“Nough fer a man-uv-war,” grinned old Captain Hodgins.

Slowly the Flying Fish forged ahead till right under her bow lay a patch of the yellow water.

“By-a-half-two,” came a sharp hail from the fat youth, who had once more heaved the lead.

“Cut her down some more,” sharply ordered Rob, without turning his head, “we draw only three feet so I guess we’ll do nicely for a while.”

“Great hop-toads, there’s regular shark’s teeth ahead,” commented Captain Hudgins, pointing to the still shallower water indicated by the lightening tint of the channel.

“By-one-by-a-quarter-one!” came sharply from Tubby, as the Flying Fish seemed hardly to crawl along the water.

“By-a-half!” came an instant later, meaning that only three feet of water lay right ahead.

“Stop her,” roared out Rob.

But he was too late.  Instantly, almost as Merritt’s hand had flown to the lever, the nose of the Flying Fish poked into the sandbank and her motor with a gentle sigh came to a stop.

“Hard a-ground!” roared the captain, “too bad and with a fallin’ tide, too.”

“Full speed astern,” came the next order.

The propeller churned up the water aft into a white turmoil.  The Flying Fish trembled in her every timber, and began to slide slowly backward from the treacherous shoal.

“Safe, by the great horn spoon!” roared the captain, fetching Andy Bowles a slap on the back that almost toppled the small bugler into the water.

“For a time,” said Rob quietly, “come ahead a bit, Merritt.”

Slowly the little vessel slid ahead once more.  Rob seemed fairly to feel his way through the narrow channel he had picked out and finally the Flying Fish, after as much coaxing as is usually bestowed on a balky horse, floated in the deep water beyond the sandy bar.

Eagerly the boys looked about them as they “opened up,” as sailors call it, the narrow stretch of water known as the Upper Inlet.  It did not take them long to spy the island with the tent on it in which the conversation between Jack and his cronies, and the mutineer to his plans, had taken place.

“There’s their camp!” shouted Rob, eagerly sending the Flying Fish ahead at full speed, “now we’ll find out something.”

“And, maybe, use this.”  The captain, as he spoke, grimly produced his formidable weapon and flourished it about.

“No, none of that,” sternly rejoined Rob, “the Boy Scouts can take care of those fellows—­without using firearms.”

“You bet,” rejoined Merritt, grimly “musling up,” “we’ll show ’em if it comes to a fight.”

But bitter disappointment awaited the boys.  As we know, the camp was deserted and no trace or clue of the whereabouts of its occupants was to be found.  In the tent, however, lay a piece of blotting paper with ink-marks on it.  It was the material with which Jack had dried his letter.