36 



NA TURE 



[November ii, 1909 



latent heat of water, we are told that "a 

 weighed quantity of dr}' ice is now added to the 

 water." Such procedure would, needless to say, be 

 fatal to the accuracy of the measurement. It may 

 be mentioned also that in describing the measurement 

 of an electric current with a tangent galvanometer, 

 the author neither mentions the very necessary adjust- 

 ment of the coils parallel to the magnetic meridian, 

 nor does he show the bearing of the strength of the 

 earth's field on the absolute value of the current. 

 Altogether, from the point of view of practical physics 

 the book leaves much to be desired. Indeed, the 

 author goes so far as to suggest that the practical 

 part may be entirely omitted. 



A further point should be mentioned. Although 

 there is an extensive set of very suitable numerical 

 examples given, practically no specimen examples are 

 solved. It is very doubtful whether an average 

 student could, unaided, successfully attack them. 

 When it is remembered that it is mainly by the 

 frequent use of numerical and practical exercises that 

 the principles of physics are most easily and thoroughly 

 instilled into the mind, it will be recognised how 

 serious are the above omissions. 



(2) This book is the third of a series on simple 

 physical measurements, &c., and is drawn up on the 

 same general method as the previous ones, viz. to 

 leave as much as possible to the student's initiative 

 and common sense. The exercises, although still 

 very simple, are of a somewhat higher standard, and 

 include further measurements in the subjects previously 

 dealt with, and a few experiments in elementary 

 chemistry. This method of teaching is somewhat 

 novel, and probably the correct one. Where time is 

 a consideration, however, it may not be practicable. 



OUR BOOK SHELF. 

 A Brief Course in the Calculus. By W. Cain. 



Pp. x + 280. (London: Blackie and Son, Ltd.i 



1909.) Price 64-. net. 

 This is a new publication of an American book and 

 deals Willi both the differential and the integral 

 calculus. Following the more recent English treatises 

 on the same subject, the author begins with an intro- 

 duction on graphs, in which he confines himself to 

 the simplest cases of the usual functions. The value 

 of such an introduction would, perhaps, be enhanced 

 if the reader were shown how to draw quickly even 

 rough graphs of such functions as x-'+x+i, 

 If -i)/(*+2), &c., indeed, of rational functions! 

 The point of view of the author mav be obtained from 

 his own words (p. 27) :— " The aboVe examples repre- 

 sent loci whose asymptotes are easily determined by 

 inspection. For other cases, particularly where the 

 asymptotes are inclined to the axes, advanced treatises 

 on the Calculus must be consulted." 



Derivatives are introduced through the notion of 

 a limit. After the derivative of x" has been estab- 

 lished (without using the binomial theorem), dis- 

 cussion of the slope of a curve and of rates follows. 

 If the graphical part had been developed more fully, 

 the latter notions might have taken precedence of and 

 led up to derivatives. Such a mode of treatment 

 would perhaps have given a greater air of reality 

 to the derivative in the case of readers who have time 

 for only a short course in the calculus, and whose 

 NO. 2089, VOL. 82] 



power of mathematical perception has not been highly 

 trained. The author, however, has good authority 

 for the order he adopts, and he keeps well in view 

 the needs of those who want a careful study of the 

 subject as well as those who are likely to apply their 

 knowledge to geometry, mechanics, and physics. 

 He has dealt fully and carefully with the outstanding 

 parts of the subject, and works out many examples ; 

 it is doubtless in consistency with his whole aim 

 that he does not give a very large number of examples 

 to be worked out by the reader, in this respect differ- 

 ing from most authors of mathematical books. To 

 teachers and students who prefer a smaller number 

 of examples, and need a work in which the method 

 and province of the calculus are presented by a careful 

 writer, the book can be recommended as likely to be 

 a useful introduction to the subject. P. P. 



The Life of a Fossil Hunter. By Charles H. Stern- 

 berg. Pp. xiv + 286; with 46 plate illustrations. 

 (New York : Henry Holt and Co. ; London : George 

 Bell and Sons, 1909.) 



This is a simple and readable story of the experiences 

 of a fossil hunter in the wild west of North America. 

 As Prof. Osborn remarks in his brief introduction, 

 "the revivification of the past" by the discovery of 

 fossils "is attended with as great fascination as the 

 quest of live game." No one has met with greater 

 success in such pursuits than Mr. Charles Sternberg, 

 the well-known collector of extinct vertebrates, who 

 now recounts some of his experiences during the past 

 forty years ; and he has produced a small book which 

 will be read with pleasure by all who are acquainted 

 with the fine specimens which he has obtained for 

 several of the great museums. The well-printed text 

 is illustrated by a large number of inset plates repre- 

 senting scenery, fossils discovered by the author, 

 portraits, and several excellent restorations of extinct 

 reptiles from the American Museum of Natural 

 History, New York. 



In the early days of his explorations, Mr. Sternberg 

 was exposed to danger from the Indians whose 

 country he invaded, and there are several interesting 

 stories of his adventures both with them and the 

 settlers. In later years, and even under the most 

 improved conditions, the hardships have still remained 

 considerable, for the most fruitful regions for fossils 

 are always those most destitute of vegetation, where 

 the whole face of the rock is exposed and can be 

 closely scanned. The suffocating nature of the dust 

 and the alkaline or saline condition of most of the 

 available water supply always prove troublesome, and 

 the laborious excavation of fossils in such circum- 

 stances, beneath a burning sun, involves real en- 

 thusiasm for the work. Mr. Sternberg, after long 

 experience, has brought his methods to perfection, and 

 he gives interesting illustrations of the manner in 

 which the most fragile skeletons can be disinterred 

 from the rock without injury. He began by collecting 

 fossil leaves from the Dakota Cretaceous sandstone. 

 Afterwards, with the encouragement of the late Prof. 

 E. D. Cope, he obtained mosasaurs and fishes fron> 

 the chalk of Kansas. Then he made several success- 

 ful trips to the Permian of Te.xas, in which he dis- 

 covered numerous new reptiles and labyrinthodonts. 

 Finally, he has worked the Laramie Cretaceous forma- 

 tions of Wyoming, and the Loup Fork Tertiary forma- 

 tion of Kansas. Besides enriching the museums of 

 America, Mr. Sternberg has contributed many 

 important specimens to those of Europe, especially to 

 the Palaeontological Museum of Munich and the 

 British Museum. The latter is indebted to him for 

 a skull of Triceratops, a skull and a skeleton of 

 Pteranodon, several Mosasayrians, some fine chalk 



