a finial was placed. These are the domes inside and outside Cairo, which
are carved with an infinity of geometrical patterns interwoven with
conventional floral decoration. The upper portion of the dome is very
thin, so that there is little weight and comparatively no thrust, and it
is to these facts that we probably owe their preservation.

In India, in the "great mosque" of Jama Masjid (A.D. 1560) and the Gol
Gumbaz, or tomb of Mahommed Adil Shah (A.D. 1630) at Bijapur, the domes
are carried on pendentives consisting of arches crossing one another and
projecting inwards, and their weight counteracts any thrust there may be
in the dome. It is possibly for a similar reason that in the Jama Masjid
of Shah Jahan at Delhi (1632-1638) and the Taj Mahal (A.D. 1630) the
domes assume a bulbous form, the increased thickness of the dome below
the haunches by its weight served as a counterpoise to any thrust the
upper part of the dome might exert. The form is not much to be admired,
and when exaggerated, as it is in the churches of Russia, where it was
introduced by the Tatars, at times it became monstrous.

From these we pass to the domes of Perigord and La Charente, the
earliest of which date from the commencement of the 11th century. Of the
western dome of St Etienne at Perigueux (A.D. 14) only the pendentives
remain, sufficient, however, with later examples, to show that these
French domes were different from the Byzantine both in construction and
form. The pendentives are built on horizontal courses of stone, and the
voussoirs of the pointed arches which carried them form part of the
pendentives; a few feet above the top of the arches is a moulding and a
ledge, above which the dome, ovoid in section, is built. The principal
examples following St Etienne are those of S. Jean-de-Cole, Cahors,
Souillac, Solignac, Angouleme, Fontevrault, and lastly St Front at
Perigueux, built about 1150, in imitation of St Mark's at Venice. The
domes of the latter church were introduced into the old basilica about
1063, and were based on the church of the Apostles at Constantinople,
which was pulled down in the 15th century, so that we have only the
clear description of Procopius to go by. The domes over the north and
south transepts and the choir of St Mark's are smaller than those over
the nave and crossing, because they had to be fitted in between more
ancient structures. The construction of the domes of St Mark's is not
known, but at St Fro