REVIEWS 669 



and ways of regarding electrical phenomena in a manner that cannot but be 

 most helpful at a later stage in his studies when, as when dealing with the 

 thermionic valve, the electron can no longer be disregarded. 



The twelve chapters into which the volume is divided show a good balance 

 in the treatment of different sections of the subject. They are illustrated with 

 numerous useful diagrams and curves of experimental data. Throughout 

 the work the experimental side of the subject is by no means neglected, and 

 the importance of such means of verifjdng theoretical conclusions is every- 

 where emphasised. 



For readers in this country it is necessary to bear in mind that the author 

 is a Professor in an American University, with a consequent underlying natural 

 preference for American apparatus. Some more references and illustrations 

 of types of instruments used in other countries might with advantage have 

 been included, particularly in the last chapter on experiments. This, however, 

 coupled with the rather indifferent printing of some of the half-tone illustra- 

 tions, is the only point which can be criticised with any seriousness. For 

 convenience in reference, it is perhaps an advantage if the figures are num- 

 bered consecutively through the book, but this is a point on which personal 

 opinions may differ. 



After giving the general theory underlying radio methods as leading up to 

 " spark " telegraphy, the author considers in great detail the thermionic 

 vacuum tube, and the other methods of producing continuous waves for 

 telegraphic and telephonic signalling in Chapters VI to VIII, while the Theory 

 and Design of Antennae, Wavemeters, and Amplifiers are dealt with in the 

 following chapters (IX to XI). Particular mention may be made of the last 

 chapter (XII), which is devoted entirely to descriptions of various laboratory 

 tests that can be carried out by students in conjunction with their ordinary 

 studies in this subject. Philip R. Coursey. 



The Scientific Papers 0! the Honourable Henry Cavendish, F.R.S. Vol. I : 

 The Electrical Researches, edited by James Clerk-Maxwell, F.R.S., 

 Cavendish Professor of Experimental Physics in the University of 

 Cambridge. Revised by Sir Joseph Larmor, F.R.S. , M.P., Lucasian 

 Professor of Mathematics. Vol. II : Chemical and Dynamical, edited 

 by Sir Edward Thorpe, F.R.S., with contributions by Dr. Charles 

 Chree, F.R.S., Sir Frank Dyson, F.R.S., Sir Archibald Geikie, 

 O.M., F.R.S. and Sir Joseph Larmor, F.R.S. [Pp. xxvii + 452, 

 xii + 496.] (Cambridge : at the University Press, 1921. Price £<o net.) 

 In these two handsome volumes we have at last the most complete account 

 possible of the work of Cavendish. The Electrical Researches, which were 

 published in 1879 under the editorship of Clerk-Maxwell, are reprinted in 

 volume i, as revised by Sir Joseph Larmor. Volume ii deals with the chemical 

 and dynamical researches. It must have been a task of peculiar difficulty — 

 as it was indeed found by Maxwell originally — to obtain a satisfactory 

 arrangement and exposition of Cavendish's work as shown by his manu- 

 scripts ; for Cavendish was exceptionally prone to postpone any preparation 

 of his work for the Press, under the impetus of some new line of thought 

 which was beginning to take shape in his mind. In certain important respects, 

 volume i has brought Maxwell's account more up to date, by the addition of 

 references and footnotes. The headings of the chapters and sections and the 

 headlines of the pages give a distinctly better view of the nature and contents 

 of Cavendish's electrical work. Moreover, as is pointed out in the preface, 

 an account of his theory of a universal electrical fluid acting upon and with 

 material substances solely by attraction is of very considerable interest at 

 the present day, if only as a contrast to the more modern views of the ether 

 and its relation to molecules capable of polarisation. This volume contains 

 an interesting portrait of Cavendish, which is believed to have been constructed 



