Larry buzzed and buzzed, but in vain. No answer came from the interior of the _Nautilus_. What had happened? Larry was frantic as he pushed down hard and harder on the button. "Look!" cried one of the crew forward as he pointed off the starboard bow of the _Jules Verne_ at an object that had just shot up out of the water. It was the head of a man! As members of the crew of the _Jules Verne_, with Superintendent Brown and Captain Austin in the lead, swarmed to the side of the ship there came an upheaval from beneath and a tremor that shook the old boat from stem to stern. It was as though a geyser had let loose directly under the new diving ship. "The bomb! It has exploded!" Larry Seymour, his face ashen white, sought anew to get a telephone communication with the two Brighton boys whom he loved so dearly. But even as he despaired there came a welcome cry forward. "Thacker! It's Thacker! He escaped unharmed from the _Nautilus_." But where was Dick? CHAPTER XVII A DOG TO THE RESCUE Even as the crowd of sailors on the _Jules Verne_ cheered, Jay Thacker turned on his back in the waters of Long Island Sound and waved a hearty salute to his friends. Unharmed, he had completely escaped from the _Nautilus_ just a few seconds before the bomb was exploded in the sunken coal barge. "Jay! Jay! Keep afloat--we'll have you in a minute," yelled Larry Seymour as he crowded to the rail, tears of joy streaming down his face. "Catch the rope!" Jay heard the cry from the deck of the _Jules Verne_. Turning he beheld a group of sailors and from their midst one who was ready to cast a line. But even before the line was hurled the figure of another lithe youth poised for a second on the rail and then dived into the water. "Good boy, Seymour!" came the re-echoing shout. And in the next moment Jay saw the round and puffing face of Larry directly beside him. It was Larry who had dived overboard to the rescue. With a few strokes he was close up and thrust a sturdy shoulder under Jay's shoulders. Jay had turned on his back to rest for a moment. "Thank God, boy, you got out!" gasped Larry. "Are you hurt? Can you swim?" Jay replied he was still able to take care of himself. "Better look for Dick; he must be somewhere around here," was Jay's rejoinder. But taking no chances, Larry supported his old friend until the line had come over the side of the _Jules Verne_. When Jay had taken hold and was being yanked aboard Larry turned and swam back in the general direction whence Jay had come, hoping against hope that he would be able to find some trace of Dick. But he was nowhere in sight! As for Jay, he was given a wonderful welcome when at last he was hauled over the side of the _Jules Verne_. Eager hands clasped him and landed him in safety at last upon the deck of the vessel. "Thank heaven, lad, you are safe again--I had almost given up hope of ever seeing you again!" exclaimed Captain Austin as he clasped Jay with a fatherly hug.