248 WORLD-POWER AND EVOLUTION 



difference between the extremes would appear to be a hundred per 

 cent greater in one case than in the other. Since the changes in the 

 normal during the period from 1870 to 1910 amount to 50 per cent 

 even in the case of general prices and to several hundred per cent in 

 most cases, it is evident that the elimination of the secular trend adds 

 greatly to the accuracy of our judgment as to the importance and 

 character of successive cyclical fluctuations^ and that is its sole purpose. 



