“Well,” said Jack, after a moment spent in surveying the obstruction, “we might have expected something like that. The question is, what are we going to do?”

“We might land and remove it,” hazarded Ned.

But Jack shook his head.

“Jupe, go below and call Captain Andrews,” he said, in as calm a voice as he could muster. “We won’t risk landing and trying to lower the chain for two reasons. One is, that Herrera, having been cunning enough to put up the barrier, is not likely to have left it unguarded. There may be hidden eyes watching us right now. The second reason is, that it has just occurred to me that a man who is playing the game he is, may have placed other more dangerous obstacles in our path.”

“For instance?” came from Tom.

“For instance,—mines.”

“By the holy poker! That’s so,” exclaimed Ned, “I guess we’d better turn back and make our advance by land.”

“Here’s Captain Andrews now,” struck in Tom, as the skipper of the Sea King came on deck, hastily adjusting his white pith helmet.

There was no need to tell that veteran seaman what had happened. He took in the situation at a glance.

“It would have been funny if we hadn’t run up against something like this,” he remarked, almost in Jack’s words.

“The point is,—what now?” said Tom.

Captain Andrews agreed with Jack that it would be a foolish risk to land and try to remove the chain.

“I’ve quite a notion that there are some rifles in that brush, all ready for use in case we try to proceed,” he said reflectively, “my advice is to drop back down stream and hold a council of war.”

All agreed that this did seem about the only thing to do under the circumstances, and accordingly Tom handed the wheel over to the sailor while he went below to “stand by” the engines.

In that muddy stream, with its sand banks and shoals, the maneuver they were going to try would call for some delicate seamanship and swift handling of the motor.

Captain Andrews, with his lips grimly compressed, grasped the wheel and sounded a signal. Slowly the Vagrant, which had been “hanging” motionless, began to drop back with the current.

“Too bad we can’t turn around,” complained Jack.

“Wouldn’t dare to chance it,” rejoined the captain, “for all we know there may be a sandbank on either side of us right now.”

A deathlike silence hung over the Vagrant as she drifted stern first down the river. The wheel spun swiftly this way and that under the helmsman’s muscular direction.

“She goes as well backward as she does forward,” Ned was beginning, when there came a sudden shock that almost threw them off their feet. Jupe, in fact, did fall sprawling on the bridge.

At almost precisely the same instant a shower of bullets whizzed above them, singing a sinister song as they screeched about the motor craft. Dense brush lined the banks, and the shooters were well concealed in it. Not even a puff of smoke betrayed their exact whereabouts.

And, while this hailstorm of lead whistled about the adventurers, they realized all too clearly that the Vagrant had run hard and fast on one of the very sandbanks the captain had dreaded. One thing, however, speedily became evident, and that was that the bullets had not harmed them, because they were not intended to—yet. The shower of lead was aimed high above their heads. Presently it ceased altogether.

“That was a warning,” decided Captain Andrews. “Boys, your folks are certainly surrounded by a barb-wire fence.”

The lads did not answer. But as they sensed the nature of the obstacles that were piling up in the way of their enterprise, a look of consternation came over their faces. “The Chadwick Relief Expedition,” as they had christened it, appeared to have run up against a stone wall.

“I guess we are not in any danger of another fusillade if we stay where we are, or keep on dropping back,” said Captain Andrews after an interval of thought, “but if we try to keep on going we’ve had a sample of what to expect.”

The boys could not but agree with him. At length Jack spoke.

“Hadn’t we better try to get the Vagrant off whatever we’ve struck?” he said. “I’ve got a plan in my head in that case; but I don’t think this is the healthiest place to discuss it.”

“We can put out a light anchor and try to warp off,” said Captain Andrews.

It was agreed to try this plan for rescuing the Vagrant from her uncomfortable berth. The dinghy was lowered and manned by Jack and Tom, who took with them the light anchor which was attached to two hundred feet of line. A hundred feet down stream they dropped the mud-hook, and then rowed back to the Vagrant.

When they were once more on board the winch was manned and, to their delight, as the rope tightened the Vagrant’s stern began to swing.

“Keep at it, lads,” cried Captain Andrews to the perspiring laborers, “if that anchor will only hold I believe we can get off.”

The anchor did hold, and after ten minutes more of back-breaking work the craft’s bow slid out of the mud bank with a sucking sound, and she was once more free. The anchor was hauled on board, and, without further mishap, the Vagrant was set once more on her down-stream course.

The first attempt of the courageous little band to rescue their comrades had met with a rather ignominious failure. Captain Andrews said as much that evening, as they found themselves anchored near the mouth of the river they had fruitlessly ascended with so much pains.

The skipper voiced this opinion after supper, while they sat on deck casting anxious eyes to seaward now and again, for the recollection of the Tarantula was strong upon them. Above all things, they dreaded the reappearance of that drab-colored craft.

“You said you had a plan, Jack,” said Tom, as the skipper disconsolately drew on his pipe, “Now’s the time to broach it. What is it?”

“Just this,” was the simple reply, “we’ve got the aero-auto. It looks as if the time had come to use her.”

“And leave the Vagrant here to be destroyed when Herrera happens along?” demanded Tom.

“That doesn’t follow. Did you notice that small creek almost overgrown with brush that branches off about a mile above here?”

“Yes, lad,” came from Captain Andrews, whose tones gave evidence of his intense interest, “you’re planning to hide the Vagrant there till we come back again?”

“You’ve caught my idea exactly,” said the lad. “What do you think of it?”

“That it’s a dumb-gasted good one, and that I, for one, am willing to risk my neck in that flying automobubble of yours any time you say the word.”

“Then I say it right now,” shot out Jack, with flashing eyes. “We can’t ascend this river by water; we’ll try the air route.”

It was while they were still buzzing with the enthusiasm that Jack’s fiery words had created that Tom uttered a sharp exclamation.

“Jupiter!” he exclaimed, pointing seaward. “Look yonder. We’re not playing a lone hand in this thing now.”

Some distance off apparently, but rushing across the water at a swift pace, was a bright white gleam,—the light of a vessel approaching the bar at top speed.

“The Tarantula, for all I’m worth!” exploded Captain Andrews. “Confound her, why couldn’t she have kept her hands off for twelve hours longer?”