It was Monday who broke the silence that followed.

“Dat right, boss,” he said. “In old time me come here wid whaler we go on stone lots of time.”

“All same stone in our country,” added Tuesday.

Lake stared at them with a dropped jaw. It was plain to see he was astonished.

“You’ve crossed by this stone?” he asked sharply.

But Monday shook his head.

“No,” he said, “but some time we come here and rock on him.”

For some reason or other Bully Banjo seemed mightily relieved at this.

“Waal,” he said, “it’s a simple thing, arter all. Jes’ a matter of balance. But I tell yer it took nerve ther first time me an’ Zeb crossed over, although we knew the rock would work—at least, the sealer wot told us about ther mine told us that ther thing was safe. And now, perfesser, ef you’ve no objection, we’ll jes’ send one of yer blacks across since they’re used ter it, an’ when they land safe on the ledge it’ll give ther rest of you courage.”

“Monday, do you mind attempting this?” asked the professor. The kind-hearted scientist would rather have tried the experiment himself—risky as it seemed—than compel one of his servants to go unwillingly. But he was under no such compulsion. Monday gave a broad grin that showed his white teeth in an expression of almost childish pleasure.

“Me like go, boss,” he said.

“All right, then. Up with yer,” ordered Lake brusquely. “I don’t want ter fool away too much time hyar, but I jes’ had ter know about thet gold afore we sail.”

“Then you mean to sail soon?” asked the professor, as Monday clambered up the rough sides of the rock.

“Ter-morrer, I reckon,” was the rejoinder. “Yer see thet them boys uv mine are getting pretty ugly. Thet’s one reason why I don’t want to spend too long a time hyarabouts.”

“Good heaven!” exclaimed the professor at the thought of his boy left behind in the camp. “You surely don’t fear an outbreak of trouble while you’re gone.”

“No,” rejoined Lake. “Frankly I don’t, but you kain’t mos’ genally allers tell. Howsomever, I kalkerlate thet Zeb Hunt kin tackle any trouble thet comes along.”

“I sincerely hope so,” said the professor, somewhat reassured. He then turned with the rest to watch with rapt attention what was transpiring on the rocking stone.

Monday had now almost reached the summit, and under his weight the big stone was tipping gradually outward till the part of it he had reached hung above the gulch. It descended as steadily as the arm of a semaphore, and, although the experience appeared to be a terrifying one, the black was smiling as though he enjoyed it.

As the point of the stone—which, as has been said, was cone-shaped—touched the rock ledge Monday nimbly leaped from it and stood on the narrow shelf of stone. The fellow, like most islanders, was as agile as a goat. He smiled broadly back at his companions who, however, were not looking at him, but at the stone, which, relieved of its weight, now tilted back into position again as if actuated by some hidden machinery.

“Wonder how that old sealer felt the first time he tried it?” mused the professor.

“Kind er skeery like, I reckon,” said Simon Lake. “I guess he——”

But Tom interrupted him with a sharp question. It was odd, but the idea which had just struck the boy had not as yet occurred to the others.

“How do you get back again?”

Lake laughed.

“Waal, yer see thar’s a trail up thet cliff that leads to ther top. Frum thar thar’s a path thet leads to a cove the ’tother side of the island. Thar’s mighty shallow water close in shore thar, so we kain’t bring ther schooner round, but Zeb Hunt an’ me keep a boat thar so that when we get through in ther cave we’ll cut across the other half of ther island and row home in ther boat.”

That solved the mystery which for an instant had perplexed them all. Lake, who seemed to be in high spirits, confided to them that all these secrets had been contained in the map of the place the old sealer had given him. Not knowing Lake’s character, our party wondered a good deal at his flow of spirits for—except when he had his banjo in hand—he was generally taciturn and sullen. They did not know that danger acted on him like wine on some men. Affairs at the camp were far more critical than he had let them know. That morning Lake had received a note threatening his life if he did not immediately set sail. It was characteristic of the man that this only made him delay the more.

“The varmints. I’ll teach ’em,” he had muttered, as he tore the missive into shreds.

But the realization that mutiny was imminent had been the real reason for his visit that morning to the gold-bearing rocks. He wished to make sure that they were as valuable as he believed, and if they proved to be so he was quite cold-blooded enough to sail off and abandon the mutineers to their fate. Returning to the island at some later date, he would ransack it of its precious metal at his leisure.

Tuesday followed his fellow-countryman over. He made the passage in perfect safety, fairly squealing with delight as the big rock tipped with him. Then came Tom’s turn. He also made the crossing without accident, as did the professor and Mr. Chillingworth. Simon Lake came last, carrying his weapons and a sack of tools which he had brought—a drill and such implements—the better for boring and obtaining samples.

When they all stood on the ledge and watched the big stone rise majestically for the last time, Tom was conscious of a sinking sensation. What if something had happened to the trail—if it were blocked or something. They would inevitably be prisoners till death came to their relief. However, there was no time to dwell on gloomy thoughts like these.

While they had been making the passage of the gulch a change had set in in the weather. It had been bright when they set out, but now dark clouds had rolled up, obscuring the sun and casting gloom into the depths of the crevasse upon whose edge they stood. There was an oppressive feeling, too, in the air.

“Thar’s a storm of some kind comin’ up,” commented Lake, gazing overhead at the driving clouds.

“Thunder?” asked the professor sniffing the heavy, sultry air.

“Looks like it. Ef it is one, we’ll be glad of shelter. We git some hummers daown in these parts, I kin tell yer. They don’t come often, but when they do, by Chowder! they deliver ’em in large packages.”

As he spoke a few heavy drops of rain fell.

“Come on. Better hurry for the cave,” cried Lake, hastening forward with his sack of tools. They followed him, keeping as close to the cliff-face as they could. The ledge was narrow, and it was unpleasant to think of what a misstep would result in.

The cave proved to be a large one and reached back some distance into the rock. Its floor was littered with bowlders and earth, where Lake and Zeb Hunt had carried on their prospecting operations.

The professor picked up a bit of the stuff. In the dim light they could see the dull glint of metal in it. Lake watched the scientist curiously.

“Waal,” he said, “haow is it?”

“I cannot tell positively,” was the rejoinder, “but if it is all like this, it is worth considerable per ton.”

“Will she run two thousand dollars to the ton?” asked Lake curiously.

The professor shook his head.

“Impossible to say without adequate assaying implements.”

“Make me out a list of wot yer want and when I come back from ther next run I’ll bring ’em with me,” promised Lake.

To Tom this speech seemed particularly ominous. It meant that there was no intention on Lake’s part of their escaping.

“Here’s a good boring,” said Lake presently. He drew a lantern from the tool bag and lit it, holding it up against a place at the back of the cave which had been pecked at with a pick. To do this he had to squat down almost doubled up in the cramped space. This brought the tip of one of his pistol holsters against an outcropping rock and the weapon fell to the ground unnoticed by Lake, but instantly seen by Tom, who stood close behind. Without any very definite idea of what he meant to do with it, the boy slipped it inside his shirt. Perhaps he would have some opportunity to find use for it, he thought vaguely.

Lake, earnestly examining bits of rock and handing them up to the professor, did not notice the loss of his weapon.

Suddenly there came an ominous growling sound from outside. It was thunder. The storm was rapidly nearing them then.

“Gee whillakers!” exclaimed Lake, suddenly springing erect. “Ef I ain’t forgotten ter go an’ look fer thet signal.”

“What do you mean?” asked the professor.

“Why, frum ther top uv this cliff yer kin see ther camp with field-glasses. I brought mine along fer thet purpose. Afore I left I agreed with Zeb thet in the event uv trubble he wuz ter hoist a red flag. Ef everything wuz all right, he was to run up the blue one. I’m goin’ up thar now afore ther storm makes it too thick.”

He hastened from the cave and, making his way along the ledge, began to mount the face of the cliff by a narrow stairway cut at a sharp incline in the face of the acclivity. Presently he vanished at the summit. It was then that Tom, with shining eyes, turned to the others.

“Our chance to escape has come!” he exclaimed.

“How do you make that out?” asked Mr. Chillingworth listlessly.

For reply Tom drew out his pistol.

“We can make Lake prisoner on his return,” he said eagerly, “and then make our way across the island to the cove in which, as he told us, he had hidden the boat.”

“Good gracious boy!” cried the professor excitedly. “That’s a good idea. A splendid one, but—what about my boy?”

Tom, who in his excitement had quite forgotten that the son and heir of the Dingle fortunes was in the care of Zeb Hunt, looked thoughtful.

“Of course, we must get him,” he said. “I’ll tell you,” he cried, his eyes flashing at the adventurous daring of the plan he was about to propose, “we’ll make Lake prisoner and take him along with us. With him in our power, we will be in a position to make terms with the rascals. We can conceal him somewhere and refuse to give him up till we get our liberty and the boy.”

Perhaps to any one less desperately situated the plan would have appealed only as the forlornest kind of a forlorn hope. But to our party it seemed feasible, and even excellently practicable.

But as they stood discussing it in the cave mouth, there came a sudden blinding flash of lightning. Involuntarily they all stepped back within the cavern. The clap of thunder that followed the electrical display shook the cliff till it vibrated again.

“Wow! this is a real storm, sure enough!” exclaimed Tom. “I never saw such lightning.”

“And no rain,” said the professor; “that makes it doubly bad. These dry electrical storms are always more severe than those accompanied by a heavy downpour.”

As he spoke there came another blinding flash, accompanied by a terrific peal of thunder. But the figure of Lake could now be seen coming down the cliff-face on his way back to the cave. The time to put their plan into execution had arrived. Amid the turmoil of the elements, they discussed it. It was agreed that Tom, hiding behind a big fragment of rock at the entrance of the cave mouth, was to level his pistol at the unsuspecting desperado as he appeared. He was then to be disarmed and tied, and the rest of their arrangements they left in an undecided condition till the first part of the daring program was carried out. The main thing to do, so all hands agreed, was to capture Lake.

Nearer and nearer came the unsuspecting leader of the Chinese runners. Tom crouched back into his place of concealment as the other came on. The rest stood close behind him. They hardly dared to breathe as the footsteps of the man they wished to capture drew closer.

As his form was framed in the cave mouth Tom sprang erect, holding the pistol level and pointed straight at Lake’s head. He saw the rascal grow white under his tan and open his mouth as if about to speak. But at the same instant there came a crash that seemed as if heaven and earth were being devoured in one vast catastrophe. At the same time a sheet of dazzling, burning white flame enveloped them. The figures in the cave mouth were illumined in its livid glare as if cut out of black paper. Crash followed crash. Another and another. A sensation like that of the pricking of myriad pin points ran through them. The blue lightning darted, hissing viciously about them, bathing them in living electricity.

Bewildered and stunned, Tom saw Lake’s figure reel and fall backward, clutching at the rock as he fell. The boy sprang forward to catch him and save him from falling into the abyss below, when a crash that dwarfed the others fairly stopped him in his tracks.

There came a mighty splitting, rending sound and Tom, looking upward in the direction from whence it came, saw the form of the great rocking stone swaying drunkenly on the bed in which it had rested securely through the ages.

Suddenly the great rock mass toppled out, its black form impending between the lad and the sky. The noise of its falling reverberated above the shriek of the storm and the thunder’s loudest roar.

Instinctively Tom tottered backward as it fell. Stunned, half deafened, and numb from the lightning, he reeled like a sick man. But even above it all, he could hear Lake’s wild death-shriek ringing out as he plunged backward.

The next instant there was a shock that seemed to shake the cliff to its mighty foundations. The dim light of the storm-shrouded day was blocked out, and at the same moment Tom lost consciousness.

But to the others there came no such merciful blotting out of the strange horror of the situation. In the very act of overpowering their enemy, they had, in turn, been overwhelmed by a crushing disaster.

The rocking stone, driven and unseated by a terrific thunderbolt, had lost its delicate balance and toppled from its base into the abyss.

In its fall it had wedged across the narrow gorge, blocking completely with the weight of tons of stone the entrance to the cave.

The castaways of Bully Banjo’s island were buried alive beyond hope of escape.