different methods of
construction used by, or, at least, at the command of, the Assyrian
builder.

All the rooms were surmounted by flat roofs, and our horizontal sections
show how these roofs were accommodated to the domes or the timber ceilings
by which they were supported. On the left of the engraving semicircular
vaults are shown, on the right a timbered roof. The arrangement of the
latter is taken from an Etruscan tomb at Corneto, where, however, it is
carried out in stone.[223] A frame like this could be put together on the
spot and offered the means of covering a wider space with the same
materials than could be roofed in by a horizontal arrangement. Further back
rises one of those domes over square substructures whose existence seems to
us so probable. Behind this again opens one of the courts by which so much
of the area of the palace was occupied. The composition is completed by a
wall with parapet and flanking towers.

[Illustration: FIG. 59.--Fortress; from Layard's _Monuments_, 1st Series.]

After considering the method employed for roofing the palace apartments, we
come naturally to investigate their system of illumination. In view of the
extravagant thickness of their walls it is difficult to believe that they
made use of such openings as we should call windows. The small loop-holes
that appear in some of the bas-reliefs near the summits of towers and
fortified walls were mere embrasures, for the purpose of admitting a little
air and light to the narrow chambers within which the defenders could find
shelter from the missiles of an enemy and could store their own arms and
engines of war (see Fig. 59). The walls of Khorsabad even now are
everywhere at least ten feet high, and in some parts they are as much as
fifteen, twenty, and five-and-twenty feet, an elevation far in excess of a
man's stature, and they show no trace of a window. Hence we may at least
affirm that windows were not pierced under the same conditions as in modern
architecture.[224]

[Illustration: FIG. 60.--Crude brick construction; compiled by Charles
Chipiez.]

And yet the long saloons of the palace with their rich decoration had need
of light, which they could only obtain through the doorways and the
openings left in the roof. When this was of wood the matter was simple
enough, as our diagram (Fig. 60) shows. Botta noticed, during his journey
to his post, another arrangement, of which, he thinks, the Assyrians may
very well have mad