The column is a greater favourite than the pier in France, as has already been said. Sometimes, where the supports of the main arcade are really piers, they are built like circular shafts of large size; and even when they have no capital (as was the case in third-pointed examples), these piers still retain much of the air of solid strength which belongs to the column, and which the French architects appear to have valued highly. In cases where a series of mouldings has to be carried--as for example when the main arcade of a building is richly moulded--English architects would usually have provided a distinct shaft for each little group (or as Willis named them order), into which the whole can be subdivided. In France, at any rate during the earlier periods, the whole series of mouldings would spring from the square unbroken abacus of a single large column, to which perhaps one shaft, or as in our illustration (Fig. 36) four shafts, would be attached which would be carried up to the springing of the nave vault, at which point the same treatment would be repeated, though on a smaller scale, with the moulded ribs of that vault. [Illustration: FIG. 36.--PIERS AND SUPERSTRUCTURE, RHEIMS CATHEDRAL. (1211-1240.) _i._ Springing of main ribs of the vault. _h._ String-course below the clerestory. _a b._ Triforium arcade. _g._ String-course below the triform. B. Main arcade separating the nave from the aisles. A and N. Shafts attached to pier and supporting portions of the superstructure.] A peculiarity of some districts of southern France is the suppression of the external buttress; the buttresses are in fact built within the church walls instead of outside, and masonry enough is added to make each into a separating wall which divides side chapels. Some large churches, _e.g._, the cathedral at Alby, in Southern France, consist of a wide nave buttressed in this way, and having side chapels between the buttresses, but without side aisles. The plans of the secular, military, and domestic buildings of France also present many interesting peculiarities, but not such as it is possible to review within the narrow limits of this chapter. _Roofs and Vaults._