torsion balance definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
an instrument for measuring small forces, such as those caused by gravitation, electric charges, or magnetism, by recording the amount of torsion they produce in a fine wire
torsion balance definition by American Heritage Dictionary
An instrument with which small forces, as of electricity or magnetism, are measured by means of the torsion they produce in a wire or slender rod.