It was ten minutes later when Rob's sharp eye descried a trail of smoke on the horizon. A short time after, by the aid of glasses, the craft was made out to be the _Seneca_, bound at full speed for the yacht. On the latter's signal-halliards up went a gaudy string of signal flags announcing her identity. The signal was answered from the Derelict Destroyer, which also fired a gun in honor of the recovery of the castaways. By midafternoon good-byes, warm and hearty, had been said, three ringing cheers exchanged between the crews of both craft, and the _Brigand_ was headed due south, while the _Seneca_ made in toward the coast. Long before sunset both craft had vanished from each other's sight. "So that was one derelict that Uncle Sam did not have to destroy," laughed Ensign Hargreaves to Lieutenant Murray as they stood side by side on the bridge. "No," rejoined the other, "she committed suicide; but if it hadn't been for our young recruit, Donald, she wouldn't have gone to her grave alone!" CHAPTER XI. BARTON THE MACHINIST. An island, a sandy, scantily grown spot of land, shaped like a splash of gravy on a plate, loomed up over the _Seneca's_ bow. On it stood a shed, two naked masts with wireless antennæ strung between them, and some tents, and that was all, except that, removed from the shed mentioned above, was a similar and larger structure. This second structure was built on piles right out over the sea, and as the coast of the island declined abruptly at this point, there was considerable water under its corrugated iron roof. "So that's Barren Island?" asked Rob, who, with the boys and the two officers, was standing on the bridge of the _Seneca_ regarding with the most intense interest that desolate spot of land. Beyond it lay other islands equally barren, so that applicability of the name was not quite clear, while in the dim distance a faint blue line betokened the Carolina coast. "Yes, that is Barren Island," nodded Lieutenant Murray; "and strange as it may seem, the hopes of the Naval Department are centered right at this moment on that sandy patch yonder." "Seems queer, doesn't it?" commented Merritt. "Queer but safe," smiled Ensign Hargreaves. "I'm aching to get ashore," exploded Donald eagerly. "Is that a powerful wireless?" "It is capable of sending up to three hundred miles on an average, and more under favorable conditions," was the reply. "What's in that big shed?" demanded someone. "That houses the _Peacemaker_. The shore shelves off abruptly and the submarine is housed under that roof in more than forty feet of water." "And the other building?" "A combination cook house and dining room." "Shall we have lots to eat?" asked Tubby, his eyes glistening as he heard. "Plenty, I hope," rejoined the ensign smiling. "There is an ample stock of provisions, and they will be received from the mainland as occasion requires." "But how shall we reach the mainland?" "In a powerful motor boat," was the reply.