Air-Valves for a Mechanical Wing
Small cane-framed flaps that open on an oblique line during the upstroke
The note concerns the 'sportelli' (valves or flaps) of a flying machine's wing, arguing they are more useful the smaller they are, and that they should be framed with cane sinew and covered with a stretched veil. Because the raising is done upward while the whole wing moves transversely, these rows of flaps open along an oblique line and so do not impede the lift. Below the text are sketches of a wing outline and of feathered edges bearing the small serrated flaps.
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Flaps that open obliquely so as not to hinder the upstroke
These flaps are more useful the smaller they are, framed with cane sinew and covered with a stretched veil. Since the wing rises upward while its whole motion is transverse, the lines of flaps open along an oblique line, so that they do not impede the lifting.
Feathered wing edges bearing the valves
The lower part of the sheet shows a wing outline and two feathered edges drawn with small serrations, representing the rows of flaps described in the note. These are the mechanical elements that open and close as the wing beats.