November 7, 19 12] 



NATURE 



>79 



water and ice, desert conditions, and the charac- 

 teristics of lakes and mountains. \ separate 

 chapter is devoted to the Niagara Falls as a clock 

 of geological time. He hints that a large amount 

 of original and unpublished material is interwoven 

 in the older web. This may be, but much of it 

 has either been skilfully concealed, or it has a 

 familiar look. The book is quite pleasant reading, 

 and the pleasure is enhanced by the abundant and 

 excellent illustrations. There are five appendices ; 

 two on the determination of common minerals and 

 rocks are unsatisfactory and not necessary in a 

 book of this kind. The third describes the 

 author's method of explaining the meaning of 

 contoured maps by means of apparatus ; it seems 

 an elaborate way of passing the student's time. 

 The fourth is a short explanation of apparatus for 

 teaching the interpretation of geological maps ; it 

 consists of different shaped blocks, representing 

 outcrops of various kinds, to be disposed on a table 

 ruled into squares. This might be useful in setting 

 examination exercises. The fifth outlines several 

 fairly lengthy geological trips in the United States, 

 and concludes with a sketch of a geological rush 

 across Europe. 



{2) A different series of geological excursions is 

 provided for by Prof. Reynolds in his admirable 

 little guide book. Forty excursions, all within 

 easy distance of Bristol, are described on a uni- 

 form plan under the headings "special features," 

 "access," "general structure," followed by, in 

 each case, an itinerary with geological notes and 

 a short list of references. There are numerous 

 sketch maps and sections and an introduction to 

 the geology of the district is written by Prof. 

 Lloyd Morgan. 



(3) The literature on British clays and sands is 

 so meagre that any serious attempt to deal with 

 the subject is welcome. The frontispiece to Mr. 

 Searle's book, a "map of the chief clay works in 

 Great Britain," is fairly characteristic of much 

 that is to follow; it presents a medley of dots 

 conveying no information of any value whatever, 

 but representing, no doubt, a great deal of labour. 

 It would be incorrect to suggest that no informa- 

 tion can be gained from the text ; Mr. Searle has 

 produced a book containing much useful and 

 interesting matter; one who can stand the fatigue 

 and irritation caused by the lack of arrangement 

 and the interminable repetitions will be able to 

 extract a great deal. Only about half the volume 

 is devoted to the geological position, the qualities 

 and uses of British clays, and the small amount 

 of space allotted to sands is not sufficient to 

 warrant any mention in the title. The remainder 

 of the book is concerned with ordinary geology 

 and with the properties of clays in general. Much 

 NO. 2245, VOL. go] 



of the geology might have been condensed or 

 omitted; it is very bookish, and it would be easy 

 to point out many statements that are misleading 

 or only half true. There are chapters on the 

 mineral and other constituents of clays ; the 

 physical and chemical properties of clays (the 

 table of analyses is quite inadequate) ; materials 

 similar to clay (including halloysite, sillimanite, 

 kyanite, zeolites, &c.); prospecting, mining, and 

 quarrying ; the purification and preparation of 

 clays and the legal position of clays. There is 

 a large but not quite trustworthy index. Through- 

 out the work there are scarcely any references to 

 original authorities, though many are mentioned. 



(4) Prof. Tolman's small book of less than fifty 

 pages deals with a subject of the greatest impor- 

 tance to all practical geologists and mining 

 engineers. In most English text-books the move- 

 ment on fault planes is usually treated as if it 

 were quite simple, though everyone is aware that 

 it has often been very complicated. The author 

 explains very briefly, and on the whole clearly, 

 how to represent the effects of faulting. He uses 

 for this purpose two methods : the isometric pro- 

 jection, and the application of contouring. He 

 introduces several terms in the nomenclature of 

 fault movements which will be familiar to readers 

 of American geological literature ; his use, how- 

 ever, of the expression "pole" for axis is not 

 fortunate. The book would have been more satis- 

 factory in some respects if the author had per- 

 mitted Himself a little more elaboration in the 

 treatment of the subject ; it is none the less a 

 useful pamphlet. 



(5) On the mining region of Cornwall and DcAon 

 Mr. Collins has produced a valuable work of 

 reference. Perhaps the most acceptable portion 

 will be that giving short histories of individual 

 mines. There is also a separate list of mines 

 arranged alphabetically. A large part of the 

 volume is occupied with theoretical matters of the 

 usual kind, mingled with which is more interesting 

 local information as to the character of the ore 

 bodies. Occasionally the author launches out into 

 elaborate estimates of the amount of certain 

 minerals and ores contained in the rocks ; they are 

 neither of much use nor very accurate. 



(6) It was an excellent idea to gather into a 

 single volume the opinions of different mining 

 engineers upon the type of ore formation with 

 which each was most familiar. Separate chapters 

 of this book are given to the Clinton iron ores. 

 Lake Superior iron ores, the flats and pitches of 

 the Wisconsin lead and zinc district, lead and zinc 

 deposits of the Ozark region, native copper 

 deposits, the Cobalt distiict of Ontario, the Tread- 

 well mines, .Alaska, saddle reefs, contact deposits, 



