The technique is similar to that of the flat enamels of the Ishtar Gate; each colour is outlined in black, and the position marks are also employed here in the same manner. They can be better studied here than elsewhere, for the greater number of the bricks were found in their original connection. After the destruction of the wall by brick robbers the outer coating fell towards the north, and we could take them up, one piece after another, as though no accident had befallen them. The system of signs can be seen best on the capitals (Fig. 65). Here the markings consist of numerals combined with dots. They are marked on the upper edge of the bricks with a poor, somewhat blackened, glaze. The signs that distinguish the courses are in the centre, those for the lateral arrangement are close to the vertical joints. Each of the latter signs is a counterpart of the sign near the vertical joint of the brick adjoining it. Of the central signs that mark the courses the top course of the upper row of volutes has one stroke, the second has two, and so on up to seven. The seven courses of the lower row of volutes are numbered in the same way, but the groups of strokes are preceded by a dot to distinguish them from those of the upper series. For the sequence of the bricks one of the intermediate ornaments forms a single unit with the capital adjoining it on the right. All the bricks that belong to the same unit bear the same number of strokes. The counting runs from left to right. The numerals are crossed by a transverse stroke, which, in order to mark the direction of the signs, has a dot attached to it. This direction line is parallel to the vertical joint on the central ornament, and parallel with the front of the brick on the volutes. It is quite probable that the separate groups were first provisionally built together, at any rate for the purpose of drawing the design, which is still visible in red colour under the enamel, so as to secure that boldness and freedom of outline which delights us with its beauty at the present time. But when once the process of enamelling began—the transportation of the bricks, the drying, the burning, and all the unavoidable processes that had to be carried through before the bricks could be placed in the wall—it would be impossible to keep them apart. The marks would then afford the only means of placing them correctly on the walls, and rendering it easy to deliver them in groups to the respective masons. In order to close the joints completely the bricks are slightly wedge-shaped. The joints between the courses are laid in mud over asphalt, which, as we observe in other careful building, does not extend to the front of the building but stops at a distance of half a brick, thus avoiding any blotching of the face of the wall.