136 



NATURE 



[September 22, 192 1 



dary." xMany examples supporting the above principle 

 have been obtained from meteorological observations, 

 and synthetically the universal existence of the above 

 proposition is assumed. It is suggested that the 

 present principle must be derived from ' the principle 

 of equality." — C. J. P. Cave: Some notes on 

 meteorology in war-time. 



Books Received. 



An Experiment in Synthetic Education. By Emily 

 C. Wilson. With Chart for Five Years' Work. 

 Pp. 62. (London : G. Allen and Unwin, Ltd.) 45. bd. 

 net. 



Twenty-five Years in East Africa. By Rev. J. 

 Roscoe. Pp. xvi+288+19 plates. (Cambridge: At 

 the University Press.) 255. net. 



Treatise on Fractures in General, Industrial, and 

 Military Practice. By Prof. J. B. Roberts and Dr. 

 J. A. Kelly. Second edition, revised. Pp. x+755. 

 (Philadelphia and London : J. B. Lippincott Co.) 

 425. net. 



Biological Chemistry. By Prof. H. E. Roaf. Pp. 

 xvi+2ib. (London: Methuen and Co., Ltd.) los. 6d. 

 net. 



The Fourth Dimension Simply Explained : A Col- 

 lection of Essays Selected from those Submitted in 

 the Scientific American's Prize Competition. By Dr. 

 H. P. Manning. Pp. 251. (London : Methuen and 

 Co., Ltd.) 7s. 6d. net. 



Geofysiske Publikationer, vol. i, No. i. The Posi- 

 tion in Space of the Aurora Polaris, from Observa- 

 tions made at the Haldde Observatory, 1913-14. By 

 L. Vegard and O. Krogness. Pp. vii+172 + plates. 

 (Kristiania : A. W. Br0ggers.) 



Annales de I'Observatoire astronomique de Tokyo. 

 Tome 5, 4 fascicule : Studies on Astronomical Time- 

 keepers and Time-preserving Systems. By Kiyofusa 

 Sotome. Pp. ii+59. (Tokyo : Imperial University.) 



New Zealand. Department of Mines : Geological 

 Survey Branch. Palaeontological Bulletin, No. 8 : 

 Lists of New Zealand Tertiary Mollusca from various 

 Localities Examined and Named from 1913 to the 

 End of 1917. Bv H. Suter. Pp. vii+107. (Welling- 

 ton.) 



Die Tagebijcher von Dr. Emin Pascha. Heraus- 

 gegeben von Dr. Franz Stuhlmann. Band VL, 

 Zoologische Aufzeichnungen Emin's und seine Briefe 

 an Dr. G. Hartlaub, bearbeitet von Prof. Dr. H. 

 Schubotz. Pp. viii+301. (Hamburg und Braun- 

 schweig : G. Westermann.) 200 marks. 



The Advancement of Science: 192 1. Addresses 

 Delivered at the 89th Annual Meeting of the British 

 Association for the Advancement of Science, Edin- 

 burgh, September, 1921. (London: J. Murray; The 

 British Association.) 6s. net. 



A Short Course in Commercial Arithmetic and 

 Accounts. By A. Risdon Palmer. (Bell's Mathe- 

 matical Series.) Pp. x+171 + xv. (London: G. Bell 

 and Sons, Ltd.) 25. 6d. 



The Use of Graphs in Commerce and Industrv. Bv 

 A. Risdon Palmer. (Handbooks of Commerce and 

 Finance). Pp. ix+47. (London : G. Bell and Sons, 

 Ltd.) 2s. net. 



Practical Mathematics. By A. Dakin. Part i. 

 Pp. viii+362+ i2 + xxiv. (London; G. Bell and Sons, 

 Ltd.) 55. 



Index Kewensis Plantarum Phanero^amarum. 

 Supplementum Quintum Nomina et Synonvma 

 Omnium Generum et Soecierum ab Initio Ann! 

 MDCCCCXI Usque ad Finern Anni MDCCCCXV 

 Nonnulla Etiam Antea Edita Complectens. Ductu 

 et Consilio D. Prain, Confecerunt Herbarii Horti 



NO. 2708, VOL. 108] 



Regii Botanici Kewensis Curatores. Pp. iii+277. 

 (Oxonii : E Prelo Clarendoniano.) 76^. net. 



Memoirs of the Geological Survey. Summary of 

 Progress of the Geological Survey of Great Britain 

 and the Museum of Practical Geology for 1920. Pp. 

 iv-rii2. (London: E. Stanford, Ltd.; Southampton: 

 Ordnance .Survey Office.) 35. 6d. net. 



Memoirs of the Geological Survey : Scotland. The 

 Economic Geology of the Central Coalfield of Scot- 

 land. Area IX., Carluke, Strathaven, and Lark- 

 hall, with Braidvvood, Netherburn, Auchenheath, 

 Blackwood, and Stonehouse. By L. W. Hinxman 

 and others. Pp. viii+ 148. (London : E. Stanford, 

 Ltd. ; Southampton : Ordnance Survey Office.) Ss. 

 net. 



The Continents of the South. By A. B. Archer. 

 (A Secondary School Course in Geography, Book II.) 

 Pp. xvi+272. (London : W. Heinemann.) 45. 6rf. 

 net. 



Soil Conditions and Plant Growth. By Dr. E. J. 

 Russell. (Rothamsted Monographs on Agricultural 

 Science.) 4th edition. Pp. xii+406. (London : 

 Longmans, Green and Co.) i6s. net. 



The Phvsical Properties of Colloidal Solutions. Bv 

 Prof. E. F. Burton. (Monographs on Physics.) 2nd 

 edition. Pp. viii+221. (London : Longmans, Green 

 and Co.) 125. 6d. net. 



The Transition Spiral and its Introduction to Rail- 

 way Curves : With Field Exercises in Construction 

 and Alignment. By Arthur L. Higgins. Pp. viii+ 

 III. (London: Constable and Co., Ltd.) 6s. net. 



Diary of Societies. 



WEDNESDAY, Septembeh 28. 

 Faradat Societt (at Institution of Electrical Engineers), at 4.30.— 

 General Discussion on Catalysis, with Special Reference to 

 Newer Theories of Chemical Action. Part 1, The Radiation 

 Theory of Chemical Action, opened by Prof. J. Perrin. Part 2, 

 Heterogeneous Reactions, opened by Prof. I. Langmuir. Ex- 

 pected speakers : — Prof. Arrhenius, Prof. V. Henri, Prof. E. C. C. 

 Baly. Prof. P. G. Donnan, Prof. W. C. McC. Lewis, Prof. A. 

 Lindemann, Prof. A. W. Porter, and Dr. E. K. Rideal. 



CONTENTS. PAGE 



Causes of Fluctuations in the Birth-rate 105 



Indian Land Mollusca. By Lt.-Col. H. H. 



Godwin-Austen, F.R. S 106 



Chemistry of Anthracene. By Dr. M. O. Forster, 



F.R.S 108 



The Future of Geometrical Optics. By L. N. G. F. 109 



Kite Balloons. By Dr. S. Brodetsky 11 1 



Our Bookshelf iii 



Letters to the Editor: — 



Communi.sm and Science. — Dr. J.-W. Mellor . . , 113 

 The Disaster to the Airship R38. — Dr. Wm. 



Leighton Jordan; The Writer of the Article 114 

 The British Association in Edinburgh. By 



C. G. K 115 



Science and Crop Production. [IViik Diaqrams.) 



By E. J. Russell, D.Sc, F.R.S 116 



Applied Geography. By D. G. Hogarth, M.A., 



D.Litt, C.M.G 120 



Stellar Parallax. By J. Jackson 124 



Obituary: — 



John Robert Pannell. By N. R. C 127 



Notes 127 



Our Astronomical Column : — 



September Meteors 131 



Ionization in Stellar Atmospheres 131 



Variable Stars ... . 131 



Spontaneous Combustion in Coal Mines 132 



Lighting of Factories and Workshops 132 



The World's Wheat Supply i33 



University and Educational Intelligence 134 



Calendar of Scientific Pioneers 134 



Societies and Academies 135 



Books Received 136 



Diary of Societies 136 



