From the boys’ descriptions and Sam’s discoveries the Americans learned that the tramp was a “mother ship” for the submarine with a huge cradle or opening in the hull wherein the underseas boat could rest and be carried from place to place. But although a search was made of the wrecked tramp no trace of either the submarine or of bodies could be found. Mr. Pauling and the others felt convinced, however, that the leader of the gang was still at large and while discussing this matter their attention was drawn to a seaplane which they decided was a United States government machine sent from Porto Rico or St. Thomas to learn the cause of the explosion.
After the aircraft had disappeared the party returned to the destroyer and to their amazement were given a radio message from the aviator which Mr. Pauling recognized as coming from the arch criminal whom they were seeking.
But although their quarry had once more escaped them and had taken to the air, Rawlins insisted they would yet capture him and pointed out that the seaplane must descend and that when it did they should be on hand.
Although it seemed but a slim chance, still the diver’s hunches had invariably proved so reliable that Mr. Pauling had at once decided to take Rawlins’ advice and, transferring himself and his party to the partially disabled destroyer, had at once started forth to search the neighboring islands for the aircraft which had last been seen flying southward.
And as the lean gray craft slipped out of the shelter of Coral Bay and felt the heave of the Caribbean sea, Rawlins was speaking. “Airplanes aren’t so common down here that they can fly over the islands without being noticed,” he asserted. “If we stop in at them here and there we ought to be able to trail him. He’d have to head for some place and by finding out where he’s been seen we can get his direction. I’ll bet he’s got some hang-out down here. Of course, he could land on the water, but it would have to be in the lee of an island even if he was going to be picked up by a ship.”
“Or the submarine,” put in Mr. Pauling. “Don’t forget that the chances are the sub escaped and is to meet him.”
“Yes, but he can’t land on a sub and he couldn’t have started off from it. No, he’s either got some ship or a secret landing place and hangar for his plane on shore. Besides, if he tries sending messages the boys can pick them up.”
“To my mind,” declared Mr. Henderson. “It is like hunting for the proverbial needle in the haystack. There are a score and more of islands--to say nothing of cays--and although he started south we have no means of knowing how soon he may have shifted his course. Why, even now, he may be over in Santo Domingo, Cuba or Tortuga or he may have turned east to St. Barts or Barbuda. If we went to every island we would be here for the next year.”
“I’ll say we would!” laughed Rawlins. “But we don’t need to. Once we pick up his trail and know his course it’ll be easy. A fellow can’t fly far in any direction without being in sight of an island and if we lose him we can easily find his trail again by calling at an island or two.”
“Sounds easy, I admit,” remarked Mr. Henderson rather sarcastically. “But what is to prevent him from going straight across to South America for example? Then we’d have a nice job trying to find where he landed--I suppose we’d have to hunt the entire northern coast of the continent.”