The theatre after Vitruvius
Vitruvius V.6–7: the Roman plan drawn from four equilateral triangles in the orchestra circle, the Greek from three squares.
The rules it illustrates
The Greek theatre: three squares. Plan a Greek theatre by inscribing three squares in the orchestra circle; the side nearest the scene fixes the front of the stage (proscaenium), and the scene is set back to a line tangent to the circle.
The “D” plan for places of assembly. For a hall of assembly use the “D” or tribune plan, a half-circle closed by a straight side: it gives ample room to the audience, a central place to the speaker and scope for display in the architecture.
The Roman theatre: four triangles. Draw the orchestra circle and inscribe in it four equilateral triangles at equal intervals; the side nearest the scene fixes the front of the scaena, a parallel through the centre fixes the front of the stage, and the angles on the auditorium side give the directions of the stairways.
The scene: twice the orchestra. Make the scaena twice as long as the orchestra is wide; raise its podium a twelfth of the orchestra diameter, its lower columns a quarter, their entablature a fifth of the columns; above, a parapet half the podium and columns a quarter shorter than those below.
The crowning colonnade level with the scene. Roof the colonnade at the top of the seats at the same height as the top of the scene building, so that the voice rises evenly to the highest rows and is not checked on its way.
A theatre that does not face south. Build the theatre on a healthy site and do not let its curved auditorium face south, where the sun would heat the enclosed air and harm the audience sitting through the plays.
Where it appears in the book
In the styles Ancient Greek.
In the chapters The Classical World.