THE SUN'S MOTION IN SPACE. 207 



R.A. = 277°5, D.= + 38-°0 

 and employing the proper motions of 72 stars of known parallaxes, 

 he obtained by one method, assigning different weights to the 



different stars 



V = 5-85 E. 



V denoting the velocity per annum, and E the mean radius of the 

 earth's orbit. Assuming that the result is influenced overmuch 

 by stars of large parallax, he made a second calculation, obtaining 



the result 



Y = 72 E. 



A third computation, in which three stars, giving very great 

 values for V, were excluded, reduced this however to 



V = 64 E, say 30 kilometres per second. 



Again taking the mean result of 22 bright stars it was found 



that 



V = 3 5 E= 16*5 kilometres per second ; 



which agrees with Kapteyn's conclusions from motions in the line 

 of sight. 



Sixteen stars whose annual motion exceeded 2 -"6, and Arcturus, 

 were used to determine the solar motion, giving 



R. A. = 276-°3, D = + 41 -3, R" = 3-"15 

 R" being the parallactic motion in terms of the mean distance of 

 the group. 



The second part of the paper is on "The most likely position 

 of the Solar Apex." Employing the method given in his Astro- 

 nomical Papers, Vol. viii., part i., Newcomb deduced the apex of 

 solar motion as follows : — 



Stars of small proper motion. 

 Mag. »£- Weight. R.A. D. R'" 



1-2-9 64 1 263-°l 31-°7 6-59 



30-3-9 



135 



2 



262-7 



26-8 



5-61 



4-0-4-9 



327 



5 



266-5 



31-8 



3-47 



5-0-5-9 



731 



11 



268-5 



32-0 



3-14 



6-0-6-9 



1034 



16 



277-4 



30-6 



2-81 



7-0 + 



236 



4 



278-2 



33-6 



2-86 



Total 2527 Mean 272-5 31-3 



