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Section 1 Theoretical computations based on the semi-empirical formula of Rudstam and the results of a series of irradiations of CsI crystals using proton beams are used to evaluate the importance of spallation induced radioactivity as a source of background in X-ray astronomy experiments. In particular, the U.K.5 experiment 'F' is considered. The results obtained are compared with previous observations and the relative importance of other sources of background is considered. A review is made of previous observations of the diffuse cosmic X-ray flux in which it is shown that breaks in the spectrum could be largely due to inadequate allowance for this phenomenon. Suggestions are made for the location of future experiments and for the correction of data for the spallation contribution. Section 2 Data from the high energy (>360 MeV) proton telescope, experiment S24B, carried on board the HEOS Al satellite, is analysed for the period December, 1968 to April, 1970. Comparison is made with time variations observed by the Deep River neutron monitor in order to determine the rigidity dependence of several Forbush decreases. Examination is made of a change in the modulation following a decrease on June 8th, 1969. High energy particle flares are examined and time profiles and anisotropies are compared with low energy (1 - 13 MeV) proton and magnetic field data in order to obtain a more complete understanding of the propagation processes between Sun and Earth. Quiet-time data is analysed for anisotropies and evidence is provided for a radial streaming of 1 GV cosmic rays towards the Sun in addition to the corotation component. An interpretation in terns of off-ecliptic phenomena is suggested.