Abstract: The invention relates to a method for preventing leaks in a propeller shaft bearing arrangement including a plain bearing (2), which is lubricated with oil or water and which supports the propeller shaft (1) extending through an opening in the body (4) of a hull, and packing members (6,7) for keeping the lubricant in the lubrication space and for preventing water from entering the bearing arrangement. The pressure vibrations occuring in the lubricant are equalized by arranging, in the lubrication space, a medium prossesing a high compressiblility, which medium through changes in volume receives and equalizes said pressure vibrations.

Abstract: Disclosed is a method and an apparatus for analyzing pieces of ore for the purpose of sorting. Each piece falling by the analyzer is irradiated individually by means of two gamma radiation sources operating at different energy levels so selected that, as to the scattering effect, at one level the Compton effect is predominant and at the other level the Compton effect and the photoelectric effect compete with each other. The former effect is strongly dependent on the ordinal number of the element and, thus, by detecting with at least one detector the scattering intensities produced with the said two sources of radiation and comparing the scattering intensities with each other, the proportion of heavy elements in the ore piece can be determined and the ore piece can be classified on the basis thereof. For example, one energy dispersively operating scintillation detector can be used for detecting the scattered radiation.