Waterhouse, Percy Leslie: The story of architecture throughout the ages: an introduction to the study of the oldest of the arts for students and general readers (London: B. T. Batsford, 1924)

EARLY CHRISTIAN ARCHITECTURE 107

dome (shown by the dotted lines) rests securely
upon the upper course, at the level of the crown
of the arches—i.e., upon the four pendentives.
The most magnificent example of the Byzan-
tine style is the great church at Constantinople,
built during the reign of Justinian, by Anthe-
mius of Tralles and Isidorus of Miletus, a.d.
532-538, and dedicated to Hagia Sophia, the
Holy Wisdom, more commonly called the
church of S. Sophia (pl. x., p. 87). The main
building is roofed over by a great central
dome, 107 feet in diameter, lighted by a ring
of forty small arched windows ranged round
the base. The spaces on the east and west
are covered by half-domes, which in turn
cover semi-circular apses. Both the half-
domes and the apses are lighted by rings of
windows, for upon these roof-openings the
whole interior largely depends for light. The
weight of the roof is almost entirely carried
upon the massive piers which divide the aisles
into three bays ; so that the whole of the
nave, measuring more than 200 feet in length
and 100 feet in breadth, is unobstructed by
columns or piers of any kind. This result was
obtained by the development, under Greek
influence, of the possibilities of the arch as a
structural principle, to an extent unknown
among the builders of imperial Rome.
The vast nave, roofed over with dome upon
dome, culminating in the great central vault;
the numerous windows, at all heights, vying
with the arcades of arches to confuse the eye