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An account is given of observations on a number of discrete sources of radio- frequency radiation, together with a brief description of the observational techniques used in their detection, and of the methods employed to determine their positions and angular extent.Noise spectra of four of the more intense sources have been measured over a frequency range of 40-160 Mc/s. : in three cases the change of intensity with wave- length is found to be greater than that of the background continuum, and in one case less. Two of the sources have been provisionally identified with astronomically rare objects, the Crab Nebula and N.G.C. 5128.Finally, the short period fluctuations in the intensity of some of the sources, notably that in Cygnus, are discussed. Evidence is presented which, contrary to previous views, suggests that these fluctuations are of terrestrial rather than of extra-terrestrial origin.

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SummaryObservations with three forms of equipment have revealed the existence of a number of sources of angular width more than 1°.A rough analysis of the brightness distribution of one source shows that it is elongated along a parallel of galactic latitude. This source appears to be typical of a class that is generally distributed around the galactic equator, and may represent fine structure in the distribution of radiation from the Galaxy.Of the others, one appears to be associated with the abnormal galaxy NGC 5128, and another has been identified with a network of gaseous filaments in our own Galaxy.

A study has been made of the scintillations of four discrete sources at altitudes of from 0 to 10�. The observations cover the years 1947?1951 and were made at various frequencies in the range 40?300 Mc/s. It was found that the scintillation index, a measure of the amplitude of the scintillations, (1) increases with increasing wavelength, (2) decreases rapidly with increasing altitude, (3) shows seasonal and diurnal variations, the seasonal component having minima near the equinoxes and the diurnal component near dawn and sunset. The scintillation rate or the number of scintillations per minute (1) is different for sources of different declination, (2) is independent of wavelength. In the case of the Cygnus source, the data for which are the most extensive, the rate increases and the decline in the scintillation index with altitude is less rapid during the winter months.