do-chala Type of roof with curved eaves, derived from Bengali
huts (bangala). Used first in Bengali and later in
Mughal architecture.
dome Circular vaulted construction used as a means of roofing. First used in much of the Middle East and North Africa whence it spread to other parts of the Islamic world, because of its distinctive form the dome has, like the minaret, become a symbol of Islamic architecture. It seems likely that the dome originated as a roofing
method where the absence of suitable timber meant
that it was impossible to make a flat timber roof.
The earliest domes in the Middle East were
associated with round buildings and were produced
out of mud brick placed in layers which tilt slightly
inwards. Another early method of dome
construction which can still be seen in northern
Syria and Harran in Turkey is the corbelled dome
where mud bricks are placed horizontally in circular
layers of diminishing circumference producing a
corbelled dome. When the Romans conquered the
Middle East the dome was incorporated into Roman
architecture and under the Byzantines it became the
main method of roofing monumental buildings.
The chief advantage of domes is that large areas
can be roofed without the interference of columns.
At this time the wooden dome was developed
which combined the space of dome building with
the flexibility and lightness of wood. By the seventh
century wooden domes were a normal method of
roofing churches so that when the Arabs came to
build the Dome of the Rock a wooden dome was
used as the most appropriate form for this major
religious building. Wooden domes were usually
covered with sheets of metal, either copper or lead,
as protection against the weather. The exact
construction of the domes of the Caliph’s Mosque
in Baghdad is not known although the fact that it
was described as green suggests that it was covered
in copper.
Most domes, however, continued to be built of
less flexible materials such as stone, mud brick and
baked brick. One of the main problems of dome
construction was the transition from a square space
or area into a circular domed area. Usually there was
an intermediary octagonal area from which it is easier
to convert to a circular area although there is still the
problem of converting from square to octagon. Two
main methods were adopted, which are the
squinch and the
pendentive. The squinch is a mini-arch which
is used to bridge a diagonal corner area whilst a
pendentive is an inverted cone with its point set low
down into the corner and its base at the top providing
a platform for the dome. Squinches are the main
method of transition in pre-Ottoman architecture
whilst pendentives are more common after the
sixteenth century. In India, where there was no
tradition of arches before the advent of Islam, domes
rest on flat corbels which bridge the corners.
During the medieval period Islam developed a
wide variety of dome types which reflect dynastic,
religious and social distinctions as much as different
construction techniques. One of the most extravagant
dome forms is the muqarnas or conical dome which
appears as early as the eleventh century in Iraq at
Imam Dur. A conical dome consists of multiple tiers
of muqarnas which blur the distinction between
structure and decoration and between circular and
square forms. Later on the idea of the double dome
was introduced as it was recognized that there was
a conflict between the external appearance of the
dome and the aesthetics of the interior of the domed
space. The result was tall external domes with
shallower interior domes. Increasing emphasis on
the exterior can be seen in Cairo and Egypt where
masonry domes with intricately carved exteriors
were developed. In Iran and Central Asia tall domes
were covered in coloured (usually blue) glazed tiles,
culminating in the huge bulbous fluted domes on a
high circular drum which were characteristic of the
Timurid period (fifteenth century). In pre-Mughal
India the standard dome form was derived from
Hindu architecture and consisted of a squat circular
form with a lotus design around the apex and a
characteristic bulbous finial. Ottoman architecture
adopted the Byzantine dome form and developed it
to produce vast domed areas such as that of the
Selimiye in Edirne.
