can b« obtained with cha aid of elezswVi.iry residue calculus (Bed, e.g., 

 [7]). 



It Is usual, and no doubt more logical, to start an Introduction to 

 a technique of this kind by first suasaarizing all that will be required 

 in the way of results from the theory of functions of a complex variable. 

 As our problems are extreteely sisple, both frca the conceptual and from 

 the manipulative point cf view, it seems unnecessary to start here with 

 such a digression, and we shall introduce the various ideas and theorems 

 as they arise in the course of the problems. For a rigorous statement of 

 the theorems the reader is referred to standard references (e.g., 

 Titchaarsh [13]). We should warn the reader, however, that the degree 

 of rigor which is usually adoptsd by workers in wave theory is not 

 altogether a matter of mathematical pedantry. Certain problems, involving 

 coupled wave-bearing media in particular, are extremely delicate, and 

 require much more attention to mathematical rigor than do Che simple 

 problems at hand here. 



