The Motion and Distribution of the Sun-spots 



39 



for the first period: ß = PH\ 

 » » second » : ß = — 1"!'. 



The determination of these values is, however, not sufficiently accurate for us 

 to conclude tliat the zone of the greatest angular velocity might be removable on 

 the surface of the sun. If, however, we compute the values of V from (25) and 

 (26) and form the differences between the first and second period, we obtain the 

 values given in table XV. As is seen from this table, the angular velocity of the 

 northern hemisphere seems to have decreased from the first to the second period, 

 while the angular velocity of the southern 

 hemisphere has remained almost unchanged. 

 From fig. 3 or table XIV it follows that we 

 arrive at the same result in using the observed 

 angular velocities. That this circumstance can 

 hardly be accidental appears from the fact that 

 the differences between the angular velocities 

 of tlie northern hemispheres during the two 

 periods are generally greater than the mean 

 errors of F, as is seen from table XI. 



In connection with this it may be in- 

 teresting to mention that the Maundp:rs in the 

 paper cited above have found that » there 

 seems to be an apparent slight shortening of 

 the period for the northern hemisphere, whilst 

 the southern is unchanged ». 



Now the investigation of the Maunders 

 comprises the years 1879 — 1901. The Maun- 

 ders' second period thus coincides with what 1 

 call the first period. Thus the two investiga- 

 tions com])rise about three periods. Desig- 

 nating the angular velocity of a certain zone of the northern hemisphere during 

 these three periods by F^, V., and V.^ respectiveby, we can comprehend tiiese results 

 in the inequaUty 



Fj < F, > F3 . 



This inequahty seems to indicate a periodical variation in the angular velocity of 

 the northern hemisphere. For the soutliern hemisphere, however, no similar inequality 

 seems to exist. 



Should such a periodical variation in the angular velocity of the sun actually 

 exist, which, of course, cannot hitherto be considered proved, Wilczynski's ' explana- 

 tion of the periodicity of the spot-activity would possibly get a firmer basis. 



> R. .T. WiLCZYNSKi: On the Causes of the Sun-spot Period. Astrophysical Journal. Vol. VII. 1898. 



TABLE XV. 

 Computed angular Velocities at 

 different Latitudes. 



Latitude- 



First 

 Peiiod 



Second 

 Period 



Difi. 





13.959 



la.826 



+0!l33 



N, 



14.120 



13.994 



+0.132 



Nr. 





14.144 



+0.130 



^4 



14 396 



14.271 



+0.125 





14.489 



14.372 



+0.117 



N, 



14.551 



14.442 



+0.109 





14.577 



14.482 



+0.095 





li.-m 



14.488 



+0.081 





14.525 



14.4G2 



+0.063 



Ss 



14.447 



14.404 



+0.043 





14.3:i3 



14.317 



+0.021 





14.200 



14.202 



— 0.002 





14.038 



1 4.0(54 



—0.026 



s, 



13.8.-.5 



13 908 



— 0.053 



