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POPULAR SCIENCE MONTHLY 



coincidence in the past. Xo attempt can be made to answer the ques- 

 tion as yet, but it opens a most fascinating field of speculation and of 

 investigation. If the activities of the earth and of the sun are related 

 to one another in any such manner as is suggested above, the study of 

 the one will add vastly to our knowledge of the other. An examination 

 of solar changes, on the one hand, may enable us to foretell something 

 of what is about to occur upon the earth. A careful reading of the 

 geological history of the earth, on the other hand, may disclose the 

 history of the sun for millions of years past, and may shed light upon 

 the fascinating problem of the thermal history and ultimate destiny 

 of the body which, as knowledge increases, appears more and more to 

 be the arbiter of terrestrial life. 



Reference Table showing the Data used in the Construction of 



Figures 2-17 



(1) Year of maximum sunspots. 



(2) Year after maximum. 



(3) Three and one half years of 



decreasing spottedness. 



(4) Year before minimum. 



(5) Year of minimum sunspots. 



(6) Year after minimum. 



(7) One and one half years of 



increasing spottedness. 



(8) Year before maximum. 



