Civil Engineering Reference
In-Depth Information
out (cf, e.g. ABSP II, ills 279-280, ABC II, ills 190-94; ABSP I, pp. 328-29, ABC
I, P. 352).
In Egypt early in the 3rd millennium BC rock cutting was transformed in scope
and in nature to achieve the monumental. At this juncture the resources of urban
civilisation supported extensive quarrying with the consequent building construc-
tion in i nely dressed stone masonry. “Quarry” is derived from
quadro,
to make
square and it infers the accurate squaring up of masonry blocks and hence of
dressed stone construction. In this way rock cutting also proceeded on a rectan-
gular basis and required accurate setting out in this form. Since the work of rock
cutting proceeded from above downwards, the lines of the cutting were marked out
on the ceiling, which was thus the i rst surface of the compartment to be dressed
true, so that it became the surface of reference for subsequent cutting. h is setting
out procedure was ef ected by i rst driving into the rock a narrowly coni ned axial
gallery (the
cuniculus
or “pilot gallery”) immediately below the projected ceiling
level. However, whereas in surface work ancient setting out always proceeded by
way of measured distances, setting out of rock cut features necessarily involved
angular measurement—i.e. laying of angles. Also since rock cut features of the
hypogeum type involved development at dif erent levels, this in turn necessitated
laying of vertical angles as well as horizontal angles.
h e required technology for these operations was quickly developed during the
Pyramid Age in Old Kingdom Egypt, to be continued on an extended scale in the
New Kingdom rock cut Tombs of the Kings at h ebes. NB Here it is to be noted
as an aside that this technology of underground surveying developed for rock cut
premises as discussed here became fundamental in connections other than that
of building,
viz
engineering—mining engineering, hydraulic engineering, i.e. for
subterranean aqueducts, viaducts etc. But this is too large a i eld for brief, inci-
dental mention.
Where apartments to be hollowed out of bed rock were reasonably large and
of accurately dimensioned rectangular form, then the most economic method of
abstracting the rock was to quarry it out in the form of masonry blocks—i.e. to
treat the desired apartment as a subterranean quarry. h is conferred the benei t
of transforming the spoil into a valuable yield,
viz
blocks ready for use in i ne
stone masonry. In this way as far as practical there was every incentive to form
chambers in bed rock by quarrying out the rock rather than by cutting it to waste.
h e factors governing this question were both intrinsic and extrinsic. Intrinsically
it was necessary for the chamber to be reasonably large and of rectangular form,
while the rock matrix was to be suitable for use as building stone. h ere were then
extrinsic factors: possession of the technology of quarrying, possibility of removing
the quarried blocks from inside the compartment, operations to be in a region
where the masonry blocks were usable.
Egyptian
monu-
mental
rock cut
chamber
38
