Einstein looks at Maxwell´s legacy

Summary form only given. Twenty six years after Maxwell\´s death Einstein wrote a second, and most important chapter in the development of classical electromagnetism. Whereas Maxwell\´s equations were assumed valid in "absolute space", Einstein asserted that all laws of physics, including Maxwell\´s equations, should have the same form in all "inertial" frames. Both scientists had to hold revolutionary views to develop their concepts. Maxwell dropped all serious attempts to understand the propagation of light in vacuum in terms of mechanical wave-carrying structures, and advanced a theory in which the current at the end of a wire could flow further in the form of a displacement current, even in vacuum. Einstein, to respect the experimentally established constancy of the velocity of light in vacuum (the ever mysterious speed limit!) had to drop sacred concepts such as the law of addition of velocities. In a 1931 volume commemorating the centenary of Maxwell\´s birth, Einstein (together with other authors) wrote a short essay to laud Maxwell\´s revolutionary concept of physical reality. A very discussion is devoted to the "practical" relevance of the formalism, in particular for the electromechanical engineer who seeks to determine currents and fields in, for example, rotating bodies or circuits containing sliding contacts. Radio engineers, on the other hand, may mostly get away with the quasistationary approach. The theoretical validity of the latter is looked at with a critical eye, and shown to be actually wanting.