The Mechanism of Cycles 113 



ing yield of crops. It is obviously inadmissible to 

 assume that in a dynamic society there is one law of 

 demand for all commodities. The dogma of the uni- 

 formity of the law of demand is an idol of the static 

 state. 



If there are differences in types of demand curves, 

 it is quite likely that as one type has been illustrated by 

 the crops, another type will be exemplified by pure 

 producers' goods. We shall accordingly investigate 

 the demand curve of pig-iron, our representative pro- 

 ducers' good. 



In Table V of the Appendix to this chapter is con- 

 tained the material for the computation of the law of 

 demand for pig-iron. The annual percentage changes 

 in the production of pig-iron were computed from the 

 figures of annual production, which were taken from 

 the Statistical Abstract for 1912, p. 774. It was impos- 

 sible to obtain directly the mean prices for which the 

 annual production was sold, and consequently the per- 

 centage change in the mean price could not be com- 

 puted directly. The device that was utilized to ap- 

 proximate these percentage changes is illustrated in 

 Table V of the Appendix. As the data needed for the 

 solution of the problem were the annual percentage 

 changes in the mean price and not the actual mean 

 annual prices themselves, it was regarded as sufficient 

 for our purpose to substitute for the unobtainable an- 

 nual percentage changes in the mean price, the mean 

 annual percentage changes in the prices of representa- 

 tive kinds of pig-iron. The annual prices for the lead- 



