Protecting the Arno embankment at Rusciano from waves
On reflected motion, and turning the river with a gentle bend to Ricorboli
The leaf pairs a general principle of mechanics with a practical river-engineering note. The first block states that no simply reflected motion ever rises as high as the start of the incident motion that produced it. The second proposes guarding against the Arno's impact at Rusciano by turning the current with a gentle bend toward Ricorboli and building an embankment so wide that the fall of the water's leap lands back upon it. A drawing shows a wave curling over against a sloping bank; further faint script appears at the foot of the leaf.
On this page
Reflected motion never rises as high as the incident motion
Leonardo states a rule of reflected movement: no motion that is simply reflected will ever be raised as high as the beginning of the incident motion. He applies the idea to water striking and rebounding from a bank.
Embankment battered by the waves at Rusciano
To guard against the Arno's impact at Rusciano, Leonardo would turn the current with a gentle bend toward Ricorboli and raise an embankment wide enough that the falling leap of the water comes back down upon the bank itself rather than scouring it away.
Wave breaking against the sloping bank
A drawing at the center-right shows a curling wave rearing up and breaking against a sloped embankment, illustrating the percussion of the river discussed in the notes.