Our Bookshelf.: Physics

Abstract

THIS treatise, which is now in its sixth edition, is an admirably well balanced book. It is divided into four parts. The first treats of geometrical optics, a subject which some physicists forget is of great practical value. The second discusses physical optics, finishing with the Kerr effect. In part three, spectroscopy and photometry are discussed and the latest developments are described. We expected the author to be more definite about colour blindness, on which he is an authority but he has, perhaps wisely, confined himself to a brief statement of the main theories. The descriptions given of the wonderful advances made in spectroscopy, the spectral series, the infra-red, the ultra-violet, and the X-rays will be helpful to many. The last section of the book gives the foundations of the mathematical theory and its later developments, due stress being laid on the quantum theories of the propagation of light and on Poynting's theory of the pressure of light. The chapter on ether and relativity is interesting. The usual unconvincing statements are made about the relativity of time and space. The author says, “Relativity is consequently now accepted as a faith. It is inadvisable to devote attention to its paradoxical aspects.” The warning perhaps means that “this way madness lies”, and many will agree with him. It is pointed out that if we adopt Einsteins theory, since every observer has his own system of space and time, it is easier to abandon the conception of an ether and think of the light itself as having substance and moving through the void. A description of the Hilger interferometer, Moseley's work on X-ray spectra, cosmic radiation, and Kodacolor photography completes this useful volume.

A Treatise on Light.

Dr. R. A. Houstoun. Sixth edition. Pp. xi + 494. (London, New York and Toronto: Longmans, Green and Co., Ltd., 1930.) 12s. 6d. net.