REVIEWS 329 



more detailed. A welcome novelty is Chapter III, Constructions with Ruler 

 and Compasses, which explains, for instance, why regular polygons of 5 and 

 17 sides can be constructed, while those of 7 or 9 cannot. Chapter VI deals 

 with the isolation of the real roots, with the theorems of Descartes, Sturm, 

 and Budan ; and Chapter VII with Horner's and Newton's methods for the 

 solution of numerical equations ; both are workmanlike and scientific. There 

 follow chapters on determinants, symmetric functions and elimination, and, 

 in an appendix, a proof of the fundamental theorem on the lines of Cauchy. 

 There are numerous examples, references, and historical notes, and an adequate 

 index. 



It is to be hoped that the book will have a wide circulation. F. P. W. 



Readable School Physics. By J. A. Cochrane, B.Sc. [Pp. xi + 131. 8 full 

 plates and 62 illustrations.] (London: G. Bell & Sons, 1922. Price 

 2s. 4^. net.) 



The author in his preface states that this is an attempt to humanise 

 elementary physics without popularising it. He seems, however, to some 

 extent to have fallen between two stools. While attempting on the one 

 hand to give an historical and human basis to the study of science, he has 

 not produced a textbook or course of study wliich could be followed by 

 the average teacher. As a supplementary reader the book undoubtedly 

 will be of value to the practical teacher or student, but it is difficult to judge 

 from a reading of the book at what stage or stages in the school course the 

 various parts of the book should be read. An instance of this difficulty of 

 using the book to supplement or supply altogether a school course is seen 

 in the chapter on Surveying. Many schools are now having a graded course 

 of surveying as part of their mathematics. The author rightly includes a 

 description of the simple anglemeter, but gives no explanation of the optical 

 part of the instrument. He states: " A slight knowledge of the laws of 

 light (which branch of physics you will study later) enables us to find the 

 angle required. As a matter of fact, the angle is simply read off from the 

 instrument." Surely this is an excellent opportunity for teaching the 

 elementary law of physics referred to. It seems such a pity still to adhere 

 to the old habit of giving children their scientific knowledge in separate and 

 water-tight compartments. 



W. C. B. 



CHEMISTRY 



A Dictionary of Applied Chemistry. Vol. III. By Sir Edward Thorpe, C.B., 

 F.R.S., assisted by Eminent Contributors. Revised and enlarged 

 edition, with illustrations. [Pp. viii + 735.] (London : Longmans, 

 Green & Co., 1922. Price 605. net.) 



This dictionary is too well known to call for a description of its scope and 

 arrangement. In the new edition now appearing the work has undergone 

 considerable enlargement and revision; as examples may be quoted the 

 expansion of the article on Explosives from 72 to 98 pages, on Fermentation 

 from 35 to 40 pages, and on Glycerine from 13 to 17 pages. The article on 

 Coal-gas, though not markedly longer in the total number of pages, has been 

 revised and improved by economy in the space devoted to questions now of 

 less importance, such as the determination of illuminating power, and expan- 

 sion in other directions. Although some of the shorter articles have been 

 reprinted unchanged, there is no doubt that the present edition constitutes 

 an improvement on the previous one and represents a great deal more than a 

 reprint with minor corrections. It is a matter of doubt how far illustrations 

 of plant other than purely diagrammatic ones are of use in a book of this 

 kind, which cannot aim at giving the reader more than a general survey of 



