The central compartment or crossing of St. George’s, Windsor, is a most magnificent treatment of an oblong space. The aisles of the same chapel, with the smaller chapels adjoining, are charming examples, as are the aisles and small chapels of Henry VII.’s Chapel, and the cloisters of St. Stephen’s, Westminster. Bath Abbey and Sherborne Minster are thus vaulted, and a whole century later, appearing long after date, comes the beautiful ceiling of the staircase to the hall at Christ Church, Oxford (Fig. 393), a square space groined on a central pillar (Fig. 394). [Illustration: Fig. 393. Ceiling of the Staircase to the Hall, Christ Church, Oxford.] [Illustration: Fig. 394.] In the construction of the vaulting of these later periods, we have a curious instance of the manner in which extremes meet. In the earliest specimens of vaulting, all the strength lies in the vaulting surface itself. As time went on, ribs were introduced, one after another, to strengthen and support it, till at length they amounted to a permanent framework of stone, centering on which the vaulting surface lay. Now, at length, time has its revenge, and the extreme multiplication of ribs led to the loss of their uses; the whole, or nearly the whole, being cut out of the same blocks with the panels; and thus the original system was reverted to; the vaulting surface becoming again the entire structure, and the ribs and panels simply cut as ornaments out of its substance. The most remarkable production of the fan system of vaulting is the gorgeous central roof of Henry VII.’s Chapel, a work in which ingenuity, perplexity, and beauty are united in the most wonderful manner which can be conceived. Though it stands quite alone in point of intricacy and magnificence, it is not the first instance of the use of the peculiar system on which it is founded. How Fuller could have attributed its origin to the foreign studies of the King and Bishop Fox, it is difficult to conceive; for, not only is fan groining itself a purely English invention, but the special system of _this_ roof has, so far as I know, only English prototypes. The earliest of these is the vaulting of the Divinity School at Oxford,[61] finished about 1480. This was subsequently imitated, though with the loss of its leading principle, in the choir of the Cathedral (then the Church of St. Fridewide’s Convent in the same city), a work which, though popularly attributed to Wolsey, is probably of earlier date. I have often looked in vain for the leading principle on which this wonderful work was designed. Its _construction_ is plain enough; the difficulty is the ideal of its _design_. Like everything, however, which is founded on reason, its idea once perceived, it becomes perfectly simple, and one then only wonders where the difficulty lay.