tower is lighted with slits in the wall near the corners, except on the
south side, where a larger opening is introduced and filled with tracery
(see Fig. 984).
The whole of the church has been roofed with timber, but is now quite
open to the weather. The stone corbels intended to carry the principals
of the roof still remain where the walls are complete (see Fig. 983).
Externally, the most prominent features are the buttresses and base
course (see Figs. 984 and 995). These exist round most of the south wall
of the nave, part of the south transept, and the east end of the choir.
The angle buttresses have the general form, with bead on angle and
sloping table on top, of thirteenth century work, and the broad, sloping
base has also a similar character. Several small intermediate buttresses
are introduced, which are in many cases awkwardly situated as regards
the windows, being kept below the window sills. The base course on the
south side of the nave is set at a level several feet above that of the
south transept (see Fig. 995). It is stopped suddenly before reaching
the eastmost bay of the nave. The base also stops equally suddenly on
the west wall of the south transept, a few feet from the south-west
angle buttress. The base course and buttresses would thus seem, where
they exist, to indicate a rebuilding of those portions of the walls, the
portions left without a base course being possibly older. Although the
forms of the base course and buttresses are of early design, there is no
doubt but that they are late erections, and that the forms and design
are revivals or imitations of older features. Their association with the
late doorway of the nave and the late traceries of the choir and south
transept sufficiently proves their comparatively recent construction.
[Illustration: FIG. 993.--Iona Cathedral.