"There must have been, señor; it is certainly strange."
"First of all, let us clear the wall and take a general view of it. Guessing won't help us; but I have the strongest hopes that behind one of these stones lies a cavern. By the way, Dias, take a torch and go into the next chamber and see if the stones are solid there."
"They are just the same as those here," Dias said when he returned.
"I would rather that it had been the other way," Harry said, "for then I should have been more sure that there was some special reason for their building them in this way here."
It took them all half an hour's work to move the spears and arrows to the other side.
"Do you think, Harry, if we were to tap the stones we should be able to find whether there is a hollow behind any of them?"
Harry shook his head.
"Not in the least. I have no doubt these stones are two or three feet thick, and there could be no difference in the sound they would make if struck, whether they were filled in solid behind or had no backing. To begin with, we will make a careful examination of the walls. Possibly we shall see some signs of a stone having been moved. It would be very much more difficult to take one of the great blocks out and put it in again than it would be to get up one of the paving-stones."
When they had gone about half-way along, examining each stone with the greatest care, Bertie, who was ahead of the rest, and passing the candle he held along the edge of every joint, said, "Look here! this stone projects nearly half an inch beyond the rest."
The others gathered round him. The stone was of unusual size, being fully two and a half feet wide and four feet long, the bottom joint being two feet above the floor.