92 



O. A Åkesson 



sting at least for six consecutive days. As seen from table XXXTX the spots on the 

 western half of the sun give a shorter rotation-period than those on the eastern, and 

 in this fact we possibly have the explanation of the positive skewness. Such a skew- 

 ness might arise if a greater number of spots were observed on the eastern than 

 on the western half, which we know to be the case. 



Since, however, the mean errors of the skewnesses of Hiratama's curves are 

 of about the same size as the skewnesses themselves, we can, however, scarcely 

 attach any great importance to the assumption of two drifts in the motion of the 

 sun-spots. 



