Chemistry and Physics. 73 



these introductory chapters may serve as a sort of general intro- 

 duction to Mathematical Physics." 



The author's style is very concise but lucid and interesting. A 

 notable feature of his book is the admirable character of the dia- 

 grams both in clearness and sightliness. Professor Webster is to 

 be congratulated upon having produced an excellent book, which 

 is certain to be used and valued. c. s. h. 



14. Light and Sound • by E. L. Nichols and W. S. Franklin. 

 pp. 201. New York, 1897. (The Macmillan Company.) — The 

 present volume is the third and concluding part of the authors' 

 Elements of Physics. The work as a whole, though intended as 

 a college text-book, is rather a digest than a treatise upon this sub- 

 ject, and as such will doubtless find its widest circle of readers 

 among students preparing for examination, or seeking for the 

 theory of the apparatus they must use in the laboratory. 



The character of the last part is more freely descriptive than 

 its predecessors, the phenomena and the laws governing them 

 being very properly given more prominence than the formulas 

 which aid in their statement. A commendable feature of the 

 book is the introduction of Huygen's Principle at the beginning, 

 and a development in general of the subjects of reflection and re- 

 fraction as modifications of a wave-surface at the boundary of 

 different media. There are, however, dreary lapses into "rays" 

 and Optic Geometry in the discussion of mirrors and lenses 

 where the relation between the luminous point and its image is 

 stated, and the reader told that by certain substitutions the given 

 expression may be reduced to an identity. As far as possible the 

 objective wave phenomena of sound and light are treated side by 

 side. Diagrams of a simple character are lavishly distributed 

 throughout the book, and average about one to a page. 



Among minor criticisms it may be suggested that fig. 485 

 would be made much clearer by perversion and rotation through 

 a right angle, and that saturation should be admitted to co-ordi- 

 nate rank with the other characteristics of a color sensation on p. 

 101. It is questionable whether anything is gained by such 

 liberties with well-recognized scientific usage as radius of curvation 

 for radius of curvature, p. 32 ; allotropic for anisotropic, p. 128, 

 unless perchance this is a misspelling of seolotropic ; resonant dis- 

 persion for anomalous dispersion, p. 145 ; luminescence for simple 

 fluorescence, p. 146. 



The chapter on Photometry and the one on Musical Intervals 

 and Scales, which brings the work to a close, though brief, are 

 especially good. f. e. b. 



