  We prove that the homoclinic class of every hyperbolic periodic orbit of a
geodesic flow over a $C^\infty$ closed rank 1 Riemannian manifold equals the
unit tangent bundle. As an application, we give a proof using symbolic dynamics
of the theorem of Knieper on the uniqueness of the measure of maximal entropy
and theorems of Burns et al on the uniqueness of equilibrium states.
