An instrument for ascertaining the specific gravity or density of a substance.

An instrument for determining the density of a substance in absolute units, or for determining its specific gravity (ie, its relative density with respect to that of pure water). Also known as "density gauge"; "density indicator"; "gravitometer. "

A device which measures the average density of the fluid mixture in a borehole by means of a vibrating cylinder. The holdups for the heavy and light phases can be determined from the measured average density, when the bottomhole densities are known for each phase and if a contrast exists.

Equipment used to analyze the porosity of a given sheet of paper.