Turbid water, river banks, and gold-panning in the Ticino
Notes on how shaking sorts the lighter matter and how muddy water wears the banks
A text leaf in red chalk, written upside down, with two hydraulic observations. The first compares the motion of a sieve, which gathers the lighter particles apart at the top, with the pan used to fish gold in the Ticino and with the washed sweepings of goldsmiths. The second states that turbid water harms the banks more than clear water, and more low down than high up, because it is heavier and coarser.
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Shaking sorts the lighter matter to the top
The motion of a sieve gathers all the lighter parts apart at the top, and the same is done by the pan used to fish gold in the Ticino by means of the shaking, and by the goldsmiths' sweepings that are washed. Motion separates material by weight.
Turbid water wears the banks more than clear water
Muddy, turbid water harms the banks more than clear water, and more low down than high up, because it is heavier and coarser. The greater density concentrates its erosive effect near the bed.