“Come on!” cried Tom, impetuously.

“Wait a moment,” suggested the professor, “Sometimes the air in these places is foul.  We must test it.”  But a torch one of the Indians threw in burned with a steady glow.  That test was conclusive at least.  They made ready to enter.

Torches of a light bark, that glowed with a steady flame and little smoke, had been provided, as well as a good supply of electric dry-battery lamps, and the way into the cavern was thus well lighted.  At first the Indians were afraid to enter, but a word or two from Goosal reassured them, and they followed Professor Bumper, Tom, and the others into the cavern.

For several hundred feet there was nothing remarkable about the cave.  It was like any other cavern of the mountains, though wonderful for the number of crystal formations on the root and walls—­formations that sparkled like a million diamonds in the flickering lights.

“Talk about a wonderland!” cried Tom.  “This is fairyland!”

A moment later, as Goosal walked on beside the professor and Tom, the aged Indian came to a pause, and, pointing ahead, murmured: 

“The city of the dead!”

They saw the niches cut in the rock walls. niches that held the countless bones of those who had died many, many years before.  It was a vast Indian grave.

“Doubtless a wealth of material of historic interest here,” said Professor Bumper, flashing his torch on the skeletons.  “But it will keep.  Where is the city you spoke of, Goosal?”

“Farther on, Senor.  Follow me.”

Past the stone graves they went, deeper and deeper into the great cave.  Their footsteps echoed and re-echoed.  Suddenly Tom, who with Ned had gone a little ahead, came to a sudden halt and said: 

“Well, this may be a burial place sure enough, but I think I see something alive all right—­if it isn’t a ghost.”

He pointed ahead.  Surely those were lights flickering and moving about, and, yes, there were men carrying them.  The Bumper party came to a surprised halt.  The other lights advanced, and then, to the great astonishment of Professor Bumper and his friends, there confronted them in the cave several scientists of Professor Beecher’s party and a score or more of Indians.  Professor Hylop, who was known to Professor Bumper, stepped forward and asked sharply: 

“What are you doing here?”

“I might ask you the same thing,” was the retort.

“You might, but you would not be answered,” came sharply.  “We have a right here, having discovered this cavern, and we claim it under a concession of the Honduras Government.  I shall have to ask you to withdraw.”

“Do you mean leave here?” asked Mr Damon.

“That is it, exactly.  We first discovered this cave.  We have been conducting explorations in it for several days, and we wish no outsiders.”

“Are you speaking for Professor Beecher"’ asked Tom.