Septembeb 14, 1906.] 



SCIENCE, 



339 



The student of sociology, the settlement 

 worker and every seeker after truth must, in 

 order to know his subject, get an acquaintance 

 with its ancillary factors. He must have his 

 science on a positive basis. A scientific 

 knowledge is as necessary in questions of 

 education, reformation and the improvement 

 of social physical conditions as it is in the 

 treatment of a diseased individual. In this 

 book of Professor Bailey's the student will 

 find much that is helpful to his janderstand- 

 ing of the causes of the conditions of daily 

 living. Unless he has such knowledge, he is 

 in no- position to make suggestions for better- 

 ment. 



The following paragraph serves to show the 

 value of the book in this direction: 



It is estimated that at least 10 per cent, of the 

 income is squandered not only by the well-to-do, 

 but frequently also by those who have a very small 

 income and so can ill afford it, in expensive food 

 material which affords little nutrition, in unsatis- 

 factory methods of preparation, in selecting foods 

 out of season, by throwing away much valuable 

 food material, and by using badly constructed 

 cooking appliances. Much careful investigation 

 is needed along these lines, and painstaking in- 

 struction will ultimately improve these conditions 

 which are at present so much deplored. 



Ellen H. Eichards. 

 Massachusetts Institute of Technologt. 



ANIMAL MECHANICS."^ 



The author's previous contributions to ani- 

 mal mechanics, to some extent in company 

 with the late Professor W. Braune, are well 

 known to anatomists ; though it is to be feared 

 that they are held in more respect than in 

 intelligent appreciation. The anatomist who 

 is not a trained mathematician can very well 

 understand that most if not all of the models 

 and diagrams used to illustrate the simpler 



^ ' Theoretische Grundlagen flir eine Mechanik 

 der lebenden Korper, mit speziale Anwendungen 

 auf den Menschen sowie auf einige Bewegungs- 

 vorgange an Maschinen in moglichst elementar 

 Weise dargestellt.' Von Otto Fischer. Mit 67 

 in den Text gedruckten Figuren und 4 Tafeln. 

 Leipzig und Berlin, Druck und Vorlag von B. G. 

 Teubner, 1906. 



problems show at most the central principle, 

 if we may so express it, and show it in a pain- 

 fully diagrammatic way. It is much as if an 

 artist were to give us a man's face drawn in 

 straight lines. We may say, and truly, that 

 the essential idea is given, but that much is 

 left out; and we are not very clear as to the 

 precise importance of the omissions. As the 

 mathematician adopts a more thorough sys- 

 tem we feel an increasing difiiculty in follow- 

 ing it. We can see that the method is an 

 improvement; we can appreciate even without 

 full understanding (if this be not a paradox) 

 that the work is honestly done; but a clear 

 idea does not come to us. One of the causes 

 of the want of sympathy between mathe- 

 maticians, in so far as they are mathematic- 

 ians, and the rest of the world is that the 

 former with all their learning can not do 

 justice to the full stupidity of the non-mathe- 

 matician when the question is one of mathe- 

 matics. It is impossible for him to grasp 

 how sincere the outsider is in his ignorance, 

 or rather in his incapacity. 



This book is devoted to an analysis of the 

 movements of joints in their mutual relations. 

 It is clear that the simplest system is one of 

 two rigid bars playing one on the other. If 

 we restrict the motions to one plane a child 

 can understand it; but if we go beyond that 

 the ordinary man is at once out of his depth. 

 Add one more bar still keeping to one plane, 

 and the difficulty increases. Make the number 

 of the bars and the planes indefinite and where 

 are we? The mathematician would tell us to 

 go one step at a time; but somehow we lose 

 our heads as we should did we receive the 

 same instruction relative to walking on the 

 tight rope. 



The author writes as follows in his preface : 



As the whole animal organism has for its first 

 object the movement of the living body through 

 joints, I have devoted this book in the first place 

 to physicians, especially to physiologists and 

 anatomists as well as to zoologists. I have there- 

 fore attempted to make the mathematical deduc- 

 tions so elementary and to present them in so 

 clear a manner that they will be easily intelligible 

 even to those who are not mathematicians. 



