Incline Gravity Clock: powered by gravity this clock has no batteries or mainspring- however, once each day the clock must be picked up and placed back at the top of the ramp. :
umdberg / Rolling up and down
Galileo's Inclined Plane Experiment - Maple Help
TAP 205- 1: Rolling balls down ramps
Congreve rolling ball clock
Rolling Plane Clock-Down the Ramp, You Never Wind It !! | #1798892950
Small inclined plane gravity clock by Dent - Carlton Clocks