224 A- HISTORY OF ART IN CIIALD.KA AND ASSYRIA. tion which could have but one end. Real brick with good mortar could alone resist such influences, and those, no doubt, were the materials used in the Babylonian gardens. If their substructures should ever be found and laid open, we have little doubt that arches as carefully built as those of the Assyrian ruins will be brought to light. The gateways of the town built by Sargon at the foot of his palace mound were roofed with semicircular vaults. 1 In order to study their construction more closely, M. Place demolished one of these arches piece by piece, the one numbered three on his plan. 2 It was already condemned to destruction by the necessity for carrying off its sculptures. The total height from pavement to keystone, was twenty-four feet six inches, from the centre of the keystone to the springing of the arch itself was eight feet, the total width of the opening, measured at the feet of the caryatides, was fourteen feet four inches. The bricks had not been burnt in a kiln but they had been subjected to a prolonged desiccation. The system of construction was as simple as possible. The perpendicular side walls passed into the vault without any preparation, and the arch when complete had no inward projection and no structural ornament but the inner faces of the carefully placed voussoirs ; as all the bricks were of the same size and shape something more than their slightly trapezoidal form was required to keep them in place, and a softer clay was used to bind them together. With the addition of this rude cement each brick became a long and narrow wedge and determined the curve of the vault in which it was placed. Some idea of the appearance of this triple arch may be formed from the illustration we have compiled from M. Thomas's elevation of an alcove in one of the harem apart- ments at Khorsabad (Fig. 90). This vault is not in existence, but its component parts were found among the ruins of Sargon's palace. 3 There is one detail in the decoration of these doorways that should be carefully noted. Wherever the architect makes use of a round-headed opening he reinforces its outlines with a kind of semicircular frieze, to which brilliant colours or bold reliefs 1 PLACE, Ntnive, vol. i. pp. 170-182 and 256-259, vol. iii. plates 9-18. ! PLACE, Ninive, vol. iii. plate 2. 3 PLACE, Ninire, vol. i. p. 128.
