6 SCIENCE PROGRESS 



trigonometrically, has entirely revolutionised our knowledge of 

 stellar distances. To realise the magnitude of the recent 

 advance in knowledge in this direction, it is only necessary to 

 recall that several years ago, the number of reliable parallaxes 

 was only about a couple of hundred. 



The following is a selection from recent papers : 



Sampson, R. A., Theory of the Four Great Satellites of Jupiter, Memoirs, 



R.A.S., 63, 1921. 

 Martinez, H. A., Determinacion de la orbita del planeta (796) Sarita, La 



Plata Obs. Pub., 6, i, 1920. 

 Hnatek, a., Spektrum und Bahnelemente von 5 Ononis, ^5/. Nach., 213, 



No. 5090, 1921. 

 Stebbins, J., A Photo-electric Study of Algol, Astroph. Journ., 53, 105, 1921. 

 Stratton, F. J. M., The Spectrum of Nova Geminorum II, Solar Physics Obs. 



Cambs., 4, i, 1920. 

 Brill, A., Die Helligkeitsschwankungen im Spektrum der Nova Geminorum 



II, Ast. Nach., 212, Nos. 5086-7, 1921. 

 Wright, W. H., On the Occurrence of the Enhanced Lines of Nitrogen in the 



Spectra of the Novae, M.N., R.A .S., 81, 181, 1921, The Displacements of 



the Hydrogen Absorption Lines in the Spectrum of Nova Geminorum in 



March 1912, with remarks upon their interpretation, ibid., SI, 191, 1921. 

 Shapley, H., Note on Changes in the Period and Light-curve of the Cluster 



Variable S.W. Andromedae, M.N., R.A.S., 81, 208, 1921. 

 Brackett, F. S., An Examination of the Infra-red Spectrum of the Sun, X 8900 



— 9900, Astroph. Journ., 53, 121, 1921. 

 Bernewitz, E., Ueber die Dichten der Doppelsterne, Ast. Nach., 213, No. 



5089, 1921. 

 Tapia, N., Medidas micrometricas de Estrellas dobles y vecinas. La Plata 



Obs. Pub., 6, ii, 192 1. 

 Henroteau, F., The Interstellar Clouds of Metallic Gases, J.R.A.S.C., 15, 



62, 1921, 

 Russell, H. N., Radiation Pressure and Celestial Motions, Astroph. Journ., 



53, I, 1921. Note on Sobral eclipse photographs, M.N., R.A.S., 81, 



154, 1921. 

 Plummer, H. C, On the Question of Stationary Radiants, M.N., R.A.S., 



81, 131, 1921. 

 Fotheringham, J. K,, a Solution of Ancient Eclipses of the Sun, M.N., R.A .S., 



81, 104, 1921. 

 Mitchell, S. A., Parallaxes of 260 Stars derived from Photographs, Leander 



McCormick Obs. Pub., 3, 1920. 

 Van Maanen, A., and Wolfe, Coral, On the Systematic Differences in 



Trigonometrically Determined Parallaxes, Mt. Wilson Conts., No. 189, 



1921. 



METEOROLOGY. By E. V. Newnham, B.Sc, Meteorological 0£&ce, 

 London. 



Investigations on Lightning Discharges and on the Electric 

 Field of Thunderstorms," by C. T. R. Wilson, F.R.S., Phil. 

 Trans., Series A, vol. 221, pp. 73-115. — This is an account of 

 experiments made at the Solar Physics Observatory at Cam- 

 bridge, mainly during the summer of 191 7. For details of 

 the apparatus used, in the designing of which much ingenuity 



