Bk. VI. Ch. III. VAULTS. 145 Flg.l. " severeys " of the vault. This defect was remedied at Lichfield, but nowhere else, until the invention of the four-centred arch and of fan- tracery. At Lichfield (Woodcut No. 576) the triangular form of the clerestory windows afforded a perfect solution of the difiiculty, and gave a stability and propriety to the whole arrangement that never was surpassed, and never might have been relinquished had not their fatal fondness for painted glass forced the architects in this, as iu other instances, to forego constructive propriety for indulgence in that fascinating mode of decoration. Beautiful as these simple early roofs were felt to be, the great mass of the " severeys," or inverted pyramids, formed a very obvious defect. It was, however, easily rem- edied when once perceived. The earliest example of its successful removal is probably in the roof of the choir at Gloiicester(lB37-1377) (Wood- cut No. 577). In tliis in- stance the roof is almost a tunnel-vault with the window ^ spaces cutting into it, so as I to leave nearly one-third of the space unbroken ; and, as the whole is covered with rich and appropriate tracery, the effect is highly pleasing. The same principle was after- wards carried to its ittmost 1^ perfection in the roof of St. George's Chapel at Windsor. In that case a flat band was introduced as a separate con- structive compartment in the centre, supported by the seve- reys, and as the roof is orna- mented with ribbings of the most exquisite design, it forms perha[)S the most beautiful vault ever designed by a Gothic architect. The great invention of the English architects in vaulting is the form usurjly known as fan-tracery. It is so beautiful in itself, and' so exclusively English, that it may, perhaps, be worth while to retrace the step, by which it was arrived at. This may lead to a little repetition, but the stone vault is so essentially the governing modulus of the style that its principles cannot be made too clear. The original form of the intersecting vault is that of two halves of .1 hollow-sided square pyramid placed opposite o-ne another in an VOL. II. — 10
Fig. 2. D E 578. Diagrams of A'aulting
