Copper Ball Descends the Larch Beam
The copper ball, polished to a mirror sheen, rests at the top of the grooved beam in my workshop here in Padua, this December evening of 1604. The wood is seasoned larch, straight and notched at precise intervals to mark the descent. I release the sphere. My thumb remains on the water-clock orifice, timing the transit from the first notch to the second, then the first to the fourth. The Aristotelians in the university halls assert that velocity is proportional to the weight of the object and the time elapsed. They claim the motion is uniform. The water collected in my vessel tells a different story.
For the double distance, the time does not double. The weight of the water for the fourth interval is not twice that of the second; it is the square. The ratio is fixed. The ratio is stubborn. I have repeated this descent one hundred times, drying the track, ensuring the incline remains at a constant elevation. Each trial returns the same proportion. The ball accelerates. It does not merely move; it gains speed in a mathematically rigorous progression that the ancient texts fail to describe.
The instrument is not mistaken. The water-clock is a simple, honest witness, and the larch beam has been planed until the friction is negligible. The discrepancy between the parchment of the ancients and the behavior of the copper is absolute. The consensus among the professors is that motion is a quality to be debated through logic. The rolling ball is an observation. When the observation conflicts with the prior, the prior is discarded. The consensus is not evidence for the nature of falling bodies; it is a misunderstanding that the inclined plane has corrected.
The distance grows with the square of the time. This is not a suggestion or a tendency of the matter. It is a law written in the language of geometry. The Aristotelian framework cannot produce this square under any configuration of its logic. This is a decisive measurement. It narrows the space of possible truths to those that account for acceleration. I will steepen the incline to ten degrees tomorrow to confirm the constancy of the ratio.