l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 'J'] 



periods of solar change which we have discovered. It will be seen 

 that not only the long enduring downward march, but the temporary 

 recoveries of solar radiation are often duplicated in the results of 

 Montezuma and Harqua Hala. 



60i 



59. 



5. 



14 



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Oes 



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 NutVIBE.Rt 



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SON or Observed 



OMPUTEiL 

 OF DE-PAinUBES OF 



OoLAR 



Fron/l 



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 56 



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'• r, 2. ^ 3. 4. ^ 5^. ^ 6. 



/Yat/o or Departures to Probable Error. 



Fig. 10. — Theory of probability indicates possible solar variations of 



short period. 



Figure 5 gives lo-day mean values of solar radiation from 1918 

 to 1924. This indicates that the low period of solar radiation still 

 continues, although recently with a rising tendency. 



