Hinges and a River Barrage: Iron Worn by Running Water
Red-chalk study of pivots and a river gate, with a note that iron under a current never rusts
A faint red-chalk drawing shows a drum-like element mounted on a pivoting frame, part of a study of hinges and a river barrage. The accompanying note observes that iron which continually takes the percussion of running water never rusts, but instead wears away and takes on a burnished sheen. The page joins a mechanical detail with a material observation drawn from moving water.
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Iron under running water never rusts
Leonardo notes that iron continually struck by the running current never rusts; rather it is consumed, becoming burnished. It is an observation on how flowing water acts on the metal of a submerged fitting.
Hinges and a river-barrage gate
The drawing studies hinges and a barrage set across a river, with a cylindrical drum resting on a pivoted timber support. Faint triangular sail-like forms suggest the moving leaves of the gate.