With his usual penetration, Loftus divines and explains the origin of these forms. The idea must have been suggested, he thinks, by the palm trunks that were used set closely together in timber constructions, or at regular intervals in mud walls. In either case half of their thickness would be visible externally, and would naturally provoke imitation from architects in search of ornament for the bald faces of their clay structures.[312]
Fig. 100.—Façade of a ruined building at Warka; from Loftus.
As to the effect thus obtained, the rough sketch given by Loftus hardly enables us to decide (see [Fig. 100]). From Assyria, however, come better materials for a judgment. We there often find these perpendicular ribs, generally in groups of seven, in buildings that have been carefully studied and illustrated upon a sufficient scale. We give an example from one of the harem gates at Khorsabad ([Fig. 101]), by which we may see at once that an ornamental motive of no little value was afforded by these huge vertical reeds with their play of alternate light and shadow, and the happy contrast they set up between themselves and the brilliant hues of the painted walls and enamelled bricks. The whole had a certain elegant richness that can hardly be appreciated without the restoration, in every line and hue, of the original composition.
Both at Warka and in the Khorsabad harem, these vertical ribs are accompanied by another ornament which may, perhaps, have been in even more frequent use. We mean those long perpendicular grooves, rectangular in section, with which Assyrian and Chaldæan walls were seamed. In the harem wall these grooves flank the group of vertical reeds right and left, dividing each of the angle piers into two quasi-pilasters. At Warka they appear in the higher part of the façade, above the groups of semi-columns. They serve to mark out a series of panels, of which only the lower parts have been preserved. The missing parts of the decoration may easily be supplied by a little study of the Assyrian remains. The four sides of the building at Khorsabad, called by M. Place the Observatory, are decorated uniformly in this fashion. The general effect may be gathered from our restoration of one angle. The architect was not content with decorating his wall with these grooves alone; he divided it into alternate compartments, the one salient, the next set back, and upon these compartments he ploughed the long lines of his decoration. These changes of surface helped greatly to produce the varied play of light and shadow upon which the architect depended for relief to the bare masses of his walls. The most ordinary workmen could be trusted to carry out a decoration that consisted merely in repeating, at certain measured intervals, as simple a form as can be imagined, and, in the language of art as in that of rhetoric, there is no figure more effective in its proper place than repetition.
Fig. 101.—Decoration of one of the harem gates, at Khorsabad; compiled from Place.
The necessity for something to break the monotony of the brick architecture was generally and permanently felt, and in those Parthian and Sassanide periods in which, as we have said, the traditions of the old Chaldæan school were continued, we find the panel replaced by wall arcades in which the arches are divided from each other by tall pilasters. In general principle and intention the two methods of decoration are identical.