In Part 1 of the paper is given a description of the phenomena observed when using a cathode-ray direction-finder on closed coils for examining received signals on frequencies of the order of 10 000 kilocycles persec. The two outstanding features are the systematic appearance of certaincyclic forms, and the large values obtained for the horizontally polarized electric components.The former are then examined in the light of the magnetoionic theory, and it is shown that the majority of them admit of simple explanation on this basis. The latter are chiefly of interest in raising the question of angle of incidence, which appears to be much less than is generally supposed; and Part 2 is devoted to a more detailed examination of the question.