The Motion and Distribution of the Sun-spots 



17 



As there is given a complete description of the measures of the photographs in 

 every volume of the G r e e nw i c h 0 b s e r v a t i o n s, 1 need not enter into any discussion 

 of these measures. The results of the measures are published in two different ways. 

 As I shall in the following only employ the »Ledgers» where the the measures are 

 given in a more condensed form, I will here confine myself to giving a description 

 of these. In table VI I give an extract from the »Ledgers». According to the 

 description given in the Gr een wich Observations »theftst column gives for each 

 day on which the group was observed, the Greenwich civil time at which each 

 photograph was taken, expressed by the day of the month (civil reckoning) and 

 the decimals of a day reckoning from Greenwich midnight. The second and tJiird 

 columns give the sums for each day of the projected areas of all the umbrte and 

 whole sj)ots comprised in the group, the projected area being the area as it is 



TABLE VI. 



Extract from the Ledgers of Groups of Sun-spots. Group 1833. 



Date 

 Greenwich 

 Civil Time 



Projected Area of 



Area fo 





Mean 

 ot Group. 



Mean 

 Latitude 

 of Group. 



Longitude 



Umbra 



Whole 

 Spot 



Umbra 



Whole 

 Spot 



Central 

 Meridian 



1886 

 Jan. 30.2C3 

 31.231 

 Febr. 1.480 

 2.289 

 3.280 

 4.567 

 5.148 

 G.479 

 7.239 

 8.459 

 il. 449 

 10.150 

 11.151 



0 

 20 

 32 

 (37 

 81 

 45 

 39 

 30 

 15 

 22 

 9 

 0 

 0 



110 

 159 

 254 

 403 

 403 

 419 

 360 

 201 

 172 

 101 

 51 

 10 



0 

 21 

 23 

 41 

 44 

 24 

 23 

 16 



9 

 IG 

 10 



0 



0 



196 

 167 

 182 

 246 

 219 

 213 

 209 

 109 

 102 

 78 

 (58 

 13 

 18 



loe'-.s 



lOGo.l 

 106".! 

 107°.l 

 107°.4 

 108».4 

 109».4 

 108».3 

 1070.5 

 109".7 

 IIS^.S 

 106", 2 

 104».5 



— 14''.7 



— 140.8 



— 150.0 



— 150.6 



— 150.0 



— I504 



— 150.3 



— 140.6 



— 15".l 



— 140 9 



— 130.5 



— 150.0 



— 140.9 



— 740.7 



— 620.0 



— 450.6 



— 340.0 



— 20°.6 



— 207 

 + 60.0 

 + 220.4 

 + 310.7 



+ 490.8 

 + 670.0 

 + 680.5 

 + 8O0.0 



Means 







17 



140 



1()7°.75 



— 140.91 





measured upon the photograph, uncorrected for foreshortening, and expressed in 

 millionths of the sun's apparent disk. The fourth and fifth columns give the sums 

 for each day of the areas of all the umbrœ and whole spots comprised in the group, 

 corrected for foreshortening, and expressed in millionths of the sun's visible hemi- 

 sphere. The sixth and seventh columns give the mean longitude and latitude of 

 the group, found by multiplying the longitude and latitude of each separately 

 measured component of the group by its area, and dividing tlie sum of the pro- 

 ducts by the sum of the areas. The last column gives the mean longitude of the 

 group from the central meridian, and is found by subtracting the longitude of the 

 centre of the disk from the meau longitude of the group. At the foot of these 

 daily results for each group are given the mean areas of umbrœ and whole spots 

 and the mean longitude and latitude for the period of observation.» 



Lunds üniver&itets Årsskrift. N. F. Afd. 2. Bd 10. 3 



