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As a result of the work of Kapteyn, Campbell, and Boss it has been recognized for some years that the linear motions of the brighter stars vary with their spectral types, the velocities of the solar type stars being higher than those of types B and A. It is equally well-known, however, that the solar type stars in general have larger proper motions and so are much nearer to the sun than those of earlier types. Hence the stars, for which the velocities have been compared, have quite different distances, and if, as was once suggested by Eddington,1 the nearer stars move more rapidly than the distant ones this fact would account, in part at least, for the apparent variation of velocity with spectral type. In the course of an analysis of the radial velocity results from the Lick Observatory and Mount Wilson, J. C. Kapteyn derived the relationship between radial velocity and proper motion for the K type stars,2 and found that the velocity increased rapidly with the amount of proper motion. In this computation the effect of stream motion was eliminated to a large extent by a selection of stars nearly 90° from the vertices of the streams. The Mount Wilson observations of the spectra of stars having both small and large proper motions provide the material for a similar comparison for other types of spectra. This is given in Table I: the effect of stream motion, however, has not been eliminated. The average velocity v' is corrected for a solar motion of 20 km. directed toward the apex a =17 h 59m. 5= +30°.8

The Radial Velocities of the More Distant Stars