368 Scientific Intelligence. 



Thermodynamic Laws. While the book is free of the engineer- 

 ing slant of the preceding volume on Electricity it lays an excel- 

 lent foundation for Heat Engineering. f. e. b. 



8. Matter and Motion; by J. Clerk Maxwell. Pp. x, 163. 

 London, 1920 (Society for Promoting Christian Knowledge). — 

 The present interest in the foundations of Mechanics makes this 

 an opportune time for a new printing of Maxwell 's well known 

 little treatise on the principles of dynamics. It is edited by Sir 

 Joseph Larmor who has added notes, a chapter on the Equations 

 of Mition of a Connected System from the author's Electricity 

 and Magnetism, and two appendices. The first of these treats 

 of the Relativity of the Forces of Nature. The editor's discus- 

 sion of the Einstein theory is given from a refreshingly detached 

 point of view compared to the dogmatism of its avowed protag- 

 onists. 



The second appendix develops the wider aspects of the Princi- 

 ple of Least Action. The book is further enriched by the repro- 

 duction of a hitherto unpublished portrait of Maxwell. 



F. e. b. 



9. Mechanical Sciences Tripos; Pp. 57. Cambridge, 1920 

 (Cambridge I^niversity Press). — A pamphlet containing reprints 

 of the papers set in Applied Mechanics, Heat and Heat Engines, 

 Theory of Structures, and Electricity, during the years 1912, 

 1913, 1914, 1915, and 1919. They contain a mine of suggestions 

 for teachers who may desire to test the proficiency of honor 

 students. f. e. b. 



10. A Text Book of Physics; by W. AVatson. Pp. xxvi, 976. 

 London, 1920 (Longmans, Green & Co.). — Extended treatises on 

 Physics in English such as are available in German or in French 

 do not exist, but that there is a considerable demand for a full 

 one volume text is evidenced by the issue of a seventh edition of 

 Watson's Physics. Notices of the second and the fifth editions 

 have already appeared in this Journal (see 9, 296, 1900 and 35, 

 104, 1913). 



After the death of the author in war service, the revision was 

 entrusted to H. Moss, lecturer in Physics at The Imperial College 

 of Science and Technology of London, who has corrected the 

 values of the more important physical constants, and supplied 

 material for some of the lacunae which existed in the earlier edi- 

 tions. 



The new matter amounts to twenty-three pages distributed over 

 thirty or more topics, among which maj^ be noted : the McCleod 

 gauge. Moduli of Elasticity, Callendar's constant pressure air 

 thermometer and the constant flow calorimeter, sound ranging, 

 the interferometer, the echelon grating, Gauss's theorem, Kirch- 

 hoff 's laws, the d'Arsonval galvanometer, parallel connection of 

 condensers, A. C. equations, and reflections of X-rays. 



A conspicuous omission is any reference to crystal detectors, 

 or to the thermionic vacuum tube. Possibly room should also 

 have been found for the resolving power of a prism. The book 



