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.
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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.