ADVENTURES OF CAPTAIN HORN
scended into the mound, and then, moving the foot of the ladder out of the way, he vigorously began to brush away the dust from the stone pavement. When this was done, he held up the lantern and carefully examined the central portion of the floor, and very soon he discovered what he had come to look for. A space about three feet square was marked off on the pavement of the mound by a very perceptible crevice. The other stones of the pavement were placed rather irregularly, but some of them had been cut to allow this single square stone to be set in the centre.
"That's a trap-door," said Burke. "There can't be any doubt about that." And immediately he set to work to get it open.
There was no ring, nor anything by which he could lift it; but if he could get his heavy chisel under it, he was sure he could raise it until he could get hold of it with his hands. So he began to drive his chisel vigorously down into the cracks at various places. This was not difficult to do, and, trying one side after another, he got the chisel down so far that he could use it as a lever. But with all his strength he could not raise the stone.
At last, while working at one corner, he broke out a large piece of the pavement, eight or nine inches long, and found that it had covered a metal bar about an inch in diameter. With his lantern he carefully examined this rod, and found that it was not iron, but appeared to be made of some sort of bronze.
"Now, what is this?" said Burke to himself. "It's either a hinge or a bolt. It doesn't look like a hinge, for it wouldn't be any use for it to run so far into the rest of the pavement, and if it is a bolt, I don't see
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