Sediment carried by rivers, and the winding of floodwaters
Exposed riverbeds give no true measure of what the water carries
This leaf is filled with a single continuous prose passage and carries no drawing. Leonardo argues that naturally exposed riverbeds give no true rule about the nature or quantity of the material the water carries, because in high water many places fill with sand that is later lifted off the gravel where it had settled, or undermined at the foot, so that the raised sand banks collapse in succession and are borne on by the current until dropped where the flow grows quiet. He adds that the windings of rivers in flood break every barrier and order of the lowered rivers, and the note continues onto the next leaf ('turn the page').
On this page
Exposed beds give no true measure of what water carries
Leonardo warns that the naturally uncovered beds of rivers give no true precepts about the nature or the quantity of the things the water carries, because the visible bed does not record the sediment that moved through it in high water.
Sand lifted from the gravel, undermined, and re-deposited
In high water many places fill with sand; as the rivers fall through their side channels this sand is lifted above the gravels where it had settled, or undermined at the foot, so the raised banks collapse in turn. Being light, the sand travels with the current and is discharged where the water grows most quiet.
River windings in flood break every barrier
The passage closes with the claim that the windings of rivers in flood are the ones that break every defence and order of the lowered rivers, and directs the reader to turn the page for the continuation.