2. (Mech.) That force with which a thread, wire, or rod of
any material, returns, or tends to return, to a state of
rest after it has been twisted; torsibility.
{Angle of torsion} (of a curve) (Geom.), the indefinitely
small angle between two consecutive osculating planes of a
curve of double curvature.
{Moment of torsion} (Mech.) the moment of a pair of equal and
opposite couples which tend to twist a body.
{Torsion balance} (Physics.), an instrument for estimating
very minute forces, as electric or magnetic attractions
and repulsions, by the torsion of a very slender wire or
fiber having at its lower extremity a horizontal bar or
needle, upon which the forces act.
{Torsion scale}, a scale for weighing in which the fulcra of
the levers or beams are strained wires or strips acting by
torsion.