Summary and Conclusions 143 



in the conditions of the weather represented by the 

 cycles"in the amount of rainfall. 



In the cautious use of the preceding generalizations, 

 one will bear in mind that only four crops have been 

 investigated, and that, in ascertaining the critical 

 seasons, the monthly rainfall has been used. The 

 critical seaons could undoubtedly be determined more 

 accurately if the figures for the weekly rainfall were 

 employed. Furthermore, the inquiry has been limited 

 to the relation of the yield of the crops to rainfall, 

 whereas a more adequate study would include at least 

 the effects of temperature. 



Thus far the investigation has established the law 

 and cause of the cycles of the crops: The cause of the 

 cycles in the physical productivity of the crops is the 

 cyclical variation of the weather represented by the 

 cycles of rainfall, and the law of the cycles of rainfall is 

 the law of the cycles of the crops. In order to bring 

 these physical results into relation with the rhythmical 

 movements of prices and values, we had first to show 

 how the prices of the several crops vary with then* 

 respective supplies. In technical terms, we had to 

 discover the laws of demand for the individual crops. 



The equations to the law of demand for corn, hay, 

 oats, and potatoes were computed, and the graphs were 

 drawn. The degree of precision with which these 

 demand curves might be used as formulae for predicting 

 prices was ascertained, and the coefficients of the 

 elasticity of demand for the representative commodities 



