Deeper channels flow faster; weights resting on a cord
In pen, a labelled water-course (m, a, p, n); red-chalk weights on a taut cord
In pen Leonardo compares water-courses of equal width, length and slope and finds the deeper channel has the swifter flow, illustrating it with a labelled section where the thickness p m moves faster than the height a n. Turned the other way and drawn in red chalk are weights hung on a cord, with the rule that a weight free to move on a running cord settles between equal angles. The leaf pairs his hydraulics of flow with the equilibrium of loads on cords.
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Depth governs the speed of a water-course
Among courses of water of equal width, length and slope, the one of greater depth will be of swifter flow. Leonardo makes depth the decisive factor when the other conditions are equal.
Labelled section: thickness p m outruns height a n
In the diagram of a water-course lettered m, a, p, n, Leonardo notes that the water of the thickness p m moves faster than the height a n.
A weight on a running cord rests between equal angles
Every movable weight upon a running cord comes to rest between equal angles. The red-chalk figures show weights suspended so that the cord makes symmetrical angles.