‹‹‹ Vitr. 3.5.2 | Table of Contents | Vitr. 3.5.4 ›››
3If Ionic, they are to be set out so that the base may each way be equal to the thickness and three eighths of the column. Its height and that of the plinth the same as the attic base. The plinth is the same height as in that of the attic base, the remainder, which was equal to one-third part of the column’s diameter, must be divided into seven parts, three of which are given to the upper torus; the remaining four parts are to be equally divided into two, one of which is given to the upper cavetto, with its astragals and listel, the other to the lower cavetto, which will have the appearance of being larger, from its being next to the plinth. The astragals must be an eighth part of the scotia, and the whole base on each side is to project three sixteenths of a diameter.
3But if Ionic bases are to be built, their proportions shall be so determined that the base may be each way equal in breadth to the thickness of a column plus three eighths of the thickness; its height that of the Attic base, and so too its plinth; excluding the plinth, let the rest, which will be a third part of the thickness of a column, be divided into seven parts. Three of these parts constitute the torus at the top, and the other four are to be divided equally, one part constituting the upper trochilus with its astragals and overhang, the other left for the lower trochilus. But the lower will seem to be larger, because it will project to the edge of the plinth. The astragals must be one eighth of the trochilus. The projection of the base will be three sixteenths of the thickness of a column.