CLIMATE OF THE LAKE REGION. 



383 



our meteorological phenomena, the fact that the periods of greater 

 and less energy indicated by spots on its disk have a well-marked re- 

 lationship to the temperature and rainfall is not surprising. While 

 there are many fluctuations for which no solution is attempted, it 

 suffices if we are able to point out well-defined maxima and minima 

 periodical fluctuations which conform to each other within small limi- 

 tations. 



The proof does not rest alone upon the Detroit observations. 

 Though the rainfall at Milwaukee and Cleveland differs, often con- 

 siderably, in times and amount, from the Detroit record, we find a 

 close conformity in the periods. In fact, there is almost identity in 

 the periodic means of all the elements contained in the table. 



TABLE No. II. 



Maximum and Minimum Periods of Sun-Spots, Temperature, Rainfall, and 

 Water-Levels, 1834-1887. 



