June io, 1909] 



NA TURE 



425 



on to a classification of mankind and his ancestral 

 and recent history as revealed by fossil and other 

 remains, from the Tertiary period to the present day. 

 Subsequent chapters deal with comparative anatomy 

 and physiology, psychology and sociology, while the 

 last quarter of the book is devoted to the less studied, 

 or perhaps less popular, topic of comparative patho- 

 logy and therapeutics. To compress so vast a subject 

 within the limits of a small volume has led to all 

 descriptions being of the briefest. None the less, the 

 book will appeal to those who desire to acquire a 

 superficial knowledge of the main features of human 

 evolution, while the sections will serve as starting- 

 points for further study to those more deeply inter- 

 ested, and be of considerable assistance to popular 

 lecturers, who will find therein a dense array of 

 I'acts. 



The introduction comprises a summary of the sur- 

 mises made in the past as to the origin of man, and 

 loads up to the study of evolution. The history of 

 the systematic classification of mankind into races 

 unexpectedlv ends with Huxley and Max Miiller, more 

 recent authors being omitted. The section on com- 

 parative anatomy is full and freely illustrated, but is 

 uiarred, at any rate for the general reader, by a ten- 

 dency to give the names of the parts referred to in 

 Latin in the text, and in the illustrations to label 

 them sometimes in English, at others in Latin, while 

 in some cases abbreviations only are made use of. 

 This is the more to be regretted as the names em- 

 ployed are not always those found in English text- 

 books of anatomy. Space being valuable, it may be 

 •v\-ondered why long tables of chemical compositions, 

 such as that of the brain, which occupies a whole page, 

 were included. It seems at times as if the author was 

 uncertain whether he was writing for the student or the 

 s;;'eneral public. The sections on early man are 

 TOO short for the former in comparison with 

 the rest, while the number of unexplained tech- 

 nical terms must prove a stumbling-block to the 

 latter. Indeed, in many respects the volume sug- 

 gests a verj- full and illustrated syllabus of a course 

 of lectures rather than a text-book or a popular 

 description. 



Regarded in this light, the book would be a useful 

 jiid to students of human or comparative anatomv and 

 physiology. Perhaps the most interesting, because 

 most unusual, chapter in a work of this kind is that 

 dealing with pathology, which contains much that 

 .vould otherwise have to be garnered with consider- 

 able labour, since the data are scattered through a 

 multitude of technical journals. The author shows 

 that in general the phenomena of disease in man, 

 whether due to animal or vegetable parasites or to 

 disorders of metabolism, are similar to those pre- 

 sented by the higher animals, the differences being 

 largely explicable by such features as the assumption 

 of the erect attitude, the habits of feeding, and more 

 particularly by the aggregation into large communi- 

 ties, the often unhygienic methods of clothing, and 

 the abandonment of free physical exercise which has 

 characterised the recent history of man. 

 NO. 2067, VOL. So] 



PRACTICAL PHYSICS. 

 (i) Practical Physics. By L. M. Jones. Pp. viii + 



330. (London : Longmans, Green and Co., 1909.) 



Price 35. 

 (2) Handhuch fiir physikalisclie Schiileriihungen. By 



Prof. Hermann Hahn. Pp. xv+506. (Berlin : 



Julius Springer, 1909.) Price 20 marks. 

 (i) /^PINIONS will always vary as to the precise 

 V^ means to be adopted to achieve any definite 

 end, and this is notably the case in the teach- 

 ing of practical physics, as is shown by the 

 many text-books on the subject. It is the more 

 to be remarked that most teachers will readily 

 subscribe to the thesis which Mr. Jones lays down, 

 perhaps a little combatively, in the preface to 

 his book, as to the fundamental idea of practical 

 courses of physics. All students will agree that prac- 

 tice must illustrate and substantiate theory in a con- 

 nected, logical manner, so that a " course " may review 

 the fundamental conceptions of the subject, and, in 

 so doing, train the reasoning power. Several text- 

 books, however, might be conceived as conforming 

 to this canon. 



But Mr. Jones has that best of qualifications — of 

 having actually used his course for several years, and 

 proved it by success. The title of the book is slightly 

 misleading, as the book only treats of heat, light, and 

 electricity. Within these limits we have little but praise 

 for it. The explanations of theory are lucid, and give 

 an orderly, interesting, and withal simple conspectus 

 of fundamental conceptions founded upon an extremely 

 complete series of nearly 200 experiments. The illus- 

 trations are attractive and not too complex, and the 

 instructions as clear as could be desired. Practical 

 exercises at the end of chapters give scope for that 

 element of initiative which is necessary to approxi- 

 mate students' work to the conditions of research, and 

 the general revision papers at the end of the book 

 afford a useful method of eliciting the physical concep- 

 tions learned. 



The list of experiments covers such subjects as 

 vapour pressure, dispersion, and electrolysis, which 

 are not commonly included in " intermediate " courses, 

 while simple methods of electrification, the electro- 

 scope, and electrophorus are omitted which are usually 

 included. In spite of this, and a relegation of instruc- 

 tion as to probable errors to notes which might have 

 been better treated in an introduction, the book is 

 always stimulating, suggestive, and clear. 



(2) The " Handbuch " of Prof. Hermann Hahn is a 

 book of a totally different character. It offers a clear, 

 eminently logical, and complete course of practical 

 physics, with all that the term usually signifies, to 

 teachers. It is a book which one can freely praise 

 and blame with difficulty. Commencing with concep- 

 tions of space and mass, it covers very completely 

 general properties of matter. Indeed, nearly half the 

 book is devoted to this part of the subject, but we can 

 hardly regret it. Incidentally, wc find the student 

 is to be introduced, at the outset, to his apparatus of 

 calculation — an excellent idea. The slide rule comes 

 on p. 5, and a student is early to be taught habits 



