"Good night," said Tim, pulling his own blankets around him. The steel deck was anything but comfortable but after the flight from Atkinson and the busy day in New York, Tim soon dropped into a heavy sleep. It was sometime after midnight when he awoke with a feeling of alarm gripping him. He looked toward the hatch above. The light was out. Someone was in the control room! CHAPTER SIXTEEN The First Test There was no actual sound to which Tim could attribute his sudden awakening, but he was certain someone was in the control room beside Pat for he could hear the steady breathing of his companion. Tim forced sleep from his tired brain. He needed every faculty to meet this emergency. His right hand moved cautiously and his fingers closed around the hard, cold butt of his revolver. There was a slight scraping sound from the dense blackness at the base of the ladder which came down from the main hatch and Tim wished for a flashlight. He didn't even know where the switch which controlled the interior lights of the _S-18_ was located. Only the slightest of shuffling sounds warned Tim that the intruder was coming toward him. Evidently he was in his stocking feet. Tim managed to free his legs from the folds of his blankets and he crouched on the steel floor of the _S-18_, ready for whatever might happen. The hatch which led to the main deck was visible for the sky outside was much lighter than the black interior of the submarine. In this circle Tim saw the head of a man peer into the control room. Unless he did something at once, the _S-18_ soon might be swarming with unwanted visitors. Tim heard a slight grunt as the man coming toward him struck his head on the lower end of one of the periscopes. That was all Tim needed. Throwing his strength into the effort, he lunged forward, his outstretched arms enfolding the legs of the intruder. They went down with a crash that brought a muffled cry of alarm from the man Tim had tackled and a real shout of agony from Pat, on whom they had fallen. "What's going on here?" cried Pat. "I don't know," gasped Tim, "but someone turned off the light over the hatch and came down here. I just tackled him and there's another fellow at the hatch about ready to come down." The man Tim had tackled recovered suddenly from the surprise attack and struck out with a vigor that caught the flying reporter. A powerful foot struck Tim on the chest and sent him flying across the control room to land on the other side curled against a maze of pipes and valve wheels. "Have you got him?" cried Pat. "Not now," Tim replied. "He kicked me almost through the side of this tin fish. You try and get him." "I'll get him all right," vowed Pat. "You keep the boy at the hatch from joining him and making this too much of a party."