"When you went into the cave, where you found the copper box, how many chambers did you pass before coming to the large room?"
"I am not sure," he answered, "but I think four."
"Yes; and the case was found in the fifth chamber. The Plus sign indicated the cross-shaped cave, did it not?"
"Yes, and there are several other things which interest me," remarked George, gazing at John, as he continued: "Why should the inscriptions have been marked on the skulls?"
John slowly shook his head, as he looked at Clifford. The latter gazed vacantly into space, as though reflecting, and finally said: "I do not know."
It will be remembered that when Walter entered the Professor's room, where Clifford was lying, he[p. 231] appeared to be startled at the sight of the skulls. The copper box which held one of them was in the adjoining room.
During the foregoing conversation Walter was mute, nor did he appear interested in the question propounded by George.
"It seems most curious to me that the skull taken from the copper box has the inscription on the right side, whereas the other one has them on the left side," observed Harry.
John and George saw the immediate change in Walter's face while Harry was speaking. His agitation was now plain to all, and the perspiration began to appear on his forehead.
John leaned forward as he said: "Do you know?"