Falling water in sloping channels: speed versus length
Two red-chalk channel diagrams comparing how fast water descends over long and short slopes
Two channel schemes drawn in red chalk (the leaf is inverted) compare how quickly water falls when it descends the same drop through channels of different slope and length. Leonardo argues that among channels of equal obliquity starting from one level, the longer one carries the swifter current; where the height of the drop is the same, the longer channel makes the flow slower. Each sloping line is marked with letter labels at its endpoints.
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Among equal slopes, the longer channel runs faster
Water falling from one and the same level through channels of equal obliquity: that one will be of swifter course which is of greater length. The endpoints are lettered c a and d b.
Same drop, but the longer path is slower
Water falling from one and the same level, of one and the same height: that one will be slower which is longer. The scheme is lettered f a and S n.