ls of the
main body of the building, excepting the narthex and the additions at
the east end of the church, are built of large well-squared stones laid
in regular courses, and are homogeneous throughout.

Above that level the walls are built in alternate bands of brick and
stone, five courses of brick to five courses of stone being the normal
arrangement. The stones in this portion of the walls are smaller and
much more roughly squared than those below the springing of the aisle
vaults. This brick and stone walling is, so far as could be ascertained,
homogeneous right up to the domical vault and the dome. As usual the
arches and vaults are in brick. A point to be noted is that the recesses
or openings in the lower part of the north and south walls of the church
do not centre with the windows and vaulting above them; sometimes,
indeed, the head of an opening comes immediately below a vaulting arch
or rib. Again, at the north-eastern external angle of the apse the wall
up to the level of the springing of the aisle vaulting is in stone, but
above that level in brick, and the two portions differ in the angle
which they subtend. Evidently there has been rebuilding from a level
coinciding with the springing of the aisle vaulting. Projecting above
the ground at the same place is a square mass of stonework that was left
unbuilt upon when that rebuilding took place. The narthex is built of
brick, with bands of large stone at wide intervals, and is separated by
distinct joints from the upper and lower walls of the body of the
church. Furthermore, while the two eastern bays on each side of the
western portion of the nave continue and belong to the unusual system of
vaulting followed in the aisles, the bay on each side immediately
adjoining the narthex belongs to the vaulting system found in the
narthex, and has, towards the nave, an arch precisely similar to the
arches between the nave and the narthex. The division between the two
systems is well marked, both in the nave and in the aisles, and points
clearly to the fact that the narthex and the body of the church are of
different dates.

[Illustration: PLATE XXII.
(1) S. IRENE. VAULTING OVER THE SOUTH AISLE.
(2) S. IRENE. A COMPARTMENT OF SOUTH AISLE VAULTING (2) (LOOKING
DIRECTLY UPWARD).
_To face page 100._]

Thus the architectural survey of the building shows that the principal
parts of the fabric represent work done upon it on three great
occasions, a conclusion