The first two virial coefficients and their temperature derivatives for Ne and for Ar atoms adsorbed on xenon-plated graphite are reexamined with the implementation of the Mahanty’s image theory. On the assumption that the substrate is treated as a good conductor, encouraging values of the second virial coefficient β2 and the average lateral interaction energy ε2 of an isolated pair of adatoms are obtained when the “ideal surface” of the substrate is set at 1.9Å above the xenon layer, a distance which is essentially identical to the van der Waals radius of the xenon atom. Under such a situation, the strength of the adatom-adatom interaction is weakened by a factor of 0.56 and 0.60 for the Ar and the Ne case, respectively, which are in concord with the predictions asserted in earlier work. Discussions on the dependence on the dielectric constant of the substrate are also given. The present results seem to indicate that the Mahanty’s theory provides a viable alternative approach for studies of physisorption problems.