6 5 6 



NATURE 



[August 28, 191, 



interest, makes a very unsuitable course of read- 

 ing for the student. But for those who are 

 seeking specially full information on any of the 

 subjects dealt with, this work will prove a very 

 useful aid. 



The introductory chapters deal very concisely 

 with interpolation formula;, the chief developments 

 in series, and the method of least squares (with- 

 out any account of the error-function). A long 

 chapter deals with the theory of the earth's 

 rotation. This part is rathe: hard reading, owing 

 to the great number of symbols introduced. It 

 would, we think, have been worth while to set 

 out the definition of each symbol on a separate 

 line, in order that it might be more readily re- 

 ferred to; for the reader can scarcely carry in 

 his head the meaning of all the symbols, and their 

 definitions are scattered through a great many 

 pages of the text. Another long chapter deals 

 with refraction, and includes a discussion of the 

 effect of water-vapour on the constant of refrac- 

 tion. The treatment of the great problems of 

 fundamental astronomy, the determination of the 

 equinox, the obliquity of the ecliptic, and the con- 

 struction of a fundamental catalogue is most 

 thorough and satisfactory. In the chapter on 

 parallax it may be noted that the correction to 

 the ellipticity of the earth is included as an un- 

 known in the determination of the moon's parallax ; 

 ibis small illustration shows the author's practical 

 acquaintance with his subject, for the two quan- 

 tities are so closely related that it is not improbable 

 that the best determination of the figure of the 

 earth may ultimately be obtained from lunar 

 observations. 



We would strongly criticise the absence of all 

 reference to the theory of photographic observa- 

 tions. Thus, whilst the effect of precession, 

 parallax, aberration, and refraction on micrometer 

 measures is fully discussed, the formula? relating 

 to their effect on photographic measures are 

 ignored. The theory of the projection of the 

 celestial sphere on a photographic plate is 

 eminently a branch of spherical astronomy, and 

 at the present day it is most constantly required 

 by practical astronomers, yet the text-books per- 

 sist in devoting their whole attention to the 

 obsolescent position angle and distance, instead 

 of to rectangular coordinates. Such an omission 

 is misleading to the student, and it is a defect in 

 a work of reference for the observatory. Much 

 of geometrical astronomy consists in a perfunctory 

 application of three formula? of spherical trigono- 

 metry ; but the theory of rectangular coordinates 

 is a more difficult subject, and the observer could 

 not generally work out for himself the necessary 

 formula? without guidance. A. S. E. 



NO. 228/, VOL. 91] 



RECENT BOTANICAL PUBLICATIONS. 

 (i) An Introduction to Plant Geography. By Dr. 

 M. E. Hardy. Pp. 192 + 66 figures. (Oxford: 

 Clarendon Press, 1913.) Price 2s. 6d. 



(2) The Living Plant: A Description and Inter- 

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 (London : Constable and Co., Ltd. ; Xew York : 

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(3) Flowerless Plants: How and Where they 

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(4) School and Home Gardens. By W. H. D. 

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(5) Agronomy : A Course in Practical Gardening 

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 296+ 195 figures. (Boston and London. Ginn 

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(6) Das botanische Praktikum. Fiinfte Auflage. 

 By the late Dr. E. Strasburger and Dr. M. 

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(7) Palaobotanisch.es Praktikum. By Prof. H. 

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(8) Die palaeobotanische Literatur. By W. J. 

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(9) lcones of the Plants of Formosa, and Materials 

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 the Collections of the Botanical Survey of the 

 Government of Formosa. By B. Hayata. 

 Fasc. ii. Pp. 156 + 40 plates. (Taihoku : 

 Bureau of Productive Industries, 1912.) 



(1) ' I ^HE compiler of this introduction to plant 

 _1_ geography appears to be somewhat 

 out of touch with the modern development of the 

 subject from the ecological point of view. The 

 work is apparently intended for school use, but 

 one would have thought that the best method of 

 approach would be to deal at some length with 

 the conditions of plant life in general, instead of 

 devoting to this subject only twenty pages towards 

 the end of the book as the author has done, and 

 to lay stress on the idea of plant communities 

 rather than to plunge, after a brief glance at a 

 few types of British vegetation, into the descrip- 

 tions of the "main vegetations of the globe," 

 which form the greater part of the book. How- 

 ever, these descriptions, though extremely con- 

 densed, are thoroughly readable and vivid, but 

 it is very doubtful whether the author's method of 



