6o

OF HIBBED VAULTS.

when the ribs are the same arc of the same circle.It would at first seem that they could not be sup-ported, were the vault over a square plan, as in theailes of Henry the Seventh’s Chapel , Westminster,and of great width as at St. Sophia. But it is to berecollected, that the parts by position would have adouble summering, as in a dome ; and that the plate-bande of the Louvre illustrate the practicability.Yet, at the same time, it must be admitted, that theprinciple is not correct, because the direction of thesummering being acute to the soffite of the vault, thereliance is rather on the material than on the method.The Free Masons themselves were not unmindful ofthis geometrical objection; and pointed arches, formedof the intersections of the false parabola and hyper-bola, arose to obviate, conceal, and assist the practicalevil, as at King’s College Chapel , Henry the Seventh’sChapel, and St. George’s Chapel, Windsor.

The vault of the Chapel of King’s College, Cam­ bridge (Fig. 22.), has rather been a subject of wonderthan inquiry, and some observations on it may there-fore be acceptable.

The vault of this Chapel is divided into partscalled severies, each severy subtending an oblong,consequently the curves of the inverted quadrants in-tersect each other before the quadrant of the circle iscompleted (Fig. 22.), whence the intersections form aridge, declining towards the windows or smaller sideof the oblong, and again in the opposite directionparallel thereto: so that the ridge parallel with thelength of the building forms the undulation beforealluded to ; but, from the circumstance of the curveof the vaidt and the subtended plan, it is seldom ob-served. However great and however deservedly may