Nobody had. Soon after they turned in, as, despite their uneasiness, all were tired out by the exciting events of the day. Nat volunteered to take the first watch, it being arranged that at midnight he was to awaken Captain Akers, who would relieve him.
The lad took up his station by the door where the steady breathing of the others soon apprised him that they had passed into slumberland. It was an eerie sensation sitting there, looking out on the fog-laden night and speculating—for, try as he would, Nat could not help doing so—on the nature of the invader who had so sadly disturbed them.
He had his rifle in his hands and determined to keep bright and wide awake, so that if anything occurred which might have a bearing on the mystery he would be able to solve it. Just how long he had sat there before something happened to break the monotony Nat did not know. It might have been an hour or it might have been two. But he had noticed that the fog was beginning to lift when at the same instant he perceived a shadowy form come creeping along the decks, making toward the stern.
The figure was bent almost double and swung two long arms as it advanced. After his first gasp of surprise, Nat noted that the newcomer was unarmed. This thought gave him new courage and, slipping within the shadow of the door, he watched the figure's advance.
But, whatever its mission, it did not apparently mean harm to the occupants of the cabin, for, after a brief pause near there, it kept right on to the stern.
As it passed Nat slipped out of his place of concealment and took after it, treading softly the while, so as not to alarm the marauder. He was curious to see what the fellow was up to. When he did make out Nat was seized with a sudden fury and sprang forward.
The figure, after advancing right up to the stern-rail, could be seen, in the now clearing atmosphere, to be fumbling with something.
"Great Ginger! He's casting our boat loose!" gasped Nat.
As he made this discovery the boy was too engrossed to notice that a puff of wind came over the water. In their activity, since they had been on board, not one of them had thought to lower the schooner's sails. She heeled to the wind which momentarily grew steadier and forged gently ahead. But of all this Nat—to his cost, as we shall see later—was oblivious.
The discovery he had made of the nefarious work the mysterious inhabitant of the schooner was about had aroused his rage.