Chemistry and Physics. 327 



11. Water vapor in the oven heightens the intensity of metal 

 lines. — Ann. der PhysiJc, No. 2, pp. 360, 381. j. t. 



10. The Dynamics of Particles and of Rigid, Elastic, and 

 Fluid Bodies ; by A. G. Webster. Pp. xii + 588. Leipzig, 1904. 

 (B. G. Teubner.) — This book is a welcome addition to the long 

 list of text-books on mechanics. The gap between the element- 

 ary treatises and the classics of the science is wide and difficult 

 to fill. The mere extent of the field to be covered makes the 

 tasks of compression and selection as important as they are 

 difficult. And at the same time the voluminous literature in each 

 separate department makes a single-volume introductory work 

 giving adequate treatment of the methods (necessarily at the ex- 

 pense of many of the applications) very highly desirable. It is 

 this task that Professor Webster has set himself, and, in the 

 opinion of the writer, very successfully performed. 



The field covered is sufficiently indicated in the title. Kine- 

 matics is not treated as a separate subject, but is taken up as 

 introductory to each subdivision of dynamics in order. The 

 chapters on the general principles and methods of advanced dy- 

 namics are especially to be commended. Students of physics are 

 too often insufficiently acquainted with such matters as general- 

 ized coordinates, the calculus of variations, Hamilton's principle, 

 etc.; or if at all it is an academic and not a working knowledge 

 which they possess. For all such the above-mentioned chapters 

 should furnish a valuable guide. The section on rigid dynamics 

 might possibly be criticized as being disproportionately full in 

 the treatment of gyroscopic motion : a fault, if it be a fault, 

 both to be expected and condoned in an author whose original 

 contributions to this subject are so well known. The general 

 theory of the potential function forms the introduction to the 

 section on the dynamics of deformable bodies. This chapter 

 follows very closely the presentation of the same subject in the 

 author's well-known " Theory of Electricity and Magnetism." The 

 remaining chapters of this section, — those on elasticity and hydro- 

 dynamics, — are, relatively to their importance, the shortest in the 

 book. They form, however, an excellent introduction to the very 

 extensive literature of these topics. 



Typographically and in the matter of illustrations the book is 

 unusually excellent. It appears as the eleventh in the Teubner 

 collection of text-books of the mathematical sciences, l. p. w. 



11. Experimentelle Untersuchung von Gasen ; by M. W. 

 Travers. German translation by T. Estreicher. Pp. xii + 372. 

 Braunschweig, 1904 (Friedrich Vieweg und Sohn). — This German 

 edition of Professor Travers' invaluable " Experimental Study of 

 Gases " is not a mere translation, but presents considerable 

 matter that is not contained in the English edition of 1902, in 

 addition to being largely rewritten. The book is so well known 

 that it is only necessary here to point out some of the additions 

 which appear in this edition. The chapters on the liquefaction 



