Radio Broadcast (May 1929-Apr 1930)

BOOK REVIEWS TWO BOOKS FOR ENGINEERS Elements of Radio Communication, by John H. Morecroft, 269 pages, John Wiley & Sons, 1929, $3.00. Radio Telegraphy and Telephony, by Rudolph L. Duncan and Charles E. Drew, 950 pages, John Wiley & Sons, 1929, $7.50. Here are two new volumes, both broadly concerned with radio technology, both issued by the firm of John Wiley & Sons, and both presenting a valid claim for admission to the progressive radio engineer's library, yet differing considerably in their contents and mode of presentation. The difference in contents would follow naturally, of course, from the fact that the two books are issued by the same publisher at about the same time. Another point of similarity is that all the authors are well known as radio educators, although in different fields. Morecroft is professor of electrical engineering at Columbia University, and author of the classic Principles of Radio Communication. Duncan is director of the Radio Institute of America, in which Drew occupies the position of instructor in radio. The Duncan-Drew work is almost as long as Morecroft's Principles of Radio Communication. The difference between the two books may be inferred from the statement that a professional radio engineer, if he could secure only one of them, would unhesitatingly choose the Principles while a radio serviceman or operator would be likely to pick the work of Duncan and Drew. This is consistent with the object of the authors, and the fields in which they have done their work. Similarly, a student radio engineer would naturally take to Morecroft's Elements, although he might also get valuable material out of Radio Telegraphy and Telephony. He would find in all of Morecroft's writings a firm, highly evolved theoretical grasp of the type which forms the only reliable basis for practical results in engineering, and less concern with the details of contemporary equipment. The tendency of Duncan and Drew is to present the elements of the subject in much detail and to break down all subjects into easily comprehended fundamentals, and then to leap directly to lengthy apparatus desscription. Radio Telegraphy and Telephony starts off with a brief introductory chapter which is rather badly arranged. The following chapters are concerned with the elements of magnetism and electricity, motorgenerators, meters, storage batteries, etc. Chapter IX, a comprehensive review of the elements of alternating current theory, is followed by a treatment of "Condensers — Electrostatic Capacity — Capacity Measurements," preparatory to a hundred-page chapter on "Vacuum Tubes" and a 126page chapter on "Receiving Circuits." Considerable text is devoted after this to alternating current receivers and tubes, and receiving accessories, especially loud speakers. Various commercial types, from the venerable 106-D to modern tube receivers in the communication field, are described at length. With Chapter XVII the discussion turns to transmitting equipment. High voltage condensers, antennas, the phenomena of resonance, transmitter adjustment, and the characteristics of commercial broadcast and telegraph tube transmitters are considered in turn. Spark transmission is relegated to a place behind short-wave transmission and reception. The arc trans mitter and the radio compass have later chapters of their own. The last chapter, XXVI, is concerned with "Radio Telephone Broadcast Transmitter Equipment," although much material on this topic is included previously in Chapter XX ("Commercial Broadcast and Telegraph Transmitters"). An appendix and index complete the text. The somewhat confusing arrangement of broadcast transmitter material mentioned above is a characteristic fault of Messrs. Duncan and Drew's otherwise meritorious effort. The descriptions are badly arranged in places and give an appearance of imperfect digestion of the material. As a specific instance, the carbon microphone, including the broadcast type, is discussed on pages 610-614 of Chapter XX, while the condenser transmitter is described on pages 719-720 of Chapter XXI and again on page 894 of Chapter XXVI. Figs. 370 and 447a, in separate chapters, show views of condenser transmitters and stands differing only slightly in external design. The fault of illogical arrangement is not found in the Morecroft text. At times the terminology is open to criticism, as when the author refers, on page 10, to "distorted waves," when he means complex or non-sinusoidal waves. Otherwise the book sustains throughout the impression of mature reflection on the author's part. The first three chapters present the underlying laws governing the behavior of audio and radio-frequency circuits and the principles of radiation. "The Vacuum Tube and Its Uses" is the title of Chapter IV. Then fellow chapters on radio telegraphy and radio telephony, and a final chapter, VII, on "Receiving Sets." Pages 257-266 contain, in small type, problems arranged by chapters. The index is somewhat brief. Morecroft's Elements of Radio Communication contains no plethora of material, but at every turn Morecroft's wide physical knowledge is exhibited, to the profit of the student and even the experienced engineer. Such points as the calculation of the capacity of the earth on page 35, the fine range of comparative data in the discussion of "What Is a Good Vacuum?" on page 104, and the illustration, beginning on page 248, of how ordinary alternating current equations may be used to solve simple filter problems, are examples of this invaluable trait. — Carl Dreher. SERVICE MATHEMATICS Mathematics of Radio, by John F. Rider. Published by the Radio Treatise Company, New York. Price: $2.00. John F. Rider has promised a manual for servicemen for some time. It develops that there are to be two books. The first book contains the Mathematics of Radio; such is its title, and it has in it tables, formulas, and examples of radio circuits galore. The book tells how to solve all types of radio problems involving the three graces of radio, resistance, inductance, and capacity. It deals with power circuits, filament circuits, iron-core chokes, power amplifiers, screen-grid tube circuits, etc. When a serviceman can work all the examples the author gives in this 127-page book, he can make up a few for himself, and be assured that he has a pretty good working knowledge of radio circuits. There is no better way to learn radio than by solving radio problems. It is a much less expensive pastime than playing in a laboratory with sensitive meters and other apparatus that will burn or wear out. The second volume of the Service Mans Manual, of which this book is the first, deals with commercial circuits and, according to the author, uses circuit diagrams of popular receivers and power equipment as the background of its work. — Keith Henney. A THRILLING NARRATIVE International Aspects of Electrical Communications in the Pacific Area. By Leslie Bennett Tribolet, Ph.D. The Johns Hopkins Press. 282 pages. Price: $2.50. That a volume with this unpromising title should prove to be a thrilling narrative of cunning and intrigue was a surprise to the reviewer confronted with this assignment. The volume reviews the half-century of secret agreements and manoeuverings which have hampered the establishment of American communications in the Pacific. Decentralized American interests, unsupported by a definite government policy, have faced foreign governments and hostile commercial interests with far-sighted plans, so far quite successfully carried out, to control trans-Pacific communications. Only the recent success of the Radio Corporation of America in establishing direct radio communication with Japan and the Philippines has bettered the American position. In contrast to the struggle on the Pacific, the eminently successful disposition of a four-corner competitive struggle of European and American enterprises in South America demonstrates how successfully unified international action has coped with an equally difficult situation. The recent testimony before the Senate Interstate Commerce Committee considering the Couzens Bill, is ably supported by the experiences reported in this authoritative volume. The necessity for unified American policy in foreign international communications interests is so markedly brought out that any serious reader of this volume would regard as a misfortune any attempt to continue a competitive situation. The support which certain foreign governments give their commercial interests engaged in extension of international communication is an amazing contrast to the treatment accorded by our own Government to those active in this field. Experience has proved that the only reliable safeguard to uninterrupted international communication is the extension of American-owned cables and radio systems, working in coordinated and noncompetitive harmony, aided and supported by an alert and forceful government policy. — Edgar H. Felix. PRACTICAL DATA ON TUBES Radio Receiving Tubes (Including Applications for Distant Control of Industrial Processes and Precipitation Measurements) by James A. Moyer and John F. Wostrel. McGraw-Hill Book Company, New York. 297 pages, $2.50. 1929. The partnership of Moyer and Wostrel is responsible for Practical Radio and Practical Radio Construction and Repairing, from the press of the same publishers. These books have been previously reviewed in Radio Broadcast. Radio Re{Continued on page 233) 224 • • FEBRUARY 1930 •