ABSTRACT
This chapter explains how Maxwell's immediate successors tried to solve some of the problems raised by his theory. It reports the attempts to solve the first problem, the relation between charge, current and the field. During the period from Maxwell to Einstein there were two turning points in the development of field theory. The first was Hertz's demonstration of the existence of electromagnetic waves. As a result, Maxwell's theory became the point of departure for all research in electro magnetism. The second turning point was Lorentz's theory of the electrodynamics of moving bodies. Lorentz was able to explain the optics of moving bodies using Maxwell's electromagnetic theory. Thomson and G. F. Fitzgerald had shown how moving charges fit into Maxwell's theory. In the Treatise Maxwell had indicated his opposition to the idea that current is composed of moving charged particles, and he referred approvingly to Faraday's idea that charge is a state of strain in the dielectric.
