RECENT ADVANCES IN SCIENCE 361 



analysis of proper motions. The discussion of the radial velo- 

 cities strongly confirms the existence of the third drift. It is 

 further shown that this drift holds a most prominent position 

 in the B-type stars, which show the ordinary star-streaming 

 but feebly, and that it is shown least clearly in the types F and 

 G. These stars are on the average the nearest, and this leads 

 Halm to conclude that the double-drift phenomenon is of a 

 local character, whilst stars at considerable distances from the 

 ' sun belong pre-eminently to the third drift. 



The following is a selection from recent papers : 



SxRuvE, H., Die neue Berliner Sternwarte in Babelsberg, Veroff. der Univer- 



sitdissternwarte zu Berlin-Babelsberg, 3, No. i, 1919. 

 Russell, H. N., On the Origin of Periodic Comets, Astron. Journ., 33, No. 



775, 1920. 

 Meyer, W. F., A Study of Certain Nebulae for Evidences of Polarisation 



Effects, Lick Obs. Bull., 10, No. 328, 1920. 

 LuDENDORFF, H., t)ber die Beziehungen der planetarischen Nebel zu den 



Helium-Sternen, Ast. Nach, 212, No. 5065, 1920. 

 Valier, M., Die Gestalt der Nebelflecke, insbesondere der Spiralnebel, Ast. 



Nach, 212, No. 5066, 1920. 

 Daniel, Z., and Schlesinger, F., Photographic Determinations of the 



Parallaxes of 46 Stars with the Thaw Refractor, Astton. Journ., 33, No. 



773, 1920. 

 Schlesinger, F., Photographic Determinations of the Parallaxes of 50 



Stars with the Thaw Refractor, Puh. Allegheny Obs., 4, No. i, 1920. 

 Van Maanen, A., The Photographic Determination of Stellar Parallaxes 



with the 60-inch Reflector (4th Series), Mt. Wilson Cont., No. 182, 



1920. 

 JosT, E., Stemparallaxen aus Beobachtungen am Repsoldschen Meridian- 



kreis, Astron. Beob. auf der Univ. -Sternwarte zu Kdnigsberg, 4, Abt. 43, 



1919. 



Harper, W. E., Measures of Radial Velocity of k Cassiop., g Persei, 69 

 Tauri, and e Cygni, Pub. Dom. Obs., Ottawa, 4, No. 21 ; Radial Velo- 

 cities of 30 Stars, ibid.. No. 22, 1920. 



SxEBBiNS, J., The Eclipsing Variable, X Tauri, Astroph. Journ., 51, 193, 

 1920; The Ellipsoidal Variable Star, n^ Orionis, ibid., 51, 218, 1920. 



Plaskett, H. H., The Origin of Spectra, J.R.A.S.C., 14, 221, 269, 1920. 



Burns, K., The Solar Spectrum in the Region 9,000-9,900 A., Lick Obs. Bull., 

 10, 327, 1920. 



Pease, F. G., Photographs of Nebulae with the 60-inch Reflector, 191 7-19, 

 Astroph. Journ., 51, 276, 1920. 



Seares, F. H., AND Hubble, E. P., The Colour of the Nebulous Stars, ^sffo^A. 

 Journ., 52, 8, 1920. 



Seares, F. H., The General Magnetic Field of the Sun, Observatory, 43, 310, 

 1920. 



MiCHELsoN, A. A., On the Application of Interference Methods to Astro- 

 nomical Measurements, Astroph. Journ., 51, 257, 1920. 



Anderson, J. A., Application of Michelson's Interferometer Method to the 

 Measurement of Close Double Stars, Astroph. Journ., 51, 263, 1920. 



Graff, K., Photometrische Durchmusterung der Pleiaden bis zu Sternen 

 14 Grosse, Astron. Abhand. der Hamburger Sternwarte, 2, No. 3; Beo- 

 bachtungen von Mars, Jupiter, und Saturn, ibid.. No. 4 ; Die Umriste und 

 Helligkeits verbal tnisse der Milchstrasse nordliche von 25° Stidliche 

 Deklination, ibid.. No. 5, 1920. 



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