1,000 feet above the stream; in some places the water still flows over perceptible rapids, then at a sudden turn fills the so-called "Devil's Cauldron," an abyss 400 feet deep, encircled by vertical red clay walls, where the liquid mass is: churned round incessantly, forming in some places secondary eddies 12 or 14 feet

Fig, 215. — The Devil's Caldron.

in diameter. Suddenly, after passing an island which from a distance seems completely to block the way, the Congo enters its broad estuary studded with islands and sandbanks, where a granite rock on the left side, known as the "Fetish Stone," marks the former limit of the navigation for seagoing vessels.