"When I began my work... in 1876 the theory of Weber "Das electrodynamische Grundgesetz" of 1846, was rife in... continental Europe. Electrodynamics through the genius of Ampère (1821-22) had already definitely captured magnetism. Weber embraced the whole of electromagnetics in a single equation, consistent with the law of the conservation of energy. It was a beautiful theory; but it was gone mad. ...[E]ven Gauss and Riemann did not escape temptation, while Clausius revised and modified the argument throughout, bringing out a new theory of his own. ...[I]t is a superb piece of vigorous mathematical reasoning ...[W]hat these men did was to postulate a force which depended upon the states or motion of the point where force originates; but any phase of the force hammers away at any distant point co-temporaneously with the time of its origin [instantaneously]. These electrical forces... did what gravitational forces still persist in doing. ...[W]e can not but marvel how perilously near they came to the state... to-day. If they had only retarded their potentials! ...[T]hey suspected nothing as the 3 X 1010 velocity which characterizes the relation of Weber's electrostatic to his electromagnetic system of units, measured by Weber and Kohlrausch in 1856, is the velocity of light."