124 



NATURE 



[December 8, 1904 



more brightly in the centre than at the periphery. 

 This makes it possible for the leaf to orientate itself 

 in regard to light. ITius, suppose the plant to be 

 moved so that the light now strikes the leaf obliquely, 

 the bright patches of light on the inner cell walls will 

 no longer be central. This change may be believed to 

 constitute a stimulus calling forth a curvature of the 

 leaf stalk by which the leaf is brought again to its 

 normal position at right angles to the incident light. 

 Thus the leaf moves when the bright patch is not 

 central, and comes to rest when each of its epidermic 

 cells is centrally illuminated. This attractive theory 

 cannot be said to be as vet established, and botanists 

 will look with interest to its further development by 

 its author. The appendix of six pages is devoted to 

 the literature of the subject and to short discussions 

 of points which probably seemed too technical for the 

 text of the lecture. 

 Electricity in the Service of Man. By R. M. 



Walmsley. Pp. viii+1208. (London: Cassell and 



Co., Ltd., 1904.) Price 105. 6d. net. 

 When the first edition of this book was published in 

 1888, it was doubtless a comparatively easy matter to 

 WTite a treatise covering all the practical applications 

 of electricity to the service of man. As each successive 

 edition appeared the task must have become one of 

 increasing difficulty, and now that the fourth has been 

 reached Dr. Walmsley no longer finds it possible to 

 condense all his material into one volume. He has 

 therefore wisely confined himself to certain branches, 

 and left the others for treatment in a supplementary 

 volume. The book before us is divided into two parts, 

 the first being more or less theoretical, dealing with 

 the principles, and incidentally with the history, of 

 the subject, and the second dealing with the technology 

 of electricity. The first part is clearly written, and 

 forms a good introduction to the study of electricity 

 and magnetism which should be valuable to the 

 beginner or to the amateur interested in scientific 

 progress. The second part is confined in the present 

 volume to generators and motors, with a chapter on 

 measurements. The writer is of opinion that these 

 more advanced subjects are best studied by means of 

 the manv verv excellent treatises specially devoted to 

 them ; but still, there can be no doubt that a general 

 review such as the one before us appeals to a large 

 class of readers and serves a useful purpose. The 

 book is plentifully illustrated with drawings and 

 diagrams, which are for the most part good, though 

 several, especially in the earlier part, are rather crude 

 and out of date. M. S. 



The Flora of the Presidency of Bombay. By T. Cooke. 



^'ol. ii. Part i. Compositse to Boraginaceae. Pp. 216. 



(London : Taylor and Francis, 1904.) Price gs. 

 This volume begins in the middle of the series inferae 

 belonging to the gamopetalous division. The indi- 

 genous species of Compositae are numerous, but for 

 the most part are not so important as the introduced 

 composites, of vi,-hich a list is given. In the series 

 heteromerae the cohort Ericales is unrepresented, but 

 the orders Myrsineae, Sapotaceae, and Ebenaceas in- 

 clude several interesting genera. Under Bassia Dr. 

 Cooke explains how the synonym lUipe has been 

 erroneously introduced. Illipe is the Tamil name for 

 Bassia longifolia, and is applied commercially to the 

 fatty product obtained from the fruit ; this species re- 

 places in southern India the better known mahua tree, 

 Bassia latifolia, of which the flowers furnish a favourite 

 food, also a spirit to the natives of Central India. The 

 province is rich in species of Diospyros, amongst them 

 ebcnum, vielanoxylon, the calamander-like oocarpa, 

 and cruinsnata. The author agrees with Hiern in 

 uniting D. ebcnum and D. assiniilis, but separates 

 D. cordifolia and D. montaiia. The Apocynaceae in- 

 NO. 1832, VOL 71] 



elude Cerbera Odollam of the salt marshes, an endemic 

 Beaumontia, and a species, also endemic, of Erva- 

 tamia, a genus cut off by Dr. Stapf from the original 

 genus Tabernsmontana. Another dominant order 

 is that of the Asclepiadaces, which furnishes mostly 

 twining shrubs or climbers, and of which a good many, 

 as, for instance, the four species of Hoya, and seven 

 species of Ceropegia, are confined to the western side 

 of the peninsula. This part gives everv indication of 

 the same care and accuracy which distinguished the 

 first volume. 



Quadratic Partitions. By Lieut. -Colonel Allan 



Cunningham, R.E. Pp. xxiv + 266. (London: 



F. Hodgson, 1904.) Price 12s. net. 

 This contains a complete list of primes p up to 

 99991, with the factors of p—i, and resolutions of 



/ = a- + ^2 = f2 + 2(/2=A- + 3B= = i(L- + 27M=) ; 

 of p = e- — 2f- up to ^ = 24977; together with other re- 

 solutions of the type mp=x- ±Dy' for selected values 

 of ni, D, and all primes ^ up to a certain limit. 

 Besides this, there are tables relating to the Pellian 

 equation, and others directly connected therewith. 

 The introduction explains the nature and use of the 

 tables, and gives an account of their preparation. 

 Though some of the contents have already been pub- 

 lished (as explained in the introduction), a substantial 

 part appears for the first time in print ; the whole 

 forms a varied as well as extensive series of arith- 

 metical records which will be found of great value by 

 those who are interested in the theory of numbers, 

 especially in connection with the theory of residues 

 and of quadratic forms. Great care has been taken 

 to ensure accuracy, and the appendix contains lists 

 of errata detected in various preceding tables. The 

 new part of the work represents a very large amount 

 of labour, which is henceforth spared to those in search 

 of material for induction, and the grants made by the 

 Royal Society towards the expenses of computation 

 and publication have been worthily bestowed. It may 

 be added that the paper and type used are satisfactory ; 

 in the case of tables this is a matter of real import- 

 ance. All serious students of the theory of numbers 

 ought to procure this work, as well as Lieut. -Colonel 

 Cunningham's " Binary Canon," for, independently 

 of their use in solving special problems, these tables 

 may suggest or confirm new theorems of real import- 

 ance. 

 .Advanced Hand-camera Work. By Walter Kilbey. 



Pp. xvii + 98. (London : Dawbarn and \\'ard, Ltd., 



1904.) Price Ii. net. 

 In this series of photographic books already published 

 the present author is responsible for the popular volume 

 on "Hand Colour Photography," which is now in 

 its second edition. In the issue before us he deals with 

 the higher flights of hand-camera work, more 

 especially in connection with its use with the focal 

 plane shutter. The subject-matter treats of the selec- 

 tion of apparatus, the behaviour and efficiency of the 

 focal plane shutter, and practical work with the 

 camera, the last mentioned consisting of hints on 

 focusing, exposing, and the treatment of moving 

 objects. No less important are the subjects of the 

 last two chapters, which concern the plates and 

 developers suitable for such work, and the employ- 

 ment of hand cameras in telephoto, stereoscopic, and 

 orthochromatic photography. A great number of 

 excellent and appropriate illustrations from the 

 author's own negatives accompany the text. 



The easy and clear style of the author, and his 

 thorough acquaintance with the subject he is treating, 

 render the book not only delightful to read, but a valu- 

 able guide to those who wish to work successfully 

 with hand cameras. 



