Next to this, on the north, is the chapter house, which projects beyond the general line of the buildings, the portion next the cloister having the appearance of a vestibule. The inner cloister enters from the vestibule by two arches (Fig. 1002), which rest on a central round pillar and corbels at the sides. This pillar is sometimes stated to be of Norman work, and the chapter house is, consequently, regarded as of Norman date. But a careful examination of the pillar and its capital leads to the conclusion that it is comparatively a late structure. The carving of the cap (Fig. 1003) is very peculiar. On the outer or west side, the ornament, which is somewhat decayed, resembles that of the caps of the adjoining nunnery church, and may easily be mistaken for ancient. But the ornament of the inner or east side of the cap (see Fig. 1003) is quite different, and is undoubtedly of very late design, being similar to that on the carved tombstones of the fifteenth or sixteenth centuries, such as that in Figs. 991 and 992. The dog-tooth or nail-head ornament of the arches, although at first sight like first pointed work, is found, on closer inspection, to consist of late imitations--showing three small nail-heads placed close together, so as to form an enrichment in a manner not at all transition like. The same remark applies to the enrichments of the high chapel in the choir (see Fig. 1000). [Illustration: FIG. 1003.--Iona Cathedral. Details of Central Pillar in Chapter House.] The walls of the eastern part of the cloister are not over 2 feet 6 inches in thickness (which would be very unusual in Norman work), and they have been strengthened by interior piers when the present flat barrel arch was erected over the chapter house. This probably took place when the upper part of this portion of the building was raised a story in height, possibly in order to form the library on the upper floor. It is evident, from an examination of the junction of the walls on the exterior, that the upper floor of this part of the building was added at a late period. Both vestibule and chapter house appear to have had a stone seat running along the walls, and the whole may possibly have formed the place of assembly of the monks. Probably, like the chapter house at St. Andrews, the western portion, or vestibule, was the original chapter house, and the inner division was added at a later period.