276 



NA TURE 



[August 26, 1922 



wiched between local descriptions, thus " Aqueducts " 

 are treated between " Storm Waters " and " The 

 Water Supply of New York " ; " Watersheds and 

 Water-partings,'' with a long description and full-page 

 illustration of the Rhone Glacier, appears between 

 engineering details of the water-works of Glasgow and 

 of Liverpool. And between " The Birmingham Water 

 Supply " and " Proposals to supply London from 

 Wales " there is an account of the Nile storage at 

 " Assouan " in a paragraph devoted to " Other Famous 

 Dams." 



Apart, from the absence of arrangement, the book 

 fails in saying next to nothing of the rainfall of the 

 country and its fluctuations, data for which in im- 

 mense abundance are available ; nothing of the 

 system of legislation by which water supplies are 

 allocated, save for scraps in relation to individual 

 schemes. An appendix gives an account of the theory 

 (if cyclones put forward by Prof. Bjerknes ; but there 

 is nothing as to the distribution of rainfall in the 

 actual cyclones which traverse the British Isles. 



As a scrap-book of useful and often entertaining 

 information on the supply of water to modern London 

 and ancient Jerusalem the book will give pleasure to 

 many readers, and the facts as to other cities, ancient 

 and modern, are accurate wherever we have tested 

 them, though not always up to date. Our sole com- 

 plaint is that a scrap-book should be put forward as 

 an educational work, for we hold that continuity of 

 plan, clearness of arrangement, and simplicitv of state- 

 ment are essential for any such book, and these we do 

 not find. We repeat that large parts of the book 

 are excellent, and every Londoner would do well 

 to read those which refer to the Metropolitan Water 

 Board. H. R. M. 



Etude geometrique des transformations birationnelles 

 et des combes planes. Par Henri Malet. Pp. 

 viii + 261. (Paris: Gauthier-Villars et Cie, 1921.) 

 32 francs net. 



Orthodox elementary geometry deals principally with 

 the metrical properties of space, based on Euclid's 

 axioms. In the modern developments of geometry 

 the metrical properties are a secondary consideration. 

 The study of ordered aggregates of spatial elements, 

 such as points, lines and planes, became a powerful 

 weapon in the hands of the geometers of the last few 

 generations, and one of the most useful forms of this 

 study is the method of transformations and corre- 

 spondences. M. Malet sets himself the task of pre- 

 senting the fundamental ideas of correspondences, 

 leading up to the generalised type which forms the 

 title of his book. As is natural lie offers first a careful 

 study of homographic correspondences of points on 

 straight lines, then the method of projection, coining 

 finally to birational transformations. His method is 

 purely geometrical. 



The theory is applied to the type of plane curves 

 called algebraic, defined by the author in the sense 

 that one and only one algebraic curve can be made 

 to pass through a number of given points in a plane, 

 these points being independent : he examines carefully 

 the meaning of independence. 



Attention is directed to the remarkable fact that manv 



of the most important contributions to modern geometry 

 have been made by Frenchmen ; M. Malet claims that 

 this is due to " ces qualites de clarte et de precision 

 qui furent toujours l'appanage de notre race." 



S. B. 



A Manual of Indian Timbers : An Account of the 

 Growth. Distribution, and Uses of the Trees and Shrubs 

 of India and Ceylon, with Descriptions of their Wood- 

 Structure. By J. S. Gamble. Reprint of second 

 edition with some additions and corrections. Pp. 

 xxvi + 868 + 20 plates. (London: Sampson Low, 

 Marston and Co., Ltd., 1922.) 3/. 3s. net. 

 The Empire Timber Exhibition, held in London in 

 July 1920, was remarkable for the number of beautiful 

 woods which were displayed in the India section. It 

 was difficult to understand why most of these valuable 

 timbers were either unknown or not appreciated in 

 the European market. Most people in this country 

 believed that teak was the only timber of importance 

 produced in India, and were surprised to see the variety 

 of species that were made up into furniture, panelling, 

 parquet flooring, and a host of miscellaneous articles, 

 ranging from fishing-rods to scientific instruments. 

 The cause of the neglect of Indian woods may be put 

 down to lack of business methods on the part of the 

 Government, which controlled the great bulk of the 

 forests. This supineness is now a matter of the past, 

 and efficient measures have been taken to make known 

 in England the wealth of timbers available. 1 



The publication of a reprint of Gamble's " Manual 

 of Indian Timbers," which has been for many years 

 out of print, is a step in the right direction. To those 

 who are unacquainted with this splendid book, we may 

 direct attention to the accurate mass of information 

 which it contains on the timbers and forest trees of 

 India, Burma, and Ceylon. About 1500 species are 

 described ; and their uses and qualities are pointed out. 



A Guide to the Identification of our more Useful Timbers : 

 Being a Manual for the Use of Students of Forestry. 

 By Herbert Stone. Pp. viii + 52 + 3 plates. (Cam- 

 bridge : At the University Press, 1920.) Price 

 is. 6d. net. 

 The distinctive characters of the commoner kinds of 

 timber are well described in this brief manual, which 

 should prove useful in teaching students. Thirty-one 

 broad-leaved trees and ten conifers are included, all of 

 which, except four, teak and three kinds of mahogany, 

 are cultivated in this country. It is assumed that the 

 student has sufficient knowledge of the elementary 

 structure of wood to follow the descriptions. There 

 are three plates. Certain slight errors in nomenclature 

 should be corrected in the next edition. The term 

 " deciduous oaks " is chosen to designate the two 

 British species. This is not a distinctive name, as it 

 does not include in this manual the American white 

 oak and red oak, which are equally deciduous. Ulmus 

 effusa (p. 18) is not a " bad " species, as alleged, but 

 is a name applied to a distinct elm, not native to 

 Britain, which is perhaps more correctly called by the 

 prior name of U. pedunculata. 



■See " Indian trade Enquiry Reports on Timber and Paper Materials," 

 published in iQ-'i by the imperial Institute, where possible uses in this 

 country for thirteen different woods, other than teak, are suggested. 



2756, VOL. I io] 



