Ned took out his pocket map and bent over it.

"Here we are," he said, presently, "in the valley of the Madeira, with a range of mountains on each side. Below are the rapids and the falls. You must have had a sweet time traveling up from Fort San Antonio. You pa.s.sed about three hundred miles of swift rapids and falls. How many times did you have to take the Black Bear to pieces?"

"Not once there," was the reply. "We managed to steam up. But, say, we had a lovely time getting up over one waterfall!"

"Well," Ned went on, "here we are at the big bend of the upper Madeira. We are not far from a thousand miles from the place where I found Lyman. We can get there by nightfall."

"Not for me," Jack said, with a shrug of the shoulders. "We should have to ride continuously to make it in that time, and I don't like to remain in the air that long. We ought to have five rests of an hour each, and get there in the morning."

"Yes," Ned replied, "I'm getting tired of long rides myself. We'll go slower."

After breakfast the boys went to the Black Bear and looked her over.

The propeller which had been broken could easily be repaired, they found, so they left that matter to Harry, replenished the tanks of the Nelson with gasoline, and prepared for the long journey back to the mountains of Peru.

"When are you coming back?" asked Harry, as the three mounted the machine.

"In three days," replied Ned. "And we'll bring Jimmie with us."

"If they haven't fed him to the mountain lions before now!" Harry said, with a strange premonition of evil in his heart.

And the Nelson was up and away, and Harry set to work cleaning up the motor boat, hoping to forget in toil how lonely and apprehensive he was.

CHAPTER XVII

USING BOY SCOUTS FOR BAIT!

Alarmed by the swift approach of the motor car in the tunnel, Jimmie and Jackson took to their heels and made swift progress toward the east entrance, throwing the searchlight about and keeping their eyes out for some hiding place as they ran.

Before long it became evident that they could not long maintain the pace they had taken. The motor car was gaining on them rapidly, as they knew by the steady approach of the clamor which the engines were making.

"Gee!" cried Jimmie, at last. "No use! I've got to drop in somewhere!"

Jackson was as ready to stop running as was Jimmie, so they drew up against the wall and Jimmie shut off the light from his electric candle.

"Do you think they saw that light?" asked Jimmie, pushing close to the rock wall. "I hope not."

"Probably not, as there was always an angle between us," was the whispered reply, "but their light is coming around that angle now.

Stand close!"

It was of little use to stand close.

Under the great lamps every crack and crevice of the tunnel walls was in plain sight to the occupants of the car. The two fugitives might as well have attempted concealment under the limelight in the center of the stage of a Broadway theatre!

Jimmie's hand was on his automatic as the car halted in front of him. Jackson saw what was in the boy's mind and laid a hand on his arm.

"None of that!" he said.

"Well, I'm not goin' to be--"

Jackson forced the revolver out of the boy's hand as he brought it out of his pocket.

"They've got us," he whispered, "and will be only too glad of an excuse to shoot us down in cold blood."

"Well!"

This from Thomas Q. Collins, who sat in the front seat, looking at the two as if he could bite them in pieces!

Jimmie looked sullenly toward his automatic, in Jackson's hand, and said not a word. Jackson stepped forward.

"You've got us!" he said.

"You bet we have!" gloated Collins. "Where did that Nestor boy go with the man he picked up by the fire?"

"Did he get him?" asked Jimmie.

"Yes, he got him, worse luck!" was the reply. "Where did he go with him?"

"Don't know," replied Jimmie.

"I'll find a way to make you know!" gritted Collins. "Do you fellows know what it is to be hungry?"

"Honest," Jackson cut in, "we don't know where Nestor went with Lyman. When he left us, he was not certain that he could get him.

Thought Lyman might not want to go away with a stranger on such short notice."

"Oh, what's the use?" demanded one of the others. "The fellow has gone back to Asuncion. That's easy to figure out. Who set you boys at work on this case?" he added, in a moment, at a whisper from his seat-mate.

"Ned set me at work," Jimmie answered.

"Yes, but who set him at work?"

"I'll tell you," Jackson said, with a smile of satisfaction on his face, "the United States government set Ned at work. You'd better watch out how you b.u.t.t up against the Secret Service men."

"That's just what I told you!" sneered Collins. "You wouldn't believe me. Now what do you think?"

The speaker left his seat in the machine and walked over to where Jackson was standing, the revolver still in his hand.

"Give me that gun!" he demanded.

Jackson pa.s.sed it over without a word of protest.

"Now your own gun," Collins demanded, extending his hand.

"I have no gun," was the reply. "You know that very well."

"I thought you might have stolen one since leaving the cow country,"