Capacity of polygons and the surfaces of cylinder and sphere
Which figure holds most; geometric terms defined; a note on the weight b–e
A crowded geometry sheet exploring which figures of equal diameter hold the most: the polygon with more sides has greater capacity, the triangle the least and the circle the most, prompting Leonardo to ask for the 'mean capacity' between them. Diagrams compare the perimeters of inscribed and circumscribed polygons against the circle, and lower-right figures of a sphere within a cylinder and a cylinder within a cube state that the cylinder's curved surface 'clothes' a sphere whose great circle equals the cylinder's base. Along the right margin he glosses a short vocabulary of geometric terms (periphery, polygon, quadrangle, helix, perimeter), and one figure carries a note that the weight b does not bear wholly on the central line b–e. The top lines and much marginal writing remain faint and largely untranscribed.
On this page
The polygon with more sides has the greater capacity
Among polygonal figures of equal diameter, Leonardo states that the one with more sides will have the greater capacity.
Perimeters of circumscribed and inscribed polygons versus the circle
The perimeter of polygons circumscribing a circle is greater than the circle's, the more so the fewer their sides; conversely the perimeter of a polygon inscribed in the circle is smaller, the less so the fewer its sides.
Least and greatest capacity, and the mean between them
The triangle is the least in capacity of the polygonal figures and the circle the greatest. Leonardo asks to be given the mean capacity between the triangle and the circle.
The curved surface of the cylinder clothes a sphere
If a cylinder contains a square, its curved surface has the same proportion to its base as a sphere's surface has to its great circle; that curved surface, drawn from the cube, clothes a sphere whose great circle equals the cylinder's base.
The weight b does not bear wholly on the central line
A lettered figure (c b a - n - g - f e) carries the note that the weight b does not bear entirely upon the central line b–e.
Glossary of geometric terms
Beside small figures of a pentagon, triangle, square and rectangle Leonardo glosses geometric vocabulary: periphery as 'boundary', polygon as 'of many sides', and the Latin-inflected terms quadrangulus, helix ('curvature') and perimeter.
