pth of twenty feet; at Kerki,
seventy miles below Khodja Salih, it is "twice the width of the Danube
at Buda-Pesth," or about 940 yards; at Betik, on the route between
Bokhara and Merv, its width has diminished to 650 yards, but its depth
has increased to twenty-nine feet. Finally, at Gorlen Hezaresp near
Khiva, the breadth of the Oxus is so great that both banks are hardly
distinguishable at the same time; but the stream is here comparatively
shallow, ceasing to be navigable at about this point. The present course
of the Oxus from its rise in Lake Sir-i-Kol to its termination in the
Sea of Aral is estimated at 1400 miles. Anciently its course must have
been still longer. The Oxus, in the time of the Achaemenian kings, fell
into the Caspian by a channel which can even now be traced. Its length
was thus increased by at least 450 miles, and, exceeding that of the
Jaxartes, fell but little short of the length of the Indus.

The Oxus, like the Nile and the Indus, has a periodical swell, which
lasts from May to October. It does not, however, overflow its
hanks. Under a scientific system of irrigation it is probable that a
considerable belt of land on either side of its course might be brought
under cultivation. But at present the extreme limit to which culture
is carried, except in the immediate vicinity of Khiva, seems to be four
miles; while often, in the absence of human care, the desert creeps up
to the very brink of the river.

The Jaxartes, or Sir-Deria, rises from two sources in the Thian-chan
mountain chain, the more remote of which is in long. 79 deg. nearly. The two
streams both flow to the westward in almost parallel valleys, uniting
about long. 71 deg.. 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 alo