"I am at fault, it seems," said Idris, "or, it may be, the rain of centuries has washed down so much earth from the side of the mound that the guide-stones at its foot have become buried. We can do nothing without proper tools."
"Let us explore all round," suggested Beatrice, the spirit of adventure growing upon her.
They examined the entire circuit of the base, and, when that investigation was over, were no wiser than when they had begun.
Beatrice seated herself on a grassy bank facing the tumulus, and Idris took his place beside her.
"This will never do," he muttered, ruefully contemplating the hillock. "I must discover the mouth of the passage. If I begin to bore at any other point I might indeed reach the wall of the central chamber, but I should be on the outside, and it would be difficult, if not impossible, to make a way through the masonry. Besides, as I cannot admit the coöperation of any one but Godfrey, tunnelling through twenty feet of earth is a task that will take several nights, not to speak of the impossibility of concealing our work in the daytime."
"Or the risk of your tunnel falling upon you, in which case," added Beatrice, demurely, "you would have much ground for complaint."
"Wicked Miss Ravengar! Would you jest at my misfortunes? I will defeat your hopes by finding the legitimate entrance."
"And how do you propose to find it?"
"Well, I conceive that the entrance is shaped like an ordinary doorway, that is to say, it consists of two upright stones a little distance apart, with a third resting horizontally upon them. I shall have to move round the base of the hillock with an iron implement, striking into the soil till I meet with stone. A little judicious probing will soon tell me whether it be a boulder, or one of the entrance-columns. If a boulder merely, I shall have to pass on, repeating my experiment."