The Tuscan arch, where the extrados takes the form of a pointed arch.
The under or concave side of the voussoirs is called the intrados, and the upper or convex side the extrados of the arch.
The four sides of the mold formed the extrados, the intrados, and the two ends of the block; the other two sides being left open.
The lower surface or soffit of the arch is the intrados, E, and the upper surface the extrados, F.
The pavement of the terrace, which consists of a double bed of large bricks, rests upon the extrados of the upper channel.
The form of the mound may be described as reproducing the extrados of a depressed arch.
This arch was roughhewn on the flat surfaces and on about half of the outer curved surface, or extrados.
The inner surface, or intrados, and the remainder of the extrados are smoothly dressed (fig. 38).