614 Notices respecting New Books. 



The Dynamical Theory of Gases. By J. H. Jeans, M.A. Cambridge 

 University Press, 1904. 



Seyeeal excellent treatises on different departments of Natural 

 Philosophy have been recently issued by the Cambridge University 

 Press ; and the present volume cannot fail to take high rank among 

 the standard works and memoirs on the dynamical theory of gases. 

 After an introductory chapter stating the nature of the problem, 

 the author develops the foundations of the theory in four chapters 

 on the Law of Distribution, giving not only the usual statistical 

 theory, but also his own investigation based upon the methods of 

 general dynamics applied to space of n dimensions. This leads to 

 a concise demonstration of Maxwell's equipartition theorem. The 

 whole of Chapter V., dealing with the extension of the theory to 

 molecules of the most general conservative type, is of the highest 

 interest, and paves the way for valuable applications in later 

 sections. Two chapters then follow on the physical properties of 

 gases and the extent to which they can be deduced from the 

 dynamical theor}^. The significance of the failure of the theory to 

 explain the relation between the specific heats is ably discussed, and 

 leads to the introduction of the dissipative function and the investi- 

 gation of non-conservative systems along the fines already laid down. 

 The last nine chapters are grouped together under the title " Free 

 Path Phenomena," and take up questions of viscosity, conduction, 

 diffusion, propagation of sound, the problem of the constancy or 

 dissipation of planetary atmospheres, and other topics. The 

 reader who may have no special interest in the mathematical 

 methods themselves, will find a great deal worthy of his con- 

 sideration. All the known physical properties of gases are 

 introduced as illustrations of the general theory, but apart from 

 this theory in its severe analytical form there is a physical as dis- 

 tinguished from a mathematical charm about the book, which should 

 give it a place in the library of every real student of physical and 

 chemical science. We do not know which is the more to be 

 admired, the mathematical power or the physical insight of the 

 author. This book is a model of fine mathematical printing. 



Die EntivicTcelung der Elektrischen Messungen. Von Dr. 0. Fbolich. 



Mitl24 eingedruckten Abbildungen. Braunschweig : P. Vieweg 



und Sohn. 1905. Pp. xii + 192. 

 This most interesting volume, which forms No. 5 of the series 

 known as Die Wissenschaft, contains an account of the evolutionary 

 process by which our present electrical measuring instruments and 

 methods of measurement have come into being. The book is 

 divided into tw T o sections ; the first section dealing with galvanometers, 

 switchboard instruments, resistance coils, energy meters, and 

 recording instruments, while the second section is devoted to 

 methods of measurement, and deals more particularly with re- 

 sistance and inductance measurements. The subject is treated 

 in a very lucid and interesting manner, and the book should prove 

 most useful to electrical engineers and physicists. 



