32 Generating Economic Cycles 



the equation to the eight-year cycle is computed, the 

 maxima are found to occur approximately at 1882, 

 1890, 1898, 1906, 1914. And if the eight-year cycle in 

 the production of coal and iron is graphed and com- 

 pared with the graph of the eight-year cycle in the yield 

 of the crops, the coal and iron curve is found to lag 

 about three-tenths of a year behind the curve for the 

 crop yield. The graphs are given at the top of Figure 10. 



Cycles in the Production of the Raw Materials of 

 Manufacture 



The production of the farms and the mines taken 

 separately tends to run in eight-year cycles, the cycles of 

 the raw materials from the mines inclining to lag a few 

 months behind the cycles in the yield of the crops. The 

 farms and the mines together supphed, in 1900, 95 per 

 cent of the raw materials of American factories, and, 

 consequently, their joint production affords both an 

 adequate measure of the changes in the volume of raw 

 materials and a valuable index of the changes in the 

 physical volume of trade. Is there any regularity in the 

 joint production of the farms and the mines? 



In the same manner in which we constructed an index 

 nimiber of the yield of the crops and an index number 

 of the production of coal and iron, we made an index 

 nxmiber of the raw materials of manufacture. The per- 

 centage deviations of the jdeld of the crops and the 

 percentage deviations of the production of coal and iron 

 were summed, and the aggregate percentage deviations 

 were regarded as the index numbers of the production of 

 raw materials. The data are given in Tables II and V 

 of the Appendix. 



