If the interior of the rooms was lined in monochrome with white stucco, or with fresco painting, nothing of this decoration is left. But we have in sufficiently large quantities, although always much mutilated, the remains of another more original system of wall decoration, of which the Chaldæans are the inventors--that is to say, enamelled bricks. By applying a coloured paste, which the fire would vitrify, to one of the surfaces of the bricks before baking, a glaze or enamel was produced, closely united to the clay and immovably solid. It was again necessity and their ungrateful climate which induced the Chaldæans to have recourse to this ingenious method. They were in great need of a remedy for the want of stone and a means of preventing the heavy rains from spoiling the colours applied to the walls. They succeeded so perfectly in this that even at the present day the brilliancy of these glazed tiles is not affected. The colours with which they are painted are of the simplest, and vary little; they are blue, white, black, yellow and red. Unfortunately, those fine fragments which have been brought to our museums are only so far interesting that they teach us the technical methods of a manufacture which involves that of opaque glass; even those which are least mutilated contain at the most a few floral designs or portions of the figures of animals, and moreover these last are not older than the epoch of Nebuchadnezzar. The trenches dug among the massive terraces of Chaldæa have revealed other curious details of construction. We know, for instance, what steps were taken to prevent the sewage of the houses or the rain-water which fell upon them from filtering through the platforms of crude brick on which the buildings stood; a rapid disintegration would have followed. They, therefore, planned a complete system of water-channels and drainage. In one of the mounds at Tello, M. de Sarzec found a series of cylindrical pipes or tubes of baked clay, fitted into one another, and forming together a conduit for the water.[15] [Illustration: Fig. 7.--Drainage pipe at Mugheir (after Loftus).]