that abundant water supply--actually most lavish in the summer time,
owing to the melting of the snows which nature has provided in the two
great Mesopotamian rivers and their tributaries. So rapid is the fall of
the two main streams in their upper course, that by channels derived
from them, with the help perhaps of dams thrown across them at certain
intervals, the water might be led to almost any part of the intervening
country, and a supply kept up during the whole year. Or, even without
works of this magnitude, by hydraulic machines of a very simple
construction, the life-giving fluid might be raised from the great
streams and their affluents in sufficient quantity to maintain a broad
belt on either side of the river-courses in perpetual verdure.
Anciently, we know that recourse was had to both of these systems. In
the tract between the Tigris and the Upper Zab, which is the only part
of Assyria that has been minutely examined, are distinct remains of at
least one Assyrian canal, wherein much ingenuity and hydraulic skill is
exhibited, the work being carried through the more elevated ground by
tunnelling, and the canal led for eight miles contrary to the natural
course of every stream in the district. Sluices and dams, cut sometimes
in the solid rock, regulated the supply of the fluid at different
seasons, and enabled the natives to make the most economical application
of the great fertilizer. The use of the hand-swipe was also certainly
known, since it is mentioned by Herodotus, and even represented upon the
sculptures. [PLATE XXV., Fig. 1.] Very probably other more elaborate
machines were likewise employed, unless the general prevalency of canals
superseded their necessity. It is certain that over wide districts, now
dependent for productive power wholly on the spring rains, and
consequently quite incapable of sustaining a settled population, there
must have been maintained in Assyrian times some effective
water-system, whereby regions that at present with difficulty furnish a
few months' subsistence to the wandering Arab tribes, were enabled to