338 



NATURE 



[March i6, 1922 



Director of Agriculture in Nyasaland to the corre- 

 sponding directorship in the newly acquired Tangan- 

 yika Territory. His little book is a useful summary of 

 practical information on cotton and tobacco growing 

 in Nyasaland, and contains just those particulars 

 which experience shows are required by would-be 

 planters with little or no previous knowledge of these 

 crops. 



The greater part of the book is devoted to cotton, 

 a crop of which Mr. McCall had much experience. 

 Nyasaland long-staple cotton has gained a high reputa- 

 tion and finds a ready market. A controlling factor 

 in production is transport, and on this point the 

 author expresses the view that " the progress of cotton 

 growing in Africa to-day depends more than ever on 

 railways and mechanical transport. The cultivation 

 of tobacco has become one of the most important 

 planting industries of the Protectorate, and the leaf 

 (Virginian type) is well known in this country. The 

 information given regarding the growing and curing 

 of this crop forms a useful first guide to a subject 

 requiring careful study. 



A Popular Chemical Dictionary : A Compendious 

 Encyclopaedia. By C. T. Kingzett. Second edition. 

 Pp. viii -I- 539. (London : Bailliere, Tindall and 

 Cox, 1921.) 215. net. 



The first edition of this useful book has been exhausted 

 in less than one year, thus proving that it filled a 

 vacancy in chemical literature. A careful perusal 

 of the new edition shows that much new material has 

 been added which enhances considerably the utility 

 of the book. In particular the chief constants of 

 most of the chemicals named have been added, and the 

 work now forms a handy and popular book of reference 

 embracing in one moderately sized volume a mass of 

 up-to-date information on practically every branch 

 of chemistry and allied sciences. 



The information is imparted in a clear and inter- 

 esting manner, freed so far as possible from techni- 

 calities. Consequently any one wishing to ascertain 

 the meaning of a term or definition, or the nature of 

 any material or subject in the scope of chemistry or 

 mineralogy, will find without difficulty and within 

 a few seconds the information required — information 

 which is often difficult to lay hands on immediately 

 when embedded in the pages of a large text-book. 



G. M. 



The Adjustment and Testing of Telescope Objectives. 

 Third edition. Pp. 1234-3 plates. (York and 

 London : T. Cooke and Sons, Ltd., 1921.) 



This volume is the third edition of a book first pub- 

 Hshed in 1891. The favourable reception accorded 

 to the earlier editions, and the extent of their circula- 

 tion, have encouraged the publishers to re-issue the 

 work with the amplifications necessary to bring it 

 up to date. 



The book deals with the simplest and most effective 

 means of detecting flaws in telescope objectives, as 

 well as the various maladjustments and imperfections 

 of mounting, which may prevent an observer from 

 obtaining the best results from his telescope. Different 

 types of objective are treated separately, a special 

 section being devoted to the Cooke triple photo-visual 



NO. 2733, VOL. 109] 



objective. The points to which attention is given 

 include squaring-on, achromatism, astigmatism, spheri- 

 cal and zonal -aberration, mechanical strains, and other 

 smaller, but equally important, matters. There is 

 also a short chapter on the general treatment of objec- 

 tives. The volume concludes with reprints of three 

 papers by Mr. H. Dennis Taylor, originally presented 

 to the Royal Astronomical Society, dealing with 

 achromatism and the secondary colour aberrations 

 of refractors. 



The book is very clearly written, and should prove 

 of great use, not only in detecting faults in imperfect 

 objectives, but also in enabling an observer to deter- 

 mine whether defects in star images are due to the 

 objective or to the manner of its setting. It should 

 appeal especially to the amateur astronomer possessing 

 a small refractor. The directions for testing and 

 adjustment are of the simplest possible character, 

 and involve keen observation rather than mechanical 

 skill. 



The publishers have done a great service to astro- 

 nomy in preparing such a useful little book. 



Bibliographia Agrogeologica : Essay of a Systematic 

 Bibliography of Agro-Geology. By Adolf Wulff. 

 (Mededeelingen van de Landbouwhoogeschool en 

 van de Daaraan Verbonden Instituten, Deel 20.) 

 Pp. iv-i-285. (Wageningen : H. Veenman, 1921,) 

 4-50 florins. 



The study of the soil has developed so rapidly in 

 recent years that no student can keep pace with the 

 output of papers, nor can the best card index of an 

 individual worker be relied upon as being complete. 

 The necessity for such adventitious aid as is afforded 

 by a bibliography has long become pressing, and this 

 is now supplied by Dr. Adolf Wulff. No fewer than 

 3300 titles are given, the papers being drawn from 

 more than 600 journals, and the list goes up to Novem- 

 ber I, 1919. A satisfactory classification is adopted, 

 so that the student will have no difficulty in finding 

 his way through the bibliography even if he has to 

 consult it only occasionally. 



Although the title suggests to English ears only 

 the geological or mineralogical side, the index covers 

 the whole ground dealt with in this country by soil 

 investigators, including soil organisms, soil organic 

 matter, and the relations of soil to the growing plant. 

 The English is remarkably free from errors, and the 

 few misprints will cause no difficulty. 



Prof. J. van Baren contributes an interesting dis- 

 cussion on soil problems, bringing together a con- 

 siderable amount of work which is little known, and 

 forming a useful introduction to the whole volume. 

 Altogether the book is one which can safely be recom- 

 mended to students and investigators in the subject. 



E. J. R. 



Patents and Chemical Research. By H. E. Potts, 

 Pp. X -I- 198. (Liverpool: University Press, 1921.) 

 8s. 6d. net, 



A PATENT, like any other form of contract, depends 

 very largely for its value upon the skill with which 

 it has been drawn up. The form of wording, in fact, 

 may be quite as important as the subject-matter. 



