In an hour or two after leaving the ledge it grew quite dark, and Tom saw that it would be necessary to prepare for the night.  His preparations were simple, consisting in eating a half dozen biscuit.  He now began to feel a little thirsty, but manfully struggled against this feeling.  Gradually the darkness grew deeper, until at last it assumed the intense character of the preceding night.  But still Tom sat up, and the boat went on.  The wind did not slacken, nor did the boat’s progress cease.  Hours passed by in this way.  As to the tides, Tom could not tell now very well whether they were rising or falling, and, in fact, he was quite indifferent, being satisfied fully with his progress.  As long as the wind distended his sail, and bore the boat onward, he cared not whether the tide favored or opposed.

Hours passed, but such was Tom’s excitement that he still bore up, and thought nothing of rest or of sleep.  His attention was needed, too, and so he kept wide awake, and his ears were ever on the stretch to hear the slightest sound.  But at last the intense excitement and the long fatigue began to overpower him.  Still he struggled against his weakness, and still he watched and listened.

Hours passed on, and the wind never ceased to fill the sail, and the boat never ceased to go onward in a course of which Tom could have no idea.  It was a course totally different from the one which be intended—­a course which depended on the chance of the wind; and one, too, which was varied by the sweep of the tide as it rose or fell; but the course, such as it was, continued on, and Tom watched and waited until, at last, from sheer exhaustion, he fell sound asleep.

His dreams were much disturbed, but he slept on soundly, and when he awaked it was broad day.  He looked around in deep disappointment.  Fog was everywhere, as before, and nothing could be seen.  Whether he was near any shore or not he could not tell.  Suddenly he noticed that the wind was blowing from an opposite direction.  How to account for this was at first a mystery, for the fog still prevailed, and the opposite wind could not bring fog.  Was it possible that the boat had turned during his sleep?  He knew that it was quite possible.  Indeed, he believed that this was the case.  With this impression he determined to act on the theory that the boat had turned, and not that the wind had changed.  The latter idea seemed impossible.  The wind was the chill, damp fog wind—­the sou-wester.  Convinced of this, Tom turned the boat, and felt satisfied that he had resumed his true course.

After a time the wind went down, and the sail flapped idly against the mast.  Tom was in a fever of impatience, but could do nothing.  He felt himself to be once more at the mercy of the tides.  The wind had failed him, and nothing was left but to drift.  All that day he drifted, and night came on.  Still it continued calm.  Tom was weary and worn out, but so intense was his excitement that he could not think of sleep.  At midnight the wind sprung up a little; and now Tom determined to keep awake, so that the boat might not again double on her track.  He blamed himself for sleeping on the previous night, and losing so much progress.  Now he was determined to keep awake.