146 ENGLISH ARCHITECTURE. Part II. inverted position. ^ One half of such a vault is shown at a and a a (Woodcut No. 578, lig. 1). The English seem early to have tired of the endless repetition of these forms, and, after trying every mode of concealing their sameness by covering them with tracery, they hit on tiie happy expedient of cutting off their angles as shown at b and b b. This left a flat square space in the centre, which would have been awkward in the central vault, though in a side-aisle it was easily got over, and its flatness concealed by ornament. Arrived at this stage, it was easy to see that by again dividing each face into two, as at c. iu'J. Koof of Cloister, Gloucester. fig. 1, the principal original lines were restored, and the central space could be subdivided by constructive lines to any extent required. By this process the square pyramid had become a polygonal cone of 24 sides, which was practically so near a circle that it was impossible to resist the suggestion of making it one, which was accordingly done, as shown at d and d d, fig. 1. So far all was easy, but the fact of the flat central space resting on the four cones was still felt to be a defect, as indeed is apparent in ' This has already been explained in the chapters on French arcliitecture in Vol. I., especially at pages 516 and 571.
