Suspension, Bifilar.
Suspension by two vertical parallel fibres, as of a galvanometer needle.
The restitution force is gravity, the torsion being comparatively slight
and negligible. Leaving torsion out of account the restitution force is
(a) proportional to the distance between the threads;. (b) inversely
proportional to their length; (c) proportional to weight of the needle
or other object suspended; (d) proportional to the angle of
displacement.