Max 12, 192 1 ] 



NATURE 



327 



(2) We doubt whether this book is sufficiently 

 elementary to be of service to the private owners 

 and managers of goods for whose use it was 

 intended. A working-plan document, the headings 

 of which take up ten printed pages, will scarcely 

 appeal to the ordinary forester. The book is not 

 a whit simpler than the well-known manual 

 of Schlich, vol. iii., which for many years has 

 been the recognised text-book on forest manage- 

 ment in British and Indian forestry schools. 



It may, however, supplement that authority to 

 some extent, for it throws light on forestry terms 

 and usages in America — for example, the advanced 

 student will find in it interesting matter con- 

 cerning subjects like "log-rules" and "stumpage- 

 values." The chapter on "timber-cruising" will 

 be useful to foresters who intend to practise 

 abroad in wild regions where rough-and-readv 

 methods of estimating the value of timber in virgin 

 forests are the only practicable means. The book 

 concludes with an appendix of useful tables. 



(3) This volume treats of the main industries 

 which are dependent for their raw materials on 

 the miscellaneous products of the forest, and we 

 xvelcome it as the first American text-book on this 

 subject. The author spent ten years of investiga- 

 tion and travel in the United States on its pre- 

 paration, and has incorporated with his own ob- 

 servations much information from scattered reports 

 and papers. A separate chapter is devoted to each 

 industry, ample details being given of raw 

 materials, processes of manufacture, equipment 

 and machinery, costs, utilisation of waste pro- 

 ducts, etc., interspersed with specifications, tables, 

 and statistics, and concluding with a select biblio- 

 graphy. 



The industries described are important, and in- 

 clude wood-pulp and paper, tanning materials, 

 veneers, cooperage, turpentine, wood-distillation, 

 charcoal, boxes, railway sleepers, poles and posts, 

 mining timber, firewood, shingles, maple sugar, 

 dyewoods, excelsior, rubber, and cork. 



Prof. Brown's treatise is appropriately illustrated, 

 and replete with accurate information. It will 

 prove useful to foresters and manufacturers gene- 

 rally, and it should be perused by all interested in 

 the economic working of our own woodlands, for 

 it suggests methods by which thinnings, under- 

 wood, and waste timber might be utilised. 



Our Bookshelf. 



T/ie Journal of the Institute of Metals. Vol. xxiv. 

 No. 2, 1920. Edited by G. Shaw Scott. 

 Pp. xiv-f547-fxi plates. (London: The In- 

 stitute of Metals, 1920.) 315. 6d. net. 

 The latest volume of this journal contains an un- 

 usually large number of important papers. The i 

 NO. 2689, VOL. 107] 



May lecture by Dr. Benedicks deals with recent 

 work in thermo-electricity, and gives details of the 

 author's discovery of a thermo-electric effect in 

 circuits composed of a homogeneous metal. These 

 results have been published elsewhere, but they 

 are now brought together in a concise and con-. 

 venient form. The study of crystal growth in. 

 metals which have been subjected to cold work, 

 by Prof. Carpenter and Miss Elam, contains many 

 interesting observations. The authors were for- 

 tunate enough to find an alloy which preserves a 

 complete record of successive stages of crystal 

 growth on a prepared surface, and this has en- 

 abled them to trace, with remarkable clearness, 

 the course of events throughout a variety of con- 

 ditions.^. The difficult system of alloys of 

 aluminium and magnesium has been investigated 

 by metallographic methods by Mr. Hanson and 

 Miss Gayler, the results being recorded in the 

 form of an equilibrium diagram presenting several 

 unusual features, A note by Mr. Dickenson, on 

 intercrystalline brittleness produced by the action 

 of fusible metals on brass under stress, contains 

 facts which bear on the nature of brittleness in 

 general, while another note reviews the evidence 

 for the allotropy of zinc. Several papers deal with 

 practical brass foundry questions, and another 

 describes the experience on war vessels with 

 regard to the corrosion of condenser tubes, on 

 which a committee of the institute and other 

 bodies continues to conduct Elaborate investiga- 

 tions. The voluifie contains, as usual, a very 

 large number of abstracts of papers published else- 

 where, and mention should be made of the ex- 

 cellence of the numerous plates of photomicro- 

 graphs. C. H. D. 



The Bahama Flora. By Prof. N. L, Britton and 

 Dr. C, F. Millspaugh. Pp. viii-f695. (New 

 York : The Authors, New York Botanical 

 Garden; London: Dulau and Co., Ltd., 1920.) 

 375. 6d. net. 

 The first thing which strikes one on opening this 

 flora is the excellent paper, such as one seldom 

 sees on this side of the Atlantic. Prof. Britton 's 

 name is a guarantee of the excellence of the work 

 regarded as a flora ; and though some who are 

 accustomed to the older floras will probably find 

 comparisons increased in difficulty by the number 

 of splittings of genera that have been made, no 

 one who has worked with tropical plants in the 

 living condition will be likely to question the 

 necessity of this splitting in a great number of 

 cases. This is the first complete and modern flora 

 of the Bahamas, and many people, not realising 

 that the group is a trifle larger than Jamaica, and 

 much larger than all the remaining British West 

 Indian islands, may be surprised to learn that 

 thev contain 995 species of flowering plants. 



Prof. Britton states that there is no geological 

 evidence that there was ever land connection to 

 the Bahamas, but the evidence of the flora itself 

 points to such a probability. Inasmuch as the 

 flora contains 133 endemic species out of 995, or 

 13 per cent., the connection must be far back, as 



