246 CARNEGIE INSTITUTION OF WASHINGTON. 



(1) The velocities of 135 stars whose motions are constant have been 

 determined from measm-ements of 3 or more spectrograms. 



(2) The orbits of 5 spectroscopic binaries have been calculated by Mr. 

 Sanford and are ready for publication; of these, 3 show double spectra 

 and thus make it possible to determine the elements of both com- 

 ponents. The bright component of the double star OS 82 is a spectro- 

 scopic binaiy and is found to belong to the Taurus stream. An inter- 

 esting binary is Lalande 29330, which belongs to the dwarf K class. 

 The period of 4.3 days is short for stars of this type and the velocity of 

 the center of mass is large, amounting to —60 km. Several new 

 binaries have been discovered, among the most interesting of which are 

 the two long-period Algol variables SX Cassiopeise and TT Ophiuchi. 

 The blue companion of a Herculis has also been found to be a binary. 



(3) The determination by Mr. Merrill from the bright lines of the 

 radial velocities of 46 stars having spectra of type Md, in addition to 

 those previously known, gives a total of about 90 values for stars of 

 this spectral type. 



(4) A tabulation of the results for 83 of these stars with the best 

 known velocities shows that when the solar motion is eliminated 5 

 have values exceeding 100 km. 



(5) The algebraic mean of the velocities for all the Md stars is — 23 

 km. This may be explained as due either to some physical cause which 

 shifts the bright lines toward the violet with reference to the lines which 

 give the true radial velocity, or to a general group-motion of these stars 

 toward the south. If the measurements of the bright lines represent 

 the true radial velocities of these stars, their average motion is the gi eat- 

 est of any class of stars and of about the same magnitude as that of the 

 planetary nebulae. 



(6) The average systematic difference between the values given by 

 the bright and dark lines in these stars is about 20 km. 



(7) Spectrograms of 22 stars of type R have been taken bj^ Mr. 

 Sanford with the 100-inch reflector and measurements have been made 

 for radial velocity. Two stars, B.D.+20°5071 and B.D.+23°123, 

 prove to have remarkably high velocities. 



Spectroscopic Determinations of Luminosity and Parallax. 



The completion during the year of the reduction tables used for the 

 determination of absolute magnitudes from the intensities of spec- 

 tral lines led the observers to the conclusion that the most reliable 

 value of the mean absolute magnitude of a group of stars, except in the 

 case of the most distant objects, is given by the trigonometric parallaxes 

 rather than the parallactic or peculiar motions. Accordingly, the 

 method adopted for computation of the mean absolute magnitudes has 

 been to use approximate values of the magnitudes based on provisional 

 reduction curves, and to determine the value of the factor by which it 



