PENCROFF DOUBTS NO MORE—THE OLD OUTLET OF THE LAKE—A SUBTERRANEAN DESCENT—THE WAY THROUGH THE GRANITE—TOP HAS DISAPPEARED—THE CENTRAL CAVERN—THE LOWER WELL—MYSTERY—THE BLOWS WITH THE PICK—THE RETURN. Smith’s project had succeeded; but, as was his manner, he stood motionless, absorbed, his lips closed, giving no sign of satisfaction. Herbert was all enthusiasm; Neb jumped with joy; Pencroff, shaking his head, murmured:— “Indeed, our engineer does wonders!” The nitro-glycerine had worked powerfully. The opening was so great that at least a three times greater volume of water escaped by it than by the former outlet. In a little while, therefore, the level of the lake would be lowered two feet or more. The colonists returned to the Chimneys, and collecting some picks, spears, ropes, a steel and tinder, returned to the plateau. Top went with them. On the way the sailor could not resist saying to the engineer:— “But do you really think, Mr. Smith, that one could blow up the whole island with this beautiful liquid of yours?” “Doubtless,” replied the other, “island, continents, the world itself. It is only a question of quantity.” “Couldn’t you use this nitro-glycerine to load firearms.” “No, Pencroff, because it is too shattering. But it would be easy to make gun-cotton, or even common powder, as we have the material. Unfortunately, the guns themselves are wanting.” “But with a little ingenuity!—” Pencroff had erased “impossible” from his vocabulary. The colonists having reached Prospect Plateau, hastened at once to the old outlet of the lake, which ought now to be uncovered. And when the water no longer poured through it, it would, doubtless, be easy to explore its interior arrangement. In a few moments they reached the lower angle of the lake, and saw at a glance what the result was. There, in the granite wall of the lake, above the water-level, appeared the long-looked for opening. A narrow ledge, left bare, by the subsidence of the water, gave them access to it. The opening was twenty feet wide, though only two feet high. It was like the gutter-mouth in a pavement. It was not open enough for the party to get in, but Neb and Pencroff, with their picks, in less than an hour had given it a sufficient height. The engineer looked in and saw that the walls of the opening in its upper part showed a slope of from 30° to 35°. And, therefore, unless they became much steeper it would be easy to descend, perhaps, to the level of the sea. And if, as was probable, some vast cavern existed in the interior of the massive granite, it was possible that they could make use of it. “What are we waiting for, Mr. Smith,” cried the sailor, all impatience to begin the exploration, “Top, you see, has gone ahead!” “We must have some light,” said the engineer. “Go, Neb, and cut some resinous branches.”