106 Economic Cycles: Their Law and Cause 



series of figures that we shall use there are three distinct 

 movements which need to be discriminated, and when 

 any two of the series are compared, another important 

 characteristic of the series requires to be taken into 

 account. The three movements that are combined in 

 each series are: 



(a) The continuous fall or rise of the figures with the 



flow of time. This movement will be referred 

 to as the secular trend of the figures ; 



(b) The rhythmical fluctuation of the figures about 



their secular trend. When this movement 

 superposed upon the secular trend is the ob- 

 ject of investigation, the combined movement 

 will be referred to as the general cyclical 

 movement of the figures. When the rhyth- 

 mical movement unaffected by the complicat- 

 ing trend is being considered, it will be referred 

 to simply as the cycles of the figures; 



(c) The year to year temporary fluctuation about 



the general cyclical movement. These fluctua- 

 tions will be referred to as the deviations of 

 the figures. 

 When the cycles of any two series are compared, it will 

 frequently happen, particularly if the one series is the 

 cause of the other, that there is a considerable interval 

 between the corresponding parts of the cycles in the 

 two series. This interval will be referred to as the lag 

 of the second series. 



We shall be interested throughout the rest of this 

 chapter primarily in the interrelations of cycles of 



