The chapter house wing is two stories in height, and the staircase finishes on top (Fig. 598) with a cape house, after the manner of the pele towers. This wing measures on Plan about 30 feet square internally, and has a central pillar supporting the vaulting on both floors. The chapter house, which is on the ground floor, was, as we have seen, left in an unfinished state in the thirteenth century. In the early part of the fifteenth century, Bishop Lauder has evidently recommenced work at it. [Illustration: FIG. 598.--St. Mungo’s Cathedral. East End of Cathedral and Chapter House, from South-East.] The wall shafts (see Fig. 584), with their early section and first pointed caps and bases, have the appearance of being older than his time; but the Dean’s seat, which has been inserted in the east side (Fig. 599), is part [Illustration: FIG. 599.--St. Mungo’s Cathedral. Dean’s Seat in Chapter House.] of his work. It is in the design of that period, and contains the following inscription along the top--viz., Wilms: fuda: instut: Caplm: Dei, which Archbishop Eyre thus renders,[67] “William laid the foundation of this chapter house in God’s honour.” The William referred to was Bishop William Lauder, whose arms (a Griffin Segreant) occur on a shield on the lintel below the inscription. The shield is surmounted by the bishop’s crosier. [Illustration: FIG. 600.--St. Mungo’s Cathedral. Sacristy, looking North-East.] The shield of Bishop Lauder is also inserted on the exterior of the west side of the chapter house. It is shown on a slab in Fig. 600, and is a characteristic piece of heraldic decoration. Fig. 600 shows the upper apartment or sacristy. The completion of this wing was carried out by Bishop Cameron, who built the upper story, or sacristy, and vaulted the building. It is not quite clear whether the vaulting of the lower story was executed by Bishop Cameron or Bishop Lauder. The central pillar (Fig. 601) is late, and the boss of the north-west compartment seems to contain the Cameron arms. The groin ribs (=A=) are of early form, while those of the sacristy (=B=) are of a late section. The vaulting springers of the chapter house may have been built at the same time as the chapter house shafts--_i.e._, in the thirteenth century--and completed in the fifteenth century with the same section as they were begun with; while the groins of the sacristy, being entirely of fifteenth century work, are of the section of that period. [Illustration: FIG. 601.--St. Mungo’s Cathedral. Details of Central Pillar, &c., in Chapter House.] The shields in the bosses of the chapter house are somewhat difficult to decipher; but that in the south-east bay may possibly represent the royal arms of Scotland and England impaled, and stand for James I. and his wife, Margaret Tudor.[68] King James returned to Scotland in 1424, about which time the chapter house vault may have been built.