  In this paper we extend Chandrasekhar and von Neumann's analysis of the
statistics of the gravitational field to systems in which particles (e.g.
stars, galaxies) are not homogeneously distributed. We derive a distribution
function W(F,d F/dt) giving the joint probability that a test particle is
subject to a force F and an associated rate of change of F given by d F/dt. We
calculate the first moment of d F/dt to study the effects of inhomogenity on
dynamical friction.
