272 



S. HIKAYAMA. 



as the equations of condition to determine X and Y; a, b, c, 



the computed longitudes of the spots from the assumed node being 

 known. Also by interpolating other values of ô' for previously 

 selected values of a' at equal intervals, we simplify the calculation 

 exceedingly. I have found the variations of latitude per 10 degrees 

 of longitude by simply dividing the variai ion of latitudes by the 

 difference of longitude. For example, for the solar spot No. 4-1, 

 which appeared in March 1882 (see page 282 of Publicationen des 

 Astrophysikalischen Observatorium zu Potsdam Nr. 17) we lind 



1 35 



150 

 163 

 178 

 192 

 20G 

 222 

 23(3 

 250 

 201 

 277 



90°— ô . 



-0.32 



— 0.40 

 -0.48 



-0.30 

 -0.39 

 -0.37 

 -0.37 

 -0.58 

 -0.75 



- 0.80 

 -0.93 



Variations ut' 90" — ô' per lu' of a'. 



— .j 



— 



+ 7 

 •> 



+ 1 







-15 



-11 



— 4 

 -M 



Thus — 0°.05, — 0.°06, are considered to be the variations 



of latitude between longitudes 110° and 150', 150° and 160", 



respectivelv. This method of approximation will be sufficient for the 

 majority of the observations. Having found the variations of latitude 

 per 10° of longitude, we then tabulate them in the following form. 



No. 

 44. 



.130° 140° 150° 100° 170° 180° 190° 200° 210° 220° 



6 



+ 7 +1 



+ 7 -2 



+i ; +i 



