"Pretty near three hundred miles wide at the delta, including that big island," Harry said. "It is some river, eh?"

"Four thousand miles long!" Jack contributed. "It is navigable for commercial purposes for 2,200 miles, and our boats can go up clear to the foot of the Andes."

"Boats went there in the days of Columbus," Frank said. "A companion of Columbus first discovered this great delta. The river fertilizes two million square miles of territory, and is the greatest water system in the world."

"Why," Harry observed, desiring to contribute something startling to the discussion of the river, "the current is so strong that it carries fresh water and sand five hundred miles out into the Atlantic Ocean. It is just a fresh water river in a salt water sea for five hundred miles!"

That night the boys kept the engines of the Black Bear going, one remaining on watch all through the dark hours. They had plenty of gasoline in the tank, and the tender, the Wolf, was carrying a load of fuel which Jack declared would last them until the end of the year!

It may be well to state here that the Black Bear, the Boy Scout motorboat, was a specially constructed vessel, built by Harry's father for river work. The materials were light yet strong, and the boat could easily be taken apart and put together again when occasion required. Between the cross-grained slices of tough wood of which the craft was built were plates of steel, thus rendering the boat virtually bullet proof.

The Black Bear was constructed so that it could be almost entirely thrown open to the sunshine when so desired or closed tightly against cold or rain. The roof could be rolled up in a bundle in the middle like the curtain of a modern desk. The sides were composed of oblong panels which could be inserted in grooved steel uprights when it was desired to close in the interior of the boat.

The motors were very powerful.

In fact, it was just such a boat as was needed on the trip the boys had in mind. It had done excellent service on the Columbia, and nothing less could be expected of it on the Amazon. The Wolf, which was merely a tender, was watertight in construction, being shaped like a banana, and was towed by the motor-boat. Here the extra stocks of gasoline, provisions, and ammunition were packed. The interior of the Wolf was about six feet by eighteen in size, while the distance from rounded floor to convex roof was about four feet.

On both sides of the interior were gasoline tanks, which also extended under the floor, lifting the bottom of the interior s.p.a.ce three feet. Above the tanks were s.p.a.ces for provisions and ammunition. The s.p.a.ce between the tanks and the lockers was about two feet, and here one might ride in comfort, after getting used to the rolling of the boat. There were tight gla.s.s panels of thick plate gla.s.s at the ends and the top.

Ventilators and loopholes, controlled by wires from the center, were cut in the ends and protected by sliding covers. Lying in the pa.s.sageway, one might look out at either end, and shoot out, too, if occasion required. When fully loaded, the Wolf was submerged about half its height. On the top was a staff from which floated an American flag. The boys were very proud of the Wolf, and Jimmie had often declared, on the Columbia river trip, that he would some day take an exciting ride in it.

During their pa.s.sage up the river the boys were often hailed from pa.s.sing craft, but they took little heed, as they did not care to lose time gratifying the curiosity of those they met. Indeed, if they had stopped to talk with all who hailed them, they would have made slow progress. Up to about sixty years ago the Amazon was closed to all save Brazilian vessels, but now it is open to the commerce of the world.

There are now vessels coming from and going to all parts of Europe and America from Amazon ports. There are lines of great steamers on the main stream, lines of smaller steamers on the big tributaries, and launches and small craft of all sizes on the affluent branches.

Often the pa.s.sing ships, steamers, launches, etc., almost took the form of a procession on the lower waters.

Everywhere the smaller ships were gathering the products of the great Amazon basin-rubber, cocoanuts, hardwoods, dyewoods, pelts, tropical fruits and other commodities. Every year over three million tons of products come down the great river. The Amazon drains a country as large as the United States east of the Mississippi. Its feeders reach the Andes, draining watersheds within a hundred miles of the Pacific ocean. It has tributaries fifteen hundred miles long.

It did not take the Black Bear very long to pa.s.s the green islands near the delta. The river there looks like an ocean. In fact, the main branch of the Amazon is from fifty miles to two hundred miles in width. Some of the tributaries are a hundred miles wide. It is from fifty to two hundred feet deep. The water is always dark colored because of the wash brought down from the uplands. For a long time it did not seem possible to the boys that they were sailing on a river instead of an ocean.

"Ned and the boys must be over Paraguay now," Jack said, one day, after they had been on the river nearly a week without accident or important incident of any kind.

"Yes," Frank replied, "they must be there by this time. Jimmie said they were to leave San Francisco on the 7th, or about that time. It would take a week or more to get to Lima, for they couldn't remain in the air long at a time, and the resting spells would set them back a little. Suppose they got to Lima on the 14th, which was last Monday, they could rest up and go prowling over that dirty little republic--which is not a republic at all, but a despotism tempered by revolution."

"I'd like to know just what course Ned has decided on," Harry said.

"I don't see how he's going to get to Mr. Lyman."

"He'll find a way," Jack insisted. "He always has, and he always will."

It will be seen that the boys were tolerably accurate in their estimates of the speed of the Nelson. On the day they were discussing the possible location of the big airship, which was the 18th of August, the Nelson was in the center of as pretty a muss as Ned had ever mixed with.

The boys in the Black Bear put on all speed, traveling nights as well as days, and before long began watching the heavens, for an aeroplane. But the lads on the Nelson were not looking for a boat poking her nose toward the Andes--"a relief expedition," as Jack called it!

CHAPTER IV

A CHASE IN THE NIGHT

Following the excited announcement by Mike that an airship was prowling about over the mountains and Leroy's sudden cry of exultation at the prospect of a struggle for supremacy above the clouds, there was for a moment absolute silence in the hotel room where the boys stood. Finally Pedro entered and closed the door.

Ned walked to a window and looked out. The day was fading, and already the feet of the distant mountains were wrapped in purple twilight. The window faced the north, giving a fair view of the city and the Andes as they strung along in that direction, looking like a chain of bald heads lifting from the obscurity of a fog. The airship was not in sight from where he stood.

Pedro saw what he was looking for and stepped to his side, one hand pointing off to the east.

"Out there!" he said.

"When did you first see it?" asked Leroy, not waiting for Ned to conduct the cross-examination.

The Indian talked with Mike for a moment.

The latter did not seem to understand all that was said to him, but presently he turned to Ned.

"He says he saw it only a minute before he came here," he explained.

"He says a lot more that I can't understand. I've been here only a month, and I'm not quick at learning new speech."

"Ask him if he knows whether she landed anywhere near the city," Ned directed.

The Indian did not know. The airship was over the mountains when he first saw it, and that was all he could say about it.

"Do you think we've been followed down here?" asked Jimmie.

"Of course!" Leroy broke in. "What else would an airship be here for just at this time? And if she wasn't sneaking about after us, what would she be hanging up there in the sky for? Why doesn't she come down to town, like we did?"

"It may be that the arrival of this airship just at this time is a coincidence," Ned said, "but it seems to me that there is something significant about it. I have felt all along that we were not yet rid of the rascals who tried to make us trouble at San Francisco."

"Some one must want the cattle concession that Lyman has pretty badly," Leroy ventured. "Well, we'll, have to run away from them, I take it!"

"Then how are we going to find out where this Lyman person is?"

demanded Jimmie. "No, Sir!" he went on, rubbing his freckled nose in meditation. "We've just naturally got to bust 'em up!"

The proposition was indeed a serious one. If the airship was really there to take note of the activities of the boys on the Nelson, the situation could hardly be improved by following either line of conduct suggested by the boys.

Nothing could be gained by "running away" from the unwelcome visitor. Nothing was to be gained by following the advice to "bust 'em up." A race would only serve to draw the Nelson away from the point of action, away from the place where Lyman was held in captivity. To "bust 'em up" would be to set all the official rings of Paraguay in operation against the lads, place the Boy Scouts under the ban of the law!

"If we only knew just where to find this Lyman person," Jimmie went on, "we might swoop down an' get him an' give the lobsters a run for their money."

"Perhaps," Ned suggested, "we'd better wait for this new navigator of the air to show us where he is."

"I see him doing it!" cried Leroy.

"You bet he will!" Jimmie cut in. "He'll hang around the point of danger! He'll show us where the man is by standing guard over him!

What?"

"That's my idea," Ned replied, "still, he may devote his energies to keeping track of us. One can never tell what an enemy will do."

"Well," Leroy said, "I'm going back to the Nelson. There's a chance of the lobster dropping down and trying to cripple her."