I tried to say "Nonsense" again, but the word stuck in my throat--the
ring spoke for itself. In some past age vessels _had_ been moored there,
and this stone wall was undoubtedly the remnant of a solidly constructed
wharf. Probably the city to which it had belonged lay buried beneath the
swamp behind it.

"Begins to look as though there were something in the story after all,
Uncle Horace," said the exultant Leo; and reflecting on the mysterious
negro's head and the equally mysterious stonework, I made no direct
reply.

"A country like Africa," I said, "is sure to be full of the relics
of long dead and forgotten civilisations. Nobody knows the age of the
Egyptian civilisation, and very likely it had offshoots. Then there were
the Babylonians and the Phœnicians, and the Persians, and all manner
of people, all more or less civilised, to say nothing of the Jews whom
everybody 'wants' nowadays. It is possible that they, or any one of
them, may have had colonies or trading stations about here. Remember
those buried Persian cities that the consul showed us at Kilwa."[*]

[*] Near Kilwa, on the East Coast of Africa, about 400 miles south of
Zanzibar, is a cliff which has been recently washed by the waves. On the
top of this cliff are Persian tombs known to be at least seven centuries
old by the dates still legible upon them. Beneath these tombs is a layer
of _débris_ representing a city. Farther down the cliff is a second
layer representing an older city, and farther down still a third layer,
the remains of yet another city of vast and unknown antiquity.
Beneath the bottom city were recently found some specimens of glazed
earthenware, such as are occasionally to be met with on that coast to
this day. I believe that they are now in the possession of Sir John