MOUNT WILSON SOLAR OBSERVATORY. 



269 



are very rare among stars of these types. This result agrees with that 

 found by Kapteyn and Adams for the K stars. 



A question of special interest is that of the variation of radial velocity 

 with spectral type among the very distant stars represented in this list. 

 If only those stars which have a proper motion of less than 0T030 

 are selected we obtain the results given in table 3 for the average 

 radial velocities of the different types, corrected for the solar motion. 



Table 3. 



The last column of the table gives the average radial velocities with 

 approximate corrections applied for stream-motion in accordance with 

 the method due to Eddington. It is evident from these results that the 

 change of radial velocity with spectral type is a very gradual one for 

 these distant stars. 



A feature of the radial-velocity determinations in the case of the 

 stars with measured parallaxes is the large velocity of the stars of low 

 absolute brightness. The average radial velocity of 16 stars with 

 absolute magnitudes below 8 on a scale on which the sun is 5.5 is 36 km. 

 This may be compared with the value of 24 km. for 135 stars of large 

 proper motion and measured parallax. 



Among the other radial velocity results found during the year refer- 

 ence may be made to the following: 



(1) The discovery of 21 spectroscopic binaries. Six of these show 

 the presence of two spectra on the photographs. 



(2) Large radial velocities have been found for the following stars: 



Table 4. 



(3) Of 32 stars observed in the h and x Persei clusters 20 have been 

 found to have a common radial velocity of about — 40 km. Five other 



