Applications of Ultrasonics

Abstract

THE scientific study of ultrasonics, or the properties of high-frequency inaudible mechanical vibrations, may be said to date from the year 1883, when Galton published his book “Enquiries into Human Faculty”. In this book he described the construction of the Galton whistle, an instrument which, refined in some details, is used to this day by psychologists and physiologists for the production of sounds of high pitch. The subject remained of little more than academic interest until, during the Great War, Langevin devised the first practical apparatus for the transmission and reception under water of inaudible ‘sound’ signals. For this purpose, Langevin utilized (1) the discovery by the brothers J. and P. Curie of the piezo-electric properties of quartz, and (2) the methods of generating and detecting electric oscillations made possible by the invention of the three-electrode thermionic valve. Laiigevin saw quite clearly that the use of disturbances of short wave-length enabled him to exploit the effects of unidirectional propagation, reflection, refraction, interference, diffraction, etc., until then more usually associated with optical phenomena. He might justly be called the ‘Father’ of modern ultrasonics. Ultrasonics and their Scientific and Technical Applications. By Prof. Dr. Ludwig Bergmann. Translated by Dr. H. Stafford Hatfield. Pp. ix + 264. (London: G. Bell and Sons, Ltd., 1938.) 16s. net.