Flying-machine wing and the circulation of water
Flapping-wing studies with a marginal analogy of water rising like sap in a vine
The sheet is dominated by studies for a flying machine: large flapping-wing frameworks drawn in red and brown ink, with a mechanical wing dimensioned in braccia (4, 2, 8) and a hand-traction device (labelled a, 'the hand that pulls'). A long marginal passage develops Leonardo's analogy between the circulation of water and the rising of sap: as humor rises through a cut vine and pours from its severed members, so water rises and pours through the ruptures of the highest mountains' summits, both moving toward the centre of the world and returning upward through the channels of the earth. A short arithmetical operation (300, 30, 300, 10) is jotted at the upper left.
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Mechanical wing and flying-machine frameworks
A large articulated wing is dimensioned in braccia (spans of 4, 2 and 8), drawn among several red- and brown-ink flapping-wing frameworks and an operator. The studies explore the structure of a man-powered flying machine.
Water circulating through the body of the earth
Leonardo likens the running waters in the channels of the earth to the sap that vivifies a vine: as humor rises through a cut vine and pours from its severed members, so water rises and pours through the ruptures at the mountains' summits. Both desire and move toward the centre of the world, and the water, falling on the roots and penetrating them, rises again and returns to the same cut.
Hand-traction operating mechanism
A traction system is drawn for driving the wing, its pulling point marked a — 'the hand that pulls'.