Page:A History of Art in Chaldæa & Assyria Vol 1.djvu/257

 THE ARCH. 235 a restriction which is sure, sooner or later, to lead to the dis- covery in question but also by induction from the monuments we have just been studying. The arches under the hanging- gardens of Babylon, the vaults of the sewers and gateways, the domes that covered the great square chambers in the Ninevite palaces all these were derived, we may be sure, from the ancient civilization. We cannot believe that such consummate skill in the management of a difficult matter was arrived at in a day. The purely empiric knowledge of statics it implies could only have been accumulated by a long series of more or less happy experiments. Thus only can we explain the ease with which the Assyrian builder surmounted difficulties some of which would have puzzled a modern architect, such as the pise vaults erected over spacious galleries without any kind of centering, and the domes over square chambers, for which some system of pendentives that is, of arches or other intermediate forces by which the base of the cupola could be allied to the top of the supporting wall, must have been contrived. The accurate calculation of forces between the thrust of the vaults and the strength of the retaining walls, the dexterity with which the curves employed are varied and carried insensibly one into the other, the skill with which the artificial materials are prepared for their appointed office, are also surprising. By careful moulding and manipulation the Assyrian builder made his brick voussoirs as well fitted for their work as the cut stone of our day. Each brick had its own shape and size, so that it was assigned in advance a particular place in the vault and its own part in assuring the final stability of the buildinof. In all this we cannot avoid seeing the results of a o <-> patient and long-continued process of experiment and education carried on through many centuries in all the workshops of Mesopotamia. The art of builclino- vaults with small units of construction o was, then, carried farther in Mesopotamia than in Egypt ; it was there more frankly developed ; it was there forced with greater success to supply the place of stone and timber. It was in fact more of an indigenous art in the valley of the Tigris and Euphrates than anywhere else, more inspired by the permanent and unchanging conditions of the country in a word, more national.