[Illustration: FIG. 968.--Dunkeld Cathedral. Plan.] dates of the different parts of the structure of the cathedral than we have of any similar building in the country. From this account it would appear that the existing structure is chiefly of the fifteenth century. The edifice (Fig. 968) consists of an aisleless choir, a nave with two aisles, a north-west tower, and a chapter house to the north of the choir. The choir measures 103 feet long by 29 feet wide internally, and the rectangular chapter house attached to the north side is 27 feet long and 20 feet wide. Some portions of the choir indicate the style of the thirteenth [Illustration: FIG. 969.--Dunkeld Cathedral. Wall Arcade at North-West Angle of Choir.] century; but this part of the structure was almost entirely rebuilt in the beginning of the present century. An original fragment may, however, still be observed in damaged portions of a first pointed arcade (Fig. 969) in the interior of the north wall near the west end. The arcade is below the level of the window sill, and extends to six arches of trefoil form, springing from the carved caps of single shafts. All the details (Fig. 970) are pure and good. A post to support a modern gallery cuts into the arcade, as shown in Fig. 969. From the floor to the top of the caps measures 5 feet 9 inches. The choir is now fitted up and used as the parish church. The chapter house, on the north side of the choir, is now converted into a mausoleum for the families of the Dukes of Atholl, and contains several Renaissance monuments. It is two stories high (Fig. 971), the [Illustration: FIG. 970.--Dunkeld Cathedral. Details of Wall Arcade in North-West Angle of Choir.] lower story being vaulted and of considerable height (Fig. 972), and is lighted by tall lancet windows cusped at the arch head. The buttresses are simple, and the whole character of the work is early, but it has been altered. The vaulting (Fig. 972) is round arched, but the wall ribs are pointed; the roof has thus a flat appearance, and there are no horizontal ridge ribs. The chapter house structure has been added after the erection of the choir, as is evident from the portion of the original exterior base of the choir which still exists in the south-west angle of the interior of the chapter house adjoining the door (see Fig. 972). From the style of the design, this structure was probably an early addition. The upper [Illustration: FIG. 971.--Dunkeld Cathedral. Chapter House from North-West.] chamber over the chapter house is doubtless later. The staircase leading to the upper floor is inserted in the south-west angle and projects into the chamber,[20] and cuts through the groined ceiling (see Fig. 972). The heightening of the chapter house was apparently carried out by Bishop Lauder, whose arms, a griffin segreant (Fig. 973), are carved near the top on the face of the north buttress on the east side. The upper