108 Generating Economic Cycles 



made no attempt to establish the existence of other 

 cycles than the one of a supposed ten-year period. 



(4) The cause of the cycle. The discoverer of the 

 sunspot cycle did not advance a theory as to the cause 

 of the cycle. For this statement we have the authority 

 of the President of the Astronomical Society: 



"Schwabe has not entered into speculation as to the 

 nature and origin of sunspots." 



(5) The method of measuring the length of the cycle. 

 Schwabe was not embarrassed with three of the most 

 difficult problems in the mathematical theory of cycles : 

 the problem of distinguishing between real and spurious 

 cycles ; the problem of separating compound cycles into 

 their constituent elements ; and the problem of measur- 

 ing the exact length of a cycle. 



Nevertheless "the outcome of Schwabe's work was 

 the first step in the whole series of discoveries which 

 have gradually built up the modern science of Solar 

 Physics." 1 



The first momentous consequence of Schwabe's 

 discovery was the perception of an entirely new form 

 of action by the Sun upon the Earth. Until Schwabe's 

 time all theories of solar action proceeded upon the 

 assumption that the Sun could affect the Earth in 

 only three ways — through gravitation, through heat, 

 or through light. But with the estabhshment of the 

 cychcal variation of sunspots and with the accumula- 

 tion of observations bearing upon the variations of the 

 magnetic needle, it was a natural step to compare these 

 two forms of oscillation. In 1852 Sir Edward Sabine 



1 H. H. Turner, Astronomical Discovery, p. 157, also p. 176. 



