REVIEWS 523 



PHYSICS 



A Manual of Practical Physics. By H. E. Hadley, B.Sc. [Pp. viii + 265, 

 with 153 illustrations and diagrams.] (London: Macmillan & Co., 1916. 

 Price 3-y.) 



This is just a collection of some 160 recipes for performing experiments in Physics 

 up to intermediate pass standard. Very excellent recipes they are too, the author's 

 reputation as a writer of elementary text-books is a sufficient guarantee of that, 

 and the book can be strongly recommended to the notice of school teachers who 

 have large classes, so that several different experiments have to be supervised at 

 the same time. Such ample instruction is given both as to the manipulation and 

 mode of entering results in the laboratory book that students of ordinary ability 

 should not require any further assistance in these respects. It will be necessary, 

 however, for the teacher to explain the why and wherefore of the many minute 

 experimental details which the author gives so liberally, but too often without any 

 explanations being even hinted at. That is the disadvantage of the recipe method, 

 for the student at this stage cannot discover reasons for himself in a scientific 

 fashion, and, in the absence of proper guidance, will either guess, which is 

 unscientific, or carry out his instructions mechanically, which subverts the chief 

 purpose of his study. In the hands of a skilful teacher these disadvantages will 

 not arise, and the method is safe enough. 



All branches of Physics are dealt with, and a brief treatment of preliminary 

 measurements makes the book suitable for those who are commencing their study 

 of the subject. The author has exercised a wise discretion in his choice of experi- 

 ments ; he has, for example, refrained from including any of the usual and 

 misleading experiments on the magnetic force due to isolated magnetic poles. 

 Experience shows that, once the student is permitted to apply the inverse square 

 law to practical measurements with long magnets, he is very apt to apply it always. 

 On the other hand, simple quantitative measurements can be made so easily in 

 electrostatics that one or two should have been included. The use of cotton 

 wool as a lagging for calorimeters is again advocated in this book. This is 

 much to be regretted, for not only does it introduce quite unknown errors, but it 

 almost always gets wet, and then the last state is more than ever worse than 

 the first. 



D. Orson Wood. 



CHEMISTRY 



A System of Physical Chemistry. By Prof. William C. McC. Lewis, 

 M.A. (R.U.I.), D.Sc. (Liv.). In two volumes. Vol. I. [Pp. xi + 523, with 

 diagrams.] Vol. II. [Pp. vii + 552, with 98 diagrams.] Text Books of 

 Physical Chemistry. Edited by Sir William Ramsay, K.C.B., F.R.S. 

 (London : Longmans, Green & Co., 1916. Price gs. each net.) 



This, the most recent addition to the Ramsay series of Physical Text-Books, is at 

 the same time the largest and most comprehensive number yet published in this 

 admirable series. Unlike its well-known predecessors, its scope is not limited to 

 any one definite branch of physical chemistry, but embraces the whole subject so 

 far as advancement has been made in this domain of science. To all acquainted 

 with the enormous strides which physical science and its inter-relations with 

 chemistry have made in latter years, it will be judged no mean feat of the author 

 to have dealt so adequately and tersely with all its branches, and to have incor- 

 porated the large mass of new work within the confines of these two new volumes . 



