The rivers of Mammoth Cave were never crossed till 1840. Great efforts have been made to discover whence they come, and whither they go. But though the courageous Stephen has floated for hours up to his chin, and forced his way through the narrowest apertures under the dark waves, so as to leave merely his head a breathing space, yet they still remain as much a mystery as ever--without beginning or end, like eternity. They disappear under arches, which, even at the lowest stage of the water, are under the surface of it. From an unknown cause, it sometimes happens in the neighborhood of these streams, that the figure of a distant companion will apparently loom up, to the height of ten or twelve feet, as he approaches you. This occasional phenomenon is somewhat frightful, even to the most rational observer, occurring as it does in a region so naturally associated with giants and genii. From the Jordan, through Silliman's Avenue, you enter a high, narrow defile, or pass, in a portion of which, called the Hanging Rocks, huge masses of stone hang suspended over your head. At the side of this defile, is a recess, called the Devil's Blacksmith's Shop. It contains a rock shaped like an anvil, with a small inky current running near it, and quantities of coarse stalagmite scattered about, precisely like blacksmith's cinders, called slag. In another place, you pass a square rock, covered with beautiful dog's tooth spar, called the Mile Stone. This pass brings you into Wellington's Gallery, which tapers off to a narrow point, apparently the end of the cave in this direction. But a ladder is placed on one side by which you ascend to a small cleft in the rock, through which you are at once ushered into a vast apartment, discovered about two years ago. This is the commencement of Cleveland's Avenue, the crowning wonder and glory of this subterranean world. At the head of the ladder, you find yourself surrounded by overhanging stalactites, in the form of rich clusters of grapes, transparent to the light, hard as marble, and round and polished, as if done by a sculptor's hand. This is called Mary's Vineyard; and from it, an entrance to the right brings you into a perfectly naked cave, whence you suddenly pass into a large hall, with magnificent columns, and rich festoons of stalactite, in various forms of beautiful combination. In the centre of this chamber, between columns of stalactite, stands a mass of stalagmite, shaped like a sarcophagus, in which is an opening like a grave. A Roman Catholic priest first discovered this, about a year ago, and with fervent enthusiasm exclaimed, "The Holy Sepulchre!" a name which it has since borne.