‹‹‹ Vitr. 3.5.11 | Table of Contents | Vitr. 3.5.13 ›››
12The height of the tympanum, which crowns the whole work, is to be equal to one ninth part of the extent of the corona, measured from one extremity of its cymatium to the other, and set up in the centre. Its face is to stand perpendicularly over the architrave and the hypotrachelia of the columns. The coronæ over the tympanum are to be equal to that below, without the simæ. Above the coronæ are set the simæ, which the Greeks call ἐπιτιθίδες, whose height must be one-eighth more than that of the corona. The height of the acroteria is to be equal to that of the middle of the tympanum; the central ones one eighth part higher than those at the angles.
12The height of the tympanum, which is in the pediment, is to be obtained thus: let the front of the corona, from the two ends of its cymatium, be measured off into nine parts, and let one of these parts be set up in the middle at the peak of the tympanum, taking care that it is perpendicular to the entablature and the neckings of the columns. The coronae over the tympanum are to be made of equal size with the coronae under it, not including the simae. Above the coronae are the simae (in Greek ἑπαιετἱδες), which should be made one eighth higher than the height of the coronae. The acroteria at the corners have the height of the centre of the tympanum, and those in the middle are one eighth part higher than those at the corners.