Gradationes scalarum inter cuneos et sedes contra quadratorum angulos dirigantur ad primam praecinctionem, a praecinctione inter eas iterum mediae dirigantur, et ad summam quotiens praecinguntur, altero tanto semper amplificantur.
The staircases between the lowest blocks of seats are to be arranged opposite the several angles of the squares up to the first horizontal gangway; between the tops of the first staircases, higher flights are to be put at halfway intervals along the gangway. And generally speaking, they are to be doubled in number when a gangway is reached.
final_alignments\Vitruvius_Architecture_Book_5.json