No coin nor oath required. For personal study only.
BOOK REVIEWS. 637 room; in a distant city, a far-away country; at the ends of the earth and eventually perhaps beyond the confines of terrestrial space. To the uninitiated, a loud speaker will appear to be a relatively simple affair believed to have sprung forth, full-fledged, from the "forehead" of necessity at expediency's behest. To the radio engineer and others engaged in the problem of sound reproduction, a loud speaker represents the culmination of many physical and mathematical studies on the mechanics of sound waves, the characteristics of vibratory sources and the properties of resonators. Back of the instrument may be found papers, reports, treatises, experimental models and performance graphs, all of which are prerequisites to the development of any correctly constructed loud speaker.
According to the author, the purpose of this book is to provide a fairly complete treatment of the theory and practice of loud speakers. In order to fit better the varied requirements of the readers, the theory and practice have been dealt with separately in so far as was practical. The theory, coming first, will appeal to the mathematical reader, who will not find it too elementary. For the readers occupied with testing and design, the latter portion of the book will prove to be especially helpful. The author has paid particular attention to the method of presenting his subject matter. From the material available he has endeavored to evolve the theory in logical sequence, and to give its practical applications. The treatment is as rigorous as possible, but of such a nature as will appeal to engineers.
In the theoretical section the material has been arranged under such captions as: Principles of Sound Propagation, Accession to Inertia, Vibrational Modes, Spatial Distribution of Sound from Vibrating Diaphragms, Acoustic Power Radiated from Vibrating Surfaces, Theory of Moving-Coil Principle, Hornless Speaker Simulated by Coil-Driven Rigid Disk, Electrostatic Speakers, Theory of Horns, Sound Waves of Finite Amplitude, and Transients. The practical part is presented under headings such as: Driving Mechanisms, Magnets, Electrical Impedance Measurements, Response Curves, Measurement of Vibrational Frequencies of Conical Shells, Design Considerations in Hornless Moving-Coil Speakers, and Design of Horn Type Moving-Coil Speakers.
The volume is well supplied with line diagrams and graphs. In a work of this type, such illustrations will greatly assist the reader. There is also a comprehensive list of references to aid those interested in pursuing the subject further.
T. K. CLEVELAND.
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