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LAKE POYANG AND THE LOWER TANG-TZE. 208
placid uniform motion ; the monotony of its grey waters is broken here and there
by leafy islets ; the hamlets along the banks nestle amid their bamboo thickets
and clusters of trees ; the neighbourhood of the busy marts is announced by the
towers and pagodas crowning every eminence ;
the cultivated plains are intersected
on both sides by low grassy ridges, which wind away till lost in the haze of the
distant horizon. But the true alluvial plains are not reached till we get beyond
Nanking, where the Yang-tze turns eastwards and gradually expands
into a broad
estuary,
in which the tides ascend for a distance of 215 miles. Here the channel
in some places exceeds 300 feet in depth, but the bed contracts as it approaches
the coast, where it is separated by extensive sand-banks from the sea. At the
mouth the distance from headland to headland is about 60 miles ; but most of this
space is occupied by islands and shoals, where the deepest channels across the bar
have a mean depth of 13 or 14 feet, rising at high water to 24 feet and upwards.
Vessels drawing 16 or 18 feet are thus easily able to pass up, the chief danger to
navigation here being the dense fogs which settle on the shallows, and which, as
elsewhere in the Yellow Sea, are due to the sudden change of temperature pro-
duced in the currents surrounded by deeper waters.
The Yang-tze carries in solution less sedimentary matter than the Hoang-ho.
According to the observations of Guppy, the proportion of solids in the lower
reaches is j-jV in weight, and TiVr in volume. Yet the alluvium at the mouth
represents a solid mass of nearly 210 cubic feet per second. Thus the yearly
increase of fluvial deposits amounts to 6,300 millions of cubic feet, a quantity
sufficient to spread a layer of mud nearly 7 feet thick over an area of 40 square
miles. Hence the position of the navigable channels is modified from year to
year ; new sand-banks make their appearance, and the islands in the estuary are
constantly increasing in size. The island of Tsungming, or Kianshe, running
north-west and south-east, immediately north of the Wusung roadstead, is said to
have been just rising above the surface at the time of the Mongol rule. Eaten
away by erosion on the side facing inland, it is continually increasing seawards,
and is thus drifting, so to say, in the direction from west to east. Its earliest
settlers were exiles banished from the mainland ;
but these were soon followed by
free colonists, who gradually changed the aspect of the land with their canals,
embankments, villages, and cultivated fields. Some Japanese pirates also gained a
footing on the coast facing seawards, where their descendants, turning to the arts
of peace, have become intermingled with the Chinese peasantry. At present about
2,000,000 souls are crowded together in an area of scarcely more than 800 square
miles, which is thus one of the most densely peopled as well as one of the richest
spots in China. During the first half of the present century
the colonists of
Tsungrning enjoyed complete exemption from imposts, official control, and all
vexatious intermeddling on the part of the mandarins. The consequence was that
they were at once more prosperous and more civilised than their kinsmen on the
mainland. At present these islanders t:ike successive possession of all the new
lands formed in the Yang-tze estuary. In this way has been colonised the large
island of Hitei-sha, which has itself been formed of a hundred different islets