Quite a minute elapsed before they heard another hail, and by this time the two boys had pulled themselves together a bit, enough to respond with double the vigour of before, while ere many minutes had passed a steady interchange of calls made the task of the searchers so easy that the gleam of a lantern appeared, to be followed by the report of a gun, and this time there was a perfect volley of the strange echoes. "Hear that?" cried Dean, in his natural voice. "Hear it? Yes?" Dean uttered a gasp as if he were swallowing something that was hard, and then with a laugh he said, "Mark, old chap, isn't it queer! That seems to be the jolliest sound I ever heard in my life." "Yes," said Mark coolly; "but we have got a long walk before us, and no end of stones to climb, and I expect we shall get into a precious row." "Never mind the row, old fellow. I wonder what they've got for supper!" CHAPTER THIRTY SIX. THE PIGMY'S DIVE. The party were seated in their shelter close under the highest wall of the ancient ruins, well screened from the ardent rays of the tropic sun, which had not yet risen sufficiently high to interfere with their comfort, and for about the third time the boys were giving their account of the previous evening's adventure, with nothing more visible to show than a few scratches from the stones and the traces of pricks from the many thorns, when the doctor said, as if he were delivering a lecture, and frowning severely the while, "Care, care, care. If ever our eyes should be called upon to carefully discriminate where we are going, there never can be such need for discrimination as here." "You are right, doctor," said Sir James. "You must be careful, boys; eh, doctor?" "Yes," said the latter. "You see, we have done nothing yet to clear away the tangle of growth that covers the stones and the remains of old buildings. I fully believe that this place is honey-combed with passages and cell-like remains, and that there may be dozens of old wells and other reservoirs of water. There is the little river yonder, of course, but if, as I fully believe, this place for miles round was all roughly and strongly fortified, it seems quite probable that the inhabitants, who were gold-seekers, were in the course of generations besieged by the many enemies who coveted their wealth and resented the coming of strangers to settle in their land. If this were the case, in this heated district water would have been most valuable, and the approaches to the river were doubtless guarded by the enemy. Thinking of all this, one sees good reason for the existence of such a well-like place as you encountered yesterday." "Yes," said Sir James, "and I quite agree with you, doctor, that if we could find them where they are buried by the old buildings that have crumbled in, and overgrown by bushes and creepers, there are scores of such places."