There seemed but one way open to their salvation,--but one course by which they could escape from the engulfment that threatened. This was to forego any further attempt at wading, to fling themselves boldly upon the waves, and _swim_ ashore! Now that they were submerged to their necks, you may wonder at their not at once adopting this plan. It is true they were ignorant of the distance they would have to swim before reaching the shore. Still they knew it could not be more than a couple of miles; for they had already traversed quite that distance on the diagonal spit. But two miles need scarce have made them despair, with both wind and tide in their favor. Why, then, did they hesitate to trust themselves to the quick, bold stroke of the swimmer, instead of the slow, timid, tortoise-like tread of the wader? There are two answers to this question; for there were two reasons for them not having recourse to the former alternative. The first was selfish; or rather, should we call it _self-preservative_. There was a doubt in the minds of all, as to their ability to reach the shore by swimming. It was a broad bay that had been seen before sundown; and once launched upon its bosom, it was a question whether any of them would have strength to cross it. Once launched upon its bosom, there would be no getting back to the shoal water through which they were wading; the tidal current would prevent return. This consideration was backed by another,--a lingering belief or hope that the tide might already have reached its highest, and would soon be on the "turn." This hope, though faint, exerted an influence on the waders,--as yet sufficient to restrain them from becoming swimmers. But even after this could no longer have prevailed,--even when the waves began to surge over, threatening at each fresh "sea" to scatter the shivering castaways and swallow them one by one,--there was another thought that kept them together. It was a thought neither of self nor self-preservation; but a generous instinct, that even in that perilous crisis was stirring within their hearts. Instinct! No. It was a thought,--an impulse if you will; but something higher than an instinct. Shall I declare it? Undoubtedly, I shall. Noble emotions should not be concealed; and the one which at that moment throbbed within the bosoms of the castaways, was truly noble. There were but three of them who felt it. The fourth could not: _he could not swim!_ Surely the reader needs no further explanation? CHAPTER VII. A COMPULSORY PARTING. One of the four castaways could not swim. Which one? You will expect to hear that it was one of the three midshipmen; and will be conjecturing whether it was Harry Blount, Terence O'Connor, or Colin Macpherson.