Usually there is one side of the crater which is accessible. There is almost always some wind which blows the smoke away, and on the windward side the visitor can stand and breathe freely. On the present occasion, however, there was little or no wind; and the smoke, which was far denser than usual, gathered in thick, black folds, and sometimes rolled down the sides of the cone, and hid the crest from view. Michael Angelo expressed a fear that they would not be able to reach the crest; and as they drew nearer, every step showed that this fear was well founded. At last, when they were within easy distance of it, there came rolling down a cloud of smoke, so dense and so full of sulphurous vapor that they all had to stop and cover their faces with their clothes. It was now evident that they could go no farther. They waited for a time in great distress from the smoke. It rolled away at last, yet still hovered near them, every little while moving threateningly down, as though to drive them back, and prevent the crater from desecration by human footsteps. They had evidently reached their farthest limit, and could go no farther. But where was Bob? Scarcely had they discovered the impossibility of going farther than this thought came to them. Where was Bob? He had left them some time previously, and had gone far ahead of them. They had expected every moment to come up with him. But there were no signs of him anywhere. Frank called out with all his strength. David and Clive joined in the cry. There was no response. Fear came to them--a sickening, awful fear. All shouted--the boys, Uncle Moses, and Michael Angelo. Still there was no response. Again, and again, and yet again, they called, by this time in an agony of apprehension; but to all these cries the surrounding stillness gave forth not one answering sound. And the deep, dark, wrathful smoke-clouds rolled around, and above, and downward, moving close to them, and over them, as though eager to involve them in that dread fate which they feared had overwhelmed the lost boy. "I can't stand this any longer!" cried Frank, at last. "I'll go and hunt him up." "We'll all go," said David. "Wait," said Uncle Moses, as the boys were starting. "We must hunt him up as we do in the woods. We can't tell where he is. Let's form a line, an walk as nigh abreast of one another as we can get, an yet far enough away to cover the ground. In that way well be more likely to find him."