390 



NATURE 



[February 22, 1900 



OUR BOOK SHELF. 



Exercises in Practical Physics. In two parts. By R. A. 



Gregory and A. T. Simmons. Part i. pp. vi + 200 ; 



Part ii. pp. vi + 174. (London : Macmillan and Co., 



Ltd., 1899.) 

 These two volumes contain a graduated series of physical 

 experiments, compiled with the intention of furnishing a 

 basis upon which teachers may found their courses of 

 lessons. Special attention has been devoted to providing 

 a large and diversified number of exercises exemplifying 

 each of the principles considered, and the authors have 

 also admirably succeeded in bringing together many 

 ingenious experimental methods devised by various 

 teachers of their acquaintance. Throughout both volumes 

 the insertion of numerous illustrations of the apparatus 

 in position is a great help to the correct understanding 

 of the text, and, indeed, the authors state that the de- 

 scriptive matter has been purposely limited to the amount 

 necessary for the proper working of the experiments. , 



Part i., constituting the first year's course, embraces 

 experimental work in mensuration, hydrostatics, ele- 

 mentary mechanics, and the first principles of heat. 

 The apparatus necessary for each experiment is first 

 j^iven ; then the setting up, observations to be made, and 

 finally, the deductions which are to be drawn from them. 

 The simple methods of demonstrating many of the 

 properties of matter are excellent. Without appearing 

 to be over-critical, it is impossible to avoid regretting that 

 the term " apparent loss of mass " should have been 

 used to denote the change produced on immersion of a 

 solid in water to determine its specific gravity. The 

 change is simply a partial neutralisation of the gravita- 

 tional attraction on the solid, which is detected by a 

 difference in the weights required to balance it ; but this 

 does not suggest that the mass of the body has altered. 

 This is a minor point, but the relations of mass and 

 iveight are a real difficulty to the majority of elementary 

 students. 



Part ii. is designed to serve for a second year's course, 

 and furnishes experiments illustrating the chief principles 

 of heat, light, sound, magnetism, and electricity. The 

 experiments on heat in Part i. only have reference to the 

 construction and use of thermometers, thermal conduc- 

 tivity, and radiation. To render the second part com- 

 plete, these sections are repeated in it. A series of tables 

 are given at the end, comprising most of the data re- 

 quired in the working of the course of experiments. The 

 style of originality and simplicity is repeated in this 

 second volume, and the entire course can be confidently 

 recommended to teachers of the subject. C. P, B. 



Abhandliing der Dynarnik. Von D'Alembert. Pp.210. 

 Ueber die mathematische Theorie der electrodynamischen 



Induction. Von Ricardo Felici. Pp. 121. (Leipzig : 



Wilhelm Engelmann, 1899.) 

 Under the title of "Ostwald's Klassiker der exacten 

 Wissenschaften," Messrs. Engelmann publish a series 

 of small volumes intended to supply what has been for 

 some time a want in our systems of scientific education, 

 namely, the want of historical knowledge and of a proper 

 appreciation of the great works on which our scientific 

 theories have been built up. 



Every student of mechanics has heard of " D'Alem- 

 bert's Principle," but in these days few take the trouble 

 to ask who D'Alembert was, how he discovered his 

 principle, or where and when he published it. The re- 

 production of the "Traite de JDynamique" (1743) will 

 do much, not only to enlighten students on these points, 

 but to give an insight into the state of knowledge 

 existing at the time the principle was discovered. 

 Those accustomed to the modern style may, for ex- 

 ample, be interested to see D'Alembert's equations 

 written in the form d^x = a dt'^. The present volume 

 has been translated and edited by Arthur Korn, who 



NO. 1582, VOL. 61] 



has supplied a biographical notice of D'Alembert and 

 numerous explanatory notes, chiefly mathematical. 



The second volume is a translation of the papers 

 published by Felici, in 1854-1855, in the " Annali della 

 Universita Toscana." After Faraday's great discovery, 

 he and others confirmed the quantitative law of mag- 

 netic induction in a number of cases, and we learn that 

 Felici's chief service to the cause of science was that he 

 was the first (Gaugain following two years later) to 

 verify the laws of induction between two voltaic currents. 

 The present volume has been translated by Dr. B. 

 Dessau, of Bologna, and edited by E. Wiedemann. It 

 is No. 109 of the series, D'Alembert's work being 

 No. 106. 



i£quilibre des Systcmes Chimiques. By J. Willard Gibbs. 



Translated by Henri le Chatelier. Pp. xii -I- 212. 



(Paris : Georges Carrd and C. Naud, 1899.) 

 This is a translation of Prof. Gibbs's paper on the equi- 

 librium of heterogeneous systems. Part i. (chemical 

 phenomena), published in the Transactions of the Con- 

 necticut Academy in June 1876. It is the second of the 

 three classical thermodynamic memoirs by Prof Gibbs, 

 and is at the same time the best known and the most 

 important, being the paper in which the well-known " law 

 of phases" was first enunciated. Prof. Le Chatelier has 

 added several explanatory footnotes, and an introduction 

 summarising a few of the principal new laws and notions 

 of experimental interest, for which the foundations have 

 been laid by Prof. Gibbs in the memoir in question. This 

 summary will be useful in giving readers some idea of the 

 phenomena to which Prof Gibbs's conclusions are 

 applicable, a point of no small difficulty in reading the 

 original paper. Prof Le Chatelier translates " hetero- 

 geneous systems" by "systemes chimiques" on the 

 ground that " heterog^ne " in French refers to a differ- 

 ence of physical rather than chemical state. The 

 translator's own researches are sufficient guarantee of 

 his eminent qualifications for the work that he has 

 accomplished in the preparation of this French edition. 



Elementary Trigonometry. Oliver and Boyd's " Educa- 

 tional Series." By A. J. Pressland and Charles 

 Tweedie. Pp. viii + 342. (Edinburgh: Oliver and 

 Boyd, 1899.) 

 This text-book is not intended to meet the requirements 

 of any special syllabus, but is simply an elementary 

 course on trigonometry. On this account, the authors 

 have had a free path to pursue, and they have produced 

 a well-arranged course on the subject, which will be 

 found most useful for those who are getting up this 

 subject. The range of the book may be gathered from 

 the statement that the three parts into which it may be 

 divided deal with, first, the definitions and properties 

 of the trigonometrical ratios concluding with the Addition 

 Theorem ; second, the application to computation and 

 to the geometry of the triangle and quadrilateral ; and, 

 last, to the inverse functions and other applications. 

 The student is made thoroughly acquainted with log- 

 arithms and the application of mathematical tables, and 

 in the explanation of the rule of proportional parts Prof. 

 Chrystal's method has been followed. The examples are 

 numerous and suggestive. 



A Century of Science ajtd other Essays. By John Fiske. 

 Pp. vii-F477. (London: Macmillan and Co., Ltd., 

 1899.) 

 The main title of this volume is entirely misleading, for 

 it is only the title of one of fourteen essays. It gives 

 the idea that the advances of science during the present 

 century are dealt with, but what science is in the work is 

 of a very popular character, most of the contents being 

 concerned with subjects which, with the most liberal 

 interpretation, must be placed outside the bounds of 

 natural knowledge, and therefore outside our province 

 of comment. 



