142 Economic Cycles: Their Law and Cause 



crops to the cycles of the rainfall of the critical seasons 

 was carried out in two ways, first for the crops taken 

 singly, and then for the crops taken all together. In the 

 inquiry relating to the separate crops, the equations to 

 the double cycle in the yield per acre and to the double 

 cycle in the rainfall of the corresponding critical seasons 

 were computed, and the graphs were drawn. When the 

 graphs of the cycles of the crops were superposed upon 

 the graphs of the cycles of rainfall of the respective 

 critical seasons, the two curves were found to present a 

 very remarkable congruence. In the inquiry relating 

 to the crops taken all together, an index number of the 

 yield per acre of the crops and an index number of the 

 mean effective rainfall of the critical seasons were con- 

 structed. The equations to the double cycle in both 

 indices were computed, their graphs were drawn and 

 then superposed. It was found that the characteristic 

 features of the rainfall curve were reproduced in the 

 curve of the index number of the yield per acre of the 

 crops. 



These results, referring both to the crops taken singly 

 and to the crops taken all together, are the answers to 

 the second part of our general question: The yield per 

 acre of the representative crops is closely connected 

 statistically with the rainfall of the respective critical 

 seasons, and the relation is so close that the cycles of 

 the yield per acre of the crops reproduce in char- 

 acteristic ways the cycles of the rainfall of the critical 

 seasons. The fundamental, persistent cause of the 

 cycles of crops is, therefore, the rhythmical movement 



