filled = parked on magnet · open = swinging free · copper = strike
wind streaks and the compass now show the same meteorological direction ·
the sail drives a two-axis pendulum, the clapper visibly reaches the bell wall,
rebounds, then may be recaptured by the magnetic pad · a sharp veer or lull
releases it again · drag to orbit, scroll to zoom
strike – ring – damp the field sounds the wind's derivative