Relief in Architectural Mouldings
So far we have been considering the relief of form by means of line. We now come to what may be termed the relief of form by actual form and plane, or modelling in actual light and shade, as in architecture and sculptors' and carvers' work. Then relief is gained by the contrast of actually different planes, forms, surfaces, and textures. The simplest illustrations of the principles of modelled relief are to be found in architectural mouldings, by means of which buildings are relieved and enriched, and important structural or functional parts are emphasized, as in cornices and ribs of vaults, arches, and openings.
Place a concave moulding side by side with a convex one either horizontally or vertically, and a certain pleasant effect of contrasting light and shade is the result, reminding one of the recurring concave and convex of the rolling waves of the sea (a, p. [191]).
A series of flat planes of different widths and at different levels also produces a pleasant kind of relief useful in a picture frame or the jamb of a door (b).
All architectural mouldings might be said to be modifications or combinations of the principles illustrated by these two.
Very different feeling may be expressed in mouldings, and if we compare the two types, the classical and the Gothic, the comparatively broad and simple effect of the former (c, d, e, f, g) contrasts with the richness and variety and the stronger effect of light and shade, produced by deep undercutting, in the latter (h, i, j, k).
The Romans, however, produced rich and highly ornate effects in the use of these types of mouldings, as they reappeared in the Corinthian order, the ovolo cut into the egg and dart, with the Astralagus beneath, the Cyma recta above the brackets of the cornice casting a bold shadow, and both in the cornice and the hollow beneath the dentils enriched with carving, as seen in the splendid fragment of the Forum of Nerva.