But the Venetians seem to have had a morbid horror of arches which were not _on a level_. They could not endure the appearance of the roof of one arch bearing against the side of another; and rather than introduce the idea of obliquity into bearing curves, they abandoned the arch principle altogether; so that even in their richest Gothic staircases, where trefoiled arches, exquisitely decorated, are used on the landings, they ran the shafts on the sloping stair simply into the bar of stone above them, and used the excessively ugly and valueless arrangement of Fig. II., rather than sacrifice the sacred horizontality of their arch system. [Illustration: Fig. IV.] It will be noted, in Plate XI., that the form and character of the tracery bars themselves are independent of the position or projection of the cusps on their flat sides. In this respect, also, Venetian traceries are peculiar, the example 22 of the Porta della Carta being the only one in the plate which is subordinated according to the Northern system. In every other case the form of the aperture is determined, either by a flat and solid cusp as in 6, or by a pierced cusp as in 4. The effect of the pierced cusp is seen in the uppermost figure, Plate XVIII. Vol. II.; and its derivation from the solid cusp will be understood, at once, from the woodcut Fig. IV., which represents a series of the flanking stones of any arch of the fifth order, such as _f_ in Plate III. Vol. I. [Illustration: Fig. V.] The first on the left shows the condition of cusp in a perfectly simple and early Gothic arch, 2 and 3 are those of common arches of the fifth order, 4 is the condition in more studied examples of the Gothic advanced guard, and 5 connects them all with the system of traceries. Introducing the common archivolt mouldings on the projecting edge of 2 and 3, we obtain the bold and deep fifth order window, used down to the close of the fourteenth century or even later, and always grand in its depth of cusp, and consequently of shadow; but the narrow cusp 4 occurs also in very early work, and is piquant when set beneath a bold flat archivolt, as in Fig. V., from the Corte del Forno at Santa Marina. The pierced cusp gives a peculiar lightness and brilliancy to the window, but is not so sublime. In the richer buildings the surface of the flat and solid cusp is decorated with a shallow trefoil (see Plate VIII. Vol. I.), or, when the cusp is small, with a triangular incision only, as seen in figs. 7 and 8, Plate XI. The recesses on the sides of the other cusps indicate their single or double lines of foliation. The cusp of the Ducal Palace has a fillet only round its edge, and a ball of red marble on its truncated point, and is perfect in its grand simplicity; but in general the cusps of Venice are far inferior to those of Verona and of the other cities of Italy, chiefly because there was always some confusion in the mind of the designer between true cusps and the mere