REVIEWS 147 



practical character and forms a very complete contrast with the course 

 prescribed by the syllabus of our Head Master's Association with its deadly 

 dull measurements of distances, area, volumes, relative densities, and so 

 forth, which is probably responsible for much of the present-day indifference 

 to science in this country. Youngsters following Mr. Good's course are 

 kept in constant touch with their experience outside the laboratory. They 

 experiment with a pendulum and then assemble and study the parts of a 

 dissectible clock. They study liquid pressure (rather casually it must be 

 admitted) by comparing the heights of the water and mercury columns 

 which balance in a U-tube and proceed to measure the pressure of the gas 

 supply, the water supply, and the blood in their own arteries ; they make 

 up models of various kinds of pumps, and even of an hydraulic elevator, 

 with simple glass apparatus. In like manner they make models of various 

 types of hot- water systems, they test gas and water meters, and are initiated 

 into the mysteries of the vacuum-cleaner, the sewing-machine, electric 

 motors and dynamos, photography, etc., finishing up with quite a thorough 

 investigation of the working of a Ford car ! 



The book has been written with an eye to the needs of the teacher ; there 

 is a complete specification of all the apparatus required, with the reference 

 numbers in the catalogues of the appropriate manufacturers and the approxi- 

 mate cost. There is even a list of books for the laboratory bookshelf, with 

 a statement of the number of copies of each required ! A boy worldng 

 through a selection of the experiments described in the book and honestly 

 attempting to answer the questions set at the end of each experiment (otherwise 

 the course would degenerate into play) should obtain an intelligent know- 

 ledge of the mechanical and electrical world around him. He would know 

 what every boy should know on leaving school for ordinary life ; but this 

 knowledge would be qualitative only, and would need to be supplemented 

 by a good deal of training in the elements of accurate and systematic physical 

 measurement to make it suitable as a preliminary to work in the technical 

 college or university. 



D. O. W. 



The Mathematical Theory of Electricity and Magnetism. By J. H. Jeans, 

 M.A., F.R.S. [Pp. viii + 627, with 138 figures. Fourth Edition.] 

 (Cambridge : at the University Press, 1920. Price 24s. net.) 



A Text-book of Physics. By W. Watson, C.M.G., D.Sc, F.R.S. [Pp. xxvi 

 + 976, with 580 diagrams and figures.] Seventh Edition, revised by 

 Herbert Moss, M.Sc, D.I.C. (London : Longmans, Green & Co., 

 1920. Price 21S. net.) 



Prof. Jeans' s book on Electricity and Magnetism is so admirably suited to 

 the needs of the physicist who desires a treatment rather more advanced 

 than that provided by Sir J. J. Thomson's Elements, and who, at the same 

 time, is unable to bring to its study the equipment of the expert mathe- 

 matician, that it is not surprising that a fourth edition should already be 

 demanded. The main changes in the new edition consist in a rearrangement 

 of the later chapters dealing with the Electromagnetic Theory and the 

 Motion of the Electrons and, in addition, an entirely new chapter on " Rela- 

 tivity " which the author hopes " will provide a suitable introduction . . . 

 for the student who approaches the subject for the first time equipped with 

 such knowledge of general electrical theory as can be gained from the rest 

 of the book." In this short notice we can only say that the matter in this 

 chapter is presented to the reader in a style which, for lucidity and concise- 

 ness, loses nothing by comparison with the high standard set by the treatment 

 of the other branches of the subject. 



