NO. 6 BODY RADIATION ALDRICH 7 



for the large aperture and, 



= To* + 4.27V- xio"" 

 for the small aperture. 



The observations and computed temperatures are recorded in 

 table A. The part of the body exposed to the melikeron is shown in 

 the table by the position number. Interpretation of these numbers is 

 given in figure 7. 



As explained on page 8 of the paper on the melikeron, a check on 

 the ability of Melikeron No. i to absorb completely low temperature 

 radiation was made. The mean result of the test yielded a value for 

 the constant 



(T = 8.49X io~^^ 



Again in April, 1921, after returning from the Boston work. 

 Dr. Abbot made a similar test. The mean of 3 values gave 



o- = 8.58xio-" 



These values would tend to show that the constant 2.45 for Melikeron 

 No. I is perhaps a little too high. 



PRELIMINARY EXPERIMENTS IN STILL AIR 



In the preceding we have described experiments by Drs. Abbot 

 and Benedict in Boston in 1921. All the subsequent experiments de- 

 scribed in this report were performed by the writer at the Smith- 

 sonian Institution in Washington. The first series of experiments 

 was more or less preliminary in nature. They were carried out in the 

 large laboratory room of the Astrophysical Observatory under some- 

 what unsatisfactory conditions as regards the control of wall and 

 room temperatures. 



As in the Abbot-Benedict work, two instruments, one for the direct 

 measurement of radiation, and one for measurement of surface tem- 

 peratures were used. Melikeron No. 2 replaced No. i previously used, 

 but the same water circulating vestibule and " pin-cushion " shutter 

 were retained. On November 28, 1927, a test of Melikeron No. 2 

 was made, as had been done for No. i, by exposing to a black body 

 at a known low temperature. Five determinations gave the following 

 values for a 



8.ro X 10" 



8.23 



8.23 



8.42 



8.84 



Mean 8.36 X 10" 



