Of Water: Why Water Driven Under Water Does Not Whistle
and a crank-driven linkage a b c m n f turned by the handle d
Headed 'Of water,' the top note poses an acoustic question: why does water moving beneath other water make no sound, whereas air makes a sound when driven through a whistle or fife? Leonardo imagines a small bellows fitted with a fife: filled with air it whistles, but filled with water and squeezed shut under water so the water rushes out through the fife, it does not. Below, a mechanical diagram is explained in terms of parts driven by a handle d: as c turns it carries to a and a to b, so that m and f alternately meet, touch, draw apart to their first distance, and return with each turn of the crank.
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Why water forced under water makes no whistling sound
Leonardo asks why the movement of water beneath other water does not produce the sound that air makes among air when driven through a whistle or fife. He contrasts the two by imagining the same fife sounded first by air and then by water forced through it.
A bellows and fife driving water instead of air
A small bellows full of air fitted with a whistle sounds as the air passes through it. Fill the same bellows with water and drive it all under water, the fife joined to its mouth, then squeeze it forcibly shut so the water rushes with fury through the fife as the air had done.
Crank-handle d driving the linkage a b c m n f
When c turns it is carried to a, and a goes to b, and n goes under b, so that m must touch f: f turns to meet m and m to meet f, remaining briefly in contact. Then, little by little, they return to their first distance, separate and return again, all according to the turning of the handle d.