The Innocenti loggia
Brunelleschi’s Ospedale degli Innocenti, Florence: round arches on Corinthian columns, each bay a cube covered by a small sail vault.
The rules it illustrates
The bay as a cube. Make each bay of an arcade as wide as its columns are high and as deep as it is wide, so that the loggia is a row of equal cubes of space.
The sail vault over a square bay. Cover a square bay with a hemisphere whose diameter is the bay’s diagonal, cut off by the four vertical planes of its sides; the cut edges are then the four semicircular arches of the bay.
Where it appears in the book
In the styles Renaissance.
In the chapters Proportion and Number, Renaissance and Baroque.