Abstract: A uni-wheel skate has a circular wheel which has a rim arranged to rotate about a frame having a generally tilted axis so that the rim rotates in a plane which is generally tilted relative to the vertical. The frame has satellite rollers rotatably attached to the frame and engaging the rim so as to permit the rim to rotate about the frame. A foot support is pivotally carried by the frame and receives the rider's foot for transmission of the rider's body load to and through the frame to the wheel. A separate support is associated with the frame to be rotatable relative to the frame to be engaged with the rider's leg to maintain stability. The pivotable foot support may be provided with brake pads for engaging the rim.

Abstract: A choral effect is produced by operating a sound source element to produce sound traveling in a sound chamber, operating a sound detector element to detect sound traveling in the chamber, and, effecting movement of at least one of the elements so as to vary detected sound frequency and quality. A panel element may also (or alternatively) be moved to vary detected sound frequency and quality.