Quatuor aut plures aulæa premuntur in horas. It should, however, be mentioned that the ancients seem also to have had movable scenery (_scena ductilis_), to alter the appearance of the permanent scene when required. This must have consisted of painted board or canvas. Another method of illusion was by the use of masks. These were rendered necessary by the vastness of the ancient theatres, and the custom of performing in the open air. In the eastern portico of the Triangular Forum are four entrances to different parts of the greater theatre. The first two, as you enter, lead into a large circular corridor surrounding the whole cavea; the third opens on an area behind the scene, from which there is a communication with the orchestra and privileged seats; the fourth led down a long flight of steps, at the bottom of which you turn, on the right, into the soldiers' quarter, on the left, into the area already mentioned. The corridor is arched over. It has two other entrances, one by a large passage from the east side, another from a smaller passage on the north. Six inner doors, called vomitoria, opened on an equal number of stair-cases which ran down to the first præcinctio. The theatre is formed upon the slope of a hill, the corridor being the highest part, so that the audience upon entering descended at once to their seats, and the vast staircases, which conducted to the upper seats of the theatres and amphitheatres at Rome, were saved. By the side of the first entrance is a staircase which led up to the women's gallery above the corridor; here the seats were partitioned into compartments, like our boxes. The benches were about one foot three inches high and two feet four inches wide. One foot three inches and a half was allowed to each spectator, as may be ascertained in one part, where the divisions are marked off and numbered. There is space to contain about five thousand persons. Here the middle classes sat, usually upon cushions which they brought with them; the men of rank sat in the orchestra below, on chairs of state carried thither by their slaves. Flanking the orchestra, and elevated considerably above it, are observable two divisions, appropriated, one perhaps to the pro-consul, or duumvirs and their officers, the other to the vestal virgins, or to the use of the person who gave the entertainments. This is the more likely, because in the smaller theatre, where these boxes, if we may call them so, are also found, they have a communication with the stage. This theatre appears to have been entirely covered with marble; the benches of the cavea were of marble, the orchestra was of marble, the scene with all its ornaments was also of marble; and yet of this profusion of marble only a few fragments remain.