The basic equations of oscillatory (so-called tidal) motion and a first approximation to the solution are given for a ternary gas (consisting predominantly of neutral particles with traces of positive ions and electrons) in the presence of the earth's magnetic field. Present work shows promise of avoiding the assumptions used by Schuster and Chapman,1 such as (1) incompressibility, (2) plane-parallel ionized layers, (3) neglect of Coriolis forces, (4) zero vertical velocity, and (5) isotropic conductivity. Inclusion of anisotropic conductivity effects have been considered by Baker and Martyn.2

Present work begins by including in the equations of motion3 for atmospheric oscillations, collisional or frictional terms [last term of our eq. (I)] found by Johnson, and corroborated by Cowling,4 derived by idealizing diffusion in a multiple-component mixture as equivalent to all possible binary combinations. The present treatment includes a term involving the elastic collisions of positive ions and electrons, for they may very well prove to be important in the F-layer.