ally diminish in extent so that at the surface their projection is equal to the thickness of the wall of the building.
7. Furthermore, inside, to meet the mass of earth, there should be saw-shaped constructions attached to the wall, the single
RETAINING WALLS
(From the edition of Vitruvius by Fra Giocondo, Venice 1511)
teeth extending from the wall for a distance equivalent to what is to be the height of the substructure, and the teeth being constructed with the same thickness as the wall. Then at the outermost angles take a distance inwards, from the inside of the angle, equal to the height of the substructure, and mark it off on each side; from these marks build up a diagonal structure and from the middle of it a second, joined on to the angle of the wall. With this arrangement, the teeth and diagonal structures will not allow the filling to thrust with all its force against the wall, but will check and distribute the pressure.
8. I have now shown how buildings can be constructed without defects, and the way to take precautions against the occurrence
