“I saw Gradbarr, the new man, slip into the torpedo room, sir, while no one was looking. He had that wrench with him. I was following him to tell him that no one was allowed in there without your orders, when he came running out. I ran in to see if he had done any mischief, but the explosion came just as I got to the valve. I think I turned it off, though.”
“You did, Sim!” exclaimed Lockyer, glancing into the steel-walled space beyond the chamber in which they were assembled. “I can see the valve is at ‘off.’ My boy, I don’t know how to thank you. If it hadn’t been for your presence of mind more gas would have escaped and the boat been blown up.”
Then, turning to the others, who looked rather puzzled, the inventor rapidly explained.
“The gas is kept in a pressure-tank forward. I filled the tank recently to test out the engines, but a pipe did not fit, and it was disconnected. When the pipes were unjointed an open end was, of course, left in that chamber. It was thus a simple matter, by turning on the valve, to flood the chamber with gas.”
“But how did it ignite?” asked Ned.
“Evidently, that plumber’s torch overturned near the door, touched it off,” was the rejoinder. “Great Heavens, if Sim had not done the brave thing he did, the boat would have been ripped open as if she were made of tin. Only the fact that the full quantity of gas was not released saved the boat.”
Herc had picked up the wrench Sim had clasped in his unconscious hand, and was examining it curiously.
“See, sir,” he said, extending it, “it’s marked T. G.”