4 SMITHSONIAN MISCELLANFX)US COLLECTIONS VOL. 89 



January 1933 is 0.0027 calorie, or 0.15 per cent. The probable error 

 of a monthly mean value of observation as given in Table i is about 

 o.io per cent. 



I now venture to give in detail a new forecast for two years of the 

 march of solar variation. It will be seen that it contemplates experi- 



FiG. 2. — Analysis of solar variation, 1924 to 1932, and forecast 1933 to 1934 

 inclusive. A, observation ; B, summation of seven periodic curves C, D, E, F, 

 (i, H, I of 68, 45, 25, 21, II, 8, and 6j months, respectively. 



cncing solar radiation generally below normal. The expected monthly 

 mean values are stated in Table 2. 



It is emphasized that the above is a long-range forecast of tJic varia- 

 tion of the sun, and emphatically not of the departures from nornuil 

 temperature in the iveather. The weather is much more complex, 

 owing to the circumstances of mountains, deserts, vegetation, oceans. 



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