Galileo's Inclined Plane — Slowing Gravity Down
Free fall was too fast to time, so Galileo diluted it: a groove, frets that click as the ball passes, and a water clock that weighs the seconds. Tilt the groove and release the ball — the bells stay evenly spaced in time while the frets sit at 1, 4, 9, 16, so the distance grows as t² at every tilt, right up to the vertical.