All this while poor Pomp had been lying insensible upon a heap of mats in the after cabin, where he had been dragged and left.

But now the darky began to come out of his faint.

The blow upon the skull had inflicted no serious wound, and he must be all right again shortly. But for a time he was sick and dizzy.

Frank and Barney found him and gave him some stimulants. He very quickly recuperated.

Then he remembered his experience with Bowler on the deck. He felt somewhat crestfallen.

But Frank said:

“It’s all right, Pomp; you meant well, but the fellow was treacherous. Next time don’t get caught.”

“Yo’ kin jes’ bet on dat!” cried the darky. “I won’t trust nobody aftah dis.”

It is needless to say that the aerial voyagers were delighted with the result of the affair. Their deliverance was due to Frank’s shrewdness and marvelous ingenuity.

The two prisoners were confined in the after cabin. But it was now a question as to what it was best to do with them.

“Suppose we go down and talk with their companions!” said Nicodemus; “perhaps they will make up their minds to behave themselves and let us alone after this!”

“Very well,” agreed Frank. “We will try that.”

So down sank the air-ship. The gold seekers were seen grouped below in a state of much excitement.

Frank went to the rail and opened a parley with them.

“We have your two leaders, Dooley and Bowler, as prisoners!” declared the young inventor. “We want to know if you are going to play any more treacherous games upon

The gold seekers were evidently astonished at the turning of tables in so unexpected a manner.”

But finally they came to Frank’s terms and made fervid vows never to trouble the air-ship or its party again.

Their spokesman said:

“To tell ther truth, mister, we don’t believe in ther story of ther hidden gold an’ we’re sick of the whole thing. We’re goin’ back to Para.”

“Very good!” said Frank. “I will set your leaders free upon that condition.”

Then he went into the cabin and talked with Dooley and Bowler. They readily agreed to Frank’s terms.

“I shall follow you as far as the shore of the lake,” declared the young inventor; “if you dare to return I will drop dynamite bombs upon you and destroy you.”

Dooley was satisfied.

He saw that it was of no use to attempt to cope with the voyagers. Moreover, he had lost faith in the existence of the treasure.

He was in fact sick of the whole job and decided to return to America at the first chance. So he said:

“I’ll do as you say. I’m quits on this thing. It’s an accursed country, anyway.”

A short while later the two villains returned to their companions. They at once started for the shore of the lake.

Frank decided not to accompany them, for he saw that Dooley was in earnest.

As the villain dropped from the air-ship, Frank said:

“As an extra incentive, I will promise this, in spite of your bad treatment of us. If we find the gold I will overtake you and give you a fair division.”

Dooley hung his head and muttered abashed thanks. Then he and his party were off.

The aerial voyagers continued the quest for the gold. All that day they explored the sandy basin.

Toward night a find was made.

A number of human bones were mixed up with several hundred ingots of the yellow stuff. It was taken aboard the air-ship.

Frank estimated its value.

“There is about thirty thousand dollars in the pile,” he said, “there are twelve in Dooley’s party and four in ours. That will make about two thousand each on a fair division.”

“They are not entitled to any of it,” snapped Nicodemus.

“Perhaps not,” said Frank, “but we have banished them from the search and therefore ought to divide. At any rate I have promised it.”

“Oh, I don’t kick,” said the captain, cheerfully; “I am satisfied. It was not the gold I cared for so much as to solve the mystery of this lake.”

“And that we are now at liberty to do,” said Frank; “we will first overtake Dooley and his men and divide. Then we will do a little exploring.”

With this decision none found fault. So Frank took his leave of the treasure basin.

The gold seekers were overtaken on the shore of the lake. They were astonished at Frank’s generous announcement.

And when the gold was turned over to them Dooley wrung Frank’s hand and said:

“You’re the only square man I ever met in my life. I like your style. I’m going ter turn over a new leaf an’ do better.”

Then Dooley and his men set out to the eastward for the head waters of the Paraguay where they had boats. None of the aerial voyagers ever saw them again.

But one thing more now remained to be done to complete the success of the trip.

This was to find the source of the Transient Lake and if possible discover an explanation of its curious appearance and disappearance.

For full one hundred of the two hundred miles of its width the air-ship sailed over the lake. They were now very near the centre.

And here a mighty circular bowl-shaped basin was seen. It had curious galleries leading down into the earth.

These were cut out of the solid rock. This basin covered hundreds of acres. The air-ship was here brought to a stop.

“Here,” said Frank, positive............