Notices respecting JSeiv Books. 1131 



Introduction to the Mathematical Theory of the Conduction of Heat 

 in Solids. By H. S. Caeslaw, Professor of Mathematics in the 

 University of Svdney, formerly Fellow of Emmanuel College, 

 Cambridge. (Macmillan & Co. 2nd Edition, 305. net. 1921.) 



The first edition of the work, entitled ' Eourier's Series and 

 Integrals and the Mathematical Theory of the Conduction of 

 Heat,' was first published in 1906. A new edition of the part 

 dealing with Eourier's Series and Integrals was issued early in 

 1921, and the present volume forms a new and revised account 

 of the part dealing with the Conduction of Heat. There are 

 various additions to the subject matter, including a discussion of 

 all the important boundary conditions associated with the Equa- 

 tion of Conduction, which is of interest also to those who are 

 concerned with the application of modern analysis to the solution 

 of the differential equations of mathematical physics. We also 

 remark the inclusion of new matter in the chapters which deal 

 with the sphere and cone, the circular cylinder, and the chapter 

 about Green's theorem, amongst others. 



Beyond the many minor improvements which make this new 

 issue of the work of 1906 of added value, the considerable addi- 

 tions and the inclusion of a large amount of new material make 

 it of real importance as a new work. 



The Aggregation and Flow of Solids. By Sir Geoege Beilby. 

 Pp. xv -f 256. Macmillan. Price 20s. net. 



In this book Sir George Beilby has collected together the very 

 interesting work which he has carried out during the past 

 twenty years on the coexistence of the amorphous and the crys- 

 talline states in solids, aud the relative influence of the two 

 modifications on the mechanical and other physical properties of 

 metals. He has worked away from the beaten track : the pro- 

 blems which he attacks receive little attention in the ordinary 

 text -books on the properties of matter, although they are of great 

 interest to the physicist as well as to the metallurgist. The study 

 of the optical properties of thin metal leaf, to which he contributes 

 some instructive experiments, has received little attention since 

 the time of Faraday. His careful work on the hardening by 

 wire-drawing, and the effect of annealing hard-drawn metals at 

 different temperatures — work which incidentally brings out a close 

 parallelism between the thermoelectric force against a standard 

 metal and the mechanical strength of the metal in its different 

 modifications, and so indicates the importance of the thermoelectric 

 force as an index of the change of state — -simplifies a complex 

 problem of considerable practical importance which was long 

 neglected in this country. The extreme hardness of the amor- 

 phous phase and the effect of dissolved gases on the crystalline 



