  Let X be a compact manifold with boundary, and g a scattering metric on X,
which may be either of short range or `gravitational' long range type. Thus, g
gives X the geometric structure of a complete manifold with an asymptotically
conic end. Let H be an operator of the form $H = \Delta + P$, where $\Delta$ is
the Laplacian with respect to g and P is a self-adjoint first order scattering
differential operator with coefficients vanishing at the boundary of X and
satisfying a `gravitational' condition. We define a symbol calculus for
Legendre distributions on manifolds with codimension two corners and use it to
give a direct construction of the resolvent kernel of H, $R(\sigma + i0)$, for
$\sigma$ on the positive real axis. In this approach, we do not use the
limiting absorption principle at any stage; instead we construct a parametrix
which solves the resolvent equation up to a compact error term and then use
Fredholm theory to remove the error term.
