Bubbling water, wave motion, and eddies from the pool bed
Reflected bubblings, simple and composite motions, and the slow crest of a wave
A plume of water plunging into a pool at the upper right accompanies Leonardo's analysis of bubbling water: some of the water reflected from the pool bed falls back to the surface and renews its incident and reflected motions, some returns to the first fall and rises again in lateral eddies, and some settles slowly around the center of its fall. He distinguishes the simple motions of water from the composite motions, which he calls most powerful, and observes that a wave is slower at its crest than at its sides and that the incident motion is faster than the reflected. A marginal note adds that the combined slownesses of a wave, taken with its sides and summit, equal the common course of its river, a point he reserves for his conclusions.
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How bubblings reflected from the pool bed behave
Of the water reflected up from the bottom of the pool, part falls back to the surface and renews its incident and reflected motions, part returns toward the first fall and submerges, rising again in lateral eddies, and part settles slowly around the center of its fall.
Simple and composite motions; the wave slower at its crest
The simple motions of water simply operate with their single motion, while the composite motions, created by various motions, are the most powerful. The wave is slower at its crest than at its sides, and the incident motion is faster than the reflected.
A wave's combined slownesses equal its river's course
Joined together, the greater and lesser slownesses of a wave, taken with its sides and its summit, become equal to the common course of its river. Leonardo notes that this is to be brought forward and proved in his conclusions.