.

The castellated rampart which thus surrounded and guarded Nineveh did
not constitute by any means its sole defence. Outside the stone basement
wall lay on every side a water barrier, consisting on the west and south
of natural river courses; on the north and east, of artificial channels
into which water was conducted from the Khosr-su. The northern and
eastern walls were skirted along their whole length by a broad and deep
moat, into which the Khosr-su was made to flow by occupying its natural
bed with a strong dam carried across it in the line of the eastern wall,
and at the point where the stream now enters the enclosure. On meeting
this obstruction, of which there are still some remains, the waters
divided, and while part flowed to the south-east, and reached the Tigris
by the ravine immediately to the south of the city, which is a natural
water-course, part turned at an acute angle to the north-west, and,
washing the remainder of the eastern and the whole of the northern wall,
gained the Tigris at the north-west angle of the city, where a second
dam kept it at a sufficient height. Moreover, on the eastern face, which
appears to have been regarded as the weakest, a series of outworks were
erected for the further defence of the city. North of the Khosr, between
the city wall and that river, which there runs parallel to the wall and
forms a sort of second or outermost moat, there are traces of a detached
fort of considerable size, which must have strengthened the defences in
that quarter. South and south-east of the Khosr, the works are still
more elaborate. In the first place, from a point where the Khosr leaves
the hills and debouches upon comparatively low ground, a deep ditch, 200
feet broad, was carried through compact silicious conglomerate for
upwards of two miles, till it joined the ravine which formed the natural
protection of the city upon the south. On either side of this ditch,
which could be readily supplied with water from the Khosr at its
northern extremity, was built a broad and lofty wall; the eastern one,
which forms the outermost of the defences, rises even now a hundred feet
above the bottom of the ditch on which it adjoins. Further, between this
outer barrier and the city moat wall interposed a species of demilune,
guarded by a double wall and a broad ditch and connected (as is
thought) by a covered way with Neneveh itself. Thus the city was
protected on this, its most vulnerable side, towards th