408 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
ward. The Median wall, I think, stretched from Tel Saféra to 
Akkar Kaif, and from there to Coche, on the Nahr Melcha, opposite 
Ctesiphon. It protected Babylonia from the Assyrians first, and 
then from the Medes in the pre-Persian days; it took the place of 
the Sakhlawia branch, which, as already twice stated, was closed 
from the earliest times. Artaxerxes opened his canal in August, dur- 
ing the time of low supply, or there would have been a catastrophe. 
Keeping south of the Median wall, the ten thousand crossed over 
to the north at some point west of Akkar Kuf, and winding their way 
round the Akkar Kuaf depression, crossed two canals, both coming 
from the Tigris near Nimrod’s dam. The latter was the Izhaki canal, 
on whose east bank was Sitaki, not far from the modern Kazimain. 
They crossed the Tigris by a bridge of boats with the same number 
of boats that the Baghdad bridge had a few years ago, before it was 
replaced by the present one of larger boats. From here they had to 
leave the river, as the country was heavily irrigated by the numerous 
canals, into which Cyrus the Great had led the Dyala. The troops 
with the transport wagons had to follow the road, which doubtless 
then, as now, went to Bakuba, and so the distance covered was 50 per 
cent in excess of the bee line which commentators ordinarily measure 
along. At Opis they crossed the Physcus, or Adhaim River by a 
bridge 100 feet long, and entered desert country. At Manjur, which 
Capt. Felix Jones, of the Indian navy, unerringly stated to be the 
site of Opis, the Adhaim River flowed into the ancient Tigris before 
the river burst into its present channel. Immediately to the north 
of this point we leave the alluvium of the Tigris, and enter t’e 
unirrigable marls which Xenophon called deserts. 
Alexander’s historians give a vivid description of the irrigatic» of 
the country and the difficulty the Babylonians had in closing ‘heir 
canals in flood and clearing them in low supply. They described the 
closing of the canals in flood as by far the more difficult operation. 
Alexander entered into the work with all his energy and genius. and 
to-day we can only admire the judgment with which he treated the 
Hindia branch or the Pallacopus, and the promptitude with wh ch he 
acted. The whole of the waters of the two rivers was used for irriga- 
tion in all but the flood season, and Alexander had to remove the 
earthen barrages thrown across the Tigris before his fleet could .ail up 
the river from the sea. 
In the time of the Sassanian kings of Persia, in the early « ituries 
of the Christian era, the delta probably saw its greatest prosperity. 
The gigantic Nahrwan Canal, 400 feet wide and 15 feet deep, irri- 
gated all the country to the east of the Tigris, and the Dijail irrigated 
that to the west. The Euphrates gave off the four canals already 
mentioned by Xenophon, and canals fed by the Babylonian branch 
from near Babylon irrigated the country right up to the ancient 
