Apparatus for detecting that the pressure at the bottom of a container does not depend on its design, but only on the liquid level. For quantitative determination of the hydrostatic pressure and examination of the linear relationship between pressure and liquid level. The liquid pressure at the bottom of the various vessels deforms a highly elastic rubber membrane whose movement is transmitted to a centimeter-graded needle. The deviation can be compensated with weights. The mass and distance of the weight from the pivot point make it possible to quantitatively determine the pressure change. A second pointer can be mounted vertically to visualize fluid level.

Dimensions: vessel height 250 mm, inside diameter, bottom 26 mm, hand length 210 mm, total height 350 mm, bottom plate 280 × 110 mm.