SOLAR VARIATION AND FORECASTING 

 By C G. abbot 



Inasmuch as there are probably still many persons both in Europe 

 and America who doubt the reality of the variation of the sun and, 

 much more, the possibility of applying it to the study of the weather, 

 it has seemed desirable to sum up some of the principal objections 

 which remain in the minds of such persons, to answer these objec- 

 tions, and after that to state some of the principal grounds of a belief 

 in the existence of solar variation. 



In order to treat the subject more definitely, I have ventured to 

 assume a personality to represent those who entertain these doubts 

 of the solar variability, and will, in what follows, speak of this per- 

 sonified doubter as " the critic." 



The Smithsonian Institution is publishing a group of three papers, 

 Nos. 5, 6, and 7 of Volume ']'] of the Smithsonian Miscellaneous 

 Collections, of which this, the first, deals with the objections to the 

 variability of the sun and the principal indications which lead us to 

 believe in it. There are a vast number of straws all of which point 

 in this direction and, combined, make up a very stiff bundle of evi- 

 dence, but in the limits of a paper of reasonable length, it is not 

 possible to include all of these minor indications, however interesting 

 they may be. 



The second paper, by Mr. H. H. Clayton, gives the major results 

 of his investigations of the past two years on the weather conditions 

 of North America in their relations to the variation of the sun. 



The third paper, by Mr. G. Hoxmark, to which I have ventured 

 to prefix a short introduction pointing out what seemed to me very 

 interesting features of his results, gives an account of the applications 

 of solar variation to the forecasting of the temperature and rainfall 

 of Buenos Aires, Argentina, for the years 1922, 1923, and 1924. 



This group of three papers have such a close connection that I 

 have brought them together in these short paragraphs of introduction. 



Although very kind expressions in regard to the accuracy of our 

 work on the solar constant of radiation come to us from all parts of 

 the world, that does not imply universal belief in solar variability. 



Smithsonian Miscellaneous Collections, Vol. 77, No. 5 



