In a previous communication to the Society the occurrence of wireless echo doublets was described and was provisionally attributed to the influence of the earth's magnetic field on the dispersive properties of the ionosphere. A more extended study of the subject, which has included an experimental determination of the polarizations of the doublet-components, has confirmed this hypothesis. In South-east England, for ionospheric reflection at vertical incidence, the echo-component of lesser delay is, in general, of right-handed, and the component of greater delay of left-handed, circular polarization, but this temporal sequence should be reversed in the Southern Hemisphere, and in certain special circumstances in the Northern Hemisphere.

No abstract