Almost before the words had died out, the explosion came, tearing more than one pillar out of position and dropping a great mass of slate down on the floor of the cross-cutting.
For a moment the gases which filled the chambers were overpowering. The only wonder was that they were not ignited. The electric lights carried by the boys shone dimly through the smoke of the confined place.
"There goes Ventner," whispered Will, pointing to a figure moving swiftly through the half-light of the place.
"He's going to see what the shot brought down!" suggested Tommy.
The boys rushed forward in a little group. When they gathered at the scene of the explosion, the detective was not there.
"If he got hold of the cash, he knew what to do with it all right!" exclaimed Tommy. "He got away with it before we got a chance to see what he had. Now we've got to catch him!"
"May as well look for a needle in a load of hay!" grumbled Sandy.
"Look here," Jimmie exclaimed. "There's a way to keep him shut up in the mine if we do the right thing. This cross-cutting runs out to a gangway on the north, and that, in turn, leads, of course, to the shaft. Now, one of you boys duck out to the shaft and see that he doesn't get up. You'll have to go some on the way there, because a man with two hundred thousand dollars in his pocket will put up some running match!"
"I'm off!" shouted Tommy. "I know I can get to the shaft before he can! He's too fat-bellied to run, anyway!"
Tommy started away at a swift pace, and the other boys closed in on the gangway, Will alone stopping at the scene of the explosion.