196 SCIENCE PROGRESS 



with a note on Ptolemy's false Equinox, M.N., R.A.S., 78, 

 406, 191 8. 



Gravitational Astronomy. — Wilkens, A., Uber die Integra- 

 tion der Differentialgleichungen der Koordinatenstorungen 

 der Planeten der Jupitergruppe, Ast. Nach. No. 4937, 191 8. 



Heinrich, A., Uber die singularen Punkte gewissen Un- 

 gleichheiten im Asteroidischen Problem, Ast. Nach. No. 4930, 

 1918. 



Sundman, K. F., Sur les conditions necessaires et suffi- 

 santes pour la convergence du developpement de la fonction 

 perturbatrice dans le mouvement plan, Ofversigt af Finsk. 

 Vetensk. Soc. Forhand, 58, No. 24, 1916. 



The Solar System. — The Sun. — Adams, W. S., Some Stellar 

 Investigations at the Mount Wilson Observatory, Journ. des 

 Observateurs, 2, No. 6, 191 8. 



Veronnet, A., La Constitution physique du Soleil. Son 

 Evolution et la notre, Rev. gen. des Sciences, 29° An. 359, 191 8. 



Perrine, C. D., The Nature of the Sun's Corona, Observa- 

 tory, 41, 253, 191 8. 



Clayton, H. H., The Effect of Short-period Variations 

 of Solar Radiation on the Earth's Atmosphere, Smithsonian 

 Miscell. Collections, 68, No. 3, 191 8. 



The Earth. — Schuster, F., Die yahrliche und die monat- 

 liche Haufigkeit der Erdbeben, Ast. Nach. No. 4942, 191 8. 



Ditto. Latitude Variation. — Courvoisier, L., Zur Frage 

 der tagliche Polhohenschwankung und des z Gleides, Ast. Nach. 

 No. 4945, 191 8. 



Dyson, F. W., The Variation of Latitude, M.N., R.A.S., 

 78, 452, 191 8. 



Turner, H. H., The Movements of the Earth's Pole : Note 

 on Sir F. W. Dyson's Analysis., M.N., R.A.S., 78, 462, 191 8. 



Dyson, from a new analysis of previous observations, finds 

 a value for the mean free period of 432 days, a slight increase 

 on Chandler's period. Turner finds discontinuities in the 

 period, giving two periods of 421 and 443 days which fit in 

 with his theory of alternating weather cycles. 



A report of a discussion on " The Movements of the Earth's 

 Pole " held under the auspices of the British Association 

 Geophysical Committee is given in the Observatory, 41, 246, 

 1918. 



