The Motion and Distribution of the Sun-spots 



51 



Hence it follows that the fact of the dispersion 

 varying with the spot-area cannot be assumed to 

 be the cause of the positive excess. 



In an investigation into the position of the 

 sun's axis mentioned in the introduction, Dyson 

 and Maunder have tabulated the distribution of 

 Ihe latitude motions of 867 recurrent spots from 

 1874—1911, which distribution has a certain bearing 

 upon Ihe question of the positive excess now under 

 discussion. We borrow from this paper table 

 XXIV containing tlie distribution of the latitude 

 motions. Calculating the characteristics of this 

 distribution we find, on an average, a northern motion 

 even of these recurrent spots. The skewness as well 

 as the excess are on the contrary = 0. The distri- 

 bution is thus quite normal. — Here it will not be 

 out of place to make a remark. In the i)aper men- 

 tioned the authors give a graphical representation 

 of the distribution in question (Fig. 5). Here the 

 scale of the ordinate as well as of the abscissa 

 is arbitrarily chosen, so that from the figure we 

 do not get any idea as to whether the distribu- 

 tion is normal or not. It would be still more 

 advantageous if a system of normal co-ordini 

 were employed in similar representations. 

 As suggested by Charlier (see page 1) 

 one might appropriately employ the disper- 

 sion as the unit of the abscissa. In order 

 that the frequency curve may not be too 

 flat the function of distribution is mul- 

 tiplied by 5, whereby the maximum ordi- 

 nate amounts to about 2 (= 1.994a). 



If we make use of these normal co- 

 ordinates, the distribution will liave the 

 appearance sliown in fig. 6. Here the 

 curve represents the normal distribution. 

 As it appears from this figure the observed 

 frequencies are very nearly in agreement 

 with the normal distribution, which is also 

 evident from the fact of the skewness as 

 well as the excess being equal to zero. 



TABLE XXIV. 

 Proper Motion in Latitude of 

 Recurrent Spot Groups. 



(,1874-1911. Dyson and iMaundek.) 



Proper Motioi 





N:o of 



in a Kotatioi 





Ob.servation.s 



From +5.5 to - 



h 5.0 



1 



+ 5.0 



-4.5 



1 



+ 4.5 



-4.0 



2 



+ 4.0 



-3.5 



3 



+ 3.5 - 



-3.0 



7 



+ 3.0 





27 



+ 2.5 - 





48 



+ 2 0 



- 1.5 



51 



-hLö - 



Lo 



90 



+ 1.0 



-0.5 



110 



+ 0.5 



0.0 



113 



0.0 



-0,5 



125 



-0.5 



-1.0 



85 



- 1.0 



-1.5 



81 



- 1.5 



-2.0 



51 



- 2.0 





33 



-2.5 



- 3.0 



26 



— ;i.o 



-3.5 



9 



— 3.5 



-4.0 



2 



- 4.0 



- 4.5 



2 



Mean 



= + 00.082 



Dispersion 



= + I'^.m 



Skewness = + 0.003 

 Excess = — 0.009 



Î page 12. 



Fig. 5 

 (The Figure 



Proper Motion in Latitude of Recurrent 

 Spot Groups, 

 ä taken from the Paper of DYSON and Maunder) 



