6The form of a theatre is to be adjusted so, that from the centre of the dimension allotted to the base of the perimeter a circle is to be described, in which are inscribed four equilateral triangles, at equal distances from each other, whose points are to touch the circumference of the circle. This is the method also practiced by astrologers in describing the twelve celestial signs, according to the musical division of the constellations. Of these triangles, the side of that which is nearest the scene will determine the face thereof in that part where it cuts the circumference of the circle. Then through the centre a line is drawn parallel to it, which will separate the pulpitum of the proscenium from the orchestra.
2Thus the pulpitum will be more spacious than that of the Greeks, and be the better, on account of our actors remaining chiefly on the scena. In the orchestra, seats are assigned to the senators, and the height of its pulpitum must not exceed five feet, so that those who sit in the orchestra may be enabled to see all the motions of the actors. The portions between the staircases (cunei) of the theatre are so divided that the angles of the triangles, which touch the circumference, point to the directions of the ascents and steps between the cunei, on the first præcinction or story. Above these the steps are placed alternately, and form the upper cunei in the middle of those below.
3The angles thus pointing to staircases will be seven in number, the remaining five will mark certain points on the scene. That in the middle, for instance, will mark the situation of the royal doors, those on the right and left, the doors of guests, and those at the extremities, the points at which the road turns off. The seats (gradus) on which the spectators sit are not to be less than twenty inches in height, nor more than twenty-two. Their width must not be more than two feet and a half, nor less than two feet.
4The roof of the portico, which is on the last step, should be on a level with the top of the scene; by which arrangement the voice will extend and be distinct to those on the upper seats and roof. For if it be not equally high, where that height is deficient, the voice, first striking thereon, will be stopped.
5One sixth part of the diameter of the orchestra is taken between the lowest steps, and level with that dimension the lower seats are disposed. A continuation of this line on the scene marks the height of the entrances: for thus proportioned, they will be of sufficient altitude.
6The length of the scene must be double the diameter of the orchestra. The height of the podium, or pedestal, with its cornice and base, from the level of the pulpitum, is a twelfth part of the diameter of the orchestra. The columns on the podium, with their capitals and bases, are to be one-fourth of its diameter high. The architraves and cornices of those columns one-fifth of their height. The upper pedestal, including the base and cornice, half the height of the lower pedestal. The columns on this pedestal one-fourth less in height than the lower columns. The architrave and its cornice a fifth of the columns. If there is to be a third order, the upper pedestal is to be half the height of that under the middle order, and the architrave and cornice a fifth of the columns.
7It is not, however, possible to produce the same effect in every theatre by the same proportions; but it behoves the architect to consider the proportions which symmetry requires, and those adapted to the nature of the place or the size of the work. Some things there are which their use requires of the same size in a large as in a small theatre; such as the steps, præcinctions, parapets, passages, stairs, pulpita, tribunals, and others which occur; in all which, the necessity of suiting them to their use, makes it impossible to form them symmetrically. So, also, if the materials are not provided in sufficient quantity, such as marble, wood, and the like, the diminution of or addition to the dimensions, so that it be not too much, and made with judgment, may be permitted: and this will be easily managed by an architect who is a man of experience, and who possesses ingenuity and talent.
8The parts of the scene are to be so distributed, that the middle door may be decorated as one of a royal palace; those on the right and left, as the doors of the guests. Near these are the spaces destined to receive the decorations; which places the Greeks call περιάκτοι, from the turning triangular machines. Each of these machines has three species of decoration, which, when the subject changes, or on the appearance of a god, are moved round with sudden claps of thunder, and alter the appearance of the decoration. Near these places the turnings run out, which give entrance to the scene from the forum and from the country.
9There are three sorts of scenes, the Tragic, the Comic, and the Satyric. The decorations of these are different from each other. The tragic scenes are ornamented with columns, pediments, statues, and other royal decorations. The comic scene represents private buildings and galleries, with windows similar to those in ordinary dwellings. The satyric scene is ornamented with trees, caves, hills, and other rural objects in imitation of nature.