[Illustration: 23.--COLORED FRIEZE IN ENAMELLED TILES.] 16. The kings of Chaldea, Babylonia and Assyria seem to have been absolutely possessed with a mania for building. Scarcely one of them but left inscriptions telling how he raised this or that palace, this or that temple in one or other city, often in many cities. Few contented themselves with repairing the buildings left by their predecessors. This is easy to be ascertained, for they always mention all they did in that line. Vanity, which seems to have been, together with the love of booty, almost their ruling passion, of course accounts for this in a great measure. But there are also other causes, of which the principal one was the very perishable nature of the constructions, all their heavy massiveness notwithstanding. Being made of comparatively soft and yielding material, their very weight would cause the mounds to settle and bulge out at the sides in some places, producing crevices in others, and of course disturbing the balance of the thick but loose masonry of the walls constructed on top of them. These accidents could not be guarded against by the outer casing of stone or burnt brick, or even by the strong buttresses which were used from a very early period to prop up the unwieldy piles: the pressure from within was too great to be resisted. [Illustration: 24.--PAVEMENT SLAB.] 17. An outer agent, too, was at work, surely and steadily destructive: the long, heavy winter rains. Crude brick, when exposed to moisture, easily dissolves into its original element--mud; even burned brick is not proof against very long exposure to violent wettings; and we know that the mounds were half composed of loose rubbish. Once thoroughly permeated with moisture, nothing could keep these huge masses from dissolution. The builders were well aware of the danger and struggled against it to the best of their ability by a very artfully contrived and admirably executed system of drainage, carried through the mounds in all directions and pouring the accumulated waters into the plain out of mouths beautifully constructed in the shape of arched vaults.[P] Under the flooring of most of the halls have been found drains, running along the centre, then bending off towards a conduit in one of the corners, which carried the contents down into one of the principal channels. [Illustration: 25.--SECTION OF ORNAMENTAL DOORWAY (ENAMELLED BRICK OR TILES). KHORSABAD. (Perrot and Chipiez.)]