A list of errata for this title is available upon request directed to A. Bers at [email protected].

The selected papers of William Phelps Allis are gathered here in celebration of his elevation from Professor to Professor Emeritus of Physics at the Massachusetts Institute of Technology. This gathering was arranged as a surprise tribute to Professor Allis and was prepared under conditions of conspiring silence. The presentation was held at M.I.T. on May 10, 1967. The papers selected here are a worthy extension of the man himself, in their directness and essential simplicity. And in their abiding value. In the words of his editor, student, and colleague Sanborn C. Brown, "he has succeeded in leading a whole generation of Physicists with such a timeless approach that this volume should be considered not as a look backward but as a compilation of fundamental insights upon which to build future progress."