Magnetism

Magnetism

June, I95o. ] BOOK R E V I E W S 509 data available to the physicist is given, including measurements of nebular distances, distributions and masse...

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June, I95o. ]

BOOK R E V I E W S

509

data available to the physicist is given, including measurements of nebular distances, distributions and masses of nebulae in space, the red shift and the "recession" of the nebulae. As a basis for the theories to follow, a n outline of tensor calculus and the generalized differential geometry of Riemannian spaces is given. The principles of general relativity are set forth and are used to derive the theories of the expanding universe. The kinematic theory of E. A. Milne is also described and compared to those of general relativity. The language is, of course, essentially mathematical, b u t the fundamentals are laid quite well in the early chapters, so t h a t the t r e a t m e n t as a whole is clear. The book suffers somewhat from the lack of revision since the first edition in 1937, because the important recent work, notably of Schrodinger and Einstein, on deriving gravitational theories from the more general relativistic theories is missing. A. D. FRANKLI,'¢

The Physical Principles of Wireless, by J. A. Ratcliffe.

110 pages. Price, $1.25. Here, in a brief 108 pages, Mr. Ratcliffe a t t e m p t s to present the underlying principle of electronics. For the a m o u n t of space allotted to the subject, the author does quite well. From the foreword it is gathered t h a t the book is intended to provide a source of easily understood material for the reader who has had practical experience with radio as a hobby and who wishes to broaden his theoretical background. When looked a t from this viewpoint, it can be said t h a t the book fulfills its purpose admirably. While this book will probably not find a place in the reference library of the electronics engineer, it will undoubtedly be welcomed by those who are looking for a concise descriptive explanation of the fundamentals of operation of vacuum tubes and their associated circuits and radiO transmitters and receivers. R. S. GRUBMEYER

Magnetism, by E. C. Stoner.

136 pages. 1948. Price, $1.25. This book describes briefly the present outlook on certain aspects of magnetism, mainly those concerned with the magnetic properties of materials. An account of diamagnetism, paramagnetism and ferromagnetism is given, dealing mainly with the behavior of atoms and the interaction of atoms characteristic of each property. The book is written primarily for those to whom the subject is not new. The author has given a reasonably systematic account of the subject, assuming as known those fundamental facts which are to be found in the usual text-books. It is believed t h a t the book is useful in a general survey of the subject, and as an introduction to those who wish to carry out research on the subject. It may also suggest new points of view to those whose main scientific interests lie in other directions. RICHARD J. SNUCK

Mercury A rcs, by F. J. Teago and J. F. Gill.

107 pages. Price, $1.50. The book is a mathematical t r e a t m e n t of the subject of mercury arcs used as power rectifiers and inverters. The practical side of the subject is covered briefly in the introduction and the chapter on constructional details. Throughout the book where theoretical results deviate from actual results, the deviation is noted but not treated in detail. Control, regulation, characteristics, wave form analysis, transformer ratings, and power factors are among the subjects presented. In all, the book presents a rather complete mathematical analysis of mercury arcs and will be of particular interest to the students of electrical engineering, physics and mathematics. E. A. MECHLER

The General Principles of Quantum Theory, by G. Temple.

120 pages. 1948. Price, $1.25. The title, " T h e General Principles of Quantum Theory," is an excellent one for this monograph. It deals with the basic concepts underlying the q u a n t u m theory. A brief, and of necessity intense, survey of the theory of linear operators is given, from which the general laws governing the interpretation of experimental observations in atomic (i.e., elemental) physics are developed. I t is shown t h a t the d o m i n a n t fact in these laws is the uncertainty principle,