Bird flight balanced among the winds; machine-part sketches

The tail governs the weight on the bird's wings

The tail gives or takes weight from the wings of the bird. Every heavy body moves along the line where it has least resistance, and finds least resistance along the line where it weighs most.

Computing a bird's line of descent among the winds

If the bird descends to the east with its body at 6 degrees of power and leans south with its wings at 2 degrees, Leonardo argues it will descend midway between sirocco and east. He weighs the eight compass quarters between east and south, putting 6 on one pan of the balance and 2 on the other.

The pole n as centre of the power; weight on a cord

The weight b holds its place with a power of one eighth of its weight upon the cord b c that sustains it. In the lettered figures below, the pole n is the centre of all the power, that is, of the values 2 and 6.

Sketches of pulleys, hinges and pierced blocks

The left side of the spread is covered with mechanical studies: circular wheels or pulleys, hinge-plates and blocks pierced with round holes, drawn in several views.

Memorandum: Marcantonio Colonna at Santo Apostolo

A note in the upper left margin records the name Marcantonio Colonna at Santo Apostolo, a personal memorandum among the technical studies.

0150 v

Nel margine sinistro del foglio, in alto:

0146 r

Figura con lettere:

Figura con lettere.

A lato della figura, capovolto:

Figura con lettere:

Nel margine destro del foglio in basso gruppo di due figure con lettere e numeri.

Sotto le figure:

In the left margin of the sheet, at the top:

Figure with letters:

Figure with letters.

Beside the figure, upside down: