Generating Cycles of Products and Prices 25 



AOO. 

 300 



200 



^ 100. 



200 

 150 . 



100 



so 



CROPS 



Coal and iron 



Raw Materims 



2 4 6 6 



THE LENQtH Of THE CYCLE IN YEARS 



Figure 7 

 Periodograms of crops, coal and iron, and raw materials of manufacture. 



periodogram shows that if there is a periodicity be- 

 tween three and twelve years in the data, its most 

 probable length is in the neighborhood of eight years. 

 When the probable cycle of eight years is computed, 

 its maxima are found to occur, approximately, at 1882, 

 1890, 1898, 1906, 1914. The graph of the eight-year 



