"بعثة لإجراء عملية مسح لنهري دجلة والفرات، تم تنفيذها بأمر من الحكومة البريطانية، في السنوات ١٨٣٥، ١٨٣٦، ١٨٣٧؛ تسبقها إشعارات جغرافية وتاريخية للمناطق الواقعة بين نهري النيل والسند. في أربعة مجلّدات. مع أربع عشرة خريطة ورسمًا، ومزينة بثلاث عشرة لوحة، بالإضافة للعديد من الرسومات بالحفر على الخشب. المجلّد الأول." [‎٣‎٨] (٩٠٥/٨٣)

38
DESCRIPTION OF THE TIGRIS.
[CHAP. II.
Derivation of from Imam Gharbi, a derivation, called El Hud, quits the
main stream on the eastern side, and runs into the Kerkhah,
near Hawizah. 1
The direction of the main branch now tends S. 34° E., and
numerous irrigating cuts are sent out from it on both sides.
At 10 or 11 miles below Imam Gharbi the river changes its
character in a very remarkable manner; instead of forming
extensive sweeps, the channel becomes deep and narrow, with
a number of short, abrupt bends. The tract about the canals
is marshy, and resembles that of Lamlum, to which also it
corresponds in point of latitude; it may, therefore, be a part
of the celebrated Chaldean lake, which, at the season of floods,
extended not only across Mesopotamia, but also to some
distance eastward of the Tigris, so as to receive the waters
both of the Kerkhah and the Karun. After passing for
about 40 miles through marshes, and coming near the tomb
of Ezra, the river resumes its former size and character, as it
winds in the general southern direction, to Kurnah; which
place is 232 miles from Kut el 'amarah by the windings, and
^ of the 144 i direct distance. The whole course thus briefly de
scribed may be estimated at 1146 miles, which is little more
than half the length of the sister stream, the Euphrates, from
the sources of the latter to their junction at Kurnah ; but it
discharges more water, owing to the numerous tributaries
which it receives on its eastern side; among which may be
particularly noticed the two Zabs, and the river Diyalah.
There are, however, as we have seen, only two feeders of
any moment on the western side, throughout the long dis
tance from Diyar Bekr to Kurnah.
SnfoftL A C0nside rable increase of the river Tigris takes place
Tigris. during the rains of November; subsequently it decreases and
swells irregularly at intervals, till the different feeders are
bound up by the frost and snow of January, in the Kurdistan
mountains. This serious check retards for a time the swelling
of the river; therefore its permanent rise, like that of the
Euphrates, does not usually begin till the middle of March ;
Mr. Rich's pilot had gone along this branch to the Kerkhah.—Rich's
Kurdistdn, Vol, II., p. 171.