§ XXIV. The reader will understand both arrangements instantly by two examples. Fig. XXVII. represents two windows, more than usually beautiful examples of a very frequent Venetian form. Here the deep cornice or string course which runs along the wall of the house is quite strong enough for the work of the capitals of the slender shafts: its own upper stone is therefore also theirs; its own lower stone, by its revolution or concentration, forms their bells: but to mark the increased importance of its function in so doing, it receives decoration, as the bell of the capital, which it did not receive as the under stone of the cornice. [Illustration: Fig. XXVII.] In Fig. XXVIII., a little bit of the church of Santa Fosca at Torcello, the cornice or string course, which goes round every part of the church, is not strong enough to form the capitals of the shafts. It therefore forms their abaci only; and in order to mark the diminished importance of its function, it ceases to receive, as the abacus of the capital, the decoration which it received as the string course of the wall. This last arrangement is of great frequency in Venice, occurring most characteristically in St. Mark's: and in the Gothic of St. John and Paul we find the two arrangements beautifully united, though in great simplicity; the string courses of the walls form the capitals of the shafts of the traceries; and the abaci of the vaulting shafts of the apse. [Illustration: Fig. XXVIII.] § XXV. We have hitherto spoken of capitals of circular shafts only: those of square piers are more frequently formed by the cornice only; otherwise they are like those of circular piers, without the difficulty of reconciling the base of the bell with its head. § XXVI. When two or more shafts are grouped together, their capitals are usually treated as separate, until they come into actual contact. If there be any awkwardness in the junction, it is concealed by the decoration, and one abacus serves, in most cases, for all. The double group, Fig. XXVII., is the simplest possible type of the arrangement. In the richer Northern Gothic groups of eighteen or twenty shafts cluster together, and sometimes the smaller shafts crouch under the capitals of the larger, and hide their heads in the crannies, with small nominal abaci of their own, while the larger shafts carry the serviceable abacus of the whole pier, as in the nave of Rouen. There is, however, evident sacrifice of sound principle in this system, the smaller abaci being of no use. They are the exact contrary of the rude early abacus at Milan, given in Plate XVII. There one poor abacus stretched itself out to do all the work: here there are idle abaci getting up into corners and doing none.