390 



NATURE 



[December io, 1914 



differential equations should not excite a learner's 

 vivid interest unless it so departs from the logical 

 order as to be historical. Often a modified logical 

 order seems the easiest and most natural order. 

 But the problem of education seems to be rather a 

 problem of awakening interest, and not of choos- 

 ing " natural " paths. Difficulties cease to matter 

 if one's interest is aroused. 



(6) Prof. Dickson's introduction to the general 

 theory of linear algebras, including also non-asso- 

 ciative algebras, shows in many places the influ- 

 ence of the German " Encyklopadie." The ex- 

 position of the main theorems of the general 

 theory follows Cartan and, to some extent, Wed- 

 derburn, and is a most useful introduction to the 

 subject. 



(7) Here is an excellent text-book for all students 

 of geometry. As seems to be always the case 

 with this subject, the treatment is, to a great 

 extent, historical, but the analytical treatment 

 begun by Riemann occupies a rather minor posi- 

 tion. A very welcome feature is that, throughout 

 this book, Euclidean geometry is exhibited as a 

 particular case of non-Euclidean geometry, and 

 the apparent want of symmetry and the occasional 

 failure of the principle of duality are explained. 

 It seems rather confusing to assume tacitly, as 

 the author does on p. 30, that through any point 

 there are in hyperbolic geometry two, and only 

 two, parallels to a given straight line. 



(8) This book claims, rather magisterially, to 

 be original. It seems to us more interesting than 

 strikingly original. The equation of a line, 

 y = mx + c, may be regarded as having the co- 

 ordinates m and c. By using the word " measure " 

 to denote a concept including both the distance 

 of two points from one another, the perpendicular 

 distance from a point to a line, and the angle 

 between two lines, it is possible to state shortly 

 what co-ordinate geometry does. This is the 

 reduction of a set of joins and intersections of 

 points and lines to functions of the measures of 

 the elements. This idea is developed by the 

 author and applied also in differential geometry. 



OUR BOOKSHELF. 



Quain's Elements of Anatomy. Eleventh edition. 

 Vol. ii., part ii.. Splanchnology. By J. Syming- 

 ton. Pp. x + 392. (London: Longmans, Green 

 and Co., 1914.) Price 105. 6d. net. 



In this further contribution to the eleventh edi- 

 tion of Quain's " Elements of Anatomy " Prof. 

 Symington describes the following systems of the 

 human body : — Digestive, Respiratory, and Uro- 

 genital. Two minor sections are devoted to the 

 ductless glands and peritoneum, the latter being 



NO. 2354, VOL. 94] 



written by Dr. P. T. Crymble. During the 

 eighteen years which have elapsed since the tenth 

 edition appeared — under the joint editorship of 

 Sir Edward Schafer and Prof. Symington — anato- 

 mists, physiologists, and particularly surgeons 

 have altered our conception of the splanchnology 

 of the human body in many and important details. 

 These changes are reflected in the text and illus- 

 trations of the new edition of "Quain." 



No one is better qualified to edit this standard 

 work on human anatomy than Prof. Symington. 

 We feel, however, that in giving the Belfast 

 school its full due. Prof. Symington has done less 

 than justice to those who live and work outside 

 the limits of Belfast. One example will suffice. 

 About twelve years ago a series of observations 

 were made by Keith, Barclay Smith, and T. R. 

 Elliott, which served to show that the contents 

 of the small and great intestine were separated, 

 not by a mechanical valvular apparatus as was 

 formerly supposed, but by a muscular mechanism, 

 similar in the manner of its action to a sphincter. 

 Sir William MacEwen and Dr. A. F. Hertz have 

 demonstrated the existence of an ileo-caecal 

 sphincteric mechanism in the living human body, 

 and emphasised its functional and clinical signifi- 

 cance. Yet in the text of this edition no mention 

 is made of these observations, and the erroneous 

 and antiquated description of a mechanical valve 

 is reproduced. This is the more surprising 

 because the illustrations of the ileo-csecal junction, 

 reproduced from the former edition, bear out the 

 non-mechanical nature of the ileo-caecal orifice. 



(i) The Great Ball on which we Live. Pp. 249. 

 (2) Our Good Slave Electricity. ■ Pp. 246. By 

 C. R. Gibson. (London : Seeley, Service and 

 Co., Ltd., 1915.) Price each volume, 35. 6d. 

 Mr. Gibson has attempted with considerable suc- 

 cess the solution of the old problem — how to 

 interest children and at the same time instruct 

 them. In the first volume he tells the story of 

 the earth, and invites his readers to accompany 

 him on imaginary visits to our planet before man's 

 appearance on it. The fact that at one place a 

 jelly-fish tells the story of what happened in the 

 sea, and at another a worm records its experiences 

 underground, will indicate the style of treatment 

 adopted. 



The second book describes in a similar simple 

 manner some of the achievements of electrical 

 science, and young readers will probably be led 

 by these chapters to take up serious study later. 



If it is possible to form sound elementary ideas 

 of experimental and observational science merely 

 by reading, it would be difficult to find more 

 attractive introductions than Mr. Gibson has 

 prepared. 



Brown's Marine Electrician: for Sea-going En- 

 gineers. By A. E. and A. H. Larkman. Pp. 

 XV + 244. (Glasgow: James Brown and Son. 

 Second edition, 1914.) Price 55. net. 

 In this book "the authors seek to give practical 

 information on such matters as the installation, 

 repair, and use of electric lighting, heating, and 



