AKARISTOS. MOSAIC IN THE DOME OF THE PARECCLESION.
_To face page 154._]

The exterior of the chapel, like the facade of S. Theodore (p. 247),
presents a carefully considered scheme of decoration, characteristic of
the later Byzantine school both here and in the later schools outside
Constantinople. The southern wall is divided externally as it is also
internally, into three stories, and forms two main compartments
corresponding to the narthex and to the cross arm. They are marked by
high arches of two orders, which enclose two triple windows in the upper
story of the narthex and of the cross arm. The clue to the composition
is given by the middle story, which contains the two large triple
windows of the narthex and of the cross arm, and the two single lights
of the angle compartment, one on each side of the cross arm triple
light. These windows are enclosed in brick arches of two orders and
linked together by semicircular arched niches, of which those flanking
the narthex window are slightly larger than the rest, thus giving a
continuous arcade of a very pleasant rhythmic quality.

In the lower story the piers of the arches round the triple windows are
alone carried down through the inscribed string-course which separates
the stories and forms the window-sill. The system of niches is repeated,
flat niches being substituted for the angle compartment windows above.

The highest story contains the large single windows which light the
cross arm and the gynecaeum, the former flanked by two semicircular
niches, the latter by two brick roundels with radiating joints. Between
them, above the west angle compartment window, is a flat niche with a
Turkish arch. It is possible that there was originally a break here
extending to the cornice, and that this was filled up during Turkish
repairs. The cornice has two ranges of brick dentils and is arched over
the two large windows. The domes on the building have flat angle
pilasters supporting an arched cornice.

The masonry is in stripes of brick and stone courses, with radiating
joints to the arched niches and a zigzag pattern in the spandrils of the
first-story arches. At this level are four carved stone corbels with
notches on the upper side, evidently to take a wooden beam. These must
have supported the roof of an external wood cloister. The inscribed
string-course already mentioned between the ground and first stories
bears a long epitaph in honour of Michael Glabas Tarchaniot