In tliese formulfe 



w = the class-interval, 

 7^'(,t) = the number of observations belonging to a class with a class-number .53. 



Only in this way is it possible to compare different distributions directly. 



X 



-3 -2 -1 +1 +2 +?, +4 



Fig. 2. The Distribution of the Motions in Longitude compared with a normal Distribution. 

 1886-1909: N, and Ä, . 



In Table XIII I have given the characteristics of the motions in longitude, both 

 hemispheres as well as both periods being taken together. 



C. The Rotation Period of the Sun, computed from the Longitude 

 Motions of the Spots. 



The longitude motions of the spots are given in reference to a system of 

 co-ordinates the sidereal rotation period of which is 25.38 days. This rotation period 

 we shall in the following designate by t^. The angular velocity is thus 35'. 461 

 per hour. Between and the following relation exists: 



