With the advent of short-wave telegraphy, a new technique of echo and facsimile measurement has been developed, facilitating signal-intensity measurements in the wavelength range between 14 and 50 metres. Part (1) of this paper deals with the method adopted of making facsimile measurements, and describes the results obtained, whilst in Part (2) the author discusses transmission problems in the light of these data and suggests the theoretical methods to be employed in solving such problems.Part (3) discusses the problem of scattering, while in Part (4) the author deals with theory.