This book is designed to emphasize those aspects of classical electricity and magnetism most useful to the modern student as a background both for experimental physics and for the quantum theory of matter and radiation. We have made no attempts at novelty beyond those inherent in looking at subject matter that has become a part of the foundations of physics, and has thus gained in usefulness as it has lost in immediacy. While no rigid adherence to historical development is attempted, the emphasis is on physical theory as evolved from fundamental empirical laws rather than on mathematics and strict internal logic. Thus Maxwell's equations are derived from the experimental laws of Coulomb, Ampere, and Faraday, instead of being postulated initially. In the opinion of the authors the physical concepts emerge more clearly in this way, and the approach represents the manner in which physical theory evolves in practice. The field formulation is preferred to the action-at-a-distance viewpoint even in electrostatics, however, since for the conventional treatment it is more readily extended to the nonfetatic case. This despite the fact that it is possible, both for static and for nonstatic phenomena,-to formulate' an entirely consistent electromagnetic theory based on the delayed-action-at-a-distance principle.