absorbed on the surface. The subsequent chapters contain clarification of various processes of emission in compound cathodes and of processes of replenishing the supply of emitted electrons by their passage through one or another intermediate layer. Chapter 14 examines phenomena in oxide thermocathodes and, finally, the last, 15th chapter, processes in cathodes with a barrier layer.

The large amount of experimental and theoretical material collected in the book under review, treated from an original point of view of the author (to a considerable degree quite justified), compels one to recommend a detailed acquaintance with it to all those working practically in the field of the photoelectric effect and oxide cathodes, as well as to all those concerned with the theory of these questions. The publication of de Boer’s book in Russian is highly desirable.

N. Kaptsov

M. T. ZARAFYANTS—What Is Entropy. State Scientific-Technical Publishing House of Ukraine, Kharkov—Kiev, 1935, pp. 83, price 2 rubles, print run 4000.

M. T. Zarafyants’s book compels us once again to raise the question of the responsibility of our scientific publishing houses for the literature they issue. This book can do much harm, since, while it will give the qualified reader only a few merry hours, it will disorient the beginning reader and create complete confusion in his head.

The aim of the book is characterized by the preface: “There are no scientific novelties in this book. The novelties here are methodological, pedagogical. They have been partially borrowed by the author from Prof. Fater, Satkevich, and others. But into the difficult task of popularizing entropy the author has also introduced something of his own, which, as experience has shown, leads to brilliant results.” Let us look closely at this “something.”

In order to give an idea of the character of the book, let us cite the “first conception of entropy.” In the author’s opinion, “the peculiarity of heat energy when it is transformed into work is best formulated as follows: when heat is transformed into work in a real heat engine, nature, as it were, levies a tax. The temperature coefficient of this apparent tax is called entropy.”

Thus, according to this “conception,” which the author calls “dynamic,” entropy is nothing other than the temperature coefficient of the tax which, as it were, is levied by nature. It is not worth citing other conceptions, since the author himself considers that “the first definition should be recognized as the most fruitful.”

The author again gives this utterly meaningless formulation on p. 73 among the classical formulations of Clausius, Planck, and others, as equivalent to them.

In general, instead of giving a clear and vivid interpretation of the most successful classical formulations of entropy, the author followed the path of piling up a large number of naive and confused arguments, which have completely obscured the essence of the question. Thus, for example, on p. 78 a list is given of 12 formulations of the second principle, and on p. 71, under the title “Content of the Concept of Entropy,” there are also 12 points which, in the author’s idea, are supposed to convey the essence of this concept. Let us cite several of them, since in essence they summarize the material and characterize very clearly the style of the book:

1. Entropy is not an a priori concept, not a concept that lends itself to direct perception. The only concept related to entropy is the moment of inertia of an area.

2. Entropy and moment of inertia are concepts introduced into science by science itself. Entropy and moment of inertia are auxiliary functions for solving practical problems.

Apart from the unexpected analogy with the moment of inertia, these formulations contain a number of word combinations whose meaning is entirely problematic. For example, “entropy and moment of inertia are concepts introduced into science by science itself.”

...“science,” and so on. The assertion, however, that the “sole concept akin to entropy is the moment of inertia” is based on three propositions (see pp. 61–63): 1) both concepts are “not a priori concepts,” 2) moment of inertia and entropy are factors “hindering” the full utilization, the first, of “beam material,” and the second, of heat, and 3) both have a formal-mathematical means of formulation.

In general, in many places in the book one feels that, for the author himself, in setting forth the question there exist not only pedagogical difficulties. As an example let us consider the paragraph on p. 27 entitled “the increase of entropy.”

The author needs to show that, in a closed system, in irreversible processes entropy increases. How does he do this? The author proposes that

\[ S=\int_{T_1}^{T_2}\frac{dQ}{T} \]

be considered as the limit of the sum:

\[ \frac{\Delta Q_1}{T_1}+\frac{\Delta Q_2}{T_2}+\cdots \]

In doing so he reasons: let the temperature fall, i.e.

\[ T_1>T_2>T_3, \]

and \(\Delta Q\) be constant; then each of the following fractions is greater than the preceding one.

Next there follows a completely unexpected assertion: “the sum \(\frac{\Delta Q_1}{T_1}+\)

\[ +\frac{\Delta Q_2}{T_2}+\cdots \]

increases; hence entropy increases.”

Since

\[ \int_{T_1}^{T_2}\frac{dQ}{T} \]

is a definite quantity, the author’s argument is equivalent to the following reasoning: since \(6=1+2+3\) and \(3>2>1\), \(6\) increases. In general, the whole proof is so absurd that criticism of it is superfluous.

However, since the author sets himself not scientific but pedagogical tasks, let us turn again to this side of the book. When the author wants to explain something by example, he invents some unnatural analogies, instead of borrowing examples from the practice of heat engines. We have already mentioned one such analogy with the moment of inertia.

On p. 20 the author offers the reader a problem: “For the assimilation of entropy in its strictly scientific conception the reader must perform independent work of thought; therefore we shall offer him the problem of constructing a mechanical model of the phenomenon represented by the formula

\[ \frac{Q_1}{Q_2}=\frac{T_1}{T_2}. \]

To facilitate the solution of this difficult problem, we shall give one example taken from another branch of science. This example is a model of the ‘cat paradox’ in mechanics. If the reader’s attempts to create the required mechanical model are crowned with success, then the labor and time spent on this work will be repaid by the fact that his thought will be prepared for the assimilation of entropy in its scientific conception, which is preceded by the abstract aspects of reversibility (the ideal case). It is known that if a cat is held with its feet up and dropped from a height, etc.”

Further, after two pages devoted to the “cat paradox,” the author solemnly declares: “This scheme must therefore be called a mechanical model of the phenomenon of the falling cat in the full sense of the word.”

Lack of space does not allow us to reproduce in full the “comparison of Linné” (p. 18), which is a ridiculous story about how “some man \(X\) gave \(Y\) 10,000 rubles. In the author’s opinion, this comparison is successful in that, by means of a life example, it explains not only a caprice of nature (the act \(X\)), but also reveals the dependence of the tax (the cost of the film)

from entropy (the merit of the ticket) and on the lowest available temperature (the height of the whale)*.

After compliments addressed to Boltzmann’s theory (“a profound theory”) the author resorts to yet another analogy. He writes: “The reader here may ask the question—can one not give an example that would vividly, life-like illustrate Boltzmann’s theory. One can.” What, then, does the analogy consist in? As an analogue for entropy the degree of moral disintegration of an army is taken (I). The author writes: “Similarly, the degree of uniformity of the disorganization (moral disintegration) of an army in all its parts determines its entropy” (p. 41). True, at the end the author warns the reader, proposing to consider everything written above merely an “analogy,” and not an “identity.” What all that has been said above actually amounts to is clear even without comment. The whole book is full of numerous incorrect formulations, erroneous assertions, and at times very strange conclusions.

Let us give a few examples. There is in the book, for instance, the following comical phrase: “while reading Mach, however, one must not forget that Mach, being a historian of physics, as a philosopher, remains a Machist” (p. 80). On p. 47 the author gives a definition of irreversibility, calling it correct, and right there writes in a footnote: “of this definition Prof. Satkevich rightly says: ‘such a formulation essentially saves nothing, but only obscures the meaning of the question.’” One should also note the author’s inclination toward cheap verbal effects. It is enough to list the headings in order to get a clear idea of his style. Chapter I. Entropy follows from entropy. Three conceptions of entropy. Ch. II. Genesis of entropy. Aspect of the ideal case. Or such expressions as “the feathered arrow” (p. 22), “gifted,” etc. Everything set forth above gives an idea of the character of the “tape.”

The Scientific and Technical Publishing House of Ukraine should restructure its work so as to avoid the further publication of similar books.

A. Zhukhovitsky and M. Tezhkin

NEW BOOKS

A. N. TUDOROVSKY — Electricity and Magnetism. Part II. L.–M., ONTI, Main Editorial Office of General Technical Literature, 1935. Part II. Magnetism, electromagnetism, electrodynamics and induction of currents, 503 pp., with drawings and graphs, 3000, 6 rub.+1 rub. binding.

Contents. Basic facts and properties of permanent magnets. Magnetic field. Mechanical actions of a magnetic field on magnets. Earth’s magnetism. Magnetic induction. Magnetic properties of various substances. Magnetic field of an electric current. Ferromagnetic substances in the magnetic field of electric currents. Mechanical actions of a magnetic field on a current and on moving charges. On the theories of magnetic phenomena. Electromagnetic induction. Instruments (galvanometers, oscillographs, etc.) and measurements. Quasi-stationary alternating currents. Electrical oscillations and waves. An index of names and subjects is given. Part I appeared in 1933 (State Technical and Theoretical Publishing House). Intended for students of technical colleges and higher educational institutions as a textbook.

A. SCHUSTER — Introduction to Theoretical Optics. Trans. from the English. Edited by Prof. K. K. Baumgart. L.–M., ONTI, Main Editorial Office of General Technical Literature, 1935, 376 pp., with graphs, 5000, 4 rub.+1 rub. binding.

A detailed and consistent exposition of questions of wave optics, in which the ideas of the English school of physicists are reflected—the ideas of Kelvin and, chiefly, Rayleigh. Some chapters contain an exposition of the author’s own work (on white light, on interference and diffraction). New for the Russian reader is the exposition of the propagation of white light as a single impulse. Notes are appended.