“Wireless Telegraphy and Telephony”: a Handbook of Formulae, Data and Information, by W. H. Eccles, “The Electrician” Press, 1917.

In so young a field of practical application of physical knowledge, one that is still undergoing a stage of rapid growth, such as radiotelegraphy, the task of setting forth, in as concise a form as possible, all the scientific and scientific-technical information needed by anyone working in this field—whether a scientific investigator or a practical engineer—is a very difficult one, yet an extremely valuable one. This task is difficult because much such information, often still in an unprocessed form, is scattered through various scientific and scientific-technical journals; some is found in patent specifications; some is contained in the form of unpublished experience of individual persons and laboratories, handed down as “oral tradition.” In addition to collecting the material, the strictest selection and careful processing of it are also required. For all these reasons, work that accomplishes such a task is especially valuable, since it contributes greatly to the economy of scientific and technical labor.

The author of the work under review has set himself just such a task. As he says in the preface, his “book is a systematic collection of information, data, formulae, and tables which may be useful both in preparing projects and in investigations in the field of radiotelegraphy.” His intention was “not only to give a bare list of observed and recorded facts in an easily accessible form,” but also a brief exposition of the present state of scientific views on the questions under consideration.

In those cases where these questions are treated with sufficient completeness in well-known handbooks on radiotelegraphy, the author was able to confine himself to brief indications; but he had to dwell in more detail, in a number of separate notes included in the text, on those questions to which, for one reason or another, sufficient attention had not yet been paid in the literature. Such notes are scattered throughout the whole book; there are especially many of them in the section on antennas and wave propagation, as well as in the chapters dealing with atmospheric discharges and crystal detectors—questions on which the author himself has worked a great deal.

These interesting and at times valuable notes constitute one of the characteristic features of the book. Thanks to them, however, there is introduced into the exposition, somewhat,

noticeable unevenness and roughness. The author himself notes this, pointing also to one advantage of such a mode of presentation: the possibility, in future editions, as need arises, of crossing out such notes or replacing them with others, without concern for disturbing the orderliness of the exposition and the logical connection.

In accordance with the plan outlined, Eckels’s book is divided into three main parts. In the first are collected mathematical formulae and constants, mathematical tables, and also tables of physical quantities and constants related to radiotelegraphy. In the second part are given the functional relations between physical quantities—physical formulae pertaining to the field of electromagnetic oscillations (free and forced oscillations of simple and coupled systems). Special attention is paid here to formulae for calculating the electrical capacitances, coefficients of induction, and electrical resistance of conductors of various shapes; moreover, the author does not confine himself to giving formulae, but supplies, for a large number of the most important formulae, auxiliary tables and abaci that greatly facilitate calculation.

Finally, in the third part, the most extensive and most interesting, technical, experimental, and theoretical information is presented concerning methods of radiating electromagnetic waves by means of antennas, the process of their propagation, and methods of their generation and detection. This part also contains descriptions of the principal systems of wireless telegraphy and of certain powerful radiotelegraph stations. Particularly worthy of note is the rather extensive information concerning thermoelectronic three-electrode tubes (audions) and various methods of using them for receiving electromagnetic waves and for their generation. This part ends with a separate chapter on wireless telephony and with a note on a new method of telephoning and telegraphing with the aid of electromagnetic waves along wires (the method of Georg O. Squier).

Appended to the book are an explanatory list of terms, a subject index, and a separate detachable sheet with a new original slide rule belonging to the author’s graphical method (abacus) for rapidly calculating wavelengths, capacitances, and coefficients of self-induction of oscillatory circuits according to Thomson’s formula.

As is evident from this brief account of its contents, Eckels’s book embraces the entire field of radiotelegraphy up to its latest acquisitions. It should be noted, however, that, apart from a few isolated indications, it contains no information at all on methods of measurement, which are so important both for scientific investigations and for practical purposes.

In compiling such a book as Eckels’s work under review, a certain arbitrariness in the selection of material is, of course, inevitable. This, apparently, explains the absence from this book, in addition to the above-mentioned methods of measurement, of certain important formulae and items of information.

Thus, for example, data on the magnetic properties of bodies and their dependence on the frequency of alternating current are entirely lacking, although in the second part there are given very important exact formulae for the coefficient of self-induction of wires made of magnetic material. Nor are exact formulae for integral effects in coupled systems given in the second part, although these are of great importance both for measurements and for theoretical calculations. Also absent are formulae relating to the oscillations of a system consisting of an antenna and an oscillatory circuit coupled with it. On the question of the sensitivity of the telephone to alternating currents the author confines himself to only one example, taken from Austin’s experiments, without at all giving the results of the systematic experiments of M. Wien and others.

Apart from the roughness mentioned above, there are at places obscurities and inaccuracies in the exposition that may lead the reader into error. Here are two examples. In the chapter on crystal detectors, explaining the occurrence of a direct current in a circuit with a purely alternating, undamped \(EDC\) (electromotive force) containing a detector with an asymmetrical characteristic, the author makes the following remark: “it should be noted that if the alternating \(EDC\), as is usually the case, is not continuous but damped, then the constant resistance will act as a detector. This can be seen from the fact that in a group of damped waves the sum of the areas of the half-waves of one sign is greater than the sum of the areas of the half-waves of the other sign. If the current is represented by the function \(e^{-bt}\sin kt\), then the rectified current will be \(\frac{p}{p^2+k^2}\).” This remark is very apt to mislead readers, for only in special cases of a damped \(EDC\) is a direct current obtained, and in these cases this is due not at all to the property of resistance, but to the property of the \(EDC\), which must be expressed by a function whose time integral is different from zero, as is the case in the author’s example. In almost all those cases in which detectors are used, the integral of the \(EDC\), both undamped and damped, is equal to zero, and the direct current in a circuit with a constant resistance will be zero.

In another place, describing the system of the French Society of radiotelegraphy, “à onde unique,” the author confines himself to an excerpt from the patent specification, giving no indication that the question of the possibility of the occurrence of a single wave under the conditions of the circuit of this system had been examined in detail in the literature, and that the answer to it was, in the general case, negative.

Written by an Englishman for an English circle of readers, Eccles’s book naturally pays particular attention to English scientific and technical literature and to English sources. The literature of other countries is presented somewhat less fully, although in general the author has made sufficient use of it as well.

The author has, on the whole, successfully coped with the difficult and complex task that he set himself, and his book is indeed a valuable aid both for the beginning researcher and for the engineer.

N. Papaleksi.