torsion balance—A device for measuring very small forces of attraction resulting from gravitation or magnetism and consisting of a bar suspended horizontally by an elastic filament, one end of the bar being subjected to the influence of the attracting force to a much greater degree than the other end. The attracting force is balanced and its comparative strength measured by the torsional reaction of the filament.

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Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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