The Da Vinci Notebooks at sacred-texts.com
The relative proportions of the torso and of the foot.The torso a b in its thinnest part measures a foot; and from a to b is 2 feet, which makes two squares to the seat--its thinnest part goes 3 times into the length, thus making 3 squares.
180:160 : See Pl. VII, No. 2, the lower sketch.