the form required (fig. 56). The ordinary roofing consists of flat paving
slabs. When the space between the walls was not too wide, these slabs
bridged it over at a single stretch; otherwise the roof had to be supported
at intervals, and the wider the space the more these supports needed to be
multiplied. The supports were connected by immense stone architraves, on
which the roofing slabs rested.

[Illustration: Fig. 56.--"Corbelled" arch, temple of Seti I. at Abydos.]

The supports are of two types,--the pillar and the column. Some are cut
from single blocks. Thus, the monolithic pillars of the temple of the
sphinx (Note 8), the oldest hitherto found, measure 16 feet in height by 4-
1/2 feet in width. Monolithic columns of red granite are also found among
the ruins of Alexandria, Bubastis,[12] and Memphis, which date from the
reigns of Horemheb and Rameses II., and measure some 20 to 26 feet in
height. But columns and pillars are commonly built in courses, which are
often unequal and irregular, like those of the walls which surround them.
The great columns of Luxor are not even solid, two-thirds of the diameter
being filled up with yellow cement, which has lost its strength, and
crumbles between the fingers. The capital of the column of Taharka at
Karnak contains three courses, each about 48 inches high. The last and most
projecting course is made up of twenty-six convergent stones, which are
held in place by merely the weight of the abacus. The same carelessness
which we have already noted in the workmanship of the walls is found in
the workmanship of the columns.

[Illustration: Fig. 57.--Hathor pillar, Abû Simbel.]

[Illustration: Fig. 58.--Pillar of Amenhotep III., Karnak.]