"And it will be comparatively safe to go from here to our former post of observation," added Tom, "for there doesn't seem to be any opening along the tunnel, into the larger cave, except the place where we were."
Accordingly they started off. Cautiously they looked through the opening into the apartment where they had seen the diamonds made.
"There's not a soul here!" exclaimed Tom, in a whisper. The others looked. The place was deserted—the machinery silent. Mr. Jenks peered in for a moment, and then exclaimed:
"I'm going in! Now's my chance to find out all that I wish to know! It may never come again, and then we can soon leave Phantom Mountain!"
It was a daring plan, but it seemed to be the best one to follow. They were all tired of inactivity. Mr. Jenks managed to get through the opening, and dropped into the big cave. The others followed. Mr. Jenks hurried over to the steel box, and began an examination of it. Tom Swift was looking at the electrical switch. He saw how it was constructed. Mr. Damon and Mr. Parker were peering interestedly about.
Suddenly the sound of voices was heard, and the echo of footsteps. Mr. Jenks started.
