An instrument for ascertaining the specific gravity of bodies.

A geophysical device that has been particularly useful in finding salt domes. Actually, it is a weight on a spring. The spring gets longer in high-gravity areas and shorter in areas of gravity-minus. Magnetism helps the oil geologist understand its measurements

High precision instrument to measure minute variations in the Earth's gravitational attraction that exist as a result of density variations in the underlying rock formations

an extremely