g themselves up and then breaking out in a new
direction, causing swamps and turning much of the land into useless
marsh. Consequent also upon this silting-up process the banks of the
rivers are higher than the surrounding country, and there is a gentle
drop in the level of the land as it recedes from the river.

[Illustration: MUD HOUSES ON THE TIGRIS]

The object of the ancient irrigationists was to tap the rivers at the
higher part of this plain, and then, by means of great canals, lead the
water where they wanted it. Large reservoirs and lakes for storing
surplus water were made, and thus the uneven delivery of water by the
rivers was checked and a more regular and manageable supply maintained.

The greatest of these ancient channels was the Nahrwan. A regulator, the
ruins which are still traceable in the bed of the Tigris, turned
sufficient water into this high-level river at Dura. It stretched
southwards for about 250 miles along the left bank of the Tigris. It was
the neglect of this canal that led to a fearful catastrophe which must
have been responsible for the death of millions; a catastrophe which
turned some 20,000 square miles of fruitful land, teeming with populous
cities, into a dismal swamp.

The intake from the Tigris of this and other canals evidently silted up,
and thus enormous volumes of water, usually carried off by them in times
of flood, helped to swell this river till, bursting its banks, it
inundated the whole country. The result remains to-day--a vast tract of
swampy land, barren and almost useless, except to a few wandering tribes
of Arabs.

And now the land which sent its Wise Men to the West is looking towards
the West again for aid. If its ancient prosperity is to be restored, if
Chaldea is again to be a granary to the world, it is to the West that it
must turn. Science and machinery shall again make the waste places to be
inhabited and the desert blossom as the rose. Thus shall the wise men
return to them--the Wise Men of the West. In every important
agricultural centre are to be found irrigation officers--the
first-fruits of British occupation.

There was only one subject of conversation in Mesopotamia in the winter
of 1918-1919, and that was the chances of getting back home. There was
very little to do at Basra except watch steamers load up with the more
fortunate candidates for demobilization and give them a send-off. Brown
had no difficulty in getting three weeks' leave to accom