184 CARNEGIE INSTITUTION OF WASHINGTON. 



gen and the enhanced lines, have necessitated changes in reduction 

 methods, which have led to values of their absolute magnitudes some- 

 what brighter than those obtained before these peculiarities were 

 discovered. 



Professor Kapteyn has continued his researches on the parallaxes 

 and motions of the brighter galactic helium stars and has added 

 individual parallaxes and motions for practically all the known helium 

 stars within galactic longitudes 150° and 216° and latitudes +30° 

 and —30°. The proper motions of these stars are very small; but, 

 through the fortunate circumstance that their peculiar motions are 

 also exceptionally small, a solution of the problem has been possible. 

 Most of the helium stars in the vicinity of the Orion nebula appear 

 to form a local group whose parallax is 0T0054. Those outside this 

 group are somewhat less distant, their mean parallax being 0''0081. 

 The investigation affords a valuable mass of material for the study of 

 luminosity curves, which can now be extended to stars of fainter 

 intrinsic luminosity than has hitherto been possible. 



The rapid accumulation of data on radial velocities and absolute 

 magnitudes has made possible a new determination of the solar and 

 stream motions. The discussion of the stream-motion is based upon 

 stars of types F, G, and K, separated into three groups according to 

 distance. The average radial velocity for different directions leads 

 to a mean velocity surface which reveals at once the direction of 

 greatest radial mobility. The vertices thus found agree closely with 

 those derived from proper motions. Certain peculiarities in the form 

 of the surface suggest that the stars studied are mainly moving around 

 the center of the galactic system with a preferential motion in the 

 galactic plane. 



Attention has previously been called to the peculiar behavior of 

 the lines of calcium in the spectroscopic binary Boss 46, which yield 

 radial velocities differing widely from those derived from other lines 

 in the spectrum. A continuation of the observations has shown that 

 the velocities from both sources are variable and have the same period. 

 The range for the lines of hydrogen and helium is exceptionally large, 

 amounting to nearly 450 km., while that for the calcium lines is about 

 20 km. The difficulties of interpretation are increased by the fact 

 that the motion of the system as derived from the two sets of lines 

 differs by about 20 km. 



The early detection of Nova Aquilse No. 3 at Mount Wilson on 

 June 8 was fortunate, as it permitted an extensive series of spec- 

 troscopic observations to be begun at an early stage in the star's 

 outburst. Of the many interesting phenomena since recorded in the 

 rapidly changing spectrum of this object, the appearance of numerous 

 narrow enhanced absorption lines on June 10, persisting until June 

 15, is perhaps the most remarkable. Although the radial velocity of 



