  Vinen's vibrating wire experiment detected quantized vortices in superfluid
4He, with the anticipated circulation quantum h/m. In addition to this main
result, Vinen used his data to propose other properties and behaviors of
vortices, which are revisited here. Subsequent work confirmed that
non-quantized values occur when vortices cover only part of the wire's length,
and that the size of the covered section can change easily. Any motion of the
detached portion of the vortex induces changes in the circulation around the
wire, which provides a means of tracking the free vortex. Particularly
distinctive signatures correspond to a circular motion of the vortex through
the cell and to Kelvin waves along the free vortex. Another issue, the lack of
stability of multi-quantum states, can also be explained through simple
arguments, in which the possibility of a partially detached vortex again plays
a key role. Vibrating wire measurements descended from Vinen's continue to
probe superfluid flow.
