iiS 



SM rr 1 1 so N 1 A N M ISCELLA N EOUS COLLECTIONS 



VOL. 66 



As in former years a principal object of these investigations was 

 to detect and measure changes in the amount of solar heat. Results 

 of the now fully reduced work of 191^^ and 1(^14 show that in 1913 

 (a time of extremely low solar activity as indicated by the numbers 

 of sun-spots, facuke, etc.), the sun's outi>ut of radiation was nearly 



l'"i(,. 141. ( )l)SiTvinf; station of .\strt)i)liysical ( )l).scivati)iy ^>n 

 Mount Wilson witli now tower telescope. Photograph by Abbot. 



three per cent below normal, and that with the return of activity in 

 i()i4, the output of radiation rose to al)out one per cent above 

 normal. The work of 1915, not yet fully reduced, seems to indicate 

 tliat hi.nh values will be found to prevail in this year also. 



I'ductuations of solar radiation from da_\' to day, while noted, appear 

 to ha\'e been less marked in i«ji4 than in earlier years. 



