In the first place the reader will recognize those semicircular pilasters or gigantic reeds to which we have already alluded as strongly characteristic of Chaldaean architecture, and one of the most certain signs of its origin. The chevrons, the spiral lines and lozenges of the coloured decoration with which the semi-columns, and the salient buttress by which they are divided into two groups, are covered, should be curiously noticed. The ornament varies with each structural division. Loftus, however, was chiefly struck by the process used to build up the design. The whole face of the wall is composed of terra-cotta cones (Fig. 120) engaged in a mortar composed of mud mixed with chopped straw. The bases of these cones are turned outwards and form the surface of the wall. Some preserve the natural colour of the terra-cotta, a dark yellow, others have been dipped--before fixing no doubt--in baths of red and black colouring matter. By the aid of these three tints an effect has been obtained that, according to Loftus, is far from being disagreeable. The process may be compared to that of mosaic, cones of terra-cotta being substituted for little cubes of coloured stone or glass.[350] [Illustration: FIG. 120.--Cone with coloured base; from Loftus.] Upon the same site M. Loftus found traces of a still more singular decoration. A mass of crude brick had its horizontal courses divided from each other by earthenware vases laid so that their open mouths were flush with the face of the wall. Three courses of these vases were placed one upon another, and the curious ornament thus made was repeated three times in the piece of wall left standing. The vases were from ten to fifteen inches long externally, but inside they were never more than ten inches deep, so that their conical bases were solid.[351] The dark shadows of their open mouths afforded a strong contrast with the white plaster which covered the brickwork about them. The consequent play of light and shadow unrelieved by colour was pleasing enough. In spite, however, of their thick walls, these vases could hardly resist successfully the weight of the bricks above and the various disintegrating influences set up by their contraction in drying. Most of the vases were broken when Loftus saw them, though still in place.