28o 



NATURE 



[November 7, 19 12 



the Witwatersrand conglomerates, replacement 

 ore bodies, outcrops of ores, causes of ore shoots. 

 A great deal of the information has appeared 

 before, and there is naturally a certain amount of 

 divergence of opinion among the writers. 



OUR BOOKSHELF. 



Lcitfaden zum Bestinimen dcr Vogel Mittel- 

 Europas, Hirer Jugendkleider und Hirer Nester 

 nach leicht und sicher erkennbaren MerkmaJen. 

 By Prof. F. Dahl. Pp. viii+162. (Berlin: 

 (iel)ruder Borntraeger, 1912.) Price 5.20 marks. 

 The existing handbooks of bird-classification 

 and description are deficient in three im- 

 portant particulars. They are inexact and incom- 

 plete on the distinction between immature, mating 

 and ordinary adult plumages. Descriptive adjec- 

 tives, such as "short" and "long," which have 

 none but a relative application, are used instead 

 of absolute descriptions. Lastly, the study of 

 nidification is very unsatisfactory. Such defects 

 are the cause of much error and waste of labour to 

 the student. 



Prof. Friedrich Dahl, in his guide to the birds 

 of Central Europe, seeks to remedy these defects. 

 It is a model of compression; its 154 pages, each 

 fully paragraphed and subdivided, contain a very 

 complete and well-ordered fund of data. The 

 determination of species is the main object ; the 

 subject of life-habit is untouched. The study of 

 nests has a section to itself. This department, 

 naturally, is the less complete. Reference is made 

 in every case throughout the guide to the descrip- 

 tions and illustrations of Naumann. 



An introductory section tabulates those crucial 

 details of beak and pinion and claw which form 

 the elements of classification and render 

 the morphology of the bird unique in biology. 

 These are well illustrated, though on too small 

 a scale in many cases. The book is indispensable 

 as a supplement to Naumann, and English students 

 should make acquaintance with its method. 



A. E. Crawlev. 



Celluloid: Its Manufacture, Applications, and 

 Substitutes. By Masselon, Roberts, and Cillard. 

 Translated from the French by Dr. Herbert H. 

 Hodgson. Pp. XX 4- 356. (London: Charles 

 Griffin and Co., Ltd., 1912.) Price 255. net. 

 This work, which must be judged in its English 

 rendering, conforms with the forecast of the pre- 

 face. It is a fairly complete account of celluloid 

 manufacture, with a somewhat hesitating exposi 

 of its technological basis. The authors acknow- 

 ledge the collaboration of M. L. Clement in con- 

 tributing (i) a theoretical study of nitration baths, 

 and (2) a discussion of the "inflammability" of 

 celluloid. The attendant risks of manufacture, 

 storage, and use are treated, with full reference 

 to the researches of Will, \^ieille, Voigt, and 

 others. Their own conclusions from the estab- 

 lished data, in the form of "Precautions to be 

 NO. 2245, VOL. 90] 



exercised in Celluloid Works," are practical and 

 comprehensive. 



The work is logically subdivided into : — Part i. 

 "Manufacture," which comprises the processes 

 involved in the production of the celluloid mass ; 

 Part ii. , "Applications," deals with the production 

 of celluloid articles, combs, handles, hollow 

 articles, beads and buttons, and also films, includ- 

 ing lacquers and the application of celluloid solu- 

 tions in the production of filmed, or coated, and 

 impregnated fibres; Part iii., " ' Uninflammable ' 

 Celluloid and Substitutes," treats of modified 

 celluloids, and the competing varieties of plastic 

 colloids, such as the cellulose acetates, and xan- 

 thates (viscoid), as well as casein (galalith) and 

 aldehyde-phenol derivatives (bakelite). In this 

 section the authors modestly confess the insuffici- 

 ency of their knowledge and information, and we 

 shall not be thought hypercritical in remarking that 

 this section is not to be taken "seriously." 



There are unusual additions to our terminology ; 

 "pulpation" and "centrifugaliser " are instances 

 of new words, which, however, are intelligible. But 

 in the section dealing with the fibrous nitrocellu- 

 loses, we have " pile " (Fr. pile) for beater, " paste " 

 (Fr. piUe) for pulp, and for the essential working 

 parts of the beater we have "cylinder," or "drum " 

 for roll, " slab " for bed-plate, " teeth " for bars. 

 The general effect produced on the reader is that 

 of translated French, which is not English. 



The work appears at a moment which is oppor- 

 tune, in view of the appointment of a Royal Com- 

 mission to inquire into the dangers of celluloid. 

 The authors have dealt fully with this subject. 



Atlas Photo graphique des Nuages. By Julien 



Loisel. (G. Thomas : Librairie Astronomique, 



Paris, igi2.) Price 18 francs. 

 This atlas contains twenty plates of beautiful 

 reproductions from evidently very fine negatives, 

 the size of each being 6h x 4^ inches. The letter- 

 press accompanying them is extremely brief. It 

 consists of twenty-three lines describing the 

 methods adopted in securing the negatives, and 

 three or four lines of description of each photo- 

 graph, forming an index to the plates, in which is 

 stated the type of cloud, general description of 

 the formation and date of exposure. 



The photographs were for the most part taken 

 by Dr. Loisel, but they include some reproduc- 

 tions from negatives secured by M. L. Teisserenc 

 de Bord, of Trappes, and by M. J. Vincent, of 

 Uccle. 



The cloud nomenclature used in this atlas is not 

 that adopted by the International Meteorological 

 Committee in their International Cloud Atlas, but 

 it would have been an additional value to the 

 present atlas if the international classification 

 terms had been added in each case. 



The photographs are so good and represent such 

 typical clouds that the atlas should, and no doubt 

 will, find a place not only in all meteorological 

 institutions, hut in the libraries of all interested in 

 this fascinating application of photography. 



