Provision is made for spatially stabilizing standing capillary surface waves (62) in fixed and repeatable locations with respect to stationary external references. For spatially stabilizing such a wave on the free surface (23) of a volume (24) of liquid, the wave propagation characteristics of the free surface of the liquid are periodically varied in a spatially stable manner at a spatial frequency equal to the spatial frequency of the standing wave or a subharmonic thereof, thereby locking the crests (64) and troughs of the standing wave in predetermined spatial locations. A spatially periodic pattern of notches (82) in a wall (83) or base plate bounding the free surface of the liquid may be employed to physically modulate its wave propagation characteristics at a suitable spatial frequency. Alternatively freely propagating secondary capillary surface waves may be launched from spatially periodic sites along the free surface of the liquid to actively modulate its wave propagation characteristics at the desired spatial frequency.