The fête champêtre, as President Pelham named it in the trumpet-flourish of announcement, to celebrate the laying of the final stone of the great dam at the outlet of Elbow Canyon, anticipated the working completion of the irrigation system by some weeks. That the canals were not yet in readiness to furnish water to the prospective farmer really made little difference. The spectacular event was the laying of the top-stone; and in the promoter's plans a well-arranged stage-effect was of far greater value than any actual parcelling out of the land to intended settlers.

Accordingly, no effort was spared to make the celebration an enthusiastic success. For days before the auspicious one on which the guest trains began to arrive from Alta Vista and beyond, the camp force spent itself in setting the scene for the triumph. The spillway gate, designed to close the cut-off tunnel and so to begin the impounding of the river, was put in place ready to be forced down by its machinery; the camp mesa was scraped and raked and cleared of the industrial litter; a platform was erected for the orators and the brass band; a towering flagstaff – this by the express direction of the president – was planted in the middle of the mesa parade ground; and with the exception of camp cook Garou, busy with a small army of assistants over the barbecue pits, the construction force was distributed among the camps on the canals – this last a final touch of Mr. Pelham's to secure the degree of exclusiveness for the celebration which might not have been attainable in the presence of an outnumbering throng of workmen.

In the celebration proper the two engineers had an insignificant part. When the trains were in and side-tracked, and the working preliminaries were out of the way, the triumphal programme, as it had been outlined in a five-page letter from the president to Ballard, became automatic, moving smoothly from number to number as a well-designed masterpiece of the spectacular variety should. There were no hitches, no long waits for the audience. Mr. Pelham, carrying his two-hundred-odd pounds of avoirdupois as jauntily as the youngest promoter of them all, was at once the genial host, the skilful organiser, prompter, stage-manager, chorus-leader; playing his many parts letter-perfect, and never missing a chance to gain a few more notches on the winding-winch of enthusiasm.

While the band and the orators were alternating, Ballard and Bromley, off duty for the time, lounged on the bungalow porch awaiting their cue. There had been no awkward happenings thus far. The trains had arrived on time; the carefully staged spectacle was running like a well-oiled piece of mechanism; the August day, despite a threatening mass of storm cloud gathering on the distant slopes of the background mountain range, was perfect; and, thanks to Mr. Pelham's gift of leadership, the celebrators had been judiciously wrought up to the pitch at which everything was applauded and nothing criticised. Hence, there was no apparent reason for Ballard's settled gloom; or for Bromley's impatience manifesting itself in sarcastic flings at the company's secretary, an ex-politician of the golden-tongued tribe, who was the oratorical spellbinder of the moment.

"For Heaven's sake! will he never saw it off and let us get that stone set?" gritted the assistant, when the crowd cheered, and the mellifluous flood, checked for the applausive instant, poured steadily on. "Why in the name of common sense did Mr. Pelham want to spring this batch of human phonographs on us!"

"The realities will hit us soon enough," growled Ballard, whose impatience took the morose form. Then, with a sudden righting of his tilted camp-stool: "Good Lord, Loudon! Look yonder – up the canyon!"

The porch outlook commanded a view of the foothill canyon, and of a limited area of the bowl-shaped upper valley. At the canyon head, and on the opposite side of the river, three double-seated buckboards were wheeling to disembark their passengers; and presently the Castle 'Cadia house-party, led by Colonel Craigmiles himself, climbed the left-hand path to the little level space fronting the mysterious mine.

"By Jove!" gasped Bromley; "I nearly had a fit – I thought they were coming over here. Now what in the name of – "

"It's all right," cut in Ballard, irritably. "Why shouldn't the colonel want to be present at his own funeral? And you needn't be afraid of their coming over here. The colonel wouldn't wipe his feet on that mob of money-hunters around the band-stand. See; they are making a private box of the mine entrance."

The remark framed itself upon the fact. At the colonel's signal the iron-bound tunnel door had swung open, and Wingfield and Blacklock, junior, with the help of the buckboard drivers, were piling timbers on the little plateau for the party's seating.

It was Colonel Craigmiles's own proposal, this descent upon the commercial festivities at the dam; and Elsa had yielded only after exhausting her ingenuity in trying to defeat it. She had known in advance that it could not be defeated. For weeks her father's attitude had been explainable only upon a single hypothesis; one which she had alternately accepted and rejected a hundred times during the two years of dam-building; and this excursion was less singular than many other consequences of the mysterious attitude.

She was recalling the mysteries as she sat on the pile of timbers with Wingfield, hearing but not heeding the resounding periods of the orator across the narrow chasm. With the inundation of the upper valley an impending certainty, measurable by weeks and then by days, and now by hours, nothing of any consequence had been done at Castle 'Cadia by way of preparing for it. Coming down early one morning to cut flowers for the breakfast-table, she had found two men in mechanics' overclothes installing a small gasolene electric plant near the stables; this, she supposed, was for the house-lighting when the laboratory should be submerged. A few days later she had come upon Otto, the chauffeur, building a light rowboat in a secluded nook in the upper canyon.

But beyond these apparently trivial precautions, nothing had been done, and her father had said no word to her or to the guests of what was to be done when the closed-in valley should become a lake with Castle 'Cadia for its single island. Meanwhile, the daily routine of the country house had gone on uninterruptedly; and once, when Mrs. Van Bryck had asked her host what would happen when the floods came, Elsa had heard her father laughingly assure his guest in the presence of the others that nothing would happen.

That Wingfield knew more than these surface indications could tell the keenest observer, Elsa was well convinced; how much more, she could only guess. But one thing was certain: ever since the day spent with Ballard and Bromley and Jerry Blacklock at the construction camp – the day of his narrow escape from death – the playwright had been a changed man; cynical, ill at ease, or profoundly abstracted by turns, and never less companionable than at the present moment while he sat beside her on the timber balk, scowling up and across at the band-stand, at the spellbound throng ringing it in, and at the spellbinding secretary shaming the pouring torrent in the ravine below with his flood of rhetoric.

"What sickening rot!" he scoffed in open disgust. And then: "It must be delightfully comforting to Ballard and Bromley to have that wild ass of the market-place braying over their work! Somebody ought to hit him."

But the orator was preparing to do a little of the hitting, himself. The appearance of the party at the mine entrance had not gone unremarked, and the company's secretary recognised the company's enemy at a glance. He was looking over the heads of the celebrators and down upon the group on the opposite side of the narrow chasm when he said:

"So, ladies and gentlemen, this great project, in the face of the most obstinate, and, I may say, lawless, opposition; in spite of violence and petty obstruction on the part of those who would rejoice, even to-day, in its failure; this great work has been carried on to its triumphant conclusion, and we are gathered here on this beautiful morning in the bright sunshine and under the shadow of these magnificent mountains to witness the final momentous act which shall add the finishing stone to this grand structure; a structure which shall endure and subserve its useful and fructifying purpose so long as these mighty mountains rear their snowy heads to look down in approving majesty upon a desert made fair and beautiful by the hand of man."

Hand-clappings, cheers, a stirring of the crowd, and the upstarting of the brass band climaxed the rhetorical peroration, and Elsa glanced anxiously over her shoulder. She knew her father's temper and the fierce quality of it when the provocation was great enough to arouse it; but he was sitting quietly between Dosia and Madge Cantrell, and the publicly administered affront seemed to have missed him.

When the blare of brass ceased, the mechanical part of the spectacle held the stage for a few brief minutes. The completing stone was carefully toggled in the grappling-hooks of the derrick-fall, and at Ballard's signal the hoisting engine coughed sharply, besprinkling the spectators liberally with a shower of cinders, the derrick-boom swung around, and the stone was lowered cautiously into its place.

With a final rasping of trowels, the workmen finished their task, and Ballard walked out upon the abutment and laid his hand on the wheel controlling the drop-gate which would cut off the escape of the river through the outlet tunnel. There was a moment of impressive silence, and Elsa held her breath. The day, the hour, the instant which her father had striven so desperately to avert had come. Would it pass without its tragedy?

She saw Ballard give the last searching glance at the gate mechanism; saw President Pelham step out to give the signal. Then there was a stir in the group behind her, and she became conscious that her father was on his feet; that his voice was dominating the droning roar of the torrent and the muttering of the thunder on the far-distant heights.

"Mistuh-uh Pelham – and you otheh gentlemen of the Arcadia Company – you have seen fit to affront me, suhs, in the most public manneh, befo' the members of my family and my guests. This was youh privilege, and you have used it acco'ding to youh gifts. Neve'theless, it shall not be said that I failed in my neighbo'ly duty at this crisis. Gentlemen, when you close that gate – "

The president turned impatiently and waved his hand to Ballard. The band struck up "The Star-Spangled Banner," a round ball of bunting shot to the top of the flagstaff over the band-stand and broke out in a broad flag, and Elsa saw the starting-wheel turning slowly under Ballard's hand. The clapping and cheering and the band clamour drowned all other sounds; and the colonel's daughter, rising to stand beside Wingfield, felt rather than heard the jarring shock of a near-by explosion punctuating the plunge of the great gate as it was driven down by the geared power-screws.

What followed passed unnoticed by the wildly cheering spectators crowding the canyon brink to see the foaming, churning torrent recoil upon itself and beat fiercely upon the lowered gate and the steep-sloped wall of the dam's foundation courses. But Elsa saw Ballard start as from the touch of a hot iron; saw Bromley run out quickly to lay hold of him. Most terrible of all, she turned swiftly to see her father coming out of the mine entrance with a gun in his hands – saw and understood.

It was Wingfield, seeing all that she saw and understanding quite as clearly, who came to her rescue at a moment when the bright August sunshine was filling with dancing black motes for her.

"Be brave!" he whispered. "See – he isn't hurt much: he has let go of the wheel, and Bromley is only steadying him a bit." And then to the others, with his habitual air of bored cheerfulness: "The show is over, good people, and the water is rising to cut us off from luncheon. Sound the retreat, somebody, and let's mount and ride before we get wet feet."

A movement toward the waiting vehicles followed, and at the facing about Elsa observed that her father hastily flung the rifle into the mine tunnel-mouth; and had a fleeting glimpse of Ballard and Bromley walking slowly arm-in-arm toward the mesa shore along the broad coping of the abutment.

At the buckboards Wingfield stood her friend again. "Send Jerry Blacklock down to see how serious it is," he suggested, coming between her and the others; and while she was doing it, he held the group for a final look down the canyon at the raging flood still churning and leaping at its barriers like some sentient wild thing trapped and maddened with the first fury of restraint.

Young Blacklock made a sprinter's record on his errand and was back almost immediately. Mr. Ballard had got his arm pinched in some way at the gate-head, he reported: it was nothing serious, and the Kentuckian sent word that he was sorry that the feeding of the multitude kept him from saying so to Miss Elsa in person. Elsa did not dare to look at Wingfield while Blacklock was delivering his message; and in the buckboard-seating for the return to Castle 'Cadia, she contrived to have Bigelow for her companion.

It was only a few minutes after Jerry Blacklock had raced away up the canyon path with his message of reassurance that Bromley, following Ballard into the office room of the adobe bungalow and locking the door, set to work deftly to dress and bandage a deep bullet-crease across the muscles of his chief's arm; a wound painful enough, but not disabling.

"Well, what do you think now, Breckenridge?" he asked, in the midst of the small surgical service.

"I haven't any more thinks coming to me," was the sober reply. "And it is not specially comforting to have the old ones confirmed. You are sure it was the colonel who fired at me?"

"I saw the whole thing; all but the actual trigger-pulling, you might say. When Mr. Pelham cut him off, he turned and stepped back into the mouth of the mine. Then, while they were all standing up to see you lower the gate, I heard the shot and saw him come out with the gun in his hands. I was cool enough that far along to take in all the little details: the gun was a short-barrelled Winchester – the holster-rifle of the cow-punchers."

"Ouch!" said Ballard, wincing under the bandaging. Then: "The mysteries have returned, Loudon; we were on the wrong track – all of us. Wingfield and you and I had figured out that the colonel was merely playing a cold-blooded game for delay. That guess comes back to us like a fish-hook with the bait gone. There was nothing, less than nothing, to be gained by killing me to-day."

Bromley made the negative sign of assenting perplexity.

"It's miles too deep for me," he admitted. "Three nights ago, when I was dining at Castle 'Cadia, Colonel Craigmiles spoke of you as a father might speak of the man whom he would like to have for a son-in-law: talked about the good old gentlemanly Kentucky stock, and all that, you know. I can't begin to sort it out."

"I am going to sort it out, some day when I have time," declared Ballard; and the hurt being temporarily repaired, they went out to superintend the arrangements for feeding the visiting throng in the big mess-tent.

After the barbecue, and more speech-making around the trestle-tables in the mess-tent, the railroad trains were brought into requisition, and various tours of inspection through the park ate out the heart of the afternoon for the visitors. Bromley took charge of that part of the entertainment, leaving Ballard to nurse his sore arm and to watch the slow submersion of the dam as the rising flood crept in little lapping waves up the sloping back-wall.

The afternoon sun beat fiercely upon the deserted construction camp, and the heat, rarely oppressive in the mountain-girt altitudes, was stifling. Down in the cook camp, Garou and his helpers were washing dishes by the crate and preparing the evening luncheon to be served after the trains returned; and the tinkling clatter of china was the only sound to replace the year-long clamour of the industries and the hoarse roar of the river through the cut-off.

Between his occasional strolls over to the dam and the canyon brink to mark the rising of the water, Ballard sat on the bungalow porch and smoked. From the time-killing point of view the great house in the upper valley loomed in mirage-like proportions in the heat haze; and by three o'clock the double line of aspens marking the river's course had disappeared in a broad band of molten silver half encircling the knoll upon which the mirage mansion swayed and shimmered.

Ballard wondered what the house-party was doing; what preparations, if any, had been made for its dispersal. For his own satisfaction he had carefully run bench-levels with his instruments from the dam height through the upper valley. When the water should reach the coping course, some three or four acres of the house-bearing knoll would form an island in the middle of the reservoir lake. The house would be completely cut off, the orchards submerged, and the nearest shore, that from which the roundabout road approached, would be fully a half-mile distant, with the water at least ten feet deep over the raised causeway of the road itself.

Surely the colonel would not subject his guests to the inconvenience of a stay at Castle 'Cadia when the house would be merely an isolated shelter upon an island in the middle of the great lake, Ballard concluded; and when the mirage effect cleared away to give him a better view, he got out the field-glass and looked for some signs of the inevitable retreat.

There were no signs, so far as he could determine. With the help of the glass he could pick out the details of the summer afternoon scene on the knoll-top; could see that there were a number of people occupying the hammocks and lazy-chairs under the tree-pillared portico; could make out two figures, which he took to be Bigelow and one of the Cantrell sisters, strolling back and forth in a lovers' walk under the shade of the maples.

It was all very perplexing. The sweet-toned little French clock on its shelf in the office room behind him had struck three, and there were only a few more hours of daylight left in Castle 'Cadia's last day as a habitable dwelling. And yet, if he could trust the evidence of his senses, the castle's garrison was making no move to escape: this though the members of it must all know that the rising of another sun would see their retreat cut off by the impounded flood.

After he had returned the field-glass to its case on the wall of the office the ticking telegraph instrument on Bromley's table called him, signing "E – T," the end-of-track on the High Line Extension. It was Bromley, wiring in to give the time of the probable return of the excursion trains for Garou's supper serving.

"How are you getting on?" clicked Ballard, when the time had been given.

"Fine," was the answer. "Everything lovely, and the goose honks high. Enthusiasm to burn, and we're burning it. Just now the baa-lambs are surrounding Mr. Pelham on the canal embankment and singing 'For he's a jolly good fellow' at the tops of their voices. It's great, and we're all hypnotised. So long; and take care of that pinched arm."

After Bromley broke and the wire became dumb, the silence of the deserted camp grew more oppressive and the heat was like the breath of a furnace. Ballard smoked another pipe on the bungalow porch, and when the declining sun drove him from this final shelter he crossed the little mesa and descended the path to the ravine below the dam.

Here he found food for reflection, and a thing to be done. With the flow of the river cut off, the ground which had lately been its channel was laid bare; and recalling Gardiner's hint about the possible insecurity of the dam's foundations, he began a careful examination of the newly turned leaf in the record of the great chasm.

What he read on the freshly-turned page of the uncovered stream-bed was more instructive than reassuring. The great pit described by Gardiner was still full of water, but it was no longer a foaming whirlpool, and the cavernous undercutting wrought by the diverted torrent was alarmingly apparent. In the cut-off tunnel the erosive effect of the stream-rush was even more striking. Dripping rifts and chasms led off in all directions, and the promontory which gave its name to the Elbow, and which formed the northern anchorage of the dam, had been mined and tunnelled by the water until it presented the appearance of a huge hollow tooth.

The extreme length of the underground passage was a scant five hundred feet; but what with the explorations of the side rifts – possible only after he had gone back to the bungalow for candles and rubber thigh-boots – the engineer was a good half-hour making his way up to the great stop-gate with the rising flood on its farther side. Here the burden of anxiety took on a few added pounds. There was more or less running water in the tunnel, and he had been hoping to find the leak around the fittings of the gate. But the gate was practically tight.

"That settles it," he mused gloomily. "It is seeping through this ghastly honeycomb somewhere, and it's up to us to get busy with the concrete mixers – and to do it quickly. I can't imagine what Braithwaite was thinking of; to drive this tunnel through one of nature's compost heaps, and then to turn a stream of water through it."

The sun was a fiery globe swinging down to the sky-pitched western horizon when the Kentuckian picked his way out of the dripping caverns. There were two added lines in the frown wrinkling between his eyes, and he was still talking to himself in terms of discouragement. At a conservative estimate three months of time and many thousands of dollars must be spent in lining the spillway tunnel with a steel tube, and in plugging the caverns of the hollow tooth with concrete. And in any one of the ninety days the water might find its increasing way through the "compost heap"; whereupon the devastating end would come swiftly.

It was disheartening from every point of view. Ballard knew nothing of the financial condition of the Arcadia Company, but he guessed shrewdly that Mr. Pelham would be reluctant to put money into work that could not be seen and celebrated with the beating of drums. None the less, for the safety of every future land buyer with holdings below the great dam, the work must be done. Otherwise —

The chief engineer's clean-cut face was still wearing the harassed scowl when Bromley, returning with the excursionists, saw it again.

"The grouch is all yours," said the cheerful one, comfortingly, "and you have a good right and title to it. It's been a hard day for you. Is the arm hurting like sin?"

"No; not more than it has to. But something else is. Listen, Bromley." And he briefed the story of the hollow-tooth promontory for the assistant.

"Great ghosts! – worse and more of it!" was Bromley's comment. Then he added: "I've seen a queer thing, too, Breckenridge: the colonel has moved out, vanished, taken to the hills."

"Out of Castle 'Cadia? You're mistaken. There is absolutely nothing doing at the big house: I've been reconnoitring with the glass."

"No, I didn't mean that," was the qualifying rejoinder. "I mean the ranch outfit down in the Park. It's gone. You know the best grazing at this time of the year is along the river: well, you won't find hair, hoof or horn of the colonel's cattle anywhere in the bottom lands – not a sign of them. Also, the ranch itself is deserted and the corrals are all open."

The harassed scowl would have taken on other added lines if there had been room for them.

"What do you make of it, Loudon? – what does it mean?"

"You can search me," was the puzzled reply. "But while you're doing it, you can bet high that it means something. To a man up a tall tree it looks as if the colonel were expecting a flood. Why should he expect it? What does he know? – more than we know?"

"It's another of the cursed mysteries," Ballard broke out in sullen anger. "It's enough to jar a man's sanity!"

"Mine was screwed a good bit off its base a long time ago," Bromley confessed. Then he came back to the present and its threatenings: "I'd give a month's pay if we had this crazy city crowd off of our hands and out of the Park."

"We'll get rid of it pretty early. I've settled that with Mr. Pelham. To get his people back to Denver by breakfast-time to-morrow, the trains will have to leave here between eight and eight-thirty."

"That is good news – as far as it goes. Will you tell Mr. Pelham about the rotten tooth – to-night, I mean?"

"I certainly shall," was the positive rejoinder; and an hour later, when the evening luncheon in the big mess-tent had been served, and the crowd was gathered on the camp mesa to wait for the fireworks, Ballard got the president into the bungalow office, shut the door on possible interruptions, and laid bare the discouraging facts.

Singularly enough, as he thought, the facts seemed to make little impression upon the head of Arcadia Irrigation. Mr. Pelham sat back in Macpherson's home-made easy-chair, relighted his cigar, and refused to be disturbed or greatly interested. Assuming that he had not made the new involvement plain enough, Ballard went over the situation again.

"Another quarter of a million will be needed," he summed up, "and we shouldn't lose a single day in beginning. As I have said, there seems to be considerable seepage through the hill already, with less than half of the working head of water behind the dam. What it will be under a full head, no man can say."

"Oh, I don't know," said the president, easily. "A new boat always leaks a little. The cracks, if there are any, will probably silt up in a few days – or weeks."

"That is a possibility," granted the engineer; "but it is scarcely one upon which we have a right to depend. From what the secretary of the company said in his speech to-day, I gathered that the lands under the lower line of the ditch will be put upon the market immediately; that settlers may begin to locate and purchase at once. That must not be done, Mr. Pelham."

"Why not?"

"Because any man who would buy and build in the bottom lands before we have filled that hollow tooth would take his life in his hands."

The president's smile was blandly genial.

"You've been having a pretty strenuous day of it, Mr. Ballard, and I can make allowances. Things will look brighter after you have had a good night's rest. And how about that arm? I didn't quite understand how you came to hurt it. Nothing serious, I hope?"

"The arm is all right," said Ballard, brusquely. Mr. Pelham's effort to change the subject was too crude and it roused a spirit of bulldog tenacity in the younger man. "You will pardon me if I go back to the original question. What are we going to do about that undermined hill?"

The president rose and dusted the cigar-ash from his coat-sleeve.

"Just at present, Mr. Ballard, we shall do nothing. To-morrow morning you may put your entire force on the ditch work, discharging the various camps as soon as the work is done. Let the 'hollow tooth' rest for the time. If a mistake has been made, it's not your mistake – or Mr. Bromley's. And a word in your ear: Not a syllable of your very natural anxiety to any one, if you please. It can do no good; and it might do a great deal of harm. I shouldn't mention it even to Bromley, if I were you."

"Not mention it? – to Bromley? But Bromley knows; and we agree fully – "

"Well, see to it that he doesn't talk. And now I must really beg to be excused, Mr. Ballard. My duties as host – "

Ballard let him go, with a feeling of repulsive disgust that was almost a shudder, and sat for a brooding hour in silence while the fireworks sputtered and blazed from the platform on the mesa's edge and the full moon rose to peer over the background range, paling the reds and yellows of the rockets and bombs. He was still sitting where the president had left him when Bromley came in to announce the close of the fête champêtre.

"It's all over but the shouting, and they are taking to the Pullmans. You don't care to go to the foot of the pass with one of the trains, do you?"

"Not if you'll go. One of us ought to stay by the dam while the lake is filling, and I'm the one."

"Of course you are," said Bromley, cheerfully. "I'll go with the first section; I'm good for that much more, I guess; and I can come back from Ackerman's ranch in the morning on one of the returning engines." Then he asked the question for which Ballard was waiting: "How did Mr. Pelham take the new grief?"

"He took it too easily; a great deal too easily, Loudon. I tell you, there's something rotten in Denmark. He was as cold-blooded as a fish."

Hoskins, long since reinstated, and now engineman of the first section of the excursion train, was whistling for orders, and Bromley had to go.

"I've heard a thing or two myself, during the day," he averred. "I'll tell you about them in the morning. The company's secretary has been busy making stock transfers all day – when he wasn't spellbinding from some platform or other. There is something doing – something that the baa-lambs don't suspect. And Mr. Pelham and his little inside ring are doing it."

Ballard got up and went to the door with the assistant.

"And that isn't the worst of it, Loudon," he said, with an air of sudden and vehement conviction. "This isn't an irrigation scheme at all, it's a stock deal from beginning to end. Mr. Pelham knows about that hollow tooth; he knew about it before I told him. You mark my words: we'll never get orders to plug that tunnel!"

Bromley nodded agreement. "I've been working my way around to that, too. All right; so let it be. My resignation goes in to-morrow morning, and I take it yours will?"