n of this river
as if at its lowest, for fear lest we should convey an exaggerated
impression of its capabilities for navigation. Instead of from five to
fifteen feet, it was now from fifteen to thirty feet, or more, deep. All
the sandbanks and many of the islands had disappeared, and before us
rolled a river capable, as one of our naval friends thought, of carrying
a gunboat. Some of the sandy islands are annually swept away, and the
quantities of sand carried down are prodigious.

The process by which a delta, extending eighty or one hundred miles from
the sea, has been formed may be seen going on at the present day--the
coarser particles of sand are driven out into the ocean, just in the same
way as we see they are over banks in the beds of torrents. The finer
portions are caught by the returning tide, and, accumulating by
successive ebbs and flows, become, with the decaying vegetation, arrested
by the mangrove roots. The influence of the tide in bringing back the
finer particles gives the sea near the mouth of the Zambesi a clean and
sandy bottom. This process has been going on for ages, and as the delta
has enlarged eastwards, the river has always kept a channel for itself
behind. Wherever we see an island all sand, or with only one layer of
mud in it, we know it is one of recent formation, and that it may be
swept away at any time by a flood; while those islands which are all of
mud are the more ancient, having in fact existed ever since the time when
the ebbing and flowing tides originally formed them as parts of the
delta. This mud resists the action of the river wonderfully. It is a
kind of clay on which the eroding power of water has little effect. Were
maps made, showing which banks and which islands are liable to erosion,
it would go far to settle where the annual change of the channel would
take place; and, were a few stakes driven in year by year to guide the
water in its course, the river might be made of considerable commercial
value in the hands of any energetic European nation. No canal or railway
would ever be thought of for this part of Africa. A few improvements
would make the Zambesi a ready means of transit for all the trade that,
with a population thinned by Portuguese slaving, will ever be developed
in our day. Here there is no instance on record of the natives flocking
in thousands to the colony, as they did at Natal, and even to the Arabs
on Lake Nyassa. This keeping aloof renders