  We prove a formula for the polar degree of projective hypersurfaces in terms
of the Milnor data of the singularities, extending to 1-dimensional
singularities the Dimca-Papadima result for isolated singularities. We discuss
the semi-continuity of the polar degree in deformations, and we classify the
homaloidal cubic surfaces with 1-dimensional singular locus. Some open
questions are pointed out along the way.
