L. BERGMANN, Ultrasonics and their scientific and technical applications, pp. VII + 264.—G. Bell and Sons, London, 1938, Price 16 S.

Bergmann’s book is the first large monograph devoted to ultrasound and its applications. In the comparatively short interval of 10–12 years this field of investigation has undergone rapid development and has attracted great interest from the most varied points of view. In the detailed bibliography appended to the book under review, the main list contains 483 works, and in addition—in a supplementary list relating to the interval during which the book was being printed—there are about 100 more works.

The book begins with a survey of the various methods for producing and measuring ultrasounds. Mechanical (Galton whistle, etc.), magnetostrictive, and piezoelectric generators are considered, as well as various methods of recording and measuring ultrasounds. A detailed survey is also given here of work relating to the diffraction of light by ultrasonic waves. The following two chapters (Chs. IV and V) are devoted to so-called “molecular acoustics,” i.e., to questions connected with the dispersion and absorption of ultrasound in gases, liquids, and solids. Finally, the last chapter examines various technical—

technical applications of ultrasonics: television, underwater signaling, testing the strength of materials, obtaining colloidal solutions and coagulation under the action of ultrasonics, and chemical and biological effects.

The exposition throughout the book is abstract-like rather than critical in character. Despite this shortcoming, the abundance of material collected, detailed references to the literature, and the large number of excellently executed illustrations—all this makes the book very useful for general orientation in this extraordinarily interesting field. It may be noted with satisfaction that the author has taken into account the works of Soviet physicists (Sokolov, Rzhevkin, Rytov, Malov, and others). Unfortunately, the excellent photographs of the propagation of ultrasonics, published after the book appeared and made by S. N. Rzhevkin and E. Krechmer by Toepler’s method, could not be included. Apparently for the same reason, the important theoretical work of M. A. Leontovich and L. I. Mandelstam on the anomalous absorption of ultrasound in liquids was not considered.

E. Sh.