INEQUALITY IN RAINFALL. 167 



Arts, 2nd ser. vol. 1. p. 153) what seems to be a very good 

 Table, exhibiting a set of yearly values of magnetic decli- 

 nation-range extending, with slight breaks, from 1777 to 

 1868. 



Let us take this Table and treat it precisely as we have 

 treated the rainfall, except that it does not seem necessary 

 to make any attempt at equalization such as that made in 

 article 8. 



We thus obtain the following result : — 



Proportional Declination-range Inequality, as exhibited by 

 series of years. 



■ [ 33 



Eight Nine Ten Eleven Twelve Thirteen Fourteen 

 years, years, years, years, years. years, years. 



Prague, or re 



ducecl to Pra- \- 3"37 3"39 10*07 4."66 9-33 4*09 4*98 

 g'le 



Here we have decided maxima corresponding to ten 

 and twelve years. The result is thus not unlike that 

 which has been derived from rainfall-observations, where 

 the maxima correspond to nine and twelve years ; indeed 

 we could hardly expect a more perfect correspondence 

 between the two, bearing in mind the limited amount of 

 observations which we have for determining inequalities of 

 long periods. 



Note added on March bth. 



I take this opportunity of saying a few words on what I 

 imagine to be the proper line of policy that should be 

 pursued in this research. 



(i) There are manifestly two stages in the investigation. 

 In the first place we wish to ascertain whether there is any 

 connexion between the state of the sun's surface (as 

 revealed by spots) and the meteorology of the earth ; and 



