gement followed a regular order like that
shown in Fig. 46. Their external face was carefully dressed.[165]

[Illustration: FIG. 44.--Plan of angle, Khorsabad; from Place.]

[Illustration: FIG. 45.--Section of wall through AB in Fig. 44; from
Place.]

The courses consist, on plan, of "stretchers" and "headers." We borrow from
Place the plan of an angle (Fig. 44), a section (Fig. 45), and an elevation
(Fig. 46). Courses are always horizontal and joints properly bound. The
freestone blocks at the foot of the wall are very large. The stretchers are
six feet eight inches thick, the same wide, and nine feet long. They weigh
about twenty-three tons. It is astonishing to find the Assyrians, who were
very rapid builders, choosing such heavy and unmanageable materials.

The supporting wall became gradually thinner towards the top, each course
being slightly set back from the one below it on the inner face (see Fig.
45). This arrangement is general with these retaining-walls. The average
diminution is from seven to ten feet at the base, to from three to six at
the top.

The constructor showed no less skill in the use he made of his stretchers
and headers. They not only gave him an opportunity of safely diminishing
the weight of his structure and economising his materials, they afforded a
ready means of adapting his wall exactly to the work it had to do. The
headers penetrated farther into the crude mass within than the stretchers,
and gave to the junction of the two surfaces a solidity similar to that
derived by a wall from its through stones or perpenders.

[Illustration: FIG. 46.--Elevation of wall, Khorsabad; from Place.]

In describing this wall, M. Place also calls attention to the care with
which the angles are built. "The first course," he says, "is composed of
three 'headers' with their shortest side outwards and their length engaged
in the mass behind. Two of these stones lie parallel to each other, the
third crosses their inner extremities."[166] Thanks to this ingenious
arrangement, the weakest and most exposed part of the wall is capable of
resisting any attack.

The surface in contact with the core of crude brick was only roughly
dressed, by which means additional cohesion was given to the junction of
the two materials; but the other sides were carefully worked and squared
and fixed in place by simple juxtaposition. The architect calculated upon
sufficient solidity being given by the mere weight of the stones