292 Notices respecting New Boohs. 



The Theory of Optics. By Paul Drude, Professor of Physics at the 

 University of Giessen. Translated from the German by C. Rjborg 

 Mann and Egbert A. Millikan, Assistant Professors of Physics 

 at the Uniyersity of Chicago. London : Longmans, Green, 

 and Co. 1902. Pp. xxi + 546. 



The English translation of Prof. Drude's important work on 

 Optics mast be regarded as one of the most welcome additions to 

 that series of text-books for advanced students which is beginning 

 to supply a long-felt want. Our scientific literature is overloaded 

 with text-books of an extremely elementary kind, while the 

 number of books suitable for the use of the more advanced 

 student is very limited indeed. The late Professor Preston ren- 

 dered capital service to the cause of English science by the publi- 

 cation of his excellent treatises on Light and Heat ; indeed, he 

 may be said to have inaugurated a new era in the history of text- 

 books on physics : and signs are not wanting that his example is 

 likely to be followed by others. 



The new work by Drude must take its place as one of the 

 standard treatises on the subject by the side of Preston's ' Theory 

 of Light ' and the treatises on Geometrical Optics by Heath and 

 by Herman. It is, in a sense, supplementary to these. Its 

 leading features are the clear and connected account of the 

 principles underlying the construction of optical instruments, and 

 the masterly exposition of modern optical theories, considered 

 from the electromagnetic standpoint. There is no other book in 

 which the reader will find so complete an account of the present 

 state of the electromagnetic theory of light, or in which the 

 various difficulties connected with that theory are dealt with in so 

 clear and painstaking a manner. 



The work is divided into three Parts — Geometrical Optics, 

 Physical Optics, and Padiation. The first Part deals with the 

 fundamental laws of geometrical optics, the geometrical theory of 

 optical images, the physical conditions for the formation of an 

 image, apertures and the effects depending on them, and optical 

 instruments. The subjects comprised under Part II. are the 

 velocity of light, interference, Huygens's principle, diffraction, 

 polarization, the mechanical and electromagnetic theories of light, 

 propagation of light in transparent isotropic media, optical pro- 

 perties of transparent crystals, absorbing media, dispersion, optically 

 and magnetically active substances, effects produced by bodies in 

 motion. Part III. is devoted to the consideration of the energy 

 of radiation, the application of the second law of thermodynamics 

 to radiation, and the theory of incandescent vapours and gases. 



The translation is well done, with only here and there a sug- 

 gestion of foreign idiom ; the English reader would, no doubt, 

 prefer to see some of the Americanisms in the spelling removed ; 

 but that is a small matter in view of: the great service rendered by 

 the translators to the English-speaking student. The publishers 

 deserve great credit for the high-class " get-up " of the book. 



