Up to the altar circled the bats, and then wheeling they flapped down the dim aisles toward the adventurers.

“Hurry!  Hurry!” shouted Andy, who was in the rear.

He raised his rifle and fired several shots into the midst of the terrible creatures.

A number of the bats were wounded, and the others were so frightened by the sound of the shots and the flashes of fire that they turned back.  This enabled the fleeing ones to gain the entrance to the temple, and soon they were outside.

“To the ship!” yelled Bill.

“There’s little danger now!” called Andy, panting, for the run had winded him.  “They will hardly attack us in the light!”

And he was right, for, though they could hear the bats flying about inside the temple, and uttering their cries, none came outside.

But no one felt like staying near the uncanny structure, and little time was lost in reaching the Mermaid.  Then the doors were fastened, and the ship was sent high up into the air.

“Which way?” asked Jack, when Mr. Henderson told him to go to the conning tower and steer.

“Back to where we first met the giants,” replied the professor.  “We must prepare to start for our own earth again soon.”

“I’ve almost forgotten how real sunlight looks,” thought Jack, as he headed the ship around the other way.  As he turned the levers a big diamond dropped from his pocket and rolled on the floor.

“This will be a good reminder of our trip though,” he added.

The travelers, even including Mr. Henderson, were so taken up with their suddenly acquired riches that they hardly thought of meals.  At the professor’s suggestion they tied their gold and stones up in small packages convenient to carry.

“Better place them where you can grab them in a hurry in case of accident,” the old scientist went on.  “Of course if there should be too bad an accident they would never be of any use to us down here, but we’ll look on the bright side of things.”

“Do you anticipate any accident?” asked Jack anxiously.

“No, Oh no,” replied Mr. Henderson, but Jack thought the aged man had something weighing on his mind.

CHAPTER XXIX

 Back home—­ conclusion

On and on sped the Mermaid.  Now that the travelers felt their journey accomplished they were anxious to begin the homeward trip.  They made a straight course for the village where they had so nearly met with disaster, and where the king of the giants had saved them.  They went in a direct line, and did not travel here and there, as they had after they left the town.  Consequently they shortened the route by a great distance.  Yet it was long enough, and when they finally came in sight of the place the dial registered a trip of five thousand miles underground.

It was one evening when they landed almost at the spot whence they had taken flight eventually to reach the temple of the treasure.  Most of the giants had betaken themselves to their mound houses, but Hankos was walking in the fields, and, when he caught sight of the airship hovering above him he waved his great sword in welcome.