136 Economic Cycles: Their Law and Cause 



account for so general a movement. As the most 

 fundamental need of mankind is the need for food, it 

 seems probable that the observed rhythmical economic 

 changes may be produced by the physical cause through 

 its effect upon the food supply. If this be so, then, as 

 the fluctuations of the food supply are known to be 

 subject to the supposed caprices of the weather, it 

 seems not unlikely that the physical cause may be one 

 or more of the elemental forces that are summarized 

 under the term weather. The variation in the quantity 

 of the rainfall is one of the weather changes known to 

 have a marked effect upon the yield of the crops, and 

 if this fact is taken into consideration with the preceding 

 reasoning, we have a working theory as to the cause of 

 Economic Cycles: The changes in the weather repre- 

 sented by the changes in the quantity of rainfall cause 

 the changes in the yield per acre of the crops, and the 

 variations in the yield of the crops cause the economic 

 changes known as Economic Cycles. With this work- 

 ing theory in mind, we examined appropriate data with 

 reference to three things: (1) The periodicity of rain- 

 fall; (2) the effect of rainfall on the crops; (3) the rela- 

 tion of the yield of the crops to Economic Cycles. 



First, then, as to the periodicity of rainfall. The 

 problem as to whether the quantity of rainfall passes 

 through definite cycles involves two practical questions 

 that affect the utility and the validity of the results that 

 may be attained. These questions are, first, as to what 

 rainfall data shall be used in the investigation of possible 

 rainfall cycles; and, second, as to the method that shall 



