The Cube: Faces, Corners and Edges
Red-chalk cube properties with continuous-proportion series
At the top a small square is drawn as one face of a cube, and Leonardo notes that a cube has 6 faces, 8 corners and 12 edges. Below, joined circles carry the tripling series 3, 9, 27, 81, and the vocabulary of ratio theory appears: pairs labelled antecedent and consequent (4:6 and 2:3) and the term converse proportionality. A stray Latin fragment is written at the top of the sheet.
On this page
A cube's faces, corners and edges
A square is drawn as the face of a cube, and the solid's properties are listed: 6 faces, 8 corners and 12 edges. The figure sets the cube against the accompanying number series.
Continuous proportion: antecedent and consequent
The tripling series 3, 9, 27, 81 runs through linked circles. The ratios 4:6 and 2:3 are labelled with the proportion-theory terms antecedent and consequent, and the note "converse proportionality" marks inverse proportion.