Those, and the possibility of collision, seemed the only dangers that had to be guarded against; the possibility of meeting a Spanish vessel was not considered, for the chance seemed very remote. The two lookouts were both stationed in the bow. That fact and the other just mentioned sufficed to account for the fact that the real danger that threatened the crew of the merchantman was not thought of or guarded against in the least. For Clif had no way of knowing that any trouble was to come from behind him; but coming it was, and in a hurry. Within the shelter of a narrow inlet just to one side of the batteries that had made so much trouble for the Uncas had lain hidden and unsuspected an object that was destined to play an important part in the rest of the present story. It was a Spanish gunboat, of much the same kind as the Uncas, only smaller. Hidden by the land, her officers had eagerly watched the struggle we have just seen. The Spanish vessel had not ventured out to take part, for one important reason; she had not steam up. But she would probably not have done so anyhow, for the Uncas was the stronger of the two. And so venturing out would have been little better than suicide. The Spanish captain had a plan that put that one far in the shade. The Uncas was still visible down the shore, and the merchantman had hardly gotten well started out to sea before great volumes of black smoke began to pour from the furnaces of the Spaniard. Her men worked like fiends; sailors pitched in to help the firemen handle coal, while the shores of the dark little inlet flared brightly with the gleam of the furnaces. Meanwhile the officers with their glasses were feverishly watching the distant steamer, now hull down to the north, and almost invisible in the darkness. It was about half an hour later, perhaps even less, that that Spanish gunboat weighed her anchor and stole silently out to the open sea. She breasted the fierce waves at the entrance to the inlet boldly. A minute later she was plowing her way through the storming sea. It was dark then and she could see nothing; but her captain had the course to a hair's breadth. He knew which way his prey was gone, and he knew to what port she was going. He knew, too, that she would not dare go near the harbor of Key West until daylight. And so if by any chance he missed her in the darkness he would still have another opportunity. And those on the shore who saw the vessel glide away chuckled gleefully to themselves. It was something to look forward to, a chance to revenge themselves upon the impudent Yankees who had dared to elude the fire from their guns. Meanwhile the Yankees, totally unsuspicious of this last move, were buffeting their way bravely ahead.