  We prove the relation between the Hodge structure of the double cover of a
nonsingular cubic surface branched along its Hessian and the Hodge structure of
the triple cover of the ambient projective space branched along the cubic
surface. And we introduce a method to study the infinitesimal variations of
Hodge structure of the double cover of the cubic surface. Using these results,
we compute the N\'{e}ron-Severi lattices for the double cover of a generic
cubic surface and the Fermat cubic surface.
