The constructor showed no less skill in the use he made of his stretchers and headers. They not only gave him an opportunity of safely diminishing the weight of his structure and economising his materials, they afforded a ready means of adapting his wall exactly to the work it had to do. The headers penetrated farther into the crude mass within than the stretchers, and gave to the junction of the two surfaces a solidity similar to that derived by a wall from its through stones or perpenders.
Fig. 46.—Elevation of wall, Khorsabad; from Place.
In describing this wall, M. Place also calls attention to the care with which the angles are built. "The first course," he says, "is composed of three 'headers' with their shortest side outwards and their length engaged in the mass behind. Two of these stones lie parallel to each other, the third crosses their inner extremities."[166] Thanks to this ingenious arrangement, the weakest and most exposed part of the wall is capable of resisting any attack.
The surface in contact with the core of crude brick was only roughly dressed, by which means additional cohesion was given to the junction of the two materials; but the other sides were carefully worked and squared and fixed in place by simple juxtaposition. The architect calculated upon sufficient solidity being given by the mere weight of the stones and the perfection of their surfaces.[167]
Fig. 47.—Section in perspective through the south-western part of Sargon's palace at Khorsabad; compiled from Place.
The total height of this Khorsabad wall was sixty feet—nine feet for the foundations, forty-six for the retaining-wall, and five for the parapet, for the wall did not stop at the level of the roofs. A row of battlements was thought necessary both as a slight fortification and as an ornament.[168] These were finished at the top with open crenellations in brick, along the base of which ran apparently a frieze of painted rosettes. A reference to our [Fig. 47] will explain all these arrangements better than words. It is a bird's-eye view in perspective of the south-western part of the palace. The vertical sections on the right of the engraving show how the stones were bonded to the crude brick. The crenellations are omitted here, but they may be seen in place on the left.