DEPARTMENT OF MERIDIAN ASTROMETRY. 177 



3. Combining all the material, the apex of solar motion is placed 

 at A = 270°, D=+30°, and its resultant velocity is nearly 24 kilo- 

 meters. 



4. There is a distinct difference between the velocity figures of 

 "dwarf" and "giant" stars both as to variation and the relative length 

 of the axes. The velocity figure of the "dwarf" stars is fairly repre- 

 sentative of preferential motion as previously determined; that of 

 the "giant" stars is a clover-leaf figure produced by the Solar Group, 

 one wing of the "dwarf" figure, and a group of high-velocity stars 

 whose motions are directed along the galactic equator from 180° to 

 360° galactic longitude. 



5. The orientation of the velocity figure is independent of spectral 

 type but dependent upon "giant" and "dwarf" classification. The 

 axes of the velocity figure are dependent upon both type and "giant" 

 and "dwarf" classification. 



A further study of the real motions of the stars is partly completed, 

 based upon all available material. The sources of radial velocities and 

 proper-motions are mainly those which formed the basis of the first 

 study. The parallaxes were derived by application of the corrections 

 resulting from the investigation of systematic error of parallaxes 

 already alluded to. In general, the conclusions arrived at in the first 

 discussion of real stellar motions were verified. In addition there 

 appears to be a tendency of motion on the part of a small group toward 

 the region O'' to 2"' of right-ascension and 0° to +20° of declination. 

 Another feature of interest is the distribution of apices according to 

 velocity. The apices of stars whose true space velocity is over 75 kilo- 

 meters per second lie almost wholly along the Galaxy. They are defi- 

 nitely confined within the region 140° to 340° galactic longitude, and 

 contain a mixture of "dwarf" and "giant" stars. There are no apices 

 for stars of large velocity between longitudes 340° and 140°. On the 

 other hand, the distribution of the apices of stars of small velocity 

 (less than 15 kilometers per second) is quite irregular. Several more 

 or less definite features appear, however. In the first place, the con- 

 ditions of distribution of the apices of high-velocity stars along the 

 Galaxy are practically reversed; secondly, the grouping of apices in 

 the region O'' to 3*" right-ascension and 0° to +20° of declination is 

 marked; and thirdly, there is an indication of the secondary plane of 

 distribution mentioned in Year Book No. 16, 1917. 



The distribution of the apices of the A and B type stars is quite 

 irregular from 0^ to 12*^ of right-ascension. Beyond that meridian 

 there is a fairly compact clustering of apices in the neighborhood of 

 the Solar Group. One dense cluster of seven A-type stars lying between 

 285° and 295° of right-ascension and 0° and — 10° of declination has 

 the appearance of a star-stream. The mean space velocity of the 

 stream is 30 kilometers per second and the extreme deviation from 



