Fol. 15v

A mechanical bird attached to an instrument that measures its centre of gravity: the flying machine is subjected to testing. In the other drawings and in the text that accompanies them, the evaluation of the centre of gravity and the wing in relation to the various movements of the kite’s ascent and descent. Drawing the eye to the centre of the page created from recycled paper is a drawing of a red leaf.

«Quando l'uccello discende il suo centro di gravità è fuori del centro della sua resistenza come se il centro di gravità fosse sopra la linea "a" "b" e il centro di resistenza sopra la linea "c" "d". Quando l'uccello vuole innalzarsi il suo centro di gravità resta indietro rispetto al centro di resistenza »
(When the bird descends, its centre of gravity is outside the centre of its resistance, as if the centre of gravity were on line a b and the centre of resistance on the line c d. When the bird wants to ascend, its centre of gravity remains behind with respect to the centre of resistance.)

NOTE. For each page of Leonardo’s Codex we provide a brief summary, with the quotation of one that page’s most significant passages edited in modern Italian, with an English translation.

translation by Kim Williams