144 A HISTORY OF ART IN CIIALD/EA AND ASSYRIA. The Chaldaeans were among those builders, and they made frequent use of the arch. They built no long arcades with piers or columns for supports, like those of the Romans, and that simply because such structures would have been contrary to the general principles of their architecture. They made no use, as we have already explained, of those isolated supports whose employment resulted in the hypostyle halls of Egypt and Persia, in the naves of Greek temples and Latin basilicas. The want of stone put any such arrangement out of the question. We have, then, no reason to believe that their arches ever rested upon piers or upon the solid parts of walls freely pierced for the admission of light. The type from which the modern east has evolved so many fine mosques and churches was unknown in Chaldaea. In every building of which we possess either the remains or the figured representation the archivolts rest upon thick and solid walls. Under these conditions the vault was supreme in certain parts of the building. Its use was there so constant as to have almost the character of an unvarying law. Every palace was pierced in its substructure by drains that carried the rain water and the general waste from the large population by which it was inhabited down into the neighbouring river, and nearly all these drains were vaulted. And it must not be supposed that the architect deliberately. hid his vaults and arches, or that he only used them in those parts of his buildings where they were concealed and lost in their surroundings ; they occur, also, upon the most careful and elaborate facades. The gates of cities, of palaces and temples, of most buildings, in fact, that have any monu- mental character, are crowned by an arch, the curve of which is accentuated by a brilliantly coloured soffit. This arch is continued as a barrel vault for the whole length of the passage leading into the interior, and these passages are sometimes very long. Vaults would also, in all probability, have been found over those narrow chambers that are so numerous in Assyrian palaces were it not for the universal ruin that has overtaken their superstructures. Finally, certain square rooms have been discovered which must have been covered with vaults in the shape of more or less flattened domes. We must here call attention to the importance of a bas-relief belonging to the curious series of carved pictures in which
