Page:Vitruvius the Ten Books on Architecture.djvu/185

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1. the theatres of the Greeks, these same rules of construc­tion are not to be followed in all respects. First, in the circle at the bottom where the Roman has four triangles, the Greek has three squares with their angles touching the line of circumfer­ence. The square whose side is nearest to the "scaena," and cuts off a segment of the circle, determines by this line the limits of the "proscaenium" (A, B). Parallel to this line and tangent to the outer circumference of the segment, a line is drawn which fixes the front of the "scaena" (C-D). Through the centre of the orchestra and parallel to the direction of the "proscaenium," a line is laid off, and centres are marked where it cuts the circum­ference to the right and left (E, F) at the ends of the half-circle. Then, with the compasses fixed at the right, an arc is described from the horizontal distance at the left to the left hand side of the "proscaenium" (F, G); again with the centre at the left end, an arc is described from the horizontal distance at the right to the right hand side of the "proscaenium" (E, H).

2. As a result of this plan with three centres, the Greeks have a roomier orchestra, and a "scaena" set further back, as well as a stage of less depth. They call this the, for the reason that there the tragic and comic actors perform on the stage, while other artists give their performances in the entire orchestra; hence, from this fact they are given in Greek the distinct names "Scenic" and "Thymelic." The height of this "logeum" ought to be not less than ten feet nor more than twelve. Let the ascend­ing flights of steps between the wedges of seats, as far up as the first curved cross-aisle, be laid out on lines directly opposite to the angles of the squares. Above the cross-aisle, let other flights be laid out in the middle between the first; and at the top, as often as there is a new cross-aisle, the number of flights of steps is always increased to the same extent.