THE SUN S MOTION IN SPACE. 



177 



According to Gylden's hypothesis a star with large proper 

 motion has also large parallax. Recalculating with the same 

 material by dividing one side of the fundamental equations, by 

 the parallax, instead of multiplying it into the other side, the 

 normal equations are changed, and the results then became : — 

 From Argelander's P.Ms. — 



R.A'. = 275-°3; R.A. = 288-°5, D. = +4K0, E = 10-6 

 From de Ball's P.Ms.— 



R.A'. = 281-°0; R.A. = 240-°4, D. = +1K9, E= 7-83 



The inconsistency of these results, which seem to indicate that 

 the proper motions cannot be explained on the hypothesis of 

 generally indiscriminate motion, suggested a further analysis, 

 having regard to the fact that several astronomers have suspected 

 a general drift of the stars in a direction parallel to the plane of 

 the Milky Way. A selection was made of 106 stars, whose 

 galactic latitude lay between the limits ± 30°, and whose yearly 

 component of proper motion in galactic latitude did not exceed 

 # "25. The suitable investigation of the solar motion from these 

 gave, 



R.A'. = 294-°5; R.A. = 275-°8, D. = +3K9, E = 9-79 



Rancken concluded that a more accurate and thorough investi- 

 gation of the question of general motion parallel to the plane of the 

 Milky Way was essential in reaching truer views concerning the 

 proper motions of the stars. 



(77) Plummer, 1883. — In Galloway's discussion of the direction 

 of the solar motion from southern stars, the assumption of the 

 point to be determined so affects the result that, whatever the data, 

 there can be derived only a relatively small correction. Owing 

 to this fact, and to the circumstance that more exact material had 

 become available through the publication of Stone's catalogue, 1 

 Plummer in 1883, 2 undertook the investigation from Galloway's 

 stars. The method of calculation was Airy's, the magnitudes 



1 The Cape Catalogue, 1880. 



2 Mem. Eoy. Astr. Soc, Vol. xlvii., pp. 327 - 352, 1883. 



L— Not. 7, 1900 



