“Wait a bit,” said the major; “there is a lovely piece here. What’s that?”
Mark listened, as he stood close to the major, where the cavern went right in like a narrow triangle with curved sides.
A low hissing noise saluted their ears, apparently coming from a great distance off.
“Snakes!” whispered Mark.
“Steam!” said the major. “Why, Mark, this passage must lead right into the centre of the mountain. There, listen again! You can hear a dull rumbling sound.”
“Yes, I can hear it,” said Mark in an awe-stricken whisper.
“I dare say if we went on we should see some strange sights.”
“Without lights?” said the captain, who had approached them silently.
“Perhaps we should get subterranean fire to show us the interior of the mountain. What do you say?—shall we explore a little further? One does not get a chance like this every day.”
“I’m willing to come another time with lights, but it would be madness to go on in the dark. How do you know how soon you might step into some terrible chasm?”