“Regarding this case, I want you to make an instrument as depicted here. And turn the face of the plank, with its pyramidal holes, toward the direction the wind is blowing.”
Leonardo drew this instrument for
demonstrating that conical ducts with different
openings would proportionally affect the intensity of a current of air passing through.
It is constituted of a vertical structure with two
conical ducts attached having different openings.
Both of the points of the cones are directed
at a wheel equipped with copper vanes; two weights are hung on the wheel’s shaft. The current of air passing through the two conical ducts with different apertures is capable of moving the wind turbine, thus lifting the two weights that are proportional to the apertures of the cones.
The model is based on the drawing:
- Codex Arundel f. 241 r. (1490 ca.)
London, British Library