When, however, Tom gradually allowed the airship to sink towards the sea, the shark seemed to take fright, just as smaller fish are scared by signs of movement in the air above. It left the immediate neighbourhood of the mast, and its black fin could be seen describing a much larger circle some two or three hundred yards away. Clearly it had not given up hope. When the shark moved away and the strain of terror was relaxed, the two men became suddenly aware of the presence of the airship. The topmost man was almost as much scared by the sight of the airship as he had been by the presence of the shark. Tom had already noticed that both of the men were dark skinned. The larger and stronger—the brute, as Tom mentally called him—appeared to be middle-aged; the other was a stripling. Tom was struck by the difference in their demeanour when they caught sight of the airship; neither he nor Timothy was at present visible to them. The elder man was aghast with fright, his eyes dilated, his mouth gaped between black moustache and beard. The younger, however, seemed to pull himself together as with renewed hope. Tom fancied that he heard a cry from his lips. Looking round, Tom saw that the yacht had now hove to, and the boat was leaving her side. But his attention was again called to the wreck by a piercing shriek. The shark, regaining confidence, had made another dash at the mast. This time it seemed to come within an inch of the terrified youth; indeed, from the cry that had reached his ears, Tom thought that the poor wretch had actually been seized. But next moment he saw that the shark had again drawn off, scared, possibly, by the cry. There was now less of the masts above the surface. The tide was evidently rising, and with its rise the shark would have another opportunity of coming within snapping distance. Tom felt that it would not again fail. It would be at least ten minutes before the boat reached the spot; by that time the hapless lad would probably have fallen a victim. Tom had noticed that when the shark was all but upon him, and he made a convulsive movement upwards, he was met by a storm of kicks from the man above, threatening to dislodge him completely from the mast and hurl him into the very jaws of the monster.