May 30, 1 907 J 



NA TURE 



99 



PRACTICAL PHYSICS. 



A Text-book of Practical Physics. By Dr. William 

 Watson, F.R.S. Pp. xvi + 626. (London: Long-- 

 mans, Green and Co., 1906.) Price gs. 



SMALL books on practical physics have been very 

 plentiful of recent years since the subject has 

 taken a place in schools, but the number of large 

 and complete treatises in English embracing all 

 branches is still few. Lookine back, the present 

 writer can recall to mind as the earliest an English 

 translation of Kohlrausch's " Leitfaden " by Waller 

 and Procter, published in 1873, and the book, in two 

 volumes, by E. C. and W. H. Pickering, on 

 " Physical Measurements," published in 1873 and 

 1876. The latter was founded on the course of prac- 

 tical physics conducted at the Boston School of 

 Technology by the authors, who have since become 

 two of the foremost astronomers of the United 

 States. After these two books we have to pass to 

 18S4, when Glazebrook and Shaw's " Practical 

 Physics " was published. It was founded on the 

 elementary practical course conducted in the Caven- 

 dish Laboratory, Cambridge, and is still in use, and 

 is perhaps the one book on practical physics which 

 has had the widest influence on English laboratory 

 methods. All these books placed the side of accurate 

 measurement before the student, and omitted demon- 

 strations and showy lecture experiments from their 

 contents. They were written for the student's use in 

 the laboratory, and formed a great advance on the 

 descriptive books in which physics and chemistry were 

 mixed, and which constituted the science of the 

 popular lecturer of the early and middle Victorian 

 period. 



Later came a treatise by Balfour Stewart and Gee, 

 which contained very detailed descriptions of experi- 

 ments in properties of matter and in magnetism and 

 electricity. The book came from the Owens College 

 Laboratory at Manchester, and was, we believe, the 

 first in which precise descriptions of magnetic 

 methods appeared. Then from the same laboratory, 

 published in 1901, we received a course of experi- 

 ments by Schuster and Lees. This book contained 

 only selected exercises from different branches, as the 

 authors considered it sufficient to put before the 

 students a short course of typical experiments. 



Now we have before us the latest book on the 

 subject, a complete treatise by Prof. W. Watson, of 

 the Royal College of Science, South Kensington, 

 and it is framed on a plan different from those we 

 have mentioned. Prof. Watson calls it a book of 

 reference for the student when working in the labor- 

 atory. It is not intended that any one class shall 

 work through all the experiments, but that the 

 teacher shall select from it according to the require- 

 ments of the pupil and the resources of the labor- 

 atory. The descriptions and hints apply to almost 

 any form of apparatus suitable for the particular 

 experiment. 



.As to the contents of the book, the first chapter 

 \0. I 96 I, VOL. 76] 



contains a general discussion of the theory of the 

 treatment of experimental data, the use of log- 

 arithmically divided papers, the consequent deter- 

 mination of exponential laws, and the description 

 of calculating machines, including arithmometers 

 and planimeters. It would take too long to go in 

 detail through the entire contents of the book, but 

 to illustrate its scope we may mention that thirty- 

 four chapters are required to cover the whole field 

 of physics. At chapters xxxii. and xxxiii. we are 

 brought to magnetic induction and permeability. 

 The comparisons and absolute measures of the induc- 

 tion coefficients are treated very fully indeed, and in 

 chapter xxxiv. the use of the Dolezalek form of 

 quadrant electrometer and the measure of the satura- 

 tion current through air in the presence of uranium 

 oxide are described. It will be evident that the 

 author has made the field covered by the book very 

 wide, and has brought into prominence the methods 

 of recent research. We cannot omit to mention the 

 excellent chapters which occur earlier on magnetic 

 measurements and on the constants of terrestrial 

 magnetism, subjects in which the author is a well- 

 known authority. 



At the end an appendix, probably one of the most 

 useful parts of the book, contains an account of 

 laboratory arts, glass-blowing, working in quartz, 

 silvering, and other necessary processes. To these 

 descriptions we feel very confident in referring the 

 student, for the great excellence of the Royal College 

 of Science in the branch of laboratory arts is well 

 known. There is also a collection of useful 

 tables. 



The book is printed in verv clear tvpe, and the 

 diagrams are excellently drawn. The whole setting 

 of the book is of the same high standard as that of 

 Prof. Watson's large work on physics. 



Judging from the short experience which we have 

 had of the use of the book in the laboratory, we may 

 conclude by saying that it has proved most accept- 

 able to the students, and we have been able to re- 

 commend it to those studying for university degrees. 

 Schoolmasters should have a copy for reference and 

 for their higher work. S. S. 



CLASSIFICATION OF SOUTH AFRICAN 

 STONE IMPLEMENTS. 



The Stone Implements of South Africa. Bv J. P. 

 Johnson. Pp. 53. (London : Longmans, Green 

 and Co., 1907.) Price 7s. 6rf. 



'T'lil.S is a useful addition to our acquaintance with 

 the Stone age of South .Africa. Mr. Johnson 

 has exceptional qualifications for the task he has 

 undertaken, being a trained geologist and surveyor, 

 and a competent observer in the field, whilst his 

 travels have given him the opportunity of examining 

 large sections of South Africa, the collections of 

 implements described having been obtained bv him- 

 self from localities so wideh' separated as the valley 

 of the Zambezi, the Transvaal, Prieska, in the north- 



