W. T. Sproull. X-rays in practice. McGraw Hill, N. Y. 1946, 615 pp. with tables and index.
W. T. Sproull. Applications of X-Rays.

According to the author’s intention, this book is meant to be a small encyclopedia on the application of X-rays. The preface specifically states that much labor was spent in compiling an extensive subject index and an author index, so as to make it easier for the reader to find quickly any reference relating to a question. At the same time the book is written as a textbook. At the end of each chapter questions for review and problems are given in a fairly considerable number. No calculations of any kind carried out with the aid of higher mathematics are presented in the book, and most formulas are given without derivation. To read these formulas the reader must nevertheless have a certain preparation, of the kind usual for reading books on experimental physics. Some perplexity is caused by the author’s advice, given in the preface and offered to the reader of Chapter 1 as requiring prior familiarity with the concepts of cosine and sine. Of course, the book is not suited to a reader who still has to become acquainted with such elementary concepts. This is a book for a student, for an engineer, but not for a school pupil, or in general for a reader unaccustomed to technical literature. True, the book contains a number of chapters of a descriptive character—history, application in medicine and biology—but reading them, too, requires not mathematical knowledge, but sufficient qualification and development.

The book begins with a brief historical introduction, after which the design of X-ray tubes is considered first of all. Several types of typical tubes are described, and some essential details of the construction of X-ray tubes, such as anodes, cooling, etc., are explained. A short, quite successful paragraph discusses the magnitude of the focal spot. In the third chapter all the X-ray properties needed by a worker in the field of radiography are set forth.

and radiologists, questions concerning the white spectrum. As much is said about the theory of the phenomenon as is necessary for a clear practical command of the subject. In this respect, the opposite spirit is carried out in the main, where the characteristic spectrum is described. The author sets himself the goal of explaining here all the physical facts necessary for understanding the question. This, of course, is quite impossible to do in one chapter. Therefore this chapter will give nothing to the specialist in X-ray spectroscopy, while anyone wishing to understand the question will still have to turn to textbooks of physics. Suffice it to say that on fourteen pages the author gives the foundations of the theory of relativity, the foundations of wave mechanics, and Schrödinger’s equation. Here, too, the essence of the four quantum numbers is explained and a classification of spectra is given. It should be noted that such an exposition in a number of places is one of the main shortcomings of the book, and indeed a very widespread shortcoming of American books, in which the authors like to speak superficially about everything little by little.

In the chapter entitled “Absorption, Scattering, Secondary Rays,” all the necessary data on these questions are collected. The author’s attempts to give a detailed theory of the Compton effect are quite superfluous (for a reader who has only just become acquainted with the concepts of sine and cosine). The discussion of the physical properties of X-rays ends with a short chapter on refraction.

Chapter 7 describes in considerable detail the main X-ray equipment: again tubes (it is not clear why this had to be done in two chapters) and apparatus. A very detailed classification of all possible X-ray tubes is given. The tubes are divided according to 15 characteristics (cooling device, type of anode, purpose, etc.). All the most commonly used circuits of X-ray apparatus are analyzed, with the exception of the simplest and most widespread—the circuit with one kenotron and one grounded pole.

The author believes that the use of radium is a kind of supplement to radiography, and therefore attempts in a separate chapter to set forth the fundamentals of natural and artificial radioactivity.

Chapter 9 is devoted to the measurement and registration of X-rays. The types of screens and photographic films used in radiography are examined in detail. The facts concerning photographic blackening are set forth to the necessary extent. The author is apparently unfamiliar with ionization measurements, since he describes the construction of low-percentage chamber types and says nothing about the theory or about the most common designs. There are no data on the measurement and amplification of the ionization current. Likewise, nothing necessary or important is said about Geiger counters.

In the following chapter all the necessary data on protection against X-rays are collected.

The exposition of medical radiology, in all probability, because of its brevity, will be of no interest to the physician. However, the general information contained in this chapter is of interest to the engineer and technician working in the field of the industrial application of X-rays.

The chapter on industrial X-ray radiography is excellently illustrated and contains a certain amount of fresh and interesting material. The main types of technical radiography are analyzed with sufficient completeness and clarity.

The chapters listed constitute almost exactly half of the book. The second half concerns X-ray structural analysis. The exposition of these questions is not distinguished by freshness and leaves much to be desired. Throughout this part of the book the exposition is characterized by superficiality, the desire to say a little about everything, and the absence of direction in the presentation.

Chapter 14—crystallography—is set forth confusedly and foolishly. The most essential thing—the exposition of the doctrine of crystal symmetry—has found no place ...

in this chapter. The first paragraphs, taken mainly from Wyckoff’s book, are devoted to the geometry of the space lattice. Next, descriptions of the seven syngonies and 32 classes are taken from reference books (despite the fact that the concepts and classification of symmetry elements are not given). Space groups are discussed only in a few paragraphs. Further, with the aid of very few illustrative drawings, an account is given of the close packing of spheres. After all this the author again returns to the geometry of the lattice. The concept of the reciprocal lattice, for some reason, has ended up at the very end of the chapter.

The laws of diffraction of X-rays by a crystal, set forth in Chapter 15, are given in the same confused and unclear form. The Laue equations are explained in a very dubious, simplified way and their connection with Bragg’s equation is shown. Further, things entirely unnecessary (in comparison with what has been omitted) are set forth, namely an interpretation of diffraction as the reflection of quanta from crystalline planes and an imitation of Bragg’s law by refraction of X-rays.

In the following chapter the technique of work on an X-ray spectrograph and certain basic points in the structural analysis of single crystals are set forth. The Laue method and crystal rotation are presented in the following chapter, which creates the impression that the author considers the essence of structural analysis to lie only in the spectrographic method. Here too the exposition is distinguished by extreme unsystematicity and by the absence of proportionality between the importance of a question and the space allotted to it. This chapter mainly sets forth Bragg’s historically interesting work on establishing the structure of rock salt. Between these paragraphs and the paragraph on the atomic factor is “wedged in” a paragraph on quadratic forms for the seven syngonies. The author is completely helpless in explaining the structure factor, which is given mainly through the example of rock salt. A brief exposition of the method of representing electron density by a Fourier series gives no understanding either of the significance or of the essence of this method. The paragraphs on the mosaic structure of the crystal and on extinction are set forth more or less satisfactorily.

Equal space is allotted to the method of obtaining Lauegrams and rotation X-ray photographs, which in no way corresponds to the significance of these methods. On the pages allotted to these questions it would have been possible, with success, to explain methods for indexing X-ray photographs. The author was unable to do this.

The author evidently had occasion to deal with the method of obtaining Debyegrams, and therefore this chapter is set forth much better. Various types of powder photography are described; methods for determining interplanar spacings and lattice constants for the cubic, tetragonal, and hexagonal syngonies are recounted. A whole series of correct practical remarks makes this chapter a satisfactory aid for one studying the subject for the first time.

In a special chapter (the 19th) the method of chemical analysis by Debyegrams is set forth in detail. Hanawalt’s works are taken as the basis of the exposition.

Questions of determining the size and orientation of crystalline grains are set forth as usual. The chapter is illustrated with good and clear X-ray photographs. The method of constructing pole figures remains still unclear. The author knows of no camera for obtaining X-ray photographs from which the pole figure is derived directly (of the type proposed by G. S. Zhdanov).

In the chapter on determining stresses from Debyegrams there is much superfluous mathematics and few practical directions. It is unknown according to what principle the chapter on X-ray scattering in liquids, amorphous, and gaseous substances is drawn from various books.

In Chapter 23 the author sets forth those questions which, as it seemed to him, do not fall under the titles of the preceding chapters. The selection of material arouses complete bewilderment. Here are briefly presented Möller’s works on paraffins, Bradley’s studies of γ-brass, and also questions of the orientation of quartz crystals and the structure of rubber.

In the concluding chapter, too, the questions of electron diffraction are presented in an utterly incompetent manner.

The last 70 pages of the book are devoted to tables. The author has put here everything that came to hand. The tables of wavelengths of X-ray spectra and the coefficients of absorption are followed by the Mendeleev table, a table of the distribution of electrons in orbits, and ... a table of the half-lives of radioactive elements. After this are given data on the unit-cell parameters and space groups of certain compounds selected at random (by what principle is absolutely incomprehensible). There was also room in this book for tables of trigonometric functions.

It seems to us that the failure of this book is typical. Many such examples can be cited in American literature. The irresponsibility of an author and publisher who suppose that any encyclopedia whatever can successfully be compiled by a single author is the main reason for this failure. There are known examples in which one person has successfully written large surveys devoted to a single field. But then that person must be the greatest specialist in the field, having worked for many years in all its “districts.” The author of this book is evidently a practicing engineer in the field of the technical application of X-rays, only very superficially acquainted with physics; the writing of a survey on the application of X-rays in science and technology is beyond his powers. With a less commercial and more responsible approach to the matter, such a book would not have seen the light of day.

A. I. Kitaigorodskii