BOOK FIRST.

ON FOUNDATIONS. Chapter VIII.

Foundations should be twice as thick as the wall that is to be placed above them; in this, one must have regard for the quality of the ground and the size of the building, making them even wider in loose soil—though still firm—and where they must support a very great load. The bottom of the ditch must be level so that the weight presses down equally; otherwise, if it settles more in one part than another, the walls will crack. For this reason, the Ancients used to pave the said level with Travertine A light-colored limestone used extensively in Roman architecture, and we are accustomed to placing planks or beams there, and then building upon them. Foundations are made a scarpa original: "a scarpa" – meaning battered or sloped; that is, they decrease in thickness as they rise. However, they must be stepped in such a way that the same amount is left on one side as on the other, so that the center of the upper part falls exactly plumb to the center of the lower part. This must also be observed in the tapering of walls above ground, because in this way the structure gains much greater strength than if the tapering were done otherwise. Sometimes—especially in marshy grounds where columns are used—to reduce expense, the foundations are not continuous but made with several arches, and the building is then constructed upon those. In large buildings, certain vents or air-holes through the thickness of the wall from the foundations to the roof are quite praiseworthy, because they allow winds to escape so they trouble the structure less, they reduce the cost, and they are of no small convenience if spiral staircases original: "scale a lumaca" – literally 'snail stairs' are made within them to lead from the foundation to the very top of the building.

ON THE TYPES OF WALLS. Chapter IX.

The foundations being finished, it remains for us to treat the upright wall above ground. Among the Ancients, there were six types of walls: one called reticulated; another of baked earth or brick; the third of rubble (that is, rough stones from the mountain or river); the fourth of irregular stones; the fifth of squared stone; and the sixth, the filled wall. Of the reticulated style, no one uses it in our times; but because Vitruvius A Roman architect and engineer whose 1st-century BCE treatise was the foundation of Renaissance architectural theory says that it was commonly used in his day, I wanted to include the drawing of this as well. They made the angles or corners of the building out of baked stone brick, and every two and a half feet they laid three courses of bricks which bound the entire thickness of the wall.

A woodcut diagram illustrating various masonry techniques used in wall construction. The wall section shows a core of rubble or cement fill labeled E, flanked by outer layers. One section displays "opera reticolata" (C), a diamond-shaped lattice pattern. The corners or quoins (A) are made of "quadrello" (square bricks). Horizontal courses of brick (B and D) are shown running through the thickness of the wall to provide structural stability. Letters A through E correspond to the legend provided below the image.

Brick walls for city ramparts or other very large buildings should be made so that the inner and outer parts are of brick, and the middle is filled with rubble stones mixed with crushed tile original: "copo pesto" – a traditional Roman building material made of lime and pulverized bricks/tiles, known for its water-resistant properties. Every three feet of height, there should be three courses of bricks larger than the others, which take up the entire width of the wall. The first course should be "in key" original: "in chiaue" – known today as a 'header' course, where the short end of the brick faces out; that is, with the shorter side of the brick visible; the second "lengthwise" a 'stretcher' course; that is, with the longer side on the outside; and the third "in key" again. In this manner are the walls of the Pantheon original: "Ritonda" – The Pantheon in Rome, so named for its circular shape and the Baths of Diocletian in Rome, and all the ancient buildings found there.