“Yes, we’ll go back,” assented Mr. Jenks.

Mr. Parker was tapping away at the rocks.  He looked toward the black mouth of the big cave.  On what corresponded to the roof of it, some distance back from the entrance, he saw a slender metal rod sticking up into the air.

“May I ask if that’s a lightning rod?” he inquired innocently.  “If it is, I should like to ask about its action in a mountain that is so impregnated with iron ore.

“You may ask until you get tired!” cried the spokesman, again showing unreasoning anger, “but you’ll get no answer from us.  Now get away from here before we do something desperate.  You’re on private ground and you’re not wanted.  Clear out while you have the chance.”

There was no help for it.  Slowly our friends turned and began to go down the dangerous trail.  They were soon out of sight of the two men who stood before the cave, with their guns ready, but neither Tom nor any of his companions spoke for some time.

When they had rounded one of the most dangerous turns the young inventor sat down to rest, an example followed by the others.

“Well,” asked Tom, “do you think those are some of the diamond makers, Mr. Jenks?”

“I certainly do, though I never saw those two men before.  If I could once get inside the cave, I could tell whether or not it was the one where I was practically held a prisoner.  But I’m sure it is.  I know some of the men used to go off every day with guns, and not come back until night.  I have no doubt they were on guard, just as these two are.  And, also, I think I heard them speak of a second entrance to the cavern.  The one we just saw may not be the main one, through which I was taken.”

“I believe we are on the right track,” ventured Mr. Damon, “but we will either have to go up there after dark, which will be risky, on account of the narrow trail, or else we will have to find some other path.”

“The last would be better,” spoke Tom.

“That rod of metal sticking up on top of the cave interested me,” said the scientist.  “Did you hear anything of that when you were here before, Mr. Jenks?”

“No.  Probably that is only a lightning rod, or it may be a staff for a signal flag.  But what surprises me is that those men didn’t suspect that we were seeking to discover their secret.  They took us for ordinary prospectors.”

“So much the better,” remarked Tom.  “We have a chance now of getting inside that cave.  But we will have to go back to camp, and make other plans.  And we must hurry, or it will be dark before we get there.”

They hastened their steps, pausing only briefly to eat some of the lunch they had brought along, and to drink from a spring that bubbled from the side of the mountain.  It was getting dusk when they got back to their tent.  They found nothing disturbed.

“I wonder if we’ll see that phantom again to-night?” ventured Tom, as they were sitting about the campfire a little later.