"I know what you mean," grunted the big Venusian. He knelt down beside the menacing box of explosives and quickly disconnected the trip wire, throwing the box to one side.
Straightening up, Astro announced, "It's harmless now."
Cautiously the two cadets continued down the tunnel, the roaring sound growing louder and louder. After twenty minutes, Astro paused, his homely features wrinkled in a frown of worry.
"Think maybe Miles and Brett went off into one of the other side tunnels?" he asked.
Tom thought a moment. "No, I don't, Astro. We haven't hit another side tunnel since we passed that booby trap back there. What would be the use of setting that thing up if they went in another direction?"
"There must be another way out of here, then," Astro remarked.
"Why?"
"That part of the tunnel back there by the bomb was loose dirt. If the bomb had exploded, the whole tunnel would have been blocked off and how could they get out?"
Tom didn't answer. He was thinking about what he was going to do if there should be another booby trap in the tunnel. It was so dark now that they could hardly see more than a few feet ahead. The bright light was merely a pinpoint in the distance behind them.
And then Tom became aware that the roar that had been with them constantly since they had entered the shaft had now lessened in volume. But they had not passed a single branch-off tunnel where the sound could have originated. Tom made up his mind quickly.