Reducing a Dodecahedron to a Cube by Pyramids
Solids lettered pa, 2a, 3a, 4 and a note resolving the twelve-faced body into pyramids and triangles
A column of lettered solids runs down the right of the sheet: a wedge (pa), a prism inside a cylinder (2a), a transformation of cylinders (3a), a wedge (3a), a pentagonal pyramid divided into five triangles (3a), and a triangular pyramid (4), beside a cube shown built of twelve small cubes. The accompanying note undertakes to make a cube from the "pentagonal body" (the dodecahedron), which it describes as composed of twelve equal pentagonal faces giving rise to twelve pyramids that meet at the center. Each pentagonal base is then resolved into five triangles reaching from its five sides to its center. The demonstration continues into the next step but breaks off.
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The pentagonal body composed of twelve faces
From the pentagonal body a cube is to be made. Its surface is composed of twelve equal pentagonal faces, and from these faces arise twelve pyramids whose points all end at the center of the body.
Resolving each pentagonal face into five triangles
The pentagonal base of one of the twelve pyramids is resolved into five triangles that extend from the five sides of the pentagon and meet at the center of that base. This done, the construction proceeds "with the first above..." but is left unfinished.
Column of lettered solids and a cube of twelve cubes
Down the margin run a wedge, a prism within a cylinder, a transformation of cylinders, another wedge, a pentagonal pyramid split into five triangles, and a triangular pyramid, keyed pa, 2a, 3a, 4. A cube is also drawn as an assembly of twelve small cubes.