SUNSPOT MINIMA AND VOLCANIC ERUPTIONS. 51 



Professor Piazzi Smith noticed a remarkable eleven year 

 period in the temperature curve for Carlton Hill. 



German scientists of distinction, such as Prof. Foerster 

 of Berlin, and Rudolph Mewes, believe that the rainfall is 

 excessive in years of sunspot maximum and deficient at 

 minima, owing to more heat being received from the sun 

 at sunspot maxima. 



Lockyer says, — " It is generally conceded that the spots 

 on the sun are the result of greater activity in the circula- 

 tion of the solar atmosphere, and therefore indicate greater 

 heat, and consequently, also greater light production." In 

 the same writer's interesting paper in " Monthly Notices" 

 of Royal Astron. Soc, Dec. 1901, we find a reproduction 

 of curves constructed by Mr. Bruckner, which show a 

 similar variation extending over a period of thirty-five 

 years, in climatic, magnetic and sunspot conditions. There 

 seems to be some law at work which retards the sunspot 

 maximum in relation to the approaching minimum, result- 

 ing in similar conditions and similar curves every thirty- 

 fifth year. 



The close connection between solar and terrestrial pheno- 

 mena was summarised as follows by W. Ellis in Phil. Trans. 

 1880 : — (1) The diurnal ranges of the magnetic elements of 

 declination and horizontal force are subject to a periodical 

 variation, the duration of which is equal to that of the 

 eleven year sunspot period. 



(2) Epochs of maximum and minimum sunspot effect are 

 nearly coincident with periods of maximum and minimum 

 magnetic effect, and the variations in the duration of the 

 different periods is nearly the same. 



(3) Occasional outbreaks of violent sunspot and magnetic 

 energy often several months in duration, occur nearly 



