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“ The surface of slanting roofs,” says that accomplished writer,“ must be nearly flat—decoration therefore is difficult; and though it isrough when compared with the surface of columns or hewn stone ingeneral, it has no effect of light and shadow. It- has also a moreunfinished look than any other part, — a very material circumstance inwhatever is to be combined with the highly finished forms and ornamentsof architecture. It is to be considered by what means these defects maybe diminished. Few roofs of ancient buildings remain; in them,however, a peculiar attention seems to have been paid both to regularityof construction, and light and shadow. The Tower of the Winds atAthens is covered with slabs of marble, in each of which the horizontaledge projects so much as to give a strong shade; while the vertical jointsare so elevated as to form high ribs, which break the uniform surface in avery beautiful manner. The Lantern of Demosthenes is roofed in theform of laurel leaves, which, in a different way, have the same effect.The ancient mode of tiling, by semicircular tiles laid within each other,cave a sort of fluted look to the roof; and the old flat tiles of the LowerEmpire, which were joined with a high rib, something in the way of theTemple of the Winds, had the same effect of light and shadow. Eventhe ridge and hip-rolls of our roofs diminish in some degree the barenessof their appearance. The richness occasioned by variation from uni-formity of surface is also very striking in some of the old leaden roofs ofour churches, where the sheets are small and the rolls large. Theancients seem to have had it in view to give both lightness and richnessto their roofs, by a sort of lacing to the edges of them; the ridges, aswell as the eaves, were decorated with a sort of open work, of smallknobs and projections; and the same kind of ornament yet remains, withpeculiarly elegant effect, in many of our old churches and houses.”

These ornamental lacings on ridges are called crest tiles, and are