CHAPTER XIX
THE UNDERGROUND RIVER
They gathered around the opening so unexpectedly disclosed to them, and stared down into the black depths. Beyond the first few steps of the flight that led to they knew not where, nothing could be seen. In his impatience Tom was about to go down.
"Bless my match box!" cried Mr. Damon. "What are you going to do, Tom, my boy?"
"Go down there, of course! What else? I want to get to the underground city."
"Don't!" quickly advised the odd man. "You don't know what's there. It may be a trap, where the old Aztecs used to throw their victims. There may be worse things than bats there. You'll need torches—lights—and you'd better wait until the air clears. It may have been centuries since that place was opened."
"I believe that's right," agreed Ned. "Whew! Smell it! It's as musty as time!"
An unpleasant odor came up the tunnel en-
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