§ III. I have little, therefore, to say here, and that touching rather the omission than the selection of decoration, as far as regards interior roofing. Whether of timber or stone, roofs are necessarily divided into surfaces, and ribs or beams;--surfaces, flat or carved; ribs, traversing these in the directions where main strength is required; or beams, filling the hollow of the dark gable with the intricate roof-tree, or supporting the flat ceiling. Wherever the ribs and beams are simply and unaffectedly arranged, there is no difficulty about decoration; the beams may be carved, the ribs moulded, and the eye is satisfied at once; but when the vaulting is unribbed, as in plain waggon vaults and much excellent early Gothic, or when the ceiling is flat, it becomes a difficult question how far their services may receive ornamentation independent of their structure. I have never myself seen a flat ceiling satisfactorily decorated, except by painting: there is much good and fanciful panelling in old English domestic architecture, but it always is in some degree meaningless and mean. The flat ceilings of Venice, as in the Scuola di San Rocco and Ducal Palace, have in their vast panellings some of the noblest paintings (on stretched canvas) which the world possesses: and this is all very well for the ceiling; but one would rather have the painting in a better place, especially when the rain soaks through its canvas, as I have seen it doing through many a noble Tintoret. On the whole, flat ceilings are as much to be avoided as possible; and, when necessary, perhaps a panelled ornamentation with rich colored patterns is the most satisfying, and loses least of valuable labor. But I leave the question to the reader's thought, being myself exceedingly undecided respecting it: except only touching one point--that a blank ceiling is not to be redeemed by a decorated ventilator. § IV. I have a more confirmed opinion, however, respecting the decoration of curved surfaces. The majesty of a roof is never, I think, so great, as when the eye can pass undisturbed over the course of all its curvatures, and trace the dying of the shadows along its smooth and sweeping vaults. And I would rather, myself, have a plain ridged Gothic vault, with all its rough stones visible, to keep the sleet and wind out of a cathedral aisle, than all the fanning and pendanting and foliation that ever bewildered Tudor weight. But mosaic or fresco may of course be used as far as we can afford or obtain them; for these do not break the curvature. Perhaps the most solemn roofs in the world are the apse conchas of the Romanesque basilicas, with their golden ground and severe figures. Exactly opposed to these are the decorations which disturb the serenity of the curve without giving it interest, like the vulgar panelling of St. Peter's and the Pantheon; both, I think, in the last degree detestable.