Charge images in a dielectric sphere

Following the paper by the author (see ibid., vol.142, no.2, p.142-50, 1995), the comments on correspondence between himself and I. Lindell regarding the work of Carl Neumann, he after whom the familiar flux boundary condition is named. Neumann had given the solution for the image in a dielectric sphere in an appendix to a book on fluid mechanics published in Leipzig in 1883 and also that the result had been given without proof as an obiter dictum in 1985. Professor Lindell suggested that the images of charges in dielectric and diamagnetic spheres and in magnetic spheres of less than infinite permeability should be called the Neumann images. It would be helpful if the Neumann images were described in future text books on electromagnetism for they are not complicated