“But we will never get out by remaining here,” said Holman.  “If he has made the acceptance of those proposals the only grounds upon which he will grant you your liberty, I don’t see that it will serve any good to remain here taking the food he throws down.”

“That’s true,” murmured Edith, and I blessed her mentally for the calm way in which she had uttered the words.  The surrounding darkness had no terrors for her in comparison to the fate that awaited her above.  The manner in which she spoke of the sallow-faced rogue convinced me that the proposals that had been made since the time that Leith had shone out in his true colours had produced a terror which she endeavoured to hide from her father and sister.

But the dark terrified the Professor.  Although he viewed Leith’s proposals with the greatest abhorrence, the hole above his head appeared to him to be the only path back to the outer world, and he was afraid to stray.

“There might be another way out of the place,” said Holman.  “Can Verslun and I make the attempt and leave you three here?”

“No, no!” cried Barbara.  “Please stay here with us!”

“I think it will be better if we remain together,” said Edith.  “If you and Mr. Verslun did discover an opening it would be exceedingly difficult to find your way back here, and if you got out of this place you might not be able to reach the opening through which we were lowered.  Perhaps the way to it is known only to Leith.”

Edith’s argument was sound.  Our finding them in that black cavern was purely an accident, and it was hardly probable that Holman and myself would be able to find our way back to the spot if we went off on a tour of investigation.  Personally I had no desire to leave the girls.  Leith’s deviltry had so impressed me that I considered him capable of anything, and if he thought we were out of the way, I had no doubt that he would take immediate steps to break down the courage of the Professor and his daughters by means that were familiar to him.  I could well understand that Edith Herndon’s love for her father would compel her to sacrifice herself if she saw the aged Professor in front of the great stone centipede, and that might happen at any moment now that Leith considered that he had disposed of all active opposition.

For hours we debated the matter, and finally the Professor was won over.  He agreed to move forward on an inspection tour of the vast subterranean place the moment the next supply of food came from above, and we waited anxiously.  During the wait Holman and I made short trips into the darkness, but we were careful that we did not get out of the hearing of the two girls, who called at intervals so that we would be able to find our way back.  The place was awe-inspiring.  Its size could only be guessed at.  Stones that were flung in a certain direction where the floor sloped gradually downward could be heard rolling for many minutes after they left our hands.