“I’m still unable to account for his action,” said Dick. “If his object is robbery, surely he has taken a strange way to go about it.” “Perhaps he’s counting on frightening us good and plenty,” observed Brad. “Mebbe when he thinks we’re so frightened that we’ll be glad to cough up liberal he will appear and offer to conduct us back to the outer world.” “Let’s call to him,” eagerly suggested the professor. Then he lifted his voice and called loudly. When he had repeated the cry three times, they listened. “Didn’t you hear a distant answer?” asked Dick. “I judge whatever we heard was an echo,” said Brad. After a time they lifted their voices in a united shout, and then listened to the mocking echoes which fled from pillar to pillar and died in the unknown distance. “No use!” moaned Professor Gunn. “I am satisfied that we are doomed! We’ll never leave this place alive, and our fate will forever remain a mystery!” “I’m sure that was no echo!” exclaimed Dick, as far away in the darkness they seemed to hear an answer to their repeated shouts. “Be still and let me shout.” When he had lifted his strong, clear voice all hushed their breathing and listened. There was a short interval, and then out of the black distance came a faint, far-away answer. “Some one did shout, pard!” exclaimed the Texan. “It’s a dead-sure thing!” Excitedly they all joined in the hail that followed. The answer was more distinct. Dick had found an oar, and he slowly propelled the boat in the direction from which the answering cries seemed to come. Occasionally they bumped against the marble pillars, but these collisions did no damage. Soon they could hear the answers to their cries and knew they were drawing nearer to the unknown person or persons who were thus responding. Suddenly a tiny gleam of light showed amid the pillars at some distance. “Looks like that’s a match, pard,” observed Buckhart. “I reckon I’ll strike one, too.” He did so, but the other light disappeared even as he held his own above his head. Apparently his match was seen, for the voice of a man reached them, urging them to come in that direction. By answering call for call they continued to draw nearer to the strangers, for they soon heard enough to satisfy them that at least two persons besides themselves were afloat on the bosom of that buried lake. “One is a woman!” asserted Dick. Lifting his voice, he asked: “Who are you?” “We are Americans. Who are yo’?” “We are Americans, too.” “What are yo’ doing here?” “We are lost—deserted by our guide.” “So are we. How many of yo’ are there?” “Three. How many of you?” “Two; and somebody shall suffer fo’ this outrage! Somebody shall pay the penalty fo’ it! I’ll have satisfaction as sho’ ’s my name is——” “Major Mowbry Fitts, of Natchez, Mississippi,” finished Dick. “That’s my name, suh! But yo’, suh—why, is it possible that yo’ are——”