188 G. H. KNIBBS. 



R. denotes the motion as seen from the mean distance of the 

 group. It will be noticed that these results appear to confirm 

 the assumption that the P.M. is an index of a star's distance, 

 since the proportionality between it and the annual solar motion 

 is quite remarkable. 



(94) Vogel and Kempf, 1 '92. — The motion of a number of stars 

 in the line of sight had been determined by Yogel at the astro- 

 physical observatory at Potsdam, spectrographically. 1 Of these, 

 45 out of 51 observed had a probable error of not more than ±025 

 Ger. geog. miles. At the suggestion of Vogel, Kempf undertook 

 the investigation of the sun's motion. 2 In the first calculation it 

 was assumed that the influence of the proper motions of the stars 

 would disappear in the mean, and that the motions were indepen- 

 dent. This assumption gave the result 



R.A. = 206.°1, D. = + 459, V. = 2-5 German geog. miles 

 which it was alleged lay wholly outside the limit of previous 

 determinations. 



A second calculation in which different weights were assigned, 

 and the stars were grouped in certain instances gave 



R.A. = 159-7, D. = + 50°0, V. = 1 -75 German geog. miles 

 Finally accepting the values of earlier observations, viz., 

 R.A. 266 ,0 7, D. + 31 - o 3 a computation was made of the velocity 

 alone, giving V. = 1*66 German geog. miles. The provisional 

 character of the result, since it depends upon a few stars of 

 uncertain distance, is fully admitted. 



(95) Kapteyn, 1893 (Jan.) — In 1893 Kapteyn commenced the 

 publication of his researches on the distribution of the stars in 

 space, using the Draper catalogue, and taking account of their 



1 Publicationen des Astrophysik. Observ., Bd. vn., Theil 1, 1892. 



2 Versuch einer Ableitung der Bewegnng des Sonnen systems aus den 

 Potsdamer spectrographischen Beobachtungen. H. C. Vogel. — Astr. Nach. 

 Bd. cxxxn., p. 81, 1893. 



3 Best. d. Constant d. Praecess., etc.— Mem. de FAcad. St. Petersbourg 

 7me Ser., t. xxxv. 



