The kinetic theory for the escape of planetary and stellar atmospheres, developed by Stoney, Jeans, and others, is generalized to include any height above the atmospheric critical level. The theory is applied to the solar corona and the interplanetary gas; this approach may be contrasted with the use of the hydrodynamic equation of motion (Parker) and the equations of heat conduction and hydrostatic equilibrium (Chapman). The hydrodynamic expansion of the corona must actually be limited by the rate of evaporation, and Parker's large expansion velocities, presumed to correspond to a "solar wind," result from an invalid assignment of an integration constant and an ambiguity inherent in the hydrodynamic solution. Also, the mean energy per particle, which defines an equivalent gas temperature, is considerably lower at the earth's orbit than in Chapman's conduction theory, which does not allow for the evaporative escape of the more energetic particles. The mean expansion velocity, electron density, and equivalent temperature computed with the kinetic theory for two extreme situations are plotted against distance from the sun, and limitations to this simple model are discussed