MOUNT WILSON SOLAR OBSERVATORY. 199. 



(40) The large discrepancies between observers in the case of Hnes 

 of groups d and e appear to be attributable to the marked unsym- 

 nietrical broadening of these lines near the negative pole of the arc. 



(41) To eliminate the effect of this polar dissymmetry it is recom- 

 mended that the slit of the spectrograph be placed at right angles 

 to the axis of the arc at the middle point of the enlarged image. 



(42) The consistency of the various series of wave-length investi- 

 gations may be attributed to two constant factors, the complete 

 analyzing action of the plane grating and the uniform arc conditions. 



(43) The color index of the Algol variable RR Draconis increases 

 by 0.57 mag. as the star approaches minimum. 



(44) Since the eclipse is total, and the secondary star very faint, 

 this change in color measures the difference in spectral type of the two 

 components, indicating probable values of A 2 and F5. 



(45) Observations of the stars of the North Polar Sequence give 

 magnitudes between 10.5 and 15.5 which are in excellent agreement 

 with the Harvard Observatory results. 



(46) For the brighter stars there is a considerable divergence from 

 the Harvard scale. 



(47) During the year 199 plates have been obtained of a total of 

 460 required to determine the relative photographic magnitudes of 

 standard stars in the Kapteyn Selected Areas. 



(48) For the purposes of classification and the measurement of 

 radial velocity, 1,061 stellar spectrograms have been taken during 

 the year. 



(49) Radial velocity determinations are now completed for a total 

 of 372 constant velocity stars of various types. 



(50) The total number of spectroscopic binary stars hitherto dis- 

 covered at Mount Wilson is 99. 



(51) The absolute motions in space of 61 stars with measured 

 ]3arallaxes have been calculated from radial velocity determinations. 

 Twenty of these have absolute velocities ranging from 100 km. to 

 more than 300 km. per second. 



(52) A group of 9 stars, having a common radial velocity of —43 

 km. per second, has been found in the h and X Persei clusters. 



(53) Thirteen months after the discovery of Nova Geminorum Xo. 

 2, its spectrum still showed marked absorption lines. 



(54) The bright bands remain without change in width or dis- 

 placement, but the hydrogen band at X 4686 has fluctuated greatly 

 in intensity. 



(55) The companion of Rigel, though about seven magnitudes 

 fainter than the principal star, has an almost identical spectrum. 



(56) The spectra of 19 stars in the Hercules cluster M 13 range in 

 type from AO to GO. 



