The Boltzmann-Hopkinson principle of superposition as applied to dielectrics

The principle of superposition, discussed first for dielectrics by Hopkinson, has been shown for a long time in experiment. However, its validity for the several theories which have been advanced for dielectric behavior has been shown in only a few cases. One of the exceptions is the important theory of Maxwell.² This paper shows that the principle of superposition is a necessary consequence of Maxwell´s theory. It goes somewhat further and shows that the principle is valid for any theory which leads to a system of linear differential equations with constant coefficients.