In South Africa, Livingstone has made the public acquainted with that extraordinary hiatus in the crust of the earth in which the great river Zambesi is swallowed up. A stream more than a thousand yards wide, dotted with islands, flowing between fertile banks clothed with the luxuriant and gorgeous vegetation of the tropics, without the least preliminary break or rapid, suddenly drops into a dark chasm of unknown depth, which, repeatedly doubling on itself, pursues its tortuous course some forty miles through the hills before emerging again into the sunlight. "From Kalai," says Livingstone, "after some twenty minutes' sail we came in sight of the columns of vapor appropriately called smoke. * * * Five columns now arose, and, bending in the direction of the wind, they seemed placed against a low ridge covered with trees. The tops of the columns at this distance (six miles) appeared to mingle with the clouds. The whole scene was extremely beautiful." At the brink of the chasm he found the river divided into two channels of unequal width by a large island called the "Garden," on account of its rich vegetation. "Creeping with awe to the verge I peered down into a large rent which had been made from bank to bank of the broad Zambesi, and saw that a stream a thousand yards broad leaped down a hundred feet and then became suddenly compressed into a space of fifteen or twenty yards. In looking down into this fissure on the right of the island one sees nothing but a dense, white cloud. From this cloud rushed up a great jet of vapor exactly like steam, and it mounted two hundred or three hundred feet high; then, condensing, it changed its hue into that of dark smoke, and came back in a constant shower. This shower fell chiefly on the opposite side of the fissure, and a few yards back from the top there stands a straight hedge of evergreen trees, whose leaves are always wet. From their roots a number of little rills run back into the gulf, but as they flow down the steep wall the column of vapor in its ascent licks them up clean off the rock, and away they mount again. They are constantly running down, but never reach the bottom." [Illustration: THE STAUBBACH, SWITZERLAND]