"This is a _good time of night to call_," said the man with a peculiar emphasis. To Merritt it sounded as if the words just spoken were a sort of countersign. At any rate nothing more was said. The old negro admitted the stranger to the hut and closed the door.

"Now what sort of work is on foot," muttered Merritt to himself. "What mischief are those rascals up to? It's all most mysterious. This fellow whom we've seen with Jared first borrows electric batteries and then tries to send a cipher message. I can't make it out."

He stood a moment irresolute as to what course to pursue. Should he go back and tell Mr. Raynor what he had discovered? But the next minute he decided not to. After all he had no proof; he would try to peep into the hut and see what was going on. Cautiously he reconnoitered, completely circling the hut. But not a gleam of light was visible.

Bit by bit he crept closer, using the utmost caution. At length he got close to the rear wall and here, to his huge delight, he found a crack through which he could peer at what was going on within. What he saw made his heart leap. Round a table were seated Estrada, Alverado, the strange man and Jared Applegate. Jared's face was white and frightened but the others wore a sort of deadly composure. In the background stood the old darky who had opened the door. On the table was a smoky kerosene lamp.

But on the table also were some objects that puzzled Merritt. There was a bra.s.s lever, not unlike a telegraph key, and by it an array of batteries with wires leading from them. The strange man was seated near the bra.s.s key, with which he was toying carelessly, and yet with a certain caution.

"Be careful," Alverado was warning him, "don't be premature, my dear Castro; in your eagerness you have already broken two batteries."

"Yes, but the accommodating station agent replaced them. Ha! ha! if he had known what they were for! But he wouldn't handle cipher, confound him!"

"That was the order of these hated Yankees. But after to-night we shall triumph over them. One touch of that key in the right direction and----"

Estrada, who was speaking, spread his hands expressively. The others'

eyes blazed; only Jared cowered and looked badly frightened.

"Why can't you put it off till I get out of the country?" he begged.

"So we would have, because of the service you did us in showing us where to place the--the little matter you know of. But you have been well rewarded. Why repine? As for putting it off, what time like the present?

Mainwaring is away and those cursed little rats of spies, Boy Scouts, as you call them, are with him. We are safe."

But Jared only cowered and quivered the more. As for Alverado, who had uttered the words just recorded, he lit a fresh cigarette and regarded the whining youth with scorn.

Merritt's blood almost froze as he looked on at this strange scene. He had a quick mind, and from almost the first he had guessed what that paraphernalia on the table meant, what the "patriots," as they doubtless called themselves, were waiting for. But the Boy Scout did not wait. He ran, as if on wings, from that hut in the hollow, his pulses beating like snare drums and a fearful doubt a.s.sailing his mind.

"Would he be too late?" That was the fear that pounded at Merritt's brain as he raced along for the "gold-men's" row of houses. At the summit of the little hill, leading up from the hollow of the hut, he stumbled over something, something that entangled his foot. He leaned to examine it and then gave an astonished cry. The next moment he had whipped out his scout knife and cut his foot loose of the enc.u.mbrance. After that for some reason he went more slowly, but still he ran, ran to summon aid for Uncle Sam against a gang of foul plotters.

Half an hour later the scene in the hut was not much changed, but a tense silence had fallen over its inmates. On every face was a strained, anxious look, yet underlaid by an expression of exultation. Jared alone was missing. In an agony of fear and remorse he had broken from the hut a short time before. They had not tried to check him.

"Ready?" said Estrada, who held a watch. He was deadly pale.

The strange young man by the table shoved back a stray lock of black hair with long, thin fingers. One hand trembled on that bra.s.s key that Merritt had noticed.

"Let the invader! the usurper! the tyrant take warning from to-night!"

cried Alverado solemnly in a declamatory tone.

Suddenly there came a crash outside. The door was carried inward off its hinges. A crowd of men, in the uniform of the Gatun police, burst into the room.

"Seize that man!" cried Mr. Raynor, who was in the lead. He pointed to the strange young man whose fingers were already pressing the key downward.

"Betrayed!" shrieked Alverado as a revolver was knocked upward out of his hand.

The police, taking no chances after this, sprang forward toward the man at the key with leveled weapons.

"Surrender!" they called out.

"Not till I've blown Uncle Sam's work to Kingdom Come!" cried the wretch with a hideous laugh.

His fingers pressed the key. But no earth-shaking explosion followed. The tons of dynamite that had been cunningly concealed in a spill-way half a mile off did not explode. The Gatun Dam was not hoisted skyward and the work of years ruined.

There was only a feeble "click," echoed by two more as the handcuffs were snapped on Alverado and Estrada.

Mr. Raynor fairly embraced Merritt and the rest crowded round him.

"If it hadn't been for you, my boy, and your presence of mind in guessing what that wire was you stumbled across and cutting it, the dam might have been blown up in accordance with this wretch's desires," he declared, and then, as the miscreant, who had in vain tried to send the fatal spark to the dynamite, was made a prisoner, Mr. Raynor raised his voice:

"Three cheers for the Boy Scouts!" he cried, "and in particular for Merritt Crawford of the Eagles. Had it not been for his quick wits in guessing that a plot was on foot when he saw that wretch yonder at the Gatun station, this might have been a black night for Uncle Sam and the Panama Ca.n.a.l."

The cheers were given with right good will. Soon afterward the prisoners, including the old black man, were marched off to the lock-up maintained at Gatun for offenders on the ca.n.a.l work, although, it is safe to say, it never before housed such monsters as the would-be dynamiters of the Gatun Dam.

"If only the rest were here and safe," said Merritt to Mr. Raynor late that night, "I should be perfectly happy. As it is I don't feel as if I could rest till we are reunited."

It was the next day that the entire community, already wild with excitement over the discovery of the plot against the dam and the capture of the chief conspirators, was treated to a fresh thrill. Down the river, which had somewhat subsided, came two canoes. In the first one were Rob and Mr. Mainwaring. In the second sat Tubby and Fred. How they had met is soon explained.

As Tubby had guessed, the river they had seen from the ruins was the Chepalta. Its swift current had carried them into the Chagres itself and in course of time they came to the spot where Mr. Mainwaring and Fred, sadly distressed and worried over the loss of the launch, had decided to spend the night. They had built a roaring fire to keep off serpents or wild beasts, and Tubby and Fred, as soon as they saw the blaze, had made for it. In a few seconds a joyful reunion had taken place. As more sleep that night was out of the question, they had waited till the first flush of dawn and then emptied one of the provision canoes. In this Mr.

Mainwaring and Rob seated themselves and they all paddled back to civilization.

Their amazement when they heard of what had been taking place at Gatun during their absence may be, to use a phrase hackneyed but apt, "better imagined than described." There is no s.p.a.ce here to relate all that followed or to give the details of the trial and sentencing of the rascally plotters. It was found, for they confessed in hope of immunity, that the plot was far more widely organized than had been thought. Dozens of laborers were implicated before the end, and it was the number engaged that had made it possible for them to elude the vigilance of the Gatun Guards, secrete so much dynamite and then connect it with wires to the lonely hut in the hollow. As for the strange young man, it was found that he had been a chemist specializing on explosives, who had thought to avenge his country's fancied wrongs by enlisting with the plotters.

Had it not been for Merritt, who received the personal congratulations of Col. Goethals and the Commission, there is little doubt but that the great dam might have been damaged almost beyond hope of reconstruction.

The boy bore his honors modestly, as became a true Scout, and of course the story did not get to the newspapers, so that he was spared the embarra.s.sment of being interviewed and lionized. His comrades felt for him nothing but pride and admiration.

Those pebbles that Tubby picked up proved to be raw emeralds of great value and you may be sure that each of his friends was presented with one. The chums of Lucy Mainwaring, too, have noticed that she now wears a brooch set with a magnificent emerald, by which she seems to set great store. Who gave it to her we will leave our readers to guess.

Jared Applegate managed in some way to evade the drag-net set for him, and has not been seen or heard of since the night he slipped out of the hut overcome at the last minute by the thought of the terrible crime he had committed.

I should like to linger with you in this fascinating old land with its new interests and tell you how the ruined city in which Tubby and Fred pa.s.sed such an uncomfortable time was explored and rare treasures of antiquity found. I should also like to relate more of the adventures that befell the chums among the "Gold-men" of the Isthmus, but I must content myself with what has been written and my readers with the prophecy that the future will be able to recall no more n.o.ble achievement than this that has been the subject of our tale.

You are a.s.sured, however, that the Boy Scouts returned to their studies and to the States better citizens, better patriots and better Scouts for the exciting times they spent on Uncle Sam's big ditch--the eighth wonder, and the greatest of the world. Let every American boy, who gets a chance, see it. It will strengthen and cement his love for the Stars and Stripes and for the U. S. A., the country that put the gigantic enterprise through in spite of almost overwhelming difficulties.

And now the time has come to say good-bye to the Boy Scouts. So wishing them well in everything they undertake and hoping that they may ever be "good scouts and true," the author bids a reluctant adieu to them and to the readers who have followed the "Eagles" through their many adventures.

THE END