§34 SCIENCE PROGRESS 



winter with the same objectives. Although the weather 

 prospects are not too favourable it is greatly to be hoped that 

 one at least of the expeditions will meet with success. In the 

 present state of the theory, the importance of this further test 

 cannot be over-estimated. 



The following is a selection of the more important papers 

 which have appeared : 



Crum, W. L., The Perturbations caused by a Close Approach 

 of Two Asteroids, Ast. Journ, 31, No. 742, 191 8. 



Hirayama, K., A Possible Explanation of the Gaps in the 

 Distribution of the Mean Motions in Asteroids, Proc. Math. 

 Phys. Soc. Tokyo, 9, 264, 191 8; Groups of Asteroids probably 

 of Common Origin, ibid. 9, 354, 191 8. 



Stromgren, E., and Foschen, J., Uber eine Klasse einfach 

 periodischen retrograden Bahnen um die beiden endlichen 

 Massen im probleme restreint, Ast. Nach. 207, No. 4968, 191 8. 



Puiseux, P., and Jekhowsky, B., Sur les inegalites syst6- 

 matiques du contour apparent de la Lune, Bull. Astr. 35, 161, 

 1918. 



Harper, W. E., The Orbits of the Spectroscopic Components 

 of Boss 5173, Journ. R.A.S.C. 12, 392, 1918; The Orbit of the 

 Spectroscopic Binary 19 Lyncis, ibid. 12, 395> l 9 l %'> The Orbit 

 of the Spectroscopic Binary h Draconis, ibid. 12, 446, 191 8. 



Lunt, J., a Centauri as a Spectroscopic Binary, Astroph. 

 Journ. 48, 182, 191 8. 



Seares, F. H., and Shapley, H., The Variation in Light 

 and Colour of RS. Bootis, Astroph. Journ. 48, 214, 191 8. 



Plummer, H. C, On the Distribution of the Stars, M.N., 

 R.A.S. 78, 668, 191 8. 



Shinto, S., and Watanabe, Y., On the Rotation of Celestial 

 Bodies, Mems. Coll. Sci. Kyoto Impl. Univ. 3, No. 7, 191 8. 



Hirayama, S., On the Mean Distances of Stars of Different 

 Spectral Types, Proc. Math. Phys. Soc. Tokyo, 9, 361, 191 8. 



Lindblad, B., Die photographisch effektive Wellenlange als 

 farbenaquivalente der Sterne, Ark. for Mat. Ast. och Fysik. 

 13, No. 26, 191 8. 



Eddington, A. S., On the Conditions in the Interior of a 

 Star, Astroph. Journ. 48, 205, 191 8. 



Mention must also be made of the following important 

 Yolumes recently published : 



