Civil Engineering Reference
In-Depth Information
them to be roofed uniformly with mud brick domes over square compartments, the
transition ef ected by way of squinches. h ere is absolutely no record of squinches
in traditional mud brick building of Pharaonic times, so this feature in Christian
Churches is in any circumstances derived from ecumenical early Christian building
outside Egypt. h ere is, however, an important qualifying factor to this picture.
More recent research questions that the surviving domes on squinches are the
original rooi ng of theses churches. In some cases the domes appear to date from
(mediaeval) Arab times. h is does not necessarily settle the nature of the original
rooi ng, which could have been wood or wood framed (v Hamilton,
Byzantine
Architecture
, pp. 152-56; Krautheimer,
Early Christian and Byzantine Architecture
,
pp. 110-17, 304-08).
Conveniently published records of mud-brick building in Egypt are not uniformly
explicit concerning arcuated rooi ng construction. h e jist of what is specii cally
stated may be summarized as follows.
Form.
By far the most common form of arcuated rooi ng was the barrel vault.
Domes were unusual until late (Roman, Byzantine) times. A shallow domical vault
(dish vault) was known and was typically employed for rooi ng cellars dug below
houses in late times. Early Christian (Coptic) Churches of a type found mainly
in Upper Egypt are commonly roofed with a dome (rather domes) carried on
squinches. h is device betokens an external inl uence, but the antiquity of this
rooi ng has been called into question.
Construction
. As in the nature of things, 3 modes of construction were employed
to build mud brick vaulting: corbelling; pitched brick; and radially set bricks. h e
former two modes dispensed with the requirements of support by centering dur-
ing construction. h e latter mode was built both by bricks (usually square) set on
bed, or set on edge. For signii cant spans this type of arcuated rooi ng required
the temporary support from below of centering. Some evidence survives of two
types of centering. h e most basic and simplest method was to i ll the chamber or
compartment with sand, and to fashion the required arcuated proi le on and out
of the sand i lling. h is, in ef ect, was a special (total) form of standing centering.
However for larger spans, on occasion l ying centering was utilised. Lodgements
survive in walling below the springing of the vaults for inset timber beams to sup-
port the centering frames. h ese lodgements were generally blocked up with mud
at er the construction of the vaulting was completed and the centering removed
(Spencer, p. 87).
Historical Development
. Almost co-aeval with their adoption of substantial load
bearing mud brick construction during Late Pre-dynastic and Early Dynastic times
Egyptian builders appear to have gained a command over arcuated brick con-
struction. Although this was i rst developed in (underground) funerary contexts,
it came to be used in free standing building of all types (utilitarian, residential
Arcuated
brickwork,
résumé
369
370
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