Whether the tail or the wings turns the bird into the wind
The larger slant wins: a greater tail-slant faces the bird to the wind, a greater wing-slant swings the tail to it
Leonardo compares the slant of the tail behind the bird's center with the slant of the wing in front of it to decide how the wind turns the bird. If the tail's slant exceeds the wing's, the bird turns its face to the wind; if the wings' slant is the greater sum, the tail instead swings toward the oncoming wind. A single word carried over from the previous page opens the sheet, and a small bird in flight is sketched at upper right.
On this page
The greater slant decides which end meets the wind
If the slant of the tail, measured from the bird's center backward, is greater than the slant of the wing from the center forward, the bird turns its face into the wind. But if the wings' slant is the greater total, then the tail swings around toward the oncoming wind. The competing slants of tail and wings set the body's final heading.
Bird in flight sketched in the margin
A small bird is drawn in flight at the upper right of the sheet, its wings extended. It stands as a visual token for the flying bird whose balance against the wind the text analyzes.