  In this paper we calculate the Casimir energy for a dielectric-diamagnetic
cylinder with the speed of light differing on the inside and outside. Although
the result is in general divergent, special cases are meaningful. The
well-known results for a uniform speed of light are reproduced. The self-stress
on a purely dielectric cylinder is shown to vanish through second order in the
deviation of the permittivity from its vacuum value, in agreement with the
result calculated from the sum of van der Waals forces.These results are
unambiguously separated from divergent terms.
