Eight-Year Cycle in Relation to Physical Cause 111 



crops, the cause of which is connected with the cause of 

 the eleven-year cycle of the sunspots. In a subsequent 

 essay he published this confession : ^ 



"In 1875 I made a laborious reduction of the data 

 contained in Professor Thorold Rogers' admirable 

 History of Agriculture and Prices in England from the 

 Year 1259. I then believed that I had discovered the 

 solar period in the prices of corn and various agricul- 

 tural commodities, and accordingly read a paper to 

 that effect at the British Association at Bristol. Sub- 

 sequent inquiry, however, seemed to show that periods 

 of three, five, seven, nine, or even thirteen years would 

 agree with Professor Rogers' data just as well as a 

 period of eleven years; in disgust at this result I with- 

 drew the paper from further publication." 



Influence of the New Physics 



In the seventies of the last century the researches of 

 Sir William Crookes on the discharge of electricity 

 through gases initiated a course of inquiry which has 

 led to results that dominate both contemporary phys- 

 ics and contemporary astronomy. By improving de- 

 vices for exhausting the contents of discharge tubes he 

 was able to obtain much nearer approaches to vacua 

 than had previously been possible and he was conse- 

 quently able to conduct, under much more favorable 

 circumstances, experiments on the effects of electrical 

 discharges in rarefied media. 



In Figure 27 there is an outline sketch of the simplest 

 type of discharge tube. Platinum wires to conduct 



1 Investigations in Currency and Finance, p. 225. 



