Another danger lay in the violence of the sudden storms and the diluvial character of the winter rains. Doubtless the outsides of the walls were faced with well burnt bricks, carefully set, and often coated with an impenetrable enamel; but an inclined plane of a more or less gentle gradient wound from base to summit to give access to the latter. When a storm burst upon one of these towers, this plane became in a moment the bed of a torrent, for its outer edge would, of course, be protected by a low wall. The water would pour like a river over the sloping pavement and strike violently against each angle. Whether it were allowed to flow over the edges of the inclined plane or, as seems more probable, directed in its course so as to sweep it from top to bottom, it must in either case have caused damage requiring continual watchfulness and frequent repairs. If this watchfulness were remitted for an instant, some of the external burnt and enamelled bricks might become detached and leave a gap through which the water could penetrate to the soft core within, and set up a process of disintegration which would become more actively mischievous with every year that passed. The present appearance of these ruins is thus, to a great extent, to be explained. Travellers in the country agree in describing them as irregular mounds, deeply seamed by the rains; and the sides against which the storms and waterspouts that devastate Mesopotamia would chiefly spend their force are those on which the damage is most conspicuous (see Fig. 37). Even in antique times these buildings had suffered greatly. In Egypt, when the supreme power had passed, after one of those periods of decay that were by no means infrequent in her long career, into the hands of an energetic race of princes like those of the eighteenth or twenty-sixth dynasties, all traces of damage done to the public monuments by neglect or violence were rapidly effaced. The pyramids could take care of themselves. They had seen the plains at their feet covered again and again with hordes of barbarians, and yet had lost not an inch of their height or a stone of their polished cuirass. Even in the temples the setting up of a few fallen columns, the reworking of a few bas-reliefs, the restoration of a painting here and there, was all that was necessary to bring back their former splendour. [Illustration: FIG. 37.--Babil, at Babylon. From Oppert.]