“Can—­can we make it, Tom?” panted Ned.

They were almost at the river channel now, and in another instant they had reached it.

By the feeble rays of Ned’s electric torch they saw with relief that it was empty, though they would have given much to see just a trickle of water in it, for they were almost dead from thirst.

Together they climbed up the other side, and as yet their pursuers had not reached the brink.  For one moment Tom had a thought of working the black knob, and flooding the channel, but he could not doom even the head-hunters, much less the Fogers and Delazes, to such a death as that would mean.

On ran Tom and his companions, but now they could glance back and see the foremost of the other crowd dipping down into the dry channel.

“The steps!  The steps!” suddenly cried Ned, when they had run a long distance, as a faint gleam of daylight beyond shewed the opening beneath the stone altar.  “We’re safe now.”

“Hardly, but a few minutes will tell,” said Tom.  “The balloon is in shape for a quick rise, and then we’ll leave this horrible place behind.”

“And all the gold, too,” murmured Ned regretfully.  “We’ve got some,” said Mr. Damon, “and I wouldn’t take a chance with those head-hunters for all the gold in the underground city.”

“Same here!” panted Tom.  Then they were at the steps and ran up them.

Out into the big auditorium they emerged, weak and faint, and toward the hidden dirigible balloon they rushed.

“Quick!” cried Tom, as he climbed into the car, followed by Mr. Damon and Eradicate.  “Shove it right under the broken dome, Ned, and I’ll turn on the gas machine.  It’s partly inflated.”

A moment later the balloon was right below the big opening.  The blue sky showed through it—­a welcome sight to our friends.  The hiss of the gas was heard, and the bag distended still more.

“Hop in!” cried Tom.  “She’ll go up I guess.”

“There they come!” shouted Ned, as he spoke the foremost of the head-hunters emerged from the hole beneath the stone altar.  He was followed by Delazes.

“Stop them!  Get them!  Spear them!” cried the contractor.  They evidently thought our friends had all the gold from the underground city.

Fortunately the temple was so large that the balloon was a good distance from the hole leading to the tunnel, and before the foremost of the head-hunters could reach it the dirigible began to rise.

“If they throw their spears, and puncture the bag in many places we’re done for,” murmured Tom.  But evidently the savages did not think of this, though Delazes screamed it at them.

Up went the balloon, and not a moment too soon, for one of the head-hunters actually grabbed the edge of the car, and only let go when he found himself being lifted off the temple floor.

Up and up it went and, as it was about to emerge from the broken dome, Tom looked down and saw a curious sight.