O. D. Khvolson. Course of Physics. Supplementary Volume. Physics 1914–1926. Part I. State Publishing House, 1926. Pp. 306. Price 3 rub. 75 kopecks; and Part II. Pp. 275. State Publishing House, 1926. Price 4 rub. 25 kopecks.

The two parts of the supplementary volume constitute a valuable appendix to the well-known course by Professor O. D. Khvolson. Having set himself the goal of acquainting the Russian reader with the numerous and exceptionally important advances achieved by physics over the last twelve years, the author has undertaken a highly difficult and extraordinarily important and necessary task. Both the separation from Western literature that had not yet been overcome in the provinces, and the unusually rapid pace of the development of physics in recent years, placed many physicists—to say nothing of broad circles of educated readers who wished to keep abreast of scientific progress—in an almost hopeless position. The numerous popular and scientific-popular books and articles that have appeared in recent years in the Russian language have satisfied the existing need only to a certain extent. There remained a body of readers, including studying youth, insufficiently proficient in foreign languages, who had no opportunity to acquaint themselves thoroughly and in detail with the latest

scientific achievements. These circles of readers, as well as specialist physicists, will welcome the appearance of Professor O. D. Khvolson’s “supplementary volume.”

In accordance with its plan, this book is not a systematic exposition of one or another question of the new physics, but seeks to supplement the old volumes of the course, as it were replacing a new edition of it. Not only individual chapters, but sometimes even individual paragraphs, are attached to the corresponding parts of the first volumes. Yet, in keeping with the rapid development of physics, most of the chapters present an exposition of entirely new questions, of which in the literature before 1914 not even a hint can be found. These chapters give the “supplementary volume” an independent value, making it a reference book on the new literature.

The following list of chapters gives an idea of the range of questions touched upon in the “supplementary volume”: I. The charge and mass of the electron. II. The theory of quanta. III—IV. The structure of the atom. V. The theory of line spectra. VI. X-rays. VII. Band spectra. VIII. Ultraviolet and infrared rays. IX. Excitation and ionization of gases by electron impacts. X. The quantum theory of light. XI. Photoelectric phenomena. XII. Photoluminescence. XIII. Various applications of Bohr’s theory and of the theory of quanta. XIV. Isotopes. XV. Superconductors. XVI. Michelson’s new experiment of 1925. XVII. Electromagnetic spectra of metals.

With O. D. Khvolson’s characteristic thoroughness and objectivity, the most numerous and varied investigations are set forth, and detailed bibliographical references are given. One can only marvel at the venerable author’s extraordinary capacity for work and express deep gratitude for the valuable and difficult labor he has performed.

G. Landsberg.