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.