LOWELL. — TEMPERATURE OF MARS. G61 



under a cloudy one, about 1° F. or 4° C. Taking the average day 

 temperature from these data at 292°iVbs. on the centigrade scale or 

 19°C., and considering an average day sky and a clear night, we have 

 the transmission or loss 



i (.35 + .50)eoT A25e; 

 while for an average day and a cloudy night it is 



i (.35 + .20) e or .275 

 We form the following equation to determine e : 



292° - 10° _ A^y(l -.425e) 

 292°- 4°~^J/^(i_.275e) 



whence e = .47 



Since the radiation by day is greater by about 1.15 than by night 



292* 

 being as ^^„ 



we have more approximately 



^(.40 + .50)eoTA5e 

 for a clear night and average day and 



i(.40 4- .20) e or .30 e 

 for a cloudy night under the same conditions. 

 This gives, e = .4634, 



or substantially what it was before. It changes the final result for the 

 mean temperature of Mars by less than two tenths of a degree. 



Determination of ci. 



Since in the mean the planet radiates as much heat as it receives 

 and 



^ = 1.10 

 2/ 



