The vaulting of the Lady Chapel at Salisbury is remarkable for the extraordinary slenderness of the columns which support it, being thin Purbeck marble shafts of great height, reducing the width of the chapel by cutting off a very narrow range of vaulting from either side. Somewhat similar in idea is the vaulting of the crypt beneath the Sainte Chapelle at Paris, where, to avoid the segmental vaulting which would be the natural result of its limited height, the span is reduced by a range on either side of small pillars;--in this case so near the wall as to necessitate a great amount of stilting, and the introduction of a kind of tracery beneath the transverse ribs to give abutment to the central vault. I should, in passing, mention, that segmental vaulting is very frequent at this period, where the height is limited; and that, even where the main arches are not so, the diagonal ribs frequently assumed that form; indeed, it became necessary wherever the length of a diagonal exceeded double the height of its arch. Taking this stage of the history of vaulting as a whole, we have peculiarly favourable opportunities of studying it here in London: possessing, as we do, excellent examples of all its most leading varieties. In the Temple Church we have the curious circular aisle already described, being a specimen of the earliest era of true pointed-arched vaulting; while in the eastern portion, dating some forty or fifty years later, we have the most typical specimen conceivable of vaulting, all springing from a given level, and with level ridges. It is rendered the more marked in character by the division of the three ranges of vaulting by means of the pier-arches, which, coming close under the vaulting, assume the character of enlarged ribs. Very similar to the last-named is the vaulting of the Lady Chapel of St. Saviour (or St. Mary Overie), Southwark (Fig. 378). The only striking difference being the number of spans and the absence of pier-arches, so that it assumes the form of a space divided into twelve equal and square compartments, and carried by six similar columns. [Illustration: Fig. 378. Lady Chapel, Southwark.] In the choir of the same church we have an excellent specimen of clerestory vaulting, with oblong compartments and stilted side-cells, worked in a manner somewhat different from the usual ploughshare system.