Determination of the volume of solid bodies by plethysmometry: the bodies, such as human beings or animals, are brought into a measuring chamber (1) the volume of which is changed by means of a piston (8) within a cylinder (7). The change in pressure within the chamber (1) is measured and constitutes a measure of the volume of the body to be determined. The measurement may be performed with the aid of a reference chamber (5) in which the volume is also changed, i.e. by simultaneous movement of a piston (11) within a cylinder (10) together with piston (8) within cylinder (7). By comparison of pressures (by means of 17) between the chambers (1 and 5) a more accurate volume measurement is obtained than without reference chamber (5). The invention is based on the recognition that a quick change in volume is conducive also to a change in temperature and that living beings to be measured give off water vapour and heat, thus causing the measurement to be less accurate, and that this problem may be solved by filling the measuring chamber (1) and preferably also the reference chamber (5) for the major part thereof with a solid filler material (2, 6) having a plurality of interconnected cavities.
|Publication status||Published - 11 Dec 1980|