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
144J in direct distance. The whole course thus briefly described
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 distance
from Diyar Bekr to Kurnah.
A considerable increase of the river Tigris takes place
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 ;
1 Mr. Rich’s pilot had gone along this branch to the Kerkhah.—Rich’s
Kurdistdn, Vol. II., p. 111.
it is at its greatest height between the middle and the end
of May, when its velocity is 7-33 feet per second; and the
discharge at Baghdad, in the same time, is about 164,103
cubic feet. After this time, the river falls with more or less
regularity and inequality, till the middle of June.
The large boats are not, however, obliged to diminish their
cargoes till the month of August; between which time and
the month of November, when the river is again at the
lowest, they should not draw more than four feet of water.
There is an active commerce along the Tigris, between Basrah
and Baghdad, by means of the large country boats, which go
in fleets; and above the latter city it takes place chiefly by
means of rafts from Mosul.
In addition to what has been ascertained during the recent
Expedition, I have availed myself of the information given by
Strabo and Pliny; the Journeys of Tavernier and Sir John
M'Donald Kinneir; the descent of the Tigris by the Right
Honourable John Sullivan in 1785, and that of Lieutenant
Ormsby, I. N., in 1830 and 1832; and Mr. Ainsworth’s
two Journeys. But, as the reader will perceive, I have made
great use of the map, and other valuable materials, kindly
furnished me by Mrs. Rich; taking advantage, at the same
time, of Lieutenant Lynch’s map in the Ninth Volume,
Part III., of the Royal Geographical Journal, to fill up
blanks, and to compare with other authorities. I am likewise
greatly indebted to Major Rawlinson and Dr. Ross. From
the MS., as well as the printed notices of the latter painstaking
and persevering gentleman, I have extracted much
that was very useful in fixing some important points near
the river; such as the site of Opis, the head of the Nahrawan,
as well as the great bund of Adhim; and I have pleasure
in adding, that the bearings he has given are found to be
very correct. Lieutenant Lynch has followed the whole
line of the Tigris, from its source to Baghdad; but we have
not had the details of this descent; nor have those of another
journey which he made along a part of the Diyalah been as
yet sent home.— See p. 471, Vol. IX. Part III., of the Journal
of the Royal Geographical Society.