DETERMINATION OF THE ELEMENTS OF THE SUN'S SPIN. 



28; 



Table II. gives, as final results, the total sums of the variations of 

 latitude per 10 degrees of longitude and the corresponding total 

 number in the year 1884. In like manner, similar sums were 

 obtained for each year from L861 to 1884. The results of the whole 

 are tabulated in Table III. 



In the last three rows of Table HI"., the results of 24 years are 

 given, the last row giving the mean value of the variation of latitudes 

 per 10 degrees of longitude. Supposing the weight of each column 

 to be proportional to the total number in the corresponding column, 

 multiply each of these mean values by its weight. Sum the whole. 

 and divide by the sum of the weights. There results a mean excess 

 of — 0°.00217, which would imply that on the whole there is an 

 average tendency toward the equator of nearly 8" in the time during 

 which the >uii rotates through 10 . But considering the approximate 

 character of the method of reduction and the probable effects of the 

 err» >rs of observations, we are. I think, justified in altogel her neglecl ing 

 this result. 



To annihilate this equal departure on either side of zero, I have 

 deducted this quantity 0°.002 from the mean values in each 

 column. 



Su thai we have finally the following; data to lind A and Y. 



0° 10° 20° 



30° 



K.i° 



50° 60° 70° 80° '.mi d 



Differences + 1.4+2.4+3.7 



Wci-ht 272 261 245 



+ 4.0 + L5+ 3.5 + :;.! + 4.6 

 238 23(i 223 208 201 



+ 2.8 

 190 



Differences 



Wei -lit. . 



90° luii 1 lu° I2'i u 130° I I"' 150 160° 170° 180° 



