The torsion balance as a tool for geophysical prospecting

We discuss whether the torsion balance can again become a key tool for geop hysical prospecting. We outline the acknowledged disadvantages of the Eotvo s torsion balance and seek designs of a torsion balance beam that would ena ble the torsion balance to be used on moving platforms. A key result is tha t torsion balance beams designed to be insensitive to the curvature and hor izontal gradients of the gravity field are insensitive to the angular motio n of the platform about horizontal axes. We suggest that a double torsion b alance using these balance beam designs could be used on moving platforms. We point out that second gradients of the gravitational field (third deriva tives of the potential) can be determined with reasonable sensitivity with current technology. We describe double torsion balance schemes where the ma ss, range, and azimuth of localized mass anomalies could be estimated or wh ere local anomalies could be rejected using information from the second gra vity gradient.