As they went along he said, "Let us have a look at these bushes, Bertie. The soil is very thin about here, and I wonder that the trees grew."
"These are pines," Bertie said, "and in the mountains we often saw pines growing among rocks where there did not seem a handful of soil for them."
On examining they found several old stumps, and thrusting a ramrod down Harry found, to his surprise, that the soil was from three to four feet deep. He tried again a little farther off, and found that it was two feet; further still, it was only one.
"The tree must have stood in a hole in the rock," he said. "Try another one, Bertie." The same results were obtained. "That explains it, Bert. Evidently when they planted the trees to prevent this place from being seen from the hills, they cut away the rock in circles about twelve feet across and made cup-shaped holes, which they filled up with earth. When they planted the young trees I dare say at first they watered them. They could easily enough fetch water up from the stream. When the trees got fairly rooted they would be able to leave them alone, perhaps giving them a good watering once every two or three months. Whenever the rains came they would be able to give up watering altogether, for in these basins the earth would keep moist for a very long time. It would be a big job, but no doubt the king who built the place had all his tribe at work on it. It is probable that the Incas had established themselves at Cuzco for many years before they came down to this place, and the trees may not have been planted till their coming was first heard of. In that case there would be plenty of time to hide the place before they came down and searched the shore. We know that the Chimoos resisted them for a considerable time before they were finally conquered. Well, for whatever purpose this place was built it is one in which either the Chimoos or the Incas, if they ever found the place, would be likely to hide treasure, which is satisfactory. Now we will sit down here for a short time and watch both windows. You look at the two top lines, Bertie, and I will look at the two lower lines. I certainly do not see any signs of life. That is how the water gets out," and he pointed to a roughly-shaped arch about twelve feet wide and as many high. Through this the little stream disappeared. "I expect there is a similar passage at the other end."
"There may have been," Bertie said. "I was hanging so close to the wall that there may very well have been one without my being able to see it. But it looks pitch-dark in there. If there were much of an opening we ought to see the light, for, as we agreed, it can't be more than a hundred feet long."
[Image: HARRY DROPPED THE BARREL OF HIS RIFLE INTO THE PALM OF HIS LEFT HAND.]
"That is the first place we will investigate, Bertie. The question of how we are to get into the house wants some thinking over. That lowest window is a good twenty-five feet above the ground."
"Of course if we had a grapnel we could fasten it to the end of a rope and chuck it in."
"We shall have to make something of that sort. If the window had been on the other side instead of this it would have been easy enough, because I could have lowered you and slipped down the rope afterwards, but that arch sticking out so far on this side makes it impossible. All that we can do now is, as far as I can see, to lower ourselves down on to the top of that wall in the ravine, then go and examine the tunnel. We have got plenty of rope to lower ourselves from here on to the wall."
They watched the building for another twenty minutes. "I am convinced that no one is there," Harry said. "I have not seen as much as a shadow pass any of the windows since. If people did live in it they would naturally be on this side of the house, because the rooms here are better lighted and more cheerful, and no doubt they are the principal rooms, as the house narrows so much at the other end."