  Stars in the solar neighbourhood do not have a smooth distribution of
velocities. Instead, the distribution of velocity components in the Galactic
plane manifests a great deal of kinematic substructure. Here I present an
analysis in action-angle variables of the Geneva-Copenhagen survey of ~14,000
nearby F & G dwarfs with distances and full space motions. I show that stars in
the so-called "Hyades stream" have both angle and action variables
characteristic of their having been scattered at an inner Lindblad resonance of
a rotating disturbance potential. This discovery seems to favour spiral
patterns as recurrent, short-lived instabilities.
