It was on the fifth day of our journey, when we had travelled, so far
as we could reckon, about one hundred and thirty-five to a hundred and
forty miles westwards from the coast, that the first event of any real
importance occurred. On that morning the usual wind failed us about
eleven o'clock, and after pulling a little way we were forced to halt,
more or less exhausted, at what appeared to be the junction of our
stream with another of a uniform width of about fifty feet. Some trees
grew near at hand--the only trees in all this country were along the
banks of the river, and under these we rested, and then, the land being
fairly dry just here, walked a little way along the edge of the river to
prospect, and shoot a few waterfowl for food. Before we had gone fifty
yards we perceived that all hopes of getting further up the stream in
the whale-boat were at an end, for not two hundred yards above where
we had stopped were a succession of shallows and mudbanks, with not six
inches of water over them. It was a watery _cul de sac_.

Turning back, we walked some way along the banks of the other river, and
soon came to the conclusion, from various indications, that it was not
a river at all, but an ancient canal, like the one which is to be seen
above Mombasa, on the Zanzibar coast, connecting the Tana River with
the Ozy, in such a way as to enable the shipping coming down the Tana
to cross to the Ozy, and reach the sea by it, and thus avoid the very
dangerous bar that blocks the mouth of the Tana. The canal before us
had evidently been dug out by man at some remote period of the world's
history, and the results of his digging still remained in the shape of
the raised banks that had no doubt once formed towing-paths. Except here
and there, where they had been hollowed out by the water or fallen in,
these banks of stiff binding clay were at a uniform distance from each
other, and the depth of the stream also appeared to be uniform. Current