110 Generating Economic Cycles 



spots to the crops through variations of the weather. 

 He assumed that the variation in the number of the 

 sunspots was probably accompanied with a varia- 

 tion in the amount of heat received upon the Earth 

 which would be manifested in a quickened or blighted 

 vegetation. Indeed, he made the first attempt, as far 

 as I am aware, to establish a relation between changes 

 in the number of sunspots and changes in the price of 

 wheat. Necessarily his pioneer undertaking could be 

 only suggestive because of the lack of data, but since 

 Schwabe's time there has been unremitting effort to 

 show correlation between the sunspots and changes 

 in the terrestrial weather.^ 



W. S. Jevons, as every economist knows, attempted 

 to work out the Herschel theory of the synchronism 

 of sunspots and the yield of the crops. His heroic 

 honesty in confessing his failure in his study of Euro- 

 pean data is not so commonly known. Assuming that 

 the true length of the cycle in trade was eleven years — 

 the true length of the principal sunspot cycle at the 

 time of the publication of Jevons' essay had been shown 

 to be approximately eleven years — Jevons arranged 

 the prices of English crops during the 13th and 14th 

 centuries in series of eleven years, and without making 

 any statement as to whether the cycles of sunspots 

 were congruent with the cycles of the crops, he advanced 

 the theory of an eleven year cycle in the prices of farm 



of Light and Heat; with Remarks on the Use that may possibly be 

 drawn from solar Observations." Philosophical Transactions of the 

 Royal Society of London, 1801, pp. 265 to 318. Particularly pp. 313-318. 

 1 For a vast amount of data, see The Computer's Handbook, published 

 by the English Meteorological Office, 1919. 



