‹‹‹ Vitr. 10.11.3 | Table of Contents | Vitr. 10.11.5 ›››
4Having thus determined the size of the hole, which in Greek is called περίτρητος, a sight hole (scutula) is described two holes and a quarter in length, and two holes and one sixth wide. Let the line described be bisected, and when so bisected, let the figure be obliquely turned till its length be equal to one sixth part, and its width on which it turns that of the fourth part of a hole. In the part where the curvature is, at which the points of the angles project, and the holes are turned, the contractions of the breadth return inwardly, a sixth part. The hole must be as much longer as the epizygis is thick. When it has been described, the extremity is to be so divided that it may have a gentle curvature.
4Having determined the size of the hole, design the “scutula,” termed in Greek περἱτρητοϛ, . . . holes in length and two and one sixth in breadth. Bisect it by a line drawn diagonally from the angles, and after this bisecting bring together the outlines of the figure so that it may present a rhomboidal design, reducing it by one sixth of its length and one fourth of its breadth at the (obtuse) angles. In the part composed by the curvatures into which the points of the angles run out, let the holes be situated, and let the breadth be reduced by one sixth; moreover, let the hole be longer than it is broad by the thickness of the bolt. After designing the scutula, let its outline be worked down to give it a gentle curvature.