BOOK :REVIEWS. 52I
tion. Professor James' contribution to the subject during a period of more than two decades uniquely qualified him to write this definitive work. The treatment appears to meet the needs both of experienced workers, who will appreciate the organization and discussion of this large amount of material, and of newcomers into the field of X-rays, who will find this book pedagogically excellent. It is this latter characteristic mainly that accounts for its length, but this reader, for one, is grateful for the opportunity to be led so thoughtfully, albeit slowly, through this type of subject matter. Examination of any topic in the book makes it apparent that Professor James has given great care to organization, illustration, and reference. The book is, then, a unique combination that will make it a much used reader and reference in a fundamental field of modern physics written by a man prominent in its development.
The book begins with the geometrical aspects of diffraction, utilizing reciprocal lattice concepts, and considers effectsof lattice variations upon intensities. Then the entire subjectof intensities of reflections is discussed, closing with Ewald's dynamical theory. A chapter on the atomic scattering factor follows, which includes a discussion of calculation methods. Then follow sections on anomalous scatter and temperature effects, containing thorough discussion of experimental tests of the several theories. A complete chapter is given to experiments dealing with the intensity formulae. The chapter on Fourier methods is brief, as this subject has been treated elsewhere and will be the subject of a later volume in this series. Laue's dynamical theory is the subjectof a chapter. An intensive treatment of the scattering of X-rays by non-crystalline matter and by small crystals occupies the last quarterof the book.
JOSEPH SINGER.