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.