Geometry: circles, squares, Pythagoras and cubes
Plane figures, the classic squares-on-a-triangle proof, proportional cubes, and mechanical sketches
The upper half of the leaf is a workshop of geometry: a triangle, two squares and a small square, two circles each crossed by a diameter, and a crescent, followed by two versions of the classic figure for the theorem of Pythagoras, with squares built on the sides of a tilted square and diagonals drawn in. Below sit sketches of cubes that the catalogue caption calls 'proportional cubes,' relating solid geometry to proportion. Lower on the page are mechanical sketches - an inclined bar carrying a ball and a weight suspended over a large circle - like the indeterminate figures on the facing leaf 40v. No running text was transcribed.
On this page
Two circles, two squares and a triangle
Along the top of the leaf are a triangle, two squares of differing size and a small square, plus two circles each crossed by a diameter and a crescent. They read as a set of elementary plane figures.
Figures for the Pythagorean theorem
Two diagrams show a tilted square with further squares set on its sides and its diagonals drawn in, the standard construction illustrating the theorem of Pythagoras that the square on the hypotenuse equals the sum of the squares on the other two sides.
Proportional cubes
A group of cube figures, one subdivided into smaller cells, is captioned as 'proportional cubes,' linking solid geometry to the study of proportion and volume.
Lever and suspended weight
Toward the foot of the leaf are mechanical sketches: an inclined bar or lever bearing a ball and, lower still, a weight hung over a large circle. The catalogue links these to the indeterminate figures on folio 40v.