The blacksmith's tunnel--the tunnel leading off from the level--was blocked by fallen timbers where a belt of lime formation cut across; and fragments of wood, splintered into toothpick size, had been thrown out when the mountain settled to its place. But a short distance from the main shaft, which was a double compartment, carrying two cages up and down, in every level the air was foul down to the five-hundred foot, and below that the mine was filled with water.

Patiently Dick and the veteran explored these windings as far as they might until the guttering of their candles warned them that the air was loaded with poison, and often they retreated none too soon to scale the slippery, yielding rungs of the ladder with dizzy heads.

Expert and experienced, they were puzzled by what was disclosed.

Either the mine had yielded exceedingly rich streaks and had been, in mining parlance, "gophered," or else the management had been as foolish as ever handled a property.

In the assay-house, where the furnaces were dust-covered, the scale case black with grime, and the floor littered with refuse crucibles, cupels, mufflers, and worn buckboards, they discovered a bundle of old tablets. Almost invariably these showed that the assays had been made from samples that would have paid to work, but this alone gave them no hope.

But this was not all. A mysterious enmity seemed to pursue all their efforts. Yet its displays were unaccountable for by natural causes. On their arrival at the mine they found water, fresh and clear, piped into every cabin, the mess-house, and the superintendent's quarters.

They traced it back and discovered a small lake formed and fed by a large spring on what was evidently land of the mine. It suddenly failed them, and proved unwholesome. An investigation of the tiny reservoir disclosed masses of poisonous weeds in the water. They decided that they must have been blown there after their arrival, cleared the supply and yet, but two days later, when there had been no wind of more than noticeable violence, the weeds were there again.

They abandoned their water supply for the time being and resorted to the stream at the bottom of the canon.

A day later one of their burros died mysteriously, and Bill, puzzled, said he believed that it had lost its sense of smell and eaten something poisonous. On the day following the other died, apparently from the same complaint. The veteran miner grieved over them as for friends.

"I've been acquainted with a good many of 'em," he said, sorrowfully, "but I never knew two that had finer characters than these two did.

They were regular burros! No cheaters--just the square, open and above-board kind, that never kicked without layin' back their ears to give you warnin' and never laid down on the trail unless they wanted to rest. The meanest thing a burro or a man can do is to die voluntarily when you're dependin' on him, or when he owes you work or money. So it does seem as if I must have been mistaken in these two, after all, because we may need 'em."

Dick did not smile at his homily, for he caught the significance of it, that the Croix d'Or would have to make a better showing than they had so far discovered to warrant them in opening it. They had come almost to the end of the investigations possible. They scanned plans and scales in the office to familiarize themselves with the property, and there was but one portion of it they had not visited. That was a shaft which had been the "discovery hole," where the first find of ore had been made. And it was this they entered on the day when Fate seemed most particularly unkind. Yet even Fate appeared to relent, in the end, through one of those trifling afterthoughts which lead men to do the insignificant act. They had prepared everything for the venture. They had an extra supply of candles, chalk for making a course mark, sample bags for such pieces of ore as might interest them, and the prospectors' picks and hammers when they started out.

They were a hundred yards from the office when the younger man hesitated, stopped and turned back.

"I've an idea we might need those old maps," he said. "We haven't gone over them very much and they might come in handy."

Bill protested, but despite this Dick went back to the quarters and got them. They were crude, apparently, compared with the later work when competent engineers had opened the mine in earnest; but doubtless had served their purpose. The men came to the mouth of the old shaft which had been loosely covered over with poles, and around which a thicket of wild blackberry bushes had sprung up in stunted growth. An hour's work disclosed the black opening and a ladder in a fair state of preservation. They lowered a candle into the depths and saw that it burned undimmed, indicating that the air was pure, and then descended cautiously, testing each rung as they went. The shaft was not more than fifty feet deep, and they found themselves standing on the bottom and peering off into a drift which had been crudely timbered and had fallen in here and there as the unworked ground had settled.

"There doesn't seem to be much of anything here except some starved quartz," Bill said, staring at the wall after they had gone in some thirty or forty feet, and they had come to a place where the lagging had dropped away. He caught another piece of the half-rotted timbering and jerked it loose for a better inspection. It gave with a dull crack, then, immediately after, and seeming almost an echo, there was a terrific rumble, and a report like the explosion of a huge gun back in the direction of the shaft. Their candles flickered in the air impact, and for an instant they feared that the roof was coming down on them to crush them out of all resemblance to human beings.

They turned and ran toward the shaft. A few loose pebbles and pieces of rock were dripping from above like a shower of porphyry. For an instant they dared not step out, but stood inside the drift, waiting for what might happen and staring at each other with set faces exposed in the still flickering light. They had said nothing up to this time, being under too great stress to offer other than sharp exclamations.

"Sounds like that shaft had given way!" the veteran exclaimed. "If it has----"

He leaned forward and looked into Dick's face.

"If it has," the latter took up, "we are in a bad predicament."

They stood tensed and anxious until the pebbles stopped falling and a silence like that of a tomb, so profound as to seem thick and dense, invaded the hollows; then Dick started out into the shaft. He felt a restraining hand on his arm.

"Wait a minute, boy," the elder man said. "You're the owner here. It's dangerous. I ought to be the one to go first and find out what's happened. You wait inside the drift."

But Dick shook his hand off and stepped out to look upward. A dense blackness filled what should have been a space of light. This he had partially expected from the fact that when they came out toward the shaft there had been no sign of day; but he had not anticipated such a complete closing of the opening.

"Lord! We're buried in!" came an exclamation from behind him, and he felt a sudden sinking of the heart.

"I'll go easily till I come to it," he said, his voice sounding strained and loud although he had spoken scarcely above a whisper.

"You stand clear so that if anything gives, Bill, you won't be caught."

The elder miner would have protested, but already he was slowly and cautiously climbing the ladder. Step by step he ascended, holding the light above his head to discover the place where the shaft had given way, and then Bill, standing anxiously below, heard a harsh shout.

"I think the ladder will bear your weight as well as mine. Come up here."

The big man climbed steadily upward until he stood directly beneath the younger man's feet. He ventured an exclamation that was almost an oath.

"Not the shaft at all," he said, an instant later. "It's just a bowlder so big that it filled the whole opening. We're plugged and penned in here like rats in a trap!"

Dick took his little prospecting hammer and tapped the bowlder, at first gently, then with firmer strokes, and looked down at his partner with a distressed face.

"Hear that?" he exclaimed, rather than questioned. "It's a big one, and solid. It sounds bad to me."

For a minute they waved their candles round the edge, inspecting the resting place of the rock that had imprisoned them. Everywhere it was set firmly. A fitted door could have been no more secure. They consulted, and at last Bill descended and stepped back into the entrance to the drift to avoid falling stone, while the younger man attacked the edge beneath the bowlder, inch by inch, trying to find some place where he could pick through to daylight. At last, his arm wearied and the point of his prospecting hammer dulled, he rested.

"Come down, Dick, and I'll take a spell," Bill called up from below, and he obeyed.

The big miner, without comment, climbed up, and again the vault-like space was filled with the persistent picking of steel on stone. For a half-hour it continued, and then, slowly, Bill descended. He sat down at the foot of the shaft, wiped the sweat from his face, thrust his candlestick in a crevice and rolled a cigarette before he said anything, and then only as Dick started to the foot of the ladder.

"It's no use," he said. "We're holed up all right. I picked clear around the lower edge and there isn't a place where she isn't resting on solid rock. Nothing but dynamite could ever move that stone. Unless we can find some other way out we're----"

He paused and Dick added the finishing word, "Gone!"

"Exactly! No one knows we're here. No one comes to the mine. We're in the old works which I don't suppose a man has been inside of in five or ten years, and the map shows that it doesn't connect with the other ones. Answer--the finish!"

Dick pulled the worn and badly drawn plans from his pocket and then lighted his own candle, indulging in the extravagance of two that he might study the faint and smudged penciled lines.

"Here, Bill," he said, pointing at the drawing. "These two side drifts each end in what are now sump holes. We've got to watch out for them.

That makes it safe for us to take the main drift and see where it leads. The two end drifts evidently ran but a few feet and were then abandoned. So, if these plans are any good, they, too, are safe, if we can get into them."

The elder miner peered at the plans and studied them. He stood up and blew out his candle. He thrust his hands into his pockets.

"I've got three candles left," he said, "and I cain't just exactly say why I put that many in unless the Lord gave me a hunch we'd need 'em.

How many you got!"

"One in my pocket, and this."

"Then we'd better move fast, eh?"

They took a desperate chance on foul air and plunged down the drift, pausing only now and then when they came to the first side drifts to make sure of their course. They were informed by the plans that they had barely three hundred feet to explore, yet they had gone even farther than that before they came to a halt, a threatening one, for directly ahead of them the timbering had given way, the shaft caved, and there seemed at first no opening through the debris.

"Well, this looks pretty tough!" exclaimed Bill, stooping down and examining the face of the barrier.

His companion lighted his own candle and together they went over the face of the obstruction.

"It looks to me as if we could open her up a little if we can shift this timber here and use it as a lever," he said, pointing to one projecting near the roof.

"May bring the whole mountain down, but it's our only chance," agreed Bill. "Here she goes. Stand back. No use in both of us getting it."

He caught the end of the timber in his heavy hands, planted his feet firmly on the floor and heaved. The big timber creaked, but did not give. Again he planted himself and this time his great shoulders seemed to twist and writhe until the muscles cracked and then, with a crash, the barrier gave way. He sprang back with amazing quickness and they ran back up the drift for twenty or thirty feet while the mass again readjusted itself and settled slowly into position. A cloud of dust bellowed toward them, half-choking them with its gritty fineness, and then, in a minute, the air had cleared. They went cautiously forward.

"Well, we got some farther, anyhow, unless she comes down while we're working through. We've got a hole to crawl into, and that's something," the big miner asserted.

Before he could say anything more Dick had crowded him to one side and was entering the aperture. He had prevented his partner from taking the first perilous chance. Painfully he made his way, while the man behind listened with terrified apprehension; for none knew better than he the risk of that progress.