358 SCIENCE PROGRESS 



slender, his results were substantially accurate and have been 

 supported by more recent investigations. It will be remem- 

 bered that Kapteyn's determination of the galactic condensa- 

 tion, upon which much doubt was thrown, has recently been 

 proved to be accurate. Dr. Schouten's results still further 

 increase our confidence in it. 



The Real Motions of the Stars. — An analysis of the real motions 

 of the stars has been given by B. Boss in the Astronomical 

 Journal, 31, No. 736, 191 8, based upon 219 stars contained 

 in the list of Adams and Joy, whose radial velocities and 

 parallaxes are known and whose proper-motions are given in 

 Boss's P.G.C. For these stars, therefore, the complete elements 

 of their motions are known. It is found that there is evidence 

 of a definite solar group of stars which is moving in the direction 

 A=27o°*3, D=+ i5°*7> at the rate of 22*7 cm. per sec, and 

 that this group is composed mainly of giant stars. It is further 

 shown that the solar motion derived from the giant stars alone 

 is in sufficiently close agreement with that derived from the 

 dwarf stars alone to support the conclusion that they all belong 

 to the same system. 



From all stars together the position for the solar apex of 

 269°-r-30 is deduced, and for the solar velocity +23*8 km., 

 results in agreement with the mean of the results derived from 

 determinations based respectively upon radial velocity and 

 proper motion determinations. 



Since the parallaxes of the stars are known, it is possible 

 to separate the giant from the dwarf stars. When the velocity 

 figures for the two classes are drawn, it is found that they differ 

 considerably, a marked effect in the case of the giant stars 

 being produced by the solar group. On the other hand, the 

 orientation of the velocity figure is found to be independent 

 of spectral type. The axes of the velocity figure are, however, 

 dependent upon both type and the giant and dwarf classification. 



It is suggested that these results explain why different 

 results have been obtained by various investigators for the 

 pole of preference in the cases of large and small proper- 

 motions and of early and 4ate types. The large proper-motions 

 and late type stars which have been used have been mainly 

 dwarfs, the small proper-motions and early type stars mainly 

 giants. 



