Preface xi 



in which it appears in the Mecanique Celeste; it passed 

 to the stage of tested, working theory after tidal ob- 

 servations upon a vast scale had been collected, sub- 

 mitted to analysis, and the results found to be in 

 agreement with the tidal theory; the method of research 

 was statistical, and the mathematical instrument was 

 the hannonic analysis; the course of progress in tidal 

 forecasting was to isolate the primary cycles and then 

 to approximate more accurate measurements by com- 

 bining primary changes with minor disturbances; the 

 primary cycles were shown to be the effects of cosmical 

 causes, and these causes were not discredited when 

 their effects were not immediately discernible over 

 one-half of the Earth; the phases of lag and lead and 

 the complication of cosmical causes with general ter- 

 restrial and local causes were found to give an increas- 

 ingly accurate account of the observed phenomena. 



These features in the theory and history of tides will 

 probably be found to have their counterparts in the 

 theory and history of economic cycles. Will the theory 

 of the cosmical origin of generating cycles, like Kepler's 

 theory of the cosmical origin of terrestrial tides, incur 

 the scorn of eminent critics and receive an adequate 

 development only after two hundred years? 



