They had proceeded for an hour or more and felt that they must be approaching the spot where Sam had seen the fire when they noticed that the darkness was less dense, that there was a subdued light upon the water, and that the clumps of trees were sharper and clearer.
“Hanged if the moon isn’t rising!” exclaimed Rawlins. “Crickey, it must be near midnight.”
Mr. Pauling looked at his watch. “It’s after eleven,” he announced. “We’ve been searching for five hours.”
“I’ll say those kids are some little travelers!” declared Rawlins. “They must have thought they were rowing for a bet to get clean over here.”
“Ah 'spec’ tha’ tide made to help them, Chief,” remarked Sam. “It makes right strong an’ po’ful up these creeks.”
“Yep, that must have been it,” agreed Rawlins. “Hadn’t thought of it before, I’ll bet they got caught in a strong current and couldn’t pull against it. Hello! What the——”
Instantly the men stopped rowing. From far away, as if from the air itself, came a low throbbing vibration, a sound felt rather than heard, and those in the boat stared at one another questioningly.
“Thunder!” suggested Mr. Pauling, in a low tone.
Rawlins shook his head. “Nix,” he replied crisply. “Thunder doesn’t keep up like that and it doesn’t throb that way. Sounds to me more like a ship’s screw half out of water.”
“Some bird then,” suggested Mr. Pauling. “Bittern or owl, perhaps.”