August 16, 1901.] 



SCIENCE. 



259 



without deduction, as statements of physical 

 laws. For elementary students this is often 

 necessary, and the mathematical formulation is 

 quite as desirable as verbal expression. State- 

 ments of fact are so generally accurate that 

 the author can afFoi:d to be reminded of an error 

 on page 188, where he has defined 'discord' 

 more sharply than the facts warrant, by failure 

 to recognize Mayer's law, which expresses the 

 duration of the residual auditory sensation as a 

 function of vibration frequency, the equation 

 being expressible in a curve which Professor 

 Mayer published in 1894 {Am. Jour. Sci., Jan., 

 1894). In the chapter on electricity a very clear 

 elementary discussion is given of such recent 

 developments as the "VVehnelt interrupter, self- 

 regulating vacuum tubes, and wireless teleg- 

 raphy. The book is abundantly worthy of 

 commendation. 



Snyder and Palmer's little volume on ' Prob- 

 lems in Physics ' is a good collection intended 

 for use in secondary schools, every problem 

 having borne already the test of class use. For 

 the convenience of overworked teachers it seems 

 very desirable that a collection of answers 

 should be published. Any competent teacher 

 can work out all these problems for himself ; 

 but in the majority of cases it is only necessary 

 that the pupil should work out such as have 

 been assigned him. The teacher may assume 

 the labor of verification wherever this may seem 

 desirable, but he should not be subjected to un- 

 necessary burdens. 



Tory and Pitcher's 'Manual of Laboratory 

 Physics ' constitutes the course of elementary 

 physics given in the laboratory of McGill Uni- 

 versity, Montreal. For each experiment there 

 is a list of references, a list of apparatus, a short 

 statement of the theory involved, practical di- 

 rections, and a tabulated example. The ar- 

 rangement is excellent, and the deductions of 

 formulae under the head of * Theory of Ex- 

 periment ' constitute a good review of princi- 

 ples which the student is supposed to have mas- 

 tered before entering the laboratory. Like all 

 manuals of this kind, the book is a collection 

 of the separate manuscripts prepared by the 

 authors, while they were associated together as 

 demonstrators in the physical laboratory of Mc- 

 Gill University. 



The manual by Schuster and Lees covers 

 much the same ground as that of Tory and 

 Pitcher, but the instructions given are more 

 discursive and the book is not so well method- 

 ized. For somewhat advanced students, who 

 are not so dependent as the beginner is apt to 

 be on the oral guidance of an instructor, the 

 book will be found very valuable. The authors 

 have not aimed at completeness, ' being con- 

 vinced that a student learns more by carefully 

 working through a few selected and typical ex- 

 ercises, than by hurrying through a large num- 

 ber, which are often but slight modifications of 

 each other.' They attach great importance to 

 neat and accurate work, recorded in good form. 

 The introductory chapter includes a satisfac- 

 tory discussion of errors of observation. 



The acceptability of a new book depends 

 jointly on the author and the publisher. On 

 opening it the reader expects to be able to con- 

 sult any page without doing roughly by hand 

 what the publisher ought to have done neatly 

 by machinery. The manual just noticed is 

 mechanically unsatisfactory, because the jDub- 

 lishers have been guilty of the unreasonable 

 slovenliness of issuing it with edges untrimmed. 

 This fault is bad enough in the case of a maga- 

 zine, where the insufficient excuse is to make 

 allowance for future binding ; but in the case 

 of a book already bound it is inexcusable. 

 American publishers have for the most part 

 risen superior to such a senseless fad ; but in 

 England it seems still to hold sway. The pres- 

 ent volume of 368 pages is most readily com- 

 mended to any one who is willing to cut its 

 leaves, to submit to the inconvenience of frayed 

 edges, and to endure the untidiness of such 

 edges after the book has been in use for some 

 time in the laboratory. 



W. LeConte Stevens. 



Lehrbueh der vergleichenden Anatomie der ivir- 

 hellosen Thiere. Von Arnold Lang. Zweite 

 umgearbeitete Auflage. Zweite Lieferung. 

 Protozoa, vollstiindig neu bearbeitet von 

 Arnold Lang. Jena, G. Fischer, 1901. 

 Mk. 10. 



That this account of the Protozoa in the sec- 

 ond edition of Lang's well-known 'Lehrbueh' 

 is practically a new work is at once evident on 



