Preface to the Second Edition
The recent war induced a considerable development in the science of acoustics and in the mathematical
techniques that are particularly useful in theoretical acoustics. Studies in ultrasonics have quickened
interest in problems of radiation and scattering and in transient phenomena; and the rapid development
of microwave techniques, which parallel acoustic techniques, has stimulated interest in the general
theory of wave motion.
Reflecting these developments, the present edition of this volume includes more detail than the first
edition on radiation problems and introduces the important subject of transient phenomena and the
technique of the operational calculus. Both of these subjects are usually shunned because of their
reputed difficulty. The writer is convinced that they are not particularly difficult conceptually, although they
usually necessitate calculations of rather wearisome extent. They are here discussed with the intent to
bring out fundamental ideas, rather than to ensure mathematical rigor of treatment.