38 O. A. Åkesson 



First Feriod (1886—1897): 



(23) V — 36'.443 + O'. 240 sin ß — 5'. 804 sin^ß . 

 Second Feriod (1898—1909): 



(24) V = 36'. 22:? — O'.un sin ß — 5'. 390 sin^ß . 



In these equations V is expressed in minutes of arc per hour. Expressing the 

 angular velocities in degrees per mean solar day, we obtain the following equations. 



First period: 



(25) V = U".577 + 0".096 sin ß — 2«.322 sin-ß . 

 Second period: 



(26) V = ]4«.489 — 00.076 sin ß — 2".l66 sin^ß . 



These two curves are represented in tig. 3. In this tigure, the velocities obtained 

 from the observations are in the first period indicated by small circles and in the 



+ 10° +15° +20» +25° +30° +35« 



3. The angular Velocity of the Sun at different Latitudes. 

 ■ First Period (1886—1907). Second Period (1898—1909). 



second by crosses. As shown in the figure the curves (25) and (26) express the 

 variation of the angular velocity with the latitude in a satisfactory way. 



During both these periods the zone of greatest angular velocity does not 

 coincide with the equator. By derivating the expressions for V the latitude o£ 

 the greatest angular velocity is obtained. We get 



