PROPERTIES OF MATTER 229 



and state in terms of the absolute temperature. A German translation by 

 Dr Ernst Lecher was published in 1885 (Wien, Toeplitz und Deuticke). 



The book on Light (second edition 1889 ; third edition 1900) was based 

 on the article " Light " which he supplied to the ninth edition of the 

 Encyclopaedia Britannica. Many paragraphs are identical in the two 

 publications ; but the article contains a sketch of Hamilton's Characteristic 

 Function which does not appear in the book ; while the book contains an able 

 discussion of Radiation and Spectrum Analysis, which are done under separate 

 headings in the Encyclopaedia. The mathematical discussions are of a higher 

 order than in Heat, the geometrical theorem on which he finally builds the 

 explanation of the rainbow being especially worthy of note. Particularly 

 interesting are the quotations from Newton, Huyghens, and Laplace with 

 reference to the undulatory and emission theories of light. 



Of these text-books written by Tait on different branches of natural 

 philosophy perhaps the most characteristic is the Properties of Matter (1885, 

 successive editions, 1890, 1894, 1899 and 1907, the last under the able 

 editorship of Professor W. Peddie). A German translation by G. Siebert 

 was published in 1888 (Wien, A. Pichler's Witwe und Sohn). The Properties 

 of Matter is the book which will best recall to his former students the 

 personality of Tait as a lecturer. It embodies much of the earlier half of 

 the course of study through which Tait gave his many students a " common 

 sense view of the world we live in." 



The headings of the chapters show the scope of the book, concerning 

 which Lord Rayleigh in his review (see Nature, August 6, 1885, Vol. xxxn) 

 remarked that it was not easy to give a reason why electric and thermal 

 properties of matter should be excluded. The reason is undoubtedly historic, 

 the phrase " Properties of Matter " dating from the time when the mechanical 

 ponderable matter was distinguished from the imponderables heat, light, 

 electricity and magnetism. The first three chapters are devoted to a dis- 

 cussion of what matter is, and contains lively criticism of the metaphysicians. 

 Then come Time and Space ; Impenetrability, Porosity, Divisibility ; Inertia, 

 Mobility, Centrifugal Force ; Gravitation ; Deformability and Elasticity ; 

 Compressibility of Gases and Vapours ; of Liquids ; Compressibility and 

 Rigidity of Solids ; Cohesion and Capillarity ; Diffusion, Osmose, Transpira- 

 tion, Viscosity ; Aggregation of Particles. 



Lord Rayleigh in his review specially referred to the treatment of 

 elasticity, remarking that the Chapters on Deformation and Compression 



