Investigations of Kennelly-Heaviside layer heights for frequencies between 1,600 and 8,650 kilocycles per sound

The results of observations of the height of the Kennelly-Heaviside layer carried out near Washington, D. C, during 1930 are presented. Evidence for the existence of two layers (corresponding closely in virtual height to the E and F regions discussed by Professor Appleton) is found during daylight on frequen- cies between three and five megacycles. The modification in the virtual height of the higher F ayer produced by the existence of a low E layer is investigated theoretically, and the possibility of large changes in virtual height near the highest frequency returned by the E layer is pointed out. A number of oscil- lograms showing the characteristic types of records observed during the tests are presented together with a graph of average heights from January to October, 1930.