all right, and Tom was about to leave when a peculiar noise attracted his attention. It was the sound of metal scraping on metal, and the lad's quick and well-trained ear told him it was somewhere about the ship.
He turned to leave the tank, but as he wheeled around his light flashed on a solid wall of steel back of him. The emergency outlet had been closed! He was a prisoner in the water compartment, and he knew, from past experience, that shout as he would, his voice could not be heard ten feet away. His father and Mr. Sharp, as he was aware, had gone to a near-by city for some tools, and Mr. Jackson, the engineer, was temporarily away. Mrs. Baggert, in the house, could not hear his cries.
"I'm locked in!" cried Tom aloud. "The worm gear must have shut of itself. But I don't see how that could be. I've got to get out mighty soon, though, or I'll smother. This tank is airtight, and it won't take me long to breath up all the oxygen there is here. I must get that slide open."
He sought to grasp the steel plate that closed the emergency opening. His fingers slipped over the smooth, polished surface. He was hermetically sealed up—a captive! Blankly he set his
