A ferromagnetic disc is placed between two conducting plates of infinite extent, so that the axis of the disc is perpendicular to the plates. The magnetization in the disc is homogeneous and varies with time t>0 in a known but arbitrary fashion. The eddy current distribution in the plates and the magnetic field which they generate in the disc are represented with the help of a Laplace transform with respect to time and a Hankel transform with respect to the distance from the center of the disc. In the special case where the distances perpendicular to the conducting plates are small compared to the radius of the disc, these two transforms can be inverted. The eddy currents and the generated magnetic fields are then easily visualized. © 1961 Springer-Verlag.