...toward a formal mastery of its foundations and a complete helplessness in applying it to concrete physical problems. In this part of the book, the thoughtfulness and elaboration of the entire subject matter are especially evident.

But the greatest interest is represented by the last part of the book, devoted to cosmological problems. Whereas the contents of the preceding two parts of the book repeat to a considerable extent the contents of the well-known books by Weyl and Eddington, the last, third part contains the results of work of recent years, not yet presented even once in systematic form. After a detailed analysis of the old static models of the universe and a comparison of them with observational data, the author proceeds to an exposition of modern nonstatic models. Even a specialist in the field of the theory of relativity will find in this part much that is new, which may have escaped him in reading the journal literature. Here the author’s material and exposition are of an especially original character.

It should be stated as a wish that the book be translated into Russian as soon as possible. If the considerable size of the book (502 pp.) creates certain difficulties in publication, one may confine oneself to translating and publishing the most valuable and important last part, relating to cosmological problems; this is all the more permissible since, in view of the independent significance of the third part, it is possible to read it without the first two parts, in place of which one may use the newly published translations of Eddington’s book.

Yur. Rumer

BRÜCHE E. und O. SCHERZER, Geometrische Elektronenoptik. Grundlagen und Anwendungen. Berlin Springer, 1934, XI, 332 S., 403 Abb., Mr. 26.

E. BRÜCHE and O. SCHERZER, Geometrical Electron Optics. Fundamentals and Applications.

The analogy between optics and mechanics played a colossal role in the development of physics. Hamilton’s classical works, based on this analogy, constitute the foundation of modern analytical mechanics and physics. In his fundamental works on wave mechanics, Schrödinger likewise proceeded from the analogy with optics; he indicated that macroscopic mechanics is analogous to geometrical optics, whereas micromechanics (the mechanics of the atomic world) is analogous to wave optics.

The wave nature of the electron was experimentally demonstrated in 1927. From that time on, several hundred works have been done on the diffraction of electrons, their polarization, and other questions of the wave optics of electrons.

The analogy between geometrical optics and the macromechanics of the electron for a long time had a purely theoretical character. But in connection with the development of cathode oscillographs, the question arose of focusing an electron beam, i.e., the question of the geometrical optics of electrons emerged. There arose a need to calculate the action of magnetic and electric lenses. Finally, in 1932, works began to appear on the electron microscope, which gives an image in the “light” of electrons; moreover, the action of this microscope is quite analogous to that of an optical microscope. Questions arose of correcting systems of lenses for electrons (immersion objectives, etc.).

The book under review gives an exposition of the geometrical optics of electron beams; although it also contains the results of old works on cathode rays (for example, Lenard’s shadow method), the exposition is, of course, conditioned by works on the electron microscope, and the presentation of questions connected with it constitutes the center of gravity of the book. The contents are divided into two equal parts: “Fundamentals” and “Applications.” “Fundamentals” contains four chapters.

The first chapter is devoted to the exposition of general questions connected with the analogy between light and electrons. Here the basic...

Bibliography

the results from the wave theory of electrons are set forth, and the limits of the analogy are indicated (in our opinion, not sufficiently fully).

The second chapter is on refracting media of electron optics, i.e., the refractive index for electrons in electric and magnetic fields. In addition to the exposition of theoretical questions, experimental methods for investigating complex electric and magnetic fields are described.

The third chapter is on refracting elements of electron optics. First symmetrical lenses, electric and magnetic, are discussed; then cylindrical lenses and simple deflecting devices. In calculating the action of electric elements, the analogy with the optics of fields is more complete, as a result of which optical methods are widely used here. For magnetic elements the similarity is only in the final results (the formation of images). This chapter gives a detailed exposition of the theory of refracting elements, describes their construction in detail, and gives images obtained by means of various lenses.

The fourth chapter is on fields of space charge, i.e., the focusing and reflection of an electron beam by ionic fields. This part is analogous to the optics of media with variable refractive indices. This chapter describes “gas focusing,” with the flow of electrons through long metallic tubes. In addition, quasi-optical experiments of Goldstein are described. With this the “Fundamentals” end.

“Applications” comprises three chapters.

The fifth chapter is on Braun tubes. As we have already indicated, Braun tubes (cathode oscillographs) are one of the principal instruments whose appearance was brought about by the geometrical optics of electrons.

The authors have wisely selected only the basic material, since there is a whole series of special books on each oscillograph. In the chapter, a fairly large amount of space is devoted to the newest achievements in this field (for example, cathode television).

The sixth chapter is on the electron microscope. As we have already indicated, the electron microscope is the culmination of an entire stage in the development of electron optics. Electron microscopes exist in two types: electric and magnetic, according as the microscope is composed of electric or magnetic lenses. The authors are clearly adherents of the electric system. However, they point out that up to now sharper images have been obtained with the magnetic microscope (among other things, the historic magnetic microscope appeared earlier—the inventors were Knoll and Ruska). Nevertheless, the authors believe that in the region of high magnifications the electric microscope will have the advantage. In the sixth chapter, in addition to descriptions of various microscope designs, many results obtained with the aid of electron microscopes are presented.

It must be said that the images reproduced are striking in their sharpness (for example, on p. 260 and the title page). It is simply hard to believe that these are not light photographs. Up to now the electron microscope has been used chiefly for the investigation of oxide cathodes emitting electrons. The authors, in a whole series of examples, convincingly show the advantages of electron optics over light optics for the investigation of the properties of cathodes. This circumstance is entirely clear, since what interests us is the electron emission of the cathode, not light emission. Especially interesting are investigations of the “life” of the cathode, i.e., of the processes of activation and destruction. Considerable space is devoted to the causes producing distortions of electron images; in addition, the question of the limit of resolving power of the electron microscope is examined. Separately, results are presented that were obtained not with “self-luminous” objects, but with objects “illuminated” by electrons.

The last, seventh chapter is devoted to the spectrography of material particles (not only electrons, but also neutral particles and ions).

The authors themselves point out that this chapter goes beyond the limits of the main theme of the book. It seems to us that this chapter disrupts the unity of the book and

is superfluous. It presents very interesting material, which, however, has no direct relation to the geometrical optics of electrons.

At the end of the book there is an extensive bibliography (452 titles) and a subject index. Externally the book is beautifully produced. Numerous illustrations facilitate understanding of the text. Especially successful are the photographs of atomic-field models (pp. 87, 92, 102, 319, etc.).

On the whole, the book gives an exhaustive picture of an entirely new field of physics that has developed literally over the last three or four years.

V. Fabrikant

M. A. ROSENSTIEHL, Traité de la couleur au point de vue physique, physiologique et esthétique. 2-ème éd. Paris. Dunod, 1934, XVI, 247, 53 fig., 8 pl., Fr. 98

M. A. ROSENSTIEHL, Treatise on Color from the Point of View of Physics, Physiology, and Aesthetics, Containing an Account of the Present State of the Question of the Harmony of Colors. 2nd ed., revised and supplemented by J. Bodeno.

This book is the second edition of Rosenstiehl’s well-known work, published in 1912, i.e. 22 years ago. In its time it was one of the best books on applied color science, containing a clear and detailed exposition of a number of classic works in this field (Lambert, Chevreul, Young, Maxwell).

Unfortunately, even then this book was striking in that it said not a word, for example, about the studies of the mixing of spectral colors by Ebney, Koenig, and Dieterici, which were more perfect and accurate than Maxwell’s studies and already then were of only historical interest. In the exposition of Young’s theory of color vision, not a word was said about Helmholtz’s work in this field, etc.

All this has remained in the new edition as well. Moreover, reading this book, revised and supplemented by J. Bodeno, one may think that color science in general stopped developing 22 years ago: not a single work from the enormous number that appeared during this interval is mentioned in Bodeno’s additions, which in fact amount to the addition to the book of a 24-color circle, very similar to Ostwald’s circle, bearing his name, and works in the field of color science are not mentioned, however, even once.

Despite all these shortcomings, Rosenstiehl’s book, in addition to the above-mentioned detailed exposition of a number of classic investigations, is of great value for its detailed presentation of Rosenstiehl’s own works, a thoughtful and careful experimenter (for example, on distinguishing complementary colors and colors of successive contrast, on the change of color tone when white is added, on the construction of an equisaturated circle of colors, etc.).

And if it is approached precisely from this point of view, it deserves attention and should be taken into account by all specialists working in the field of color science.

There is no point in translating it into Russian, since the number of specialists in color science in our Union for whom this book is needed and valuable, and who will be able to perceive and use what is valuable in it, does not exceed several dozen people.

The exposition of the doctrine of the harmony of colors itself belongs, incidentally, as is customary, to the author’s merits and, as one of the weak points of the book, which in this respect is inferior, for example, to N. D. Nyberg’s Course of Color Science (Goslegprom Publishing House, 1930).

N. T. Fedorov

Responsible editor: E. V. Shpolsky. Technical editor: A. V. Smirnova.

ONTI No. 22. Index T-60. Print run 3,900 + 50 separate impressions. Submitted for typesetting 8/II-35. Signed for printing 1/IV-35. Paper format 62 × 94. Author’s sheets 12. Publisher’s sheets 15. Paper sheets 5⅛ + 1 insert. Printing signs per paper sheet 101,000. Order No. 213. Authorized by Glavlit B-15477. Released April 1935.

3rd printing house of ONTI named after Bukharin. Leningrad, Monseenko St., 10.