The Jaxartes, or Sir-Deria, rises from two sources in the Thian-chan
mountain chain, the more remote of which is in long. 79° nearly. The two
streams both flow to the westward in almost parallel valleys, uniting
about long. 71°. After their junction the course of the stream is still
to the westward for two degrees; but between Khokand and Tashkend the
river sweeps round in a semicircle and proceeds to run first due north
and then north-west, skirting the Kizil Koum desert to Otrar, where
it resumes its original westerly direction and flows with continually
diminishing volume across the desert to the Sea of Aral. The Jaxartes
is a smaller stream than the Oxus. At Otrar, after receiving its last
tributary, it is no more than 250 yards wide. Below this point it
continually dwindles, partly from evaporation, partly from the branch
stream which it throws off right and left, of which the chief are the
Cazala and the Kuvan Deria. On its way through the desert it spreads but
little fertility along its banks, which are in places high and arid, in
others depressed and swampy. The branch streams are of some service for
irrigation; and it is possible that a scientific system might turn the
water of the main channel to good account, and by its means redeem from
the desert large tracts which have never yet been cultivated. But no
such system has hitherto been applied to the Sir, and it is doubtful
whether success would attend it. The Sir, where it falls into the Sea
of Aral, is very shallow, seldom even in the flood season exceeding four
feet. The length of the stream was till recently estimated at more than
1208 miles; but the latest explorations seem to require an enlargement
of this estimate by at least 200 or 250 miles.

In rivers of the second class the Persian Empire was so rich that it
will be impossible, within the limits prescribed for the present work,
to do more than briefly enumerate them. The principal were, in Asia