BOOK REVIEWS [J. F. I.
thin and thick lenses, and spherical mirrors. In addition separate chapters are spent on the effects of stops, the often neglected subject of ray-tracing, lens aberrations, and the application of the principles outlined to the construction of optical instruments. In all of these first chapters illustrative numerical examples are included; these are set off from the text itself by horizontal lines to point them out.
Part II contains 19 chapters dealing with the wave nature of light and the phenomena which can be explained on the hypothesis that light consists of waves--interference, diffraction, absorption and scattering, spectra of light sources, dispersion, polarization, refraction, optical activity, reflection, and magneto and electro-optical effects. Included in these chapters are many striking photographs of interference and diffraction fringes and spectra. Another feature which enhances the usefulness of the book as a text for a course in optics is the inclusion throughout this section of descriptions of illustrative demonstration experiments which can be set up in the lecture room. These experiments are set off from the rest of the text in the same manner as the numerical examples of Part I.
The mention of various recent developments in the field, such as the phase contrast microscope, the interference filter, and the electron microscope brings this section on physical optics very much up to date.
The book is concluded with a single chapter on quantum optics. Entitled "Photons," this chapter treats briefly the evidence for light quanta, the development of quantum mechanics, and the interpretation of the dual character of light.
Comprehensive problems are 'included at the[end of each chapter of the text, with the answers to all the even-numbered ones given at the back of the book.