In the eastern half of Westminster Abbey, including the transepts, we have the vaulting of the oblong space (with ploughshare side cells), and of the square space, and of the four-sided space of all degrees of irregularity; we have apses of two dimensions, viz., the great apse of the Sanctuary and those of the radiating chapels, which are as beautiful specimens of the apse vault as can be found; we have, in the Chapter-house, the vaulted octagon, with central pillar carried out in noble proportions and with excellent detail;[58] while in the crypt below is a repetition of the same vaulting, of depressed proportions, and carried out with the severest simplicity. [Illustration: Fig. 379.--St. Faith’s Chapel, Westminster Abbey. View looking East.] We have in its inner vestibule two oblong vaults [Illustration: St. Faith’s Chapel, Westminster Abbey. View looking west.] placed side by side, one apparently the square, and the other of the narrowest proportions; and in the outer vestibule beautiful miniature vaulting, on minute columns, and with the segmental arch; while in St. Faith’s Chapel, hard by, we have an excellent example of the sexpartite vault (Figs. 379, 380). Parts of the aisles, too, are remarkable for the subdivision of their bays by transverse arches of the double orders of mouldings, giving a great nobleness and strength to their effect; and all these varieties are carried out with admirable detail and studied art. It would lead me into too great length if I were to go into the moulding of the ribs, their combinations where grouping and intersecting one another in the springers, and the mode in which the shafts are arranged for their support. My illustrations will, however, do much to explain this. I must not omit to mention that in French buildings, and frequently in the earlier English specimens, the plans of the abaci of these shafts assume both forms and positions indicating the general section and the directions of the ribs they carry,[59] and that this is even shared by the _bases_; showing that the vaulting was the _very first_ thing thought of and designed; and that, from the very floor of the building, it influenced the general design. This was lost in England by the introduction of the circular abacus. I have hitherto dwelt wholly upon vaulting which has none but what I have termed _functional_ ribs; that is to say, such as have a specific utility, as transverse ribs to mark the boundaries of the bays, and to strengthen the vault in its main span; diagonal ribs to fortify the angles of intersection; and wall-ribs to support the vaulting surfaces at their junction with the walls; and occasionally ridge ribs, though these more properly belong to the succeeding stage. The next stage in the history of vaulting is that in which other than merely functional ribs are made use of--intermediate ribs, in fact, to subdivide the spaces between those used during the previous period. [Illustration: Fig. 381.]