than 5 cm., while
above the ground they vary to a much greater degree, rendering minute
measurements quite valueless. Lastly, as the marble panelling was fitted
after the completion of the body of the building, it had to be adapted
to any divergence that had previously occurred in the settling of the
walls or the spreading of the vaults. The marble panelling, it should
also be observed, is here cut to the diagonal at one angle, and not at
the other.

Apart from the set back of the masonry at the middle string-course, this
church, therefore, supplies no evidence for an intentional widening of
the structure from the ground upwards. Any further widening than that at
the middle string-course was accidental, due to the nature of the
materials employed, not to the device of the builder, and was allowed by
the architect because unavoidable. Such irregularities are inherent in
the Byzantine methods of building.

[Illustration: PLATE XLIX.
(1) S. MARY DIACONISSA. SOUTH EIKON FRAME.
(2) S. MARY DIACONISSA. DETAIL IN THE SOUTH EIKON FRAME.
_To face page 188._]

[Illustration: FIG. 61.]

[Illustration: FIG. 62.]

[Illustration: PLATE L.
(1) S. MARY DIACONISSA, LOOKING WEST.
(2) S. MARY DIACONISSA. CAPITAL ON COLUMN AT THE ENTRANCE TO THE
CHURCH.
_To face page 190._]

[293] _De top. C.P._ iii. c. 6.

[294] P. 351.

[295] _Archaeologia_, vol. lv. part 2, p. 431.

[296] P. 352.

[297] Their names appear in the Letter addressed to Menas, by the
monks of the city, at the Synod of 536.

[298] In the Epistle to Pope Agapetus the monastery 'near the
aqueduct' is described as 'Anastasii prope Agogum,' Mansi, viii. p.
907.

[299] _Esquisses top._ p. 70.

[300] Const. Porphr. _De cer._ i. p. 75.

[301] P. 428; Banduri, i. p. 18; viii. pp. 697-98.

[302] _Archaeologia_, vol. lv. part 2, p. 438.

[303] _Mediaeval Art_, p. 66.

[304] _Manuel d'art byzantin_, p. 312.

CHAPTER X

THE CHURCH OF SS. PETER AND MARK,
HOJA ATIK MUSTAPHA JAMISSI

The Byzantine church, now Hoja Atik Mustapha Jamissi, situated in the
Aivan Serai quarter, close to the Golden Horn, is commonly regarded as
the church of SS. Peter and Mark, because it stands where the church
dedicated to the chief of the apostles and his companion stood, in the
district of Blachernae (Aivan Serai) and near the Golden Horn.[305] Such
indications are too vague for a positive opinion on the subject, but
perhaps the Patriarch Consta