Tom watched the boat very attentively while the tide was up; and, when at length it began to retreat, and leave it once more aground, he noticed that it was not more than half full of water. If any confirmation had been needed to the conclusions which he had drawn from seeing the improved buoyancy of the boat, it would have been afforded by this. Tom accepted this with delight, as an additional circumstance in his favor; and now, having become convinced of this much, he set his wits to work to see if some plan could not be hit upon by means of which the boat could once more be made sea-worthy. Tom's indefatigable perseverance must have been noticed by this time. To make the best of circumstances; to stand face to face with misfortune, and shrink not; to meet the worst with equanimity, and grasp eagerly at the slightest favorable change,--such was the character that Tom had shown during his experience of the past. Now, once more, he grasped at this slight circumstance that appeared to favor his hopes, and sought to find some way by which that half-floating boat could be made to float wholly, and bear him away to those shores that were so near by. Too long had he been submitting to this imprisonment; too long had he been waiting for schooners to pass and to bring him help; too long had he been shut in by a fog that seemed destined never to lift so long as he was here. If he could only form some kind of a boat that would float long enough to land him on the nearest coast, all that he wished would be gratified. As he thought over this subject, he saw plainly what he had felt very strongly before--that the boat could not be sea-worthy unless he had some tar with which to plaster over the broken bow, and fill in the gaping seams; but there was no tar. Still, did it follow that there was nothing else? Might not something be found upon the island which would serve the purpose of tar? There must be some such substance and perhaps it might be found here. Tom now thought over all the substances that he could bring before his mind. Would clay do? No; clay would not. Would putty? No, and besides, he could not get any. What, then, would serve this important purpose?