§ XVIII. So also are, of course, the jagged or crown-like finishings of walls employed where no real parapet of protection is desired; originating in the defences of outworks and single walls: these are used much in the east on walls surrounding unroofed courts. The richest examples of such decoration are Arabian; and from Cairo they seem to have been brought to Venice. It is probable that few of my readers, however familiar the general form of the Ducal Palace may have been rendered to them by innumerable drawings, have any distinct idea of its roof, owing to the staying of the eye on its superb parapet, of which we shall give account hereafter. In most of the Venetian cases the parapets which surround roofing are very sufficient for protection, except that the stones of which they are composed appear loose and infirm: but their purpose is entirely decorative; every wall, whether detached or roofed, being indiscriminately fringed with Arabic forms of parapet, more or less Gothicised, according to the lateness of their date. I think there is no other point of importance requiring illustration respecting the roof itself, or its cornice: but this Venetian form of ornamental parapet connects itself curiously, at the angles of nearly all the buildings on which it occurs, with the pinnacled system of the north, founded on the structure of the buttress. This, it will be remembered, is to be the subject of the fifth division of our inquiry. FOOTNOTES: [54] Not of Renaissance alone: the practice of modelling buildings on a minute scale for niches and tabernacle-work has always been more or less admitted, and I suppose _authority_ for diminutive battlements might be gathered from the Gothic of almost every period, as well as for many other faults and mistakes: no Gothic school having ever been thoroughly systematised or perfected, even in its best times. But that a mistaken decoration sometimes occurs among a crowd of noble ones, is no more an excuse for the habitual--far less, the exclusive--use of such a decoration, than the accidental or seeming misconstructions of a Greek chorus are an excuse for a school boy's ungrammatical exercise. CHAPTER XV. THE BUTTRESS.