Frank felt upon himself the responsibility of the rest to an unusual degree. He was only a few weeks older than David, but he was far stronger and more mature in many respects. David was a hard student, and perhaps a bit of a book-worm, and had a larger share of the knowledge that may be gained from books; but Frank had seen more of the world, and in all that relates to the practical affairs of common life he was immeasurably superior to David. For this reason Frank often assumed, and very naturally too, the guardianship of the party; and so appropriate was this to him, that the rest tacitly allowed it. As for Uncle Moses, none of them ever regarded him as their protector, but rather as an innocent and simple-hearted being, who himself required protection from them. Frank, therefore, on this occasion, kept warning the whole party, above all things, not to let themselves go to sleep. He had heard that the air of the Pontine Marshes had a peculiar tendency to send one to sleep; and if one should yield to this, the consequences might be fatal. Fever, he, said, would be sure to follow sleep, that might be indulged in under such circumstances. The anxiety which was created in his own mind by his sense of responsibility was of itself sufficient to keep him awake, and left him to devote all his energies to the task of trying to keep the others awake also, and thus save them from the impending danger. At first they, all laughed at him; but after a time, as each one felt the drowsiness coming over him, they ceased to laugh. Then they tried to sing. They kept up this for some time. They exhausted all their stock of school songs, nigger songs, patriotic songs, songs sentimental and moral, and finally tried even hymns. But the singing was not a very striking success; there was a lack of spirit in it; and under this depressing sense of languor, the voice of music at last died out. Singularly enough, the one who felt this drowsiness most strongly was Bob. Frank had not thought of him as being at all likely to fall asleep; but whether it was that his mobile temperament made him more liable to extremes of excitement and dullness, or whether the reaction from his former joviality and noisiness had been greater than that of the rest, certain it is that Bob it was who first showed signs of sleep. His eyes closed, his head nodded, and lifting it again with a start, he blinked around. "Come, Bob," said Frank, "this won't do. You don't mean to say that _you're_ sleepy." Bob said nothing. He rubbed his eyes, and yawned. "Bob," said Frank, "take care of yourself." "O, I'm all right," said Bob, with a drawl; "never fear about me. I'm wide awake." Scarce had he finished this when his eyes closed again, and his head fell forward. Frank shook him, and Bob raised himself up with an effort at dignified surprise which was, however, a failure. "You needn't shake a fellow," he said in a husky, sleepy voice. "But I will shake you," cried Frank.