But before they could move to do so, in strode a lean, middle-aged Norwegian Larry sensed must be Captain Petersen himself, and on his weathered face was an expression of such gravity that it was obvious to everyone something serious had happened. * * * * * Ignoring Larry, after one brief look of inquiry that was answered by Professor Stevens, he reported swiftly what he had to say. While cruising full speed at forty fathoms, with kite-aerial out, their wireless operator had received a radio warning to turn back. Answering on its call-length, he had demanded to know the sender and the reason for the message, but the information had been declined, the warning merely being repeated. "Was it a land station or a ship at sea?" asked the professor. "Evidently the latter," was the reply. "By our radio range-finder, we determined the position at approximately latitude 27, longitude 65." "But that, Captain, is in the very area we are headed for." "And that, Professor, makes it all the more singular." "But--well, well! This is indeed peculiar! And I had been on the point of turning back with our impetuous young stowaway. What would you suggest, sir?" Captain Petersen meditated, while Larry held his breath. "To turn back," he said at length, in his clear, precise English, "would in my opinion be to give the laugh to someone whose sense of humor is already too well developed." "Exactly!" agreed Professor Stevens, as Larry relaxed in relief. "Whoever this practical joker is, we will show him he is wasting his talents--even though it means carrying a supernumerary for the rest of the voyage." "Well spoken!" said the captain. "But as far as that is concerned, I think I can keep Mr. Hunter occupied." "Then take him, and welcome!" Whereupon, still elated but now somewhat uneasy, Larry accompanied Captain Petersen from the mess-room; started to, that is. But at a glance of sympathy from Diane, he dared call out: "Say--hold on, folks! I haven't had lunch yet!" * * * * * When young Larry Hunter reported to the captain of the _Nereid_, after this necessary meal, he found that the craft had returned to the surface. Assigned a pair of powerful binoculars, he was ordered to stand watch in the conning-tower and survey the horizon in every direction, in an effort to sight the vessel that had sent out that mysterious radio, but though he cast his good brown eyes diligently through those strong lenses, he saw not so much as a smoke tuft upon the broad, gray-blue surface of the hazy Atlantic. Gradually, however, as the afternoon wore away, something else came in view. Masses of brownish seaweed, supported by small, berry-like bladders, began drifting by. Far apart at first, they began getting more and more dense, till at last, with a thrill, he realized that they were drawing into that strange area known as the Sargasso Sea.