Every traveller tells that there is not a ruin at Babylon in which hundreds of these enamelled bricks may not be picked up, and they are to be found elsewhere in Chaldaea.[354] A certain number of fragments are now in the British Museum and the Louvre with indications upon them leaving no doubt as to whence they came.[355] As for the blocks of the same kind coming from Nineveh and its neighbourhood they are very numerous in our collections. It is easy therefore to compare the products of Chaldaean workshops with those of Assyrian origin. The comparison is not to the advantage of the latter. The enamel on the Babylonian bricks is very thick and solid; it adheres strongly to the clay, and even when brought to our comparatively humid climates it preserves its brilliancy. It is not so with bricks from Khorsabad and Nimroud, which rapidly tarnish and become dull when withdrawn from the earth that protected them for so many centuries. Their firing does not seem to have been sufficiently prolonged.[356] Necessity is the mother of invention, the proverb says. If there be any country in which clay has been compelled to do all that lay in its power it must surely be that in which there was no other material for the construction and decoration of buildings. The results obtained by the enameller were pretty much the same in Assyria and Chaldaea, and we are inclined to look upon the older of the two nations as the inventor of the process, especially as it could hardly have done without it so well as its younger rival, and in this opinion we are confirmed by the superior quality of the Babylonian enamel. It is possible that there may be some truth in the assertion that most of the glazed bricks that have come down to us belonged to the restorations of Nebuchadnezzar; but even supposing that to be so, they show a technical skill so consummate and sure of itself that it must then have been very far removed from its infancy. The fatherland of the enameller is Southern Mesopotamia and especially Babylonia, where enamelled bricks seem to have been used in extraordinary quantities. The wall of Dour-Saryoukin, the town built by Sargon, has been found intact for a considerable part of its height. As in the retaining wall of the palace, coloured brick has there been used with extreme discretion. It is found only over the arches of the principal doors and, perhaps, in the form of rosettes at the springing of the battlements. The remainder of the great breadths of crude brick was coated with white plaster.[357]