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The paper presents an account of an experimental study of beyond-the horizon radio scatter propagation at a frequency of 3480 Mc/s over a path of 173 statute miles between Start Point and Wembley. Details of the path and brief details of the transmitting, receiving and recording equipment are given. Propagation data, collected from May, 1956, to April, 1957, are presented. The performance of the link is measured by the hourly median transmission loss, L, defined as the ratio, expressed in decibels, of the power transmitted to that received. The diurnal and seasonal variations in L are discussed. The distribution of the amplitude of the received signal within a period of an hour is used to investigate the characteristic rapid fading of the scattered signal. Some attempt has been made to associate variations in L with general trends in the weather. Experimental estimates of the aerial coupling loss are given and compared with various theoretical predictions. Preliminary measurements on double diversity, using aerials which can be separated in the vertical direction by distances varying from 9 to 17 ft, are reported. The effects produced by aircraft flying through the beam are discussed, and a series of tests in which a naval aircraft flew both along and transversely across the transmission path are described.