Cube, board and cylinder in equal proportion
A deleted proof relating a cube, its cylinder and a board through the ratio of their sides.
Most of this spread is blank; the writing sits in a corner of folio 208v beside a small lettered diagram, and is struck through. The note relates a cube a b o p to a cylinder o p c d, stating that their ratio equals that of the side b p to the side p d, drawn between the parallel lines a b and c d at the point p. A further deleted line describes deriving the greater cube from a natural board b and making a board a that contains the quantity of the cube a b o p.
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Cube a b o p reduced to the cylinder o p c d
Between the parallel lines a b and c d at the point p, Leonardo states that the ratio of the cube a b o p to the cylinder o p c d is the same as that of the side b p to the side p d. The claim ties the proportion of two solids to the proportion of two line-segments.
The natural board b, the greater cube, and board a
Leonardo says he now has b, the natural board from which he derives the greater cube, here reduced into the cylinder o p c d, and that he has made the board a which contains in itself the quantity of the cube a b o p.