"Shut it off!" cried Tom quickly. "It's coming too fast! Shut her off!"
The man sprang to obey the command, and, with nervous fingers, sought to fit the wrench over the nipple of the controlling valve. Then his face seemed to turn white with fear.
"I can't move it!" Mr. Sharp yelled. "It's jammed! I can't shut off the gas! Run! Look out! She'll explode!"
Tom Swift, the young inventor, whose acquaintance some of you have previously made, gave one look at the gauge, and seeing that the pressure was steadily mounting, endeavored to reach, and open, a stop-cock, that he might relieve the strain. One trial showed him that the valve there had jammed too, and catching up a roll of blue prints the lad made a dash for the door of the shop. He was not a second behind his companion, and hardly had they passed out of the structure before there was a loud explosion which shook the building, and shattered all the windows in it.
Pieces of wood, bits of metal, and a cloud of sawdust and shavings flew out of the door after the man and the youth, and this was followed by a cloud of yellowish smoke.
"Are you hurt, Tom?" cried Mr. Sharp, as he swung around to look back at the place where the hazardous experiment had been conducted.
"Not a bit! How about you?"
"I'm all right. But it was touch and go! Good thing you had the gauge on or we'd never have known when to run. Well, we've made another failure of it," and the man spoke somewhat bitterly.
"Never mind, Mr. Sharp," went on Tom Swift. "I think it will be the last mistake. I see what the trouble is now; and know how to remedy it. Come on back, and we'll try it again; that is if the tank hasn't blown up."
"No, I guess that's all right. It was the aluminum container that went up, and that's so light it didn't do much damage. But we'd better wait until some of those fumes escape. They're not healthy to breathe."