that the water had escaped through a subterranean channel below the rocks from which he looked down.
He climbed down the sides of the gorge, and walked along its bottom for two or three hundred yards, until around a jutting point of rock he saw that the sides of the defile separated for a considerable distance, and then, coming together again below, formed a sort of amphitheatre. The bottom of this was a considerable distance below him, and he did not descend into it, but he saw plainly that it had recently contained water, for pools and puddles were to be seen everywhere.
At the other end of it, where the rocks again approached each other, was probably a precipice. After a few minutes' cogitation, Captain Horn felt sure that he understood the whole matter: a subway from the lake led to this amphitheatre, and thus there had been no audible rush of the waters until they reached this point, where they poured in and filled this great basin, the lower end of which was probably stopped up by accumulations of sand and deposits, which even in that country of scant vegetation had accumulated in the course of years. When the waters of the lake had rushed into the amphitheatre, this natural dam had held them for a while, but then, giving way before the great pressure, the whole body of water had suddenly rushed down the ravine to the sea.
"Yes," said the captain, "now I understand how it happened that although I opened the valve at noon, the water did not reach the Rackbirds until some hours later, and then it came suddenly and all at once, which would not have been the case had it flowed steadily from the beginning through the outlet made for it."
When the captain had returned and reported his discoveries, and he and his party had finished their noonday meal, which they ate outside on the plateau, with the fire burning and six servants to wait on them, Mrs. Cliff said:
"And now, captain, what are we going to do? Now that our danger is past, I suppose the best thing for us is to stay here in quiet and thankfulness, and wait for Mr. Rynders. But, with the provisions we have, we can't wait very long. When there were but five of us, we might have made the food hold out for a day or two longer, but now that we are ten, we shall soon be without anything to eat."
"I have been talking to Maka about that," said the captain, "and he says that Cheditafa reports all sorts of necessary things in the Rackbirds' storehouse, and he proposes that he and the rest of the black fellows go down there and bring us some supplies. They are used to carrying these stores, and six of them can bring us enough to last a good while. Now that everything is safe over there, I can see that Maka is very anxious to go, and, in fact, I would like to go myself. But although there doesn't seem to be any danger at present, I do not want to leave you."
"As for me," said Miss Markham, "I want to go there. There is nothing I like better than exploring."
"That's to my taste, too," said the captain, "but it will be better for us to wait here and see what Maka has to say when he gets back. Perhaps, if Mr. Rynders doesn't turn up pretty soon, we will all make a trip down there. Where is Ralph? I don't want him to go with the men."
"He is up there on his lookout, as he calls it," said his sister, "with his spy-glass."
"Very good," said the captain. "I will send the men off immediately. Maka wants to go now, and they can come back by the light of the young moon. When they have loads to carry, they like to travel at night. We shall have to get our own supper, and that will give Ralph something to do."
The party of Africans had not gone half-way from the plateau to the beach before they were discovered by the boy on the outlook rock, and he came rushing down to report that the darkies were running away. When he was told the business on which they had gone, he was very much disappointed that he was not allowed to go with them, and, considerably out of temper, retired to his post of observation, where, as it appeared, he was dividing his time between the discovery of distant specks on the horizon line of the ocean and imaginary jaguars and pumas on the foot-hills.
CHAPTER XI
A NEW HEMISPHERE
With a tin pail in his hand, the captain now went to the cavern of the lake. He wished very much to procure some better water than the last that had been brought, and which Mok must have dipped up from a very shallow puddle. It was possible, the captain thought, that by going farther into the cavern he might find a deeper pool in which water still stood, and if he could not do this, he could get water from the little stream in the ravine. More than this, the captain wished very much to take another look at the machine by which he had let out the water. His mind had been so thoroughly charged with the sense of danger that, until this had faded away, he had not been able to take the interest in the artificial character of the lake which it deserved.
As the captain advanced into the dimmer recesses of the cavern, he soon found a pool of water a foot or more in depth, and having filled his pail at this, he set it down and walked on to see what was beyond. His eyes having now conformed themselves to the duskiness of the place, he saw that the cavern soon made a turn to the left, and gazing beyond him, he judged that the cave was very much wider here, and he also thought that the roof was higher. But he did not pay much attention to the dimensions of the cavern, for he began to discern, at first dimly and then quite plainly, a large object which rose from the bottom of the basin. He advanced eagerly, peering at what seemed to be a sort of dome-like formation of a lighter color than the rocks about him, and apparently about ten feet high.
Carefully feeling his way for fear of pitfalls, the captain drew close to the object, and placed his hand upon it. He believed it to be of stone, and moving his hand over it, he thought he could feel joints of masonry. It was clearly a structure built by men. Captain Horn searched his pockets for a match, but found none, and he hastened back to the cave to get the lantern, passing, without noticing it, the pail which he had filled with water. He would have brought the lantern with him when he first came, but they had no oil except what it contained, and this they had husbanded for emergencies. But now the captain wanted light—he cared not what might happen afterwards. In a very short time, with the lantern in his hand, which lighted up the cave for a considerable distance about him, the captain again stood at the foot of the subterranean dome.
He walked around it. He raised and lowered his lantern, and examined it from top to bottom. It was one half a sphere of masonry, built in a most careful manner, and, to all appearances, as solid as a great stone ball, half sunken in the ground. Its surface was smooth, excepting for two lines of protuberances, each a few inches in height, and about a foot from each other. These rows of little humps were on opposite sides of the dome, and from the bottom nearly to the top. It was plain they were intended to serve as rude ladders by which the top of the mound could be gained.
The captain stepped back, held up his lantern, and gazed in every direction. He could now see the roof of the cavern, and immediately above him he perceived what he was sure were regular joints of masonry, but on the sides of the cave he saw nothing of the sort. For some minutes he stood and reflected, his brain in a whirl. Presently he exclaimed:
"Yes, this cave is man's work! I am sure of it. It is not natural. I wondered how there could be such a cave on the top of a hill. It was originally a gorge, and they have roofed it over, and the bottom of the basin has been cut out to make it deeper. It was made so that it could be filled up with water, and roofed over so that nobody should know there was any water here, unless they came on it by means of the passage from our caves. That passage must have been blocked up. As for the great opening in the side of the cave, the rocks have fallen in there—that is easy enough to see. Yes, men made this cave and filled it with water, and if the water were high enough to cover the handle of that machine, as it was when I struck it, it must also have been high enough to cover up this stone mound. The lake was intended to cover and hide that mound. And then, to make the hiding of it doubly sure, the men who built all this totally covered up the lake so that nobody would know it was here. And then they built that valve apparatus, which was also submerged, so that they could let out the water when they wanted to get at this stone thing, whatever it is. What a scheme to hide anything! Even if anybody