Ipsae autem scaenae suas habent rationes explicitas ita, uti mediae valvae ornatus habeant aulae regiae, dextra ac sinistra hospitalia, secundum autem spatia ad ornatus comparata, quae loca Graeci periactus dicunt ab eo, quod machinae sunt in his locis versatiles trigonos habentes in singula tres species ornationis, quae, cum aut fabularum mutationes sunt futurae seu deorum adventus, cum tonitribus repentinis ea versentur mutentque speciem ornationis in frontes.
The scenery itself is so arranged that the middle doors are figured like a royal palace, the doors on the right and left are for strangers. Next on either side are the spaces prepared for scenery. These are called periaktoi in Greek (revolving wings) from the three-sided machines which turn having on their three sides as many kinds of subject. When there are to be changes in the play or when the gods appear with sudden thunders, they are to turn and change the kind of subject presented to the audience.
final_alignments\Vitruvius_Architecture_Book_5.json