Walnut-wood frame with 4 glass tubes in brass mounts joined together by a crossbar fixed to the frame. Liquids of different densities are fed into the tubes from containing vessels. A brass pump screwed to the crosspiece pumps out air from the upper parts of the tubes. With decreased pressure the liquids rise to higher levels; the lower their density, the higher they rise. Levels may be measured using the two scales, from 1 to 24 Paris inches, on the sides of the frame.
Device on display.