The dust-free space surrounding hot bodies

It is generally accepted that the dust-free space around hot bodies is due to the combined action of a radiometer force and an aerodynamic force caused by convection currents but no attempt has yet been made to derive a quantitative theory. Starting from the published work on the derivation of these forces a method has been evolved for equating them and the theory is worked out quantitatively for a vertical plate and for a horizontal cylinder in terms of temperature difference and the properties of the surrounding medium. The resulting relations are in good agreement with published experimental data.