Generating Cycles of Products and Prices 



33 



When the index numbers of raw materials from 1882 

 to 1913 were scrutinized for the purpose of discovering 

 periodicities, it was found that the periodogram took 

 the shape of the bottom curve in Figure 7 showing that 



Eight-Year Cycles in Crops 



Ekjht-Year Cycles in Coal and Iron 



Eight -Year Cycles in Raw Materials 



Figure 10 

 Cycles in the yield of the crops, the production of coal and iron, and the produc- 

 tion of the raw materials of manufacture. 



Crops: y = 20.0 sin (io'l + 109°), origin at 1882; 

 Coal and Iron: y = 11.0 sin (45°< + 93°), origin at 1882; 

 Raw Materials: y = 30.3 sin (45°< + 103°), origin at 1882. 



if there is a cycle in the production of raw materials of 

 manufacture in the United States, its probable length is 

 about eight years. The computations referring to the 

 periodogram are given in Table III of the Appendix. 

 If the eight-year cycle in the production of the raw mate- 



