CHAPTER VI. 



The Distribution of Spots on the Sun's Surface. 

 A The Distribution of Spots in the two Hemispheres. 



To the question of the distribution of the sun-spots in the two hemispheres I shall 

 here only devote a few remarks, as the manner in which the material of observation 

 is catalogued is not suitable for a closer investigation. 



In discussing the motions of the spots, the material of observation withiu 

 different latitude-zones was divided according to the logarithm of the spot-area 

 (log A = co), chiefly because the distribution according to this variable, proved to be 

 almost normal, as also appears from table XXXII, where the characteristics of 

 this distribution are stated. The mean value (wj of the logarithms is evidently 

 nothing but the logarithm of the geometrical naean. The quantities , Vg and 

 designate, as before, the second, third and fourth moments about the mean w^. An 

 expression of the arithmetical mean (A^) of the spot-areas may approximately be 

 deduced in the following manner. Since 



Ai= 10'"' (•*=], 2. 3 ... n) 



we may write 



(54) Ai - e'"' 



where 



'"loge 



From (54) it follows that 



àa = 1 P ' 



n 



Designating the deviation of the logarithms from the mean co^ by 3, we obtain 



