'The Expedition for the survey of the rivers Euphrates and Tigris, carried on by order of the British government, in the years 1835, 1836, and 1837; preceded by geographical and historical notices of the regions situated between the rivers Nile and Indus. In four volumes. With fourteen maps and charts, and embellished with ninety-seven plates, besides numerous wood-cuts. Volume the first.' [‎39] (84/905)

CHAP. II.]
DESCRIPTION OF THE TIGRIS.
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it is at its greatest lieight between the middle and the end its velocity,
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 Authorities
Expedition, I have availed myself of the information given by consu tet '
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 pains
taking 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.