9. 



Let O be the center of the absorbing surface of the melikeron, and 

 AB the opening in the jacket. Then the area of the opening AB 

 will be 



(27rp sin 0)pd6 



and the radiation received on the horizontal surface at O will be pro- 

 portional to 



iTTp sin OpdB cos 6 



[6 



= 27rp- sin 6 cos Odd = vp- sm" 



For the whole hemisphere this becomes -n-p- 



The part of the total radiation entering" the vestibule is the ratio 



irp'^ sin^ .0/1 

 — e — =:sm- 6 



