E-text prepared by Al Haines



THE BORDER BOYS ACROSS THE FRONTIER

by

FREMONT B. DEERING

Author of "The Border Boys on the Trail," "The Border Boys with the Mexican Rangers," "The Border Boys with the Texan Rangers," "The Border Boys in the Canadian Rockies," "The Border Boys Along the St. Lawrence."



[Frontispiece: "Right off there! Look! Look!" The lanky cow puncher pointed out beyond the shadow of the solitary mesa.]



A. L. Burt Company Publishers ————— New York Copyright, 1911, by Hurst & Company



CONTENTS

CHAPTER

I. THE TRAIL OF THE HAUNTED MESA II. THE SAND STORM III. A NIGHT ALARM IV. SOME QUEER TRACKS V. THE HOLLOW ALTAR VI. THE LEGEND OF A FORGOTTEN RACE VII. WHAT CAME ACROSS THE DESERT VIII. THE DARK FACE OF DANGER IX. IN THE MESA DWELLERS' BURIAL GROUND X. A NEW MEXICAN STYX XI. THE CAMP OF THE GUN-RUNNERS XII. MADERO'S FLYING COLUMN XIII. IN THE CAMP OF THE INSURRECTOS XIV. "DEATH TO THE GRINGOES!" XV. A RACE FOR LIFE XVI. WHAT HAPPENED TO COYOTE PETE XVII. BOB HARDING DOES "THE DECENT THING" XVIII. THE TABLES TURNED XIX. BUCK BRADLEY'S AUTOMOBILE XX. AT THE ESMERALDA MINE XXI. AN ACT OF TREACHERY XXII. AT ROSARIO STATION XXIII. JACK MERRILL'S "SPECIAL" XXIV. THE ATTACK ON THE MINE XXV. THE LAST STAND.—CONCLUSION



ILLUSTRATIONS

"Right off there! Look! Look!" The lanky cow puncher pointed out beyond the shadow of the solitary mesa . . . . . . Frontispiece

As it flared up, all three recoiled with expressions of dismay. At their very feet was a deep chasm.

A tempest of lead rattled about the engine. Almost before they realized it, they had swung around the curve.



The Border Boys Across the Frontier.

CHAPTER I.

THE TRAIL OF THE HAUNTED MESA.

"Can you make out any sign of the mesa yet, Pete?"

The speaker, a sun-bronzed lad of about seventeen, mounted on a bright bay pony with a white-starred forehead, drew rein as he spoke. Shoving back his sombrero, he shielded his eyes from the shimmering desert glare with one hand and gazed intently off into the southwest.

"Nope; nary a speck, so fur. Queer, too; we ought to be seein' it by now."

Coyote Pete, as angular, rangy and sinewy as ever, gazed as intently in the same direction as the lad, Jack Merrill, himself. The pause allowed the remainder of the party to ride up. There was Ralph Stetson, a good deal browner and sturdier-looking than when we encountered him last in "The Border Boys on the Trail"; Walt Phelps, the ranch boy, whose blazing hair outrivaled the glowing sun; and the bony, grotesque form of Professor Wintergreen, preceptor of Latin and the kindred tongues at Stonefell College, and amateur archaeologist. Lest they might feel slighted, let us introduce also, One Spot, Two Spot and Three Spot, the pack burros.

"I always had an idea that the Haunted Mesa formed quite a prominent object in the landscape," put in Professor Wintergreen, referring to a small leather-bound book, which he had just taken from one of his saddle-bags.

"And I always had an idea," laughed Ralph Stetson, "that a landscape meant something with brooks and green trees and cows and—and things, in it."

The young son of "King Pin" Stetson, the Eastern Railroad King, looked about him at the gray desert, above which the sun blazed mercilessly down with all the intensity of a burning glass. Here and there were isolated clumps of rank-odored mesquite, the dreariest looking gray-green bush imaginable. The scanty specimens of this variety of the vegetable life of the desert were interspersed here and there by groups of scraggly, prickly cacti. Across such country as this, the party had been making its way for the past day and a half,—ever since, in fact, they had left behind them the foothills of the Hachetas, where, as we know, was located the ranch of Jack Merrill's father, and had entered the dry, almost untravelled solitudes of the Playas.

Jack Merrill consulted a compass that was strapped to his wrist.

"Well, we're keeping steadily in the right direction," he said. "Nothing for it but to keep on going; eh, Pete?"

"When yer cain't turn back, 'keep on goin's' a good word," assented the philosophical cow-puncher of the Agua Caliente, stroking his sun-bleached yellow moustache and untangling a knot in his pony's mane.

"It's up to us to get somewhere where there is water pretty quick," put in Walt Phelps; "the last time I hit the little drinking canteen I noticed that there wasn't an awful lot left in the others."

"No, and the stock's feelin' it, too," grunted Pete, digging his big, blunt-roweled spurs into his buckskin cayuse.

Followed by Jack on his Firewater, the professor on his queer, bony steed as angular as himself, Ralph on Petticoats—of exciting memory,—and Walt Phelps on his big gray, they pushed on.

The heat was blistering. In fact, to any one less accustomed to the arduous intensity of the sun's rays in this part of the country, it would have proved almost insupportable. But our party was pretty well seasoned by this time.

All of them wore the broad, leather-banded sombreros of the plainsmen except Professor Wintergreen, who had invested himself in a gigantic pith sun-helmet, from beneath which his spectacled countenance peered out, as Ralph said, "Like a toad peeking out from a mushroom." For the rest, the boys wore leather "chaps," blue shirts open at the neck, with loosely knotted red handkerchiefs about their throats. The latter were both to keep the sun off the back of their necks and to serve as protection for their mouths and nostrils against the dust in case of necessity,—as for example, when they struck a patch of burning, biting alkali. Of this pungent stuff, they had already encountered one or two stretches, and had been glad to muffle up the lower part of their faces as they rode through it.

As for Coyote Pete, those who have followed his earlier experiences are pretty familiar with that redoubtable cow-puncher's appearance; suffice it to say, therefore, that, as usual, he wore his battered leather "chaps," faded blue shirt, and his big sombrero with the silver stars affixed to the stamped leather band. In a holster he carried a rifle, as did the rest of the party, as well as his well-worn revolver. The others had provided themselves with similar weapons, although theirs glittered in blatant newness beside Pete's battered, but well-cleaned and oiled, "shootin' iron."

While they are pressing onward, with the Hachetas lying like a dim, blue cloud far behind them, let us tell the reader something about the quest that brings our party into the midst of this inhospitable place. As readers of "The Border Boys on the Trail" know, Professor Wintergreen had accompanied Jack Merrill and Ralph Stetson from Stonefell College, some weeks before, to spend a vacation on the Agua Caliente Ranch, belonging to Jack's father. The professor, as well as being on a vacation, was in a sense on a mission, for he bore with him the commission of a well-known institute of science in the East to investigate some of the mesas of this part of the world, and also to procure relics and trophies of the vanished race that once inhabited them, and accurate measurements of the strange formations.

Since their arrival at the ranch, some weeks before, events had so shaped themselves as to render the immediate undertaking of his mission impossible. The descent of Black Ramon de Barros on the ranch, as we have related, and the subsequent abduction of the boys to the old Mission across the border, had so fully occupied their attention, that all thought of the professor's errand had been lost sight of.

With Black Ramon, thanks to the boys, forever banished from his cattle-rustling raids, and the subsequent tranquility of routine life, had come a recollection of the professor's quest. Coyote Pete, a few days before this story opens, had volunteered to act as guide to the professor and his party to a mesa seldom visited except by wandering Indians and occasional cow-punchers. This was the Haunted Mesa, the location of which was so difficult to reach that previous relic-hunting expeditions had not included it in their travels.

Mr. Merrill was the more willing to allow the boys to go along, as he had been suddenly summoned into Chihuahua province, in Mexico, by reports of trouble at a mine—The Esmeralda—he owned there. Rumors of an insurrection had reached him—an insurrection which meant great peril to American interests. He had, therefore, lost no time in setting out to ascertain the true state of affairs at his mine, which, while a small one, was still likely to develop in time into an extremely valuable property.

Leaving the ranch in charge of Bud Wilson, he had started for the Mexican country without waiting for the departure of the professor's expedition. A short time later, "Professor Wintergreen's Haunted Mesans," as the boys insisted on calling themselves, had likewise started on their quest. With them, at Jack Merrill's invitation, went Walter Phelps, the son of a ranching neighbor of Mr. Merrill. Walt, it will be recalled, had shared the perils and adventures of the boys across the border, as related in the previous volume, and had been the instrument of piloting them out of the mysterious valley in which Black Ramon kept his plundered herds.

Mr. Merrill's last words had been ones of caution.

"Remember, boys, that if this trouble in Mexico attains real proportions, life and property along the border may be in great danger. In such a case, it will be your immediate duty to turn back."

"But, Dad," Jack had said, "you don't expect that plundering insurrectos would have the audacity to come northward into the Playas?"

Mr. Merrill laughed.

"I didn't say there was any danger even here, my boy. Least of all, out in that barren country. If there is an insurrection, it will doubtless be put down without any trouble, but it is always well to be prepared."

Like his brother ranchers along the border, Mr. Merrill at that time had no idea of the seriousness or extent of the insurrection. Had he had, he would, of course, have prohibited the party leaving the ranch. As it was, he, in common with his neighbors, deemed the insurrection simply one of those little outbreaks that occur every now and again in Mexico, and which hitherto had been promptly squashed by Diaz's army. And so, with no real misgivings, the party had bidden the bluff, good-natured rancher good-by, little dreaming under what circumstances they were to meet again.

But all this time we have been allowing our party to travel on without bestowing any attention upon them. As the afternoon wore on, Coyote Pete began to feel real apprehension about reaching their destination that evening. Walt Phelps' fear about the water had been verified. The supply was getting low. Provided they could "pick up" the mesa they were in search of before sundown, however, this was not so serious a matter as might have been supposed. Coyote Peter knew that there was a well at the mesa, the handiwork of the ancient desert-dwellers.

The really serious thing was, that although they had apparently been traveling in the right direction, they had not yet sighted it. The cow-puncher knew, though he did not tell his young companions so, that they should long since have spied its outlines. Of the real seriousness which their position might shortly assume, the boys had as yet, little idea. Coyote Pete was not the one to alarm them unless he was convinced it was really necessary.

Suddenly, Jack, who had been riding a little in advance of the rest, gave an exclamation and pointed upward at the sun.

"Say, what's the matter with the sun?" he exclaimed.

"Sun spots, I suppose," put in Ralph Stetson jokingly.

"I see what you mean," spoke up the professor; "it has turned quite red, and there seems to be a haze overcasting the sky."

"It's getting oppressive, too," put in Walt Phelps. "What's up, Pete?"

The cow-puncher had, indeed, for some time been noticing the same phenomenon which had just attracted their notice, but he had hesitated to draw their attention to it. Now, however, he spoke, and his voice sounded grave for one of Pete's usually lively temperament.

"It means that ole Mar'm Desert is gettin' inter a tantrum," he grunted, "and that we're in an almighty fix," he added to himself.

"Is it going to rain?" inquired Ralph Stetson, as it grew rapidly darker.

"Rain?" grunted Pete. "Son, it don't rain here enough to cover the back uv a dime, even if you collect all the water that fell in a year. No, siree, what's comin' is a heap worse than rain."

"An electric storm?" queried the professor.

"No, sir—a sand storm," rejoined the cow-puncher bluntly.



CHAPTER II.

THE SAND STORM.

As he spoke, a queer, moaning sort of sound, something like the low, distant bellow of a steer in pain, could be heard. The air seemed filled with it. Coming from no definite direction, it yet impregnated the atmosphere. The air, too, began noticeably to thicken, until the sun, from a pallid disc—a mere ghost of its former blazing self—was blotted out altogether. A hot wind sprang up and swept witheringly about the travelers.

"Ouch!" exclaimed Ralph Stetson suddenly. "Something stung me!"

"That's the sand, son," said Coyote Pete. "The wind's commencin' ter drive it."

"Is it going to get any worse?" inquired the professor anxiously.

"A whole lot, afore it gits any better," was the disconcerting reply.

"What'll we do, Pete?" asked Jack, turning to the cow-puncher.

It had now grown so dark that he could hardly see Pete's face. It was hot, too, with a heavy, suffocating sort of heat. The wind that drove the myriads upon myriads of tiny sand grains now darkening the air, was ardent as the blast from an opened oven-door.

"Get your saddles off, quick! Lie down, and put your heads under 'em," ordered the cow-puncher, briskly swinging himself out of his saddle as he spoke.

The others hastened to follow his example. It was not a minute too soon. Already their mouths were full of gritty particles, and their eyes smarted as if they had been seared with hot irons. The ponies could hardly be induced to stand up while the process of unsaddling was gone through. As for the burros, those intelligent beasts had thrown themselves down as soon as the halt was made. With their heads laid as low as possible, and their hind quarters turned to the direction of the hot blast, they were as well prepared to weather the sand storm as they could be.

The instant the saddles were off the ponies, down they flopped, too, in the same positions as their long-eared cousins. The bipeds of the party made haste to follow their animals' example, only, in their case, their heads were sheltered as snugly as if under a tent, by the big, high-peaked, broad-flapped Mexican saddles.

It was well they had made haste, for, as Pete had said, the sand storm was evidently going to get "a whole lot worse before it got better." The air grew almost as black as night, and the wind fairly screamed as it swept over them. Jack could feel little piles of sand drifting up about them, just as driven snow forms in drifts when it strikes an obstruction. How hot it was under the saddles! The boys' mouths felt as if they would crack, so dry and feverish had they become.

"Oh, for a drink of water!" thought Jack, trying in vain to moisten his mouth by moving his tongue about within it.

All at once, above the screaming of the wind, the lad caught another sound—the galloping of hoofs coming toward them at a rapid rate. For an instant the thought flashed across him that it was their own stock that had stampeded. He stuck his head out to see, braving the furious sweep of the stinging sand.

He withdrew it like a tortoise beneath its cover, with a cry that was only half of pain. Through the driving sand he had distinctly seen three enormous forms sweep by, seen like dim shadows in the gloom around. What could they have been? In vain Jack cudgeled his brains for a solution to the mystery.

The forms he had seen drift by had been larger than any horse. So vague had their outlines been in the semi-darkness, however, that beyond an impression of their great size, he had no more definite idea of the apparitions. That they were travelling at a tremendous pace was doubtless, for hardly had he sighted them before they vanished, and he could not have had his head out of its shelter for more than a second or so.

While the lad lay in the semi-suffocation of the saddle, his mind revolved the problem, but no explanation that he could think of would fit the case. "Might they not have been wild horses?" he thought.

But no,—these were three times the size of any horse he had ever seen. Besides, their blotty-looking outlines bore no semblance to the form of a horse.

But presently something happened which put the thought of the mysterious shadows out of his mind. The wind began to abate. To be sure, at first it hardly seemed to have diminished its force, but in the course of half an hour or so the party could once more emerge, like so many ostriches, from their sand-piles, and gaze about them.

Very little sand was in the air now, but it was everywhere else. In their eyes, mouths, ears, while, if they shook their heads, a perfect little shower of it fell all about them. The animals, too, struggling to their feet out of the little mounds that had formed around them, were covered with a thick coat of grayish dust. It was a sorry-looking party. With red-rimmed eyes, cracked, parched lips and swollen tongues, they looked as if they had been dragged through a blast furnace.

The sky above them now shone with its brilliant, metallic blue once more, while ahead, the sun was sinking lower. In a short time it would have set, and, as Ralph Stetson, in a choked voice, called for "Water," the same thought flashed across the minds of all of them simultaneously.

If they didn't get water pretty soon, their predicament promised to be a serious one.

An examination of the canteens showed that not much more than a gallon remained. If only they could yet "pick up" the mesa before dark, this would not be so serious a matter, but, situated as they were, it was about as bad as bad could be.

"Waal," said Pete, at length, stroking the last grains of sand out of his bleached moustache, "waal, I reckon we might as well hang fer a sheep as er lamb, anyhow. Ef we don't hit water purty soon, we'll be thirstier yet, so we might as well fill up now."

"Illogical, but sensible," pronounced the professor, leading an eager rush for the water canteens, which were carried on the pack burros.

"Here, hold on; that's enough!" cried Jack, as Ralph Stetson bent over backward with the canteen still at his lips.

"Why, I haven't begun to drink yet," protested Ralph.

"Chaw on a bullet, son," advised Pete. "Thet's highly recommended for the thirst."

"Water suits me better," grumbled Ralph, nevertheless yielding the canteen to Jack. The lad drank sparingly, as did Pete and the others. Ralph, alone, of all the party, appeared not to realize how very precious even the little water that remained might become before long.

Refreshed even by the small quantity they had swallowed of the tepid stuff, they remounted, and Pete clambered up upon his saddle. While his pony stood motionless beneath him, he stood erect upon the leather seat. From this elevation, he scanned the horizon on every side. Far off to the southwest was sweeping a dun-colored curtain—the departing sand-storm, but that was all. Otherwise, the desert was unchanged from its previous aspect.

"Let me hev a look at thet thar compass," said Pete, resuming a sitting posture once more.

Jack extended his wrist.

"The compass is all right, I know," he said confidently.

"And I know that we've bin hitting the right trail," declared Pete. "Last time I come this way was with an old prospector who knew this part of the country well enough to 'pick up' a clump of cactus. If that compass is right, we're headed straight."

"Yes—if," put in the professor. "But are you quite sure it is?"

This was putting the matter in a new light. Not one of the party was so ignorant as not to know that, in the many miles they had traveled, the deflection of the needle, by even the smallest degree, might have meant a disastrous error.

"Why, I—I—how can it help being right?" asked Jack, a little uncertainly.

"Which side have you been carrying your revolver on?" asked the professor.

"Why, you know—on the left side," rejoined Jack, with some surprise.

"And the compass on the left wrist?"

"Yes. Why? Isn't it——"

"No, it ain't!" roared Pete. "I see it all now, perfusser; that thar shootin' iron has bin deflectin' ther needle."

"I fear so," rejoined the professor.

Under his direction, Jack moved the compass into various positions, and at the end of a quarter of an hour they arrived at the startling conclusion that they had travelled perhaps many miles out of their way. The metal of the weapons Jack carried having, as they saw only too clearly now, deflected the needle.

"What an idiot I was not to think of such a possibility!" exclaimed Jack bitterly.

"Not at all, my boy," comforted the professor. "The same thing has happened to experienced sea-captains, and they have navigated many miles off their course before they discovered their error."

"All of which, not bein' at' sea, don't help us any," grunted Pete. "Suppose now, perfusser, that you jes' figger out as well as you kin, how far wrong we hev gone."

"It will be a difficult task, I fear," said the professor.

"It'll be a heap difficulter task, ef we don't hit water purty soon," retorted the cow-puncher.

Thus admonished, Professor Wintergreen divested himself of his weapons, and, taking out a small notebook, began, with the compass before him, to make some calculations. At the end of ten minutes or so, he raised his head.

"Well?" asked Jack eagerly.

"Well," rejoined the professor, "it's not as bad as it might be. We are, according to my reckoning, about twenty-five miles farther to the south than we should be."

He consulted his notebook once more.

"The bearings of the mesa require us to travel in that direction." He indicated a point to the northward of where they were halted.

"And it's twenty-five miles, you say?" asked Pete.

"About that. It may be more, and again it may be less."

"Waal, the less it is, ther better it'll suit yours truly. This stock is jes' about tuckered."

With the professor now bearing the compass, they set out once more, this time taking the direction indicated by the man of science.

"Suppose the professor is wrong?" Ralph whispered to Jack, as they urged their almost exhausted cayuses onward.

Jack shrugged his shoulders.

"What's the use of supposing?" he said.

It was sun-down, and a welcome coolness had begun to be noticeable in the air, when Jack gave a shout and pointed directly ahead of them.

"Look, look!" he cried. "What's that?"

"That" was only a small purplish speck on the far horizon, but it broke the monotony of the sky-line sharply. Coyote Pete scrutinized it with keen eyes for a moment, narrowing his optics till they were mere slits. Then—

"Give me the glasses, perfusser," he requested. Every one in the party knew that their lives, or deaths probably, hung on the verdict of the next few seconds, but Pete's slow drawl was more pronounced and unperturbed than ever. He put the glasses to his eyes as unconcernedly as if he were searching for a bunch of estrays. Presently he lowered them.

"Is—is it——?" began Jack, while the others all bent forward in their saddles, hanging on the rejoinder.

"It is," declared Pete, and he might have said more, but the rest of his words were drowned in a ringing cheer.



CHAPTER III.

A NIGHT ALARM.

"How far distant do you imagine it is?" inquired the professor, as they rode forward with their drooping spirits considerably revived.

"Not more than fifteen miles—if it is that, 'cording ter my calcerlations," decided Pete.

"Then we should arrive there by ten o'clock to-night."

"About that time—yep. That is, if none of ther stock give out beforehand."

"Why do they call it the Haunted Mesa?" inquired Jack.

"Some fool old Injun notion 'bout ghosts er spirits hauntin' it," rejoined Pete.

"Just as well for us they have that idea," said Walt. "They'll give it a wide berth."

It flashed across Jack's mind at that moment to tell about the vague, gigantic shapes he had seen flit by in the gloom of the sand-storm. But, viewed in the present light, it seemed so absurd that the boy hesitated to do so.

"Maybe I was mistaken after all," he thought to himself. "There was so much sand blowing at the time that I might very well have had a blurred vision."

The next minute he was doubly glad that he had refrained from telling of his weird experience, for the professor, in a scornful voice, spoke up.

"Such foolish superstitions did exist in the ancient days, when every bush held a spirit and every rock was supposed to be endowed with sentient life. Happily, nowadays, none but the very ignorant credit such things. By educated people they are laughed at."

Pete, who was jogging steadily on ahead of the rest of them, made no rejoinder. Ralph, however, spoke up.

"What would you do, if you were to see a spirit, professor?" he inquired, with an expression of great innocence in his round, plump face.

"I'd take after it with a good thick stick," was the ready reply. "That is, always supposing that one could see such a thing."

Darkness fell rapidly. Night, in fact, rushed down on them as soon almost as the sun sank behind the western rim of the desert. To the south some jagged sierras grew purple and then black in the fading light. Fortunately there was a moon, though the luminary of night was in her last quarter. However, the silvery light added to the brilliance of the desert stars, gave them all the radiance they needed to pursue their way.

The travelers could now perceive the outlines of the Haunted Mesa more clearly. It reared itself strangely out of the surrounding solitudes, almost as if it were the work of human hands, instead of the result of long-spent geological forces.

"Wish we were there now," breathed Ralph, patting his pony's sweating forequarters, "poor old Petticoats is about 'all in.'"

"It's purty hard to kill a cayuse," rejoined Pete. "I've seen 'em flourish on cottonwood leaves and alkali water—yep, and git fat on it, too. Be like a cayuse, my son, and adapt yourself to carcumstances."

"Very good advice," said the professor approvingly, as the desert philosopher concluded.

As Pete had conjectured, the ponies were far from being as tuckered out as they appeared, despite their sunken flanks and distended nostrils. As the cool night drew on, and they approached more nearly to the upraised form of the mesa, the little animals even began to prick their ears and whinny softly. The pack animals, too, seemed to pluck up spirits amazingly.

"They smell grass and water," commented Pete, as he observed these signs.

Shortly after ten, as had been surmised, they were among the bunch-grass surrounding the mesa. Striking such a spot after their long wanderings on the hot desert, was delightful, indeed. Presently, too, came to their ears the tinkling sound of flowing water.

"It's the overflow from them old-timers' well at the base of the mesa," pronounced Pete, listening.

"Yes, and here it is," cried Jack, who had been riding a short distance in advance, and had suddenly come across a small stream.

The water was but a tiny thread, but it looked as welcome just then as a whole lake. Cautioning the boys to keep their ponies back, Pete took a long-handled shovel from one of the packs, and soon excavated quite a little basin. While he had been doing this, the boys had had to restrain their thirst, for the ponies were almost crazy with impatience to get at the water. It required all the boys' management, in fact, to keep them from breaking away and getting at the water. In the heated condition of the little animals, this might have meant a case of foundering. At last Pete let the thirsty creatures take a little water, and afterward they were tethered to a clump of brush, while the boys themselves assuaged their pangs. After their first ravenous thirst was quenched—which was not soon—they took turns in dashing water over each other's heads, removing the last traces of the sand-storm. This done, they all declared that they felt like new men,—or boys,—and a unanimous cry for supper arose.

"Let me see, now," mused Pete, gazing up at the purplish, black heights of the mesa above them, "as I recollect it, there's only one path up thar. The good book says, foller the strait and narrer path, but it don't say nothing about doing it in the dark, so I reckon that the best thing we can do will be to camp right under that bluff thar, whar the water comes out, till it gets to be daylight."

This was agreed to be an excellent plan, and, accordingly, the stock having been tethered out amidst the bunch-grass, the packs were unloaded, and the work of getting a camp in shape proceeded apace. In that part of New Mexico, although it is warm enough by day, nightfall brings with it a sharp chill. It was decided, therefore, to rig up the tents and sleep under their protection. The three canvas shelters of the bell type were soon erected, and then, with mesquite roots, Coyote Pete kindled a fire and put the kettle on. Supper consisted of corned beef, canned corn and canned tomatoes, with coffee, hard biscuit and cheese.

"I'll bet we're the first folks that have eaten a meal here for many a long day," said Jack, looking about him, after his hunger had been satisfied.

"It is, in all probability, fifteen hundred years or more since the first inhabitants of this mesa dwelt here," announced the professor.

"My! My! You could boil an egg in that time," commented Pete, drawing out his old black briar and lighting it. He lay on one elbow and began to smoke contemplatively.

The others did not speak for a few moments, so engrossed were they with the ideas that the professor had summoned up. Once, perhaps, this dead, black, empty mesa above them had held busy, bustling life. Now it stood silently brooding amid the desolation stretched about it, as solitary as the Sphinx itself.

The spot at which they were camped was the sheer, or cliff side of the mesa. At the other side they knew, from Coyote Pete's description, were numerous openings and a zig-zag pathway leading up to the very summit. It was on this summit, which according to the most accurate information obtainable had once been used for the sacrificial rites of sun worship, that the professor expected to find the relics for which he was searching.

For an hour or two the lads discussed the dead-and-gone mesa dwellers, with an occasional word from the professor, who was deeply read on the subject. This was all so much Greek to Pete, who solemnly smoked away, every now and then putting in a word or two, but for the most part lying in silence, looking out beyond the black shadow of the mesa across the moonlit desert toward the rocky hills to the south.

Suddenly, the lanky cowboy leaped to his feet with a yell that punctured the silence like a pistol-shot. In two flying leaps, he had bounded clear over the professor's head, and was in among the tents, searching for his pistol. Before one of the amazed group about the fire could collect his senses at the sudden galvanizing of Coyote Pete, he was back among them again.

"Wow!" he yelled into the night, "come on, there, you, whoever you are! Come on, I say! I'll give you a fight! Yep, big as you are, I ain't skeered of you."

"Pete! Pete! Whatever is the matter?" gasped Jack, who, with the others, was by this time on his feet.

"Matter?" howled Pete. "Matter enough. I do begin to think this place shore is haunted, or suthin'. As I lay there, I felt suthin' tiptoeing about behind me, and when I whipped suddenly round ter see if one of the critters hadn't broken loose, what did I see but a great, big, enormous thing, as big as a house, looking down at me. Afore I could say a word, it was gone."

"Gone!" echoed the others. "What was it?"

"Wish you'd tell me," sputtered the cow-puncher, looking about him, and still gripping his gun, "I never saw the like in all my born days."

"Well, what did it look like?"

"Hard to tell you," rejoined Pete. "It was as big as that." He pointed right up at the moon.

"As tall as the moon? Oh, come, Pete, you had dropped off and were dreaming," laughed Ralph.

"Who said it was as tall as the moon?" demanded the excited cow-puncher angrily. "I only meant to convey to your benighted senses some idee uv what it luked like."

"Well, how high was it?" asked Jack, in whose tones was a curious note of interest, for a reason we can guess.

"About twenty feet, as near's I could judge. It had red eyes, that glared like the tail-lamps of a train, and it spat fire, and it——"

"Whoa! Whoa!" laughed Walt Phelps. "Now we know it was a nightmare, Pete. The dream of a rarebit fiend. You ate too much crackers and cheese at supper."

"How was it we didn't see it?" asked Ralph, who had not spoken up till now.

"Why, you were lying with your back toward the direction it came from," explained Pete.

"An interesting optical delusion," declared the professor. "I must make a note of it, and——"

"Wow! There it goes ag'in."

"Where? Where?" chorused the boys.

"Right off there! Look! Look!"

The lanky cow-puncher, fairly dancing about with excitement, pointed out beyond the shadow of the solitary mesa. Sure enough, there were three or four enormous, black, shadowy shapes, traveling across the sands at a seemingly great speed.

"Get your rifles, boys!" yelled Jack.

The weapons lay handy, and in a jiffy four beads had been drawn on the immense, vague shapes.

But even as their fingers pressed the triggers, and the four reports rang out as one, the indefinite forms vanished as mysteriously as they had appeared.



CHAPTER IV.

SOME QUEER TRACKS.

The hour, the surroundings, and the utter mystery of the whole affair combined to make the sudden appearance and vanishment of the great shadowy shapes the more inexplicable, not to say alarming. Small wonder was it that the inquiring faces that turned toward each other were a trifle whiter than usual.

"What do you make of it, Pete?" asked Jack.

"Stumped, by the big horn spoon!" was the expressive response.

"No doubt, some natural phenomena, with a simple explanation," came from the professor. It was noted, though, that his angular form seemed to be somewhat shivery as he spoke, and that his teeth chattered like dice rattling in a box.

"Natural phe-nothings!" burst out Pete. "The things, whatever they was, were as solid as you or me."

"How was it they didn't make any noise, then?" inquired Ralph, practically.

"Waal, son, you jes' take a run on the bunchgrass, and you'll see that you won't make no racket, nuther."

Ralph did as he was directed, and it was really wonderful how silently he sped over the springy vegetation.

"Maybe it was somebody putting up a scare on us," suggested Walt, rather lamely.

"They couldn't rig up anything as big as that," said Jack decisively, "besides, there's another thing—I didn't tell you because I thought I might have been mistaken, but I saw those same things this afternoon."

"What?" went up in a perfect roar of incredulity.

"Say, is this some kind of a josh?" asked Coyote Pete suspiciously.

"Never more serious in my life," Jack assured him, and then went on to relate the strange experience that had befallen him when he had poked his head out from under the saddle in the sand-storm.

"If they weren't so enormous, I should say they was horses," said Pete; "but the biggest horses that ever growed never even approached them critters—spooks, er whatever they are."

"There are giants among men," suggested Walt, "why shouldn't there be giants among spooks, too?"

"You get to Halifax with that spook talk," said Coyote Pete scornfully. "I'll bet my Sunday sombrero that whatever them things is, there's some sore of human mischief back uv it. But what is it? Who put it up?"

"Yes, and what for, and why?" laughed Jack. "I tell you, fellows," he went on, "it's no use of our racking our brains to-night over this. The best thing we can do is to set a watch. Then, if they come again, we can try a shot at them. If not, why then in the morning we'll make an investigation; eh?"

"Durn good advice," grunted Coyote Pete. "Now, I'd suggest that ther perfusser takes ther fust watch, and——"

"No, no, my dear sir; really, I—I have a cold already. A-hem—ach-oo!"

The man of science, it seemed, had really developed serious bronchial trouble in record time.

"Why, professor," said Jack mischievously, "haven't I heard you say that you'd like a chance to investigate such a phenomenon as this?"

"Hum, yes—yes, my young friend. I may have said so, yes. And any other time I should be only too pleased to—Good Land! what's that?"

With the agility of a grasshopper, the professor had jumped fully three feet, as one of the pack-burros, nosing about behind him, accidentally butted him in the small of his back. The others burst into a roar of laughter, which they could not check. The professor, however, adjusted his spectacles solemnly and looked about him with much dignity.

"I thought I saw a book I had dropped, almost in the fire," he explained glibly, "so I jumped to get it before a hot ember fell on it."

"I had no idea you could jump like that, professor," laughed Jack. "You should have gone in for athletics at Stonefell."

It was finally decided that Walt and Ralph should stand the first watch, and Coyote Pete and Jack the last part of the night. The professor, after carefully drawing tight the curtain of his tent, "to keep the cold out," as he explained, retired. Soon after, Jack and the cow-puncher also went to bed till the watch should summon them to go on duty in their turn.

But the night passed without any reappearance of the strange shapes which had so upset the tranquility of the little camp, and, viewed in the fresh light of a new and glorious day, somehow the affair did not seem nearly so ominous and awe-inspiring as it had the night before. Breakfast, as you may imagine, was speedily disposed of, and, having seen to the stock, the party started out to explore the mesa itself.

As has been said, the side upon which they had camped the night before was nothing but a sheer cliff. Under the guidance of Coyote Pete, they now set out to encircle the strange precipitous formation. Their hearts beat high, and their eyes shone with an aroused sense of adventure as they strode along.

The professor carried with him a small volume containing a partial translation of the symbols and sign language of the ancient tribe whose domains they were about to invade. Jack had a coil of stout, half-inch manila rope, about two hundred feet in length. Walt Phelps' burden was a shovel, while Ralph Stetson carried an axe. All bore with them their revolvers, and Coyote Pete carried, in addition, a rifle.

"Are you afraid of anything?" the professor had asked him, as he noticed the sun-bronzed plainsman pick up this latter weapon.

"Waal," Pete had rejoined, with a portentous wink at the boys, "you never kin tell in this wale of tears what you're a-goin' up aginst—queer shapes, fer instance."

As they strode along, naturally the subject of the shadowy forms which had alarmed them the night before arose. Jack would have liked to investigate them right then and there, but, after all, he decided with the rest of the party, that an exploration of the mesa was the first thing of importance to be accomplished. And an interesting sight the great abandoned aboriginal beehive, was, as they rounded the inaccessible side and emerged upon the portion which faced toward the northwest.

Pete's recollection had not played him false. There was a rough pathway constructed up its face upon this side, and at the top were three tiers of holes bored in the rock face. These were evidently intended for windows, as a larger aperture was just as evidently meant for a door. The path, which zig-zagged up the face of the mesa was about eight inches in width, not more, at its base, and varied—so far as they could see from below—from that breadth to a foot, as it grew higher.

From the base to the summit the mesa was probably about one hundred and fifty feet in height, the windows not commencing till within twenty feet of the top. Its length at the base was, roughly, three hundred feet, and its thickness varied from three hundred feet or more at the center, to a few feet at each end. Roughly, then, its basic outline was that of an irregular parallelogram, while its profile was that of a flat-topped cone. For some moments the little group stood in silence as they gazed up at the yellowish-gray walls of the once-active mound.

Finally, recovering from their reverie, they set out after Coyote Pete to scale the narrow pathway leading to the summit. But, as the cow-puncher set his feet on the lowermost part of the path, he gave an exclamation of astonishment and pointed downward.

There in the dust was a footprint,—several of them, in fact.

It was a startling discovery in that isolated part of the desert to come upon the traces of human occupancy. Robinson Crusoe on his desert island could not have looked any more astonished at the imprint of the savage's sole, than did Coyote Pete. He stood looking down speechlessly at his discovery, while the others crowded about him, asking a dozen questions at once.

"If the sand-storm had hit this section, we'd been able to form some idee of how long ago them hoofs was planted there," said Pete; "but as it is, ther feller who wondered how ther apple got in ther dumpling didn't hev a harder problem than the nut we've got to crack."

"There must have been several of them," said Jack, who had been gazing in the dust, which lay thick on the pathway to the summit of the mesa.

"A dozen at least," nodded Pete. He tipped back his sombrero and scratched his ruffled hair, fairly at a standstill to account for what they had encountered.

"Mightn't it have been prospectors?" asked Ralph.

"Might hev bin, yes," agreed Pete; "but, fer one thing, my son, prospectors don't usually travel in dozens."

"Hum—that's so," assented Jack, who at first had greeted Ralph's suggestion eagerly.

"Look here!" cried Ralph suddenly, holding up a glittering object which he had just discerned in the bunch-grass at the base of the mesa.

"What is it, my boy?" inquired the professor.

Ralph extended the object for their inspection.

"A strange coin," cried Walt.

"Not so blamed strange, either," said Pete, picking it off the boy's palm and examining it. "It's a Mexican peso."

"Then the men who were here were Mexicans?" cried Jack.

"Not so fast, my boy," admonished Pete. "Might as well say that every feller who finds a Canadian dime in his pocket is a Kanuck. Say," he suggested suddenly, "suppose you boys jes' see if you can find any tracks around the base of the mesa."

They scattered and looked carefully about them, but the bunch-grass grew in quite a broad belt all about, and no footmarks could be discerned. Nor did a careful examination of the grass show any broken or trampled blades, as would have been the case had ponies been there recently.

"That decides it," announced Pete, after this last fact had been ascertained, "whoever made those foot-marks wasn't here recent, that's a fact. But who could they have been, and what brought them here?"

"Maybe Indians," suggested Ralph sagely.

"Yep, if Indians wore boots, which they don't," grinned Pete, while poor Ralph colored to the roots of his hair over the general laugh that arose at his expense.

"I think," announced the professor finally, "that it would be our best plan to go ahead exploring the mesa. After all, there is nothing here that can hurt us. Those ruffians of Black Ramon's have been driven out of the country, and, anyway, they would not be likely to come here. As for Indians, their reservation is many miles to the north-east. Whoever was here, was either on a scientific quest, like ourselves, or else unfortunately lost in the desert."

"Jes' ther same," grunted Pete, in a low voice that nobody overheard, "I'd like ter know what all this means: Big, shadowy shapes flitting around in ther night, and footsteps here in ther mornin'. It don't look right."

He took a swift glance all about him. In every direction lay the desert—glittering, far-reaching, lonely as the open sea. The only break in the monotony came to the south—on the border—where stretched the rocky, desolate ridge.

"No one wouldn't come here without an object," reasoned Pete to himself, as they began the ascent of the narrow, tortuous trail, "now, what in thunder could that objec' hev bin?"



CHAPTER V.

THE HOLLOW ALTAR.

"Magnificent indeed!"

The words, falling from the professor's lips, echoed hollowly against the walls of the lofty, vaulted chamber in which the adventurers found themselves, after traversing a narrow passage leading inward from the causeway.

The walls of this chamber, which must have been fully thirty feet in height at its greatest altitude, were formed of the soft rock, out of which it had been excavated apparently uncounted ages before. They were daubed with grotesque figures in faded, but still discernible, colors. Most of these figures had to do with scenes of violence, and in almost all of them the figure of what appeared to be an enormous rattlesnake, with human head and arms, predominated.

Among the mural decorations were some that puzzled the professor considerably. They were crude drawings of men in what appeared to be intended for boats. The professor found these inexplicable. The very idea of boats in that arid spot seemed absurdly out of place. Why, then, should the mesa-dwellers have depicted them?

Light was furnished to the chamber by an irregularly shaped hole in the roof above. Although there was plenty of illumination, it had yet been some moments before the adventurers, coming out of the brilliant sunlight outside, grew used enough to the gloom to make out their surroundings. When they did so, the first words uttered were those of the professor recorded above.

Like some queer, long-legged bird, the man of science, with a giant magnifying glass held up to his eye, sped hither and thither on his long, angular limbs, inspecting minutely the drawings and crude attempts at decoration. Already he had out his tape-measure and sketch-book, making observations and recording measurements. Presently, however, he recalled himself from the first heat of his enthusiasm.

"After all," he said, "we shall have plenty of time in which to explore this chamber, which seems to have been used as a council hall. Let us examine the remainder of this remarkable place."

"You may well call it that, perfusser," grunted Pete. "It's remarkable fer the dust thet's in it, if nothing else. But what I'd like to know," he added to himself, "is jes' whar the owners of them footsteps vanished themselves to."

Which brings us to a remarkable discovery, made a few moments before our party had entered the "Council Hall," as the professor called it.

As you may imagine, they had traced the footsteps with some care, hoping to come upon a solution of the mystery of their origin. Picture their astonishment, then, when you are told that the footsteps abruptly vanished at the summit of the zig-zag trail. Although dust lay thick on the chambers within the mesa, not a solitary foot-mark marred its soft gray surface. With the exception of the numerous footsteps on the trail to the summit, there was no other sign of human visitors.

Like most old plainsmen and all wild animals, Pete was suspicious of anything he couldn't understand, and it certainly did seem inexplicable that a party of men should have visited the mesa and contented themselves with running or walking up and down the causeway outside, or promenading the summit. Such, however, appeared to be the only explanation, and as such they were forced to accept it.

But such speculations as these were far from monopolizing the minds of the professor and the boys. They eagerly traversed chamber after chamber, finding these latter to be small "apartments," so to speak, giving upon a common passage just beyond the "Council Hall." The professor told them that each of these small chambers was formerly the home of an aboriginal family. In the floor of the passage he pointed to numerous bowl-like holes, which, according to him, had been used for the sharpening of spears and arrow heads.

In some of the small chambers specimens of rude pottery were found, all ornamented with the same figure of the human-headed rattlesnake. Evidently the form represented must have been a deity of the tribe. Each of the small chambers was lighted by one of the holes cut in the face of the cliff, which they had noticed from below. The boys darted in and out of the various rock chambers, like ferrets in a rabbit warren, followed at a more leisurely pace by the professor and Coyote Pete.

"Maybe we'll find some treasure," suggested Ralph Stetson, as, with flushed faces, plentifully begrimed with dust, they paused in the last of the rocky chambers.

"Say, you've got treasure on the brain, ever since we found that chest of Jim Hicks' in the passage-way under the old mission, and started our bank accounts," laughed Jack. "You must be forgetting that this mesa has been visited frequently by cattlemen and wandering prospectors."

"Well, I should hardly call it frequently, Jack," put in Professor Wintergreen, who was now standing with Coyote Pete at his elbow, in the narrow entrance to the rocky chamber.

"Nope," added Coyote Pete; "you can bet your boots we didn't come here except when we had to. In the past, though, it made a mighty good watering-place for the cattlemen driving from one section of this country to another. Sence they cut up that land over to the westward inter farms, though, the big cattle drives have stopped, and I don't suppose any one's bin around here for a long time, 'cepting those varmints whose feet-marks we seen."

"How do you know they are varmints?" laughed Walt Phelps.

"Don't see what business they'd hev here otherwise, and——" began Pete, but a perfect tempest of laughter at his expense drowned the rest of his speech.

"Well, now that we seem to have pretty well explored the habitation part of the mesa, let us make our way to the summit," suggested the professor.

With a whoop and yell, the excited boys followed the suggestion at once, and a dash up the narrow causeway followed at imminent risk of one of another losing his footing.

"Hey, hold on thar!" yelled Pete, as they dashed upward, "we don't want no funerals here, an' it's er drop of more'n a hundred feet to ther ground."

This rather checked the boys' enthusiasm, and they went more slowly thereafter.

The summit of the mesa was found to consist of a small plateau, about a quarter of an acre in extent, perfectly bare, and shaped like a saucer. Near the center was the hole which gave illumination to the council hall below them, while in a spot almost exactly in the middle of the queer elevation, was a rough, square erection of sun-baked brick. This was about twelve feet in length, five feet in height, and six feet or so through. Apparently it had once been a kind of an altar. The professor thought this assumption tenable, as it was known that the aborigines who had once inhabited the mesa had been sun-worshipers.

"Ugh!" shuddered Jack, as he gazed at the altar. "And they used to offer human sacrifices here."

"I think it altogether likely," said the professor calmly; "probably that altar has witnessed the immolation of more than a hundred victims at a single tribal ceremony."

Ralph Stetson was clambering up on the altar as the professor spoke, but at hearing these words he hastily descended again.

"I guess I'll defer examining it till some other time," he said decidedly.

From the summit of the mesa a wonderful view could be obtained. At that altitude the rocky, desolate range of sierras to the south could be seen clearly, although a mile or so distant.

"Thar's the border yonder," said Pete, pointing.

"And over across there is father, I guess," said Jack. "I hope he found everything at the Esmeralda all right."

"Sure he did," said Pete confidently. "I tell you, these greaser uprisings don't amount to a busted gourd. Mister Diaz's tin soldiers come along, and 'pop-bang! Adios!' It's all over."

"But I have heard that in this case the insurrectionists of Northern Chihuahua are exceptionally well provided with arms and ammunition," objected the professor. "The American government can't make out from whence they are supplied with guns and munitions of war."

"Huh, where'd they git 'em from, I'd like to know?" snorted Pete. "The border is well guarded at any point where they would be likely to ship 'em across, and——"

"How about the unlikely points?" inquired the professor amiably.

"Um—ah—well," began Pete, somewhat stumped by this last, "I don't see what that's got to do with it."

"But I do. Mexicans, my friend, are, as you should know, a cunning race. Moreover, those of them who dwell along it know the border far better than any white could ever hope to. By the admission of our own secret agents, it has hitherto been impossible to find how the arms, which the Chihuahua rebels are receiving, can reach them. It is obvious, however, that there must be some way in which they do, hence——"

"Waal, perfusser, hev it your own way," grunted Pete, rather red and angry. The professor's logic did indeed seem unassailable. The rebels of Northern Chihuahua were getting arms—but how? The cow-puncher and the boys recalled now a visit made to Mr. Merrill's ranch some weeks before by a party of United States secret agents.

The men were puzzled and angry over their failure to locate the "leak." Somehow arms were being shipped across the border into Chihuahua from American soil, but just how had hitherto baffled all the efforts of their ingenuity to discover.

"There, there, don't be so easily offended," counseled the professor, perceiving Pete's palpable irritation. "After all, the matter has nothing to do with us. We are here to measure the mesa for scientific purposes, not to get into arguments over how a band of insurrectos are getting their arms. Come, boys, to work. Let us begin at the top, by measuring the altar. Suppose, Jack, you lay the tape on it, while I make a rough field sketch of the structure."

The boys, now over their first repulsion to having anything to do with the altar, about which such grisly memories clustered, eagerly began to carry out these orders, while Coyote Pete seated himself on the side of the summit overlooking the travelers' camp below, and amused himself by throwing small bits of detached rock down at the unoffending One Spot, Two Spot and Three Spot.

The base of the altar being duly measured and recorded, Jack, tape in hand, followed by the others, clambered up its rough sides, which afforded an easy foothold, for the purpose of ascertaining the dimensions of the top. To the lad's astonishment, however, there was no summit. That is to say, the altar was hollow.

The professor exhibited considerable scientific excitement on hearing this. The man of science had been greatly puzzled over the total absence of any traces of the human sacrifices he knew must have taken place there. He now hailed Jack eagerly.

"Are there not some bones or traces of sacrifices inside it, my boy?" he inquired excitedly.

"Nary a bone," shouted Walter cheerfully.

"Hold on, though," cried Jack. "There are some queer-looking things down in one corner."

Lowering himself inside the altar, he made for one corner of the erection, in which he had spied a heap of fragile-looking bones of some kind.

"Skeletons of snakes!" he cried, holding up one of these for the inspection of the professor, who had by this time hoisted his bony frame over the top of the altar and now stood beside them.

"That's right, my boy; they are serpents' skeletons. Doubtless in their sacrificial ceremonies these people also offered up rattlesnakes, which seem to have been a sort of sacred reptile among them; much as, in a sense, the cat was sacred to the ancient Egyptians, and the python is worshiped in certain parts of India."

"But, professor," protested Jack, "if, as you say, numerous human sacrifices were offered here in the past, why do we not find any human remains here?"

"Who can say, my boy? Many of the habits of these pre-historic peoples are veiled in mystery. We can only surmise and reconstruct. They may have burned them or disposed of them in some other way."

"Say!" exclaimed Ralph suddenly. "This floor sounds to me as if it was hollow; maybe there's a chamber or something underneath."

The boy, who had been stamping about with a vague sense of making some such discovery, hailed them with excited looks.

"Hollow, you say?" asked the professor, with every appearance of deep interest.

"Yes, listen!"

Again Ralph stamped about. There was no question about it—the stone-paving, of which the floor of the altar was formed, gave out an unmistakably hollow sound.

The professor was down on his hands and knees instantly, searching about, like a hound on the scent. In the meantime the others stamped about in other parts of the interior, but only where Ralph's feet had given out the hollow sound did the floor appear anything but solid.

"Queer!" exclaimed the professor, as, after a considerable search, he rose to his feet covered with dust and streaming with perspiration, "there should be some sort of trap-door here, to judge by the sounds, but so far as I can see, the joints between the pavement are perfectly tight, and I can find no ring or lever which might open such an aperture."

"Perhaps——" began Ralph, but he was interrupted by a sudden wild yell from Pete.

"Wow! Yee-ow! Come here quick, everybody!"



CHAPTER VI.

THE LEGEND OF A FORGOTTEN RACE.

Leaping and scrambling over the top of the hollow altar to the best of their abilities, the four explorers found their cow-puncher friend dancing wildly about on the edge of the mesa, in imminent peril of tumbling over altogether. He was wildly excited, and, as they emerged, he pointed down over the cliff edge.

"Whatever is the matter?" exclaimed Jack, regarding the antics of the usually staid cow-puncher with amazement.

"The stock! Look at the stock!" yelled Pete.

Peering over the edge at the bunch-grass belt in which their ponies were tethered, the adventurers saw a spectacle which might well have been calculated to excite the cow-puncher. One Spot, Two Spot and Three Spot were tearing round and round at the end of their tethers, in the wildest alarm, evidently, while the cayuses were stamping and snorting, with distended nostrils and wild, frightened eyes.

"What's the matter with them?" gasped Walt, astonished at the sight, as well he might be. The desert was as empty as ever, and there was no sign of anything in the rocky hills to the south that might have excited their alarms.

"Thet's jes' it," said Pete. "What is the matter with 'em? They ain't actin' up thet er way fer nuthin', you kin bet."

"Something must have scared them," said Jack. "Maybe it was those rocks you were throwing down."

"No, it warn't that, son. Ole One Spot he looked up here a minute ago, and giv' his eye a knowin' wink, as much as ter say: 'Go ahead; I know you won't hurt us.' No, siree; it's suthin' they've smelled out, er seen, that's given 'em the scare of their young lives."

"Maybe it was something on the other side of the mesa. Let's go and look," cried Jack.

Followed by the others, he ran across the flat summit, but an earnest inspection of the surroundings on that side failed to reveal any explanation for the animals' sudden terror. For all the strange objects that lay about them, they might have been in the middle of a desolate ocean.

"No wonder they call this the Haunted Mesa," snorted Pete. "I tell you, perfusser, ther sooner you git them thar measurements a-measured, and we're hiking out of this neck of the woods, the better I'll be pleased. 'Tain't natural, all these queer goings on."

"Maybe a coyote or something scared them," suggested Ralph.

"And them used ter seeing 'em every day," scoffed Pete. "Guess again, son. It takes something with hoofs, horns and red fire about it to scare a burro, and you kin bet your Sunday sombrero on that."

"Well, I propose that we adjourn the meeting till after dinner," laughed Jack; "all in favor, will signify by saying 'aye.'"

The chorus that answered him left no doubt of "the sense of the meeting," and a rapid descent of the mysterious mesa was begun. A good meal was not long in being prepared, thanks to Coyote Pete's skill as a camp cook. Seated over their dinner, the main topic of conversation was naturally the unaccountable occurrence of the morning. But although a score of explanations were advanced, nobody could hit on one that seemed to fit the case.

"This water is singularly pure and sparkling,"' said the professor finally, by way of changing the subject, and holding up his full tin cup.

"Yep; I remember hearing old cowmen say that there's no water in New Mexico any better than this from the Haunted Mesa," said Pete, stretching himself out, and lighting his inevitable after-meal-time pipe. "Though that ain't sayin' a heap," he admitted.

"Wonder how those old what-you-may-call-ums ever managed to dig such a well?" questioned Ralph.

"Comes to my mind now," said Pete, "that it ain't exactly a well. An old Injun that used ter hang around with the Flying Z outfit tole us oncet that thar was a subterranean river flowed under here, and that once upon a time afore all the country dried up, considerable more water came to the surface here than there does now."

"A subterranean river?" asked the professor, at once interested.

"Yes, sir," rejoined Pete, "and not the only one in the West, either. There's one in Californy that flows underground fer purty near fifty miles, as I've heard tell."

"This is most remarkable," said the professor. "I, too, have heard of subterranean rivers in this part of the world, but I have never had the opportunity to explore one. Did this Indian you speak of ever tell you where this river emerges?"

"He said it come out some place across the frontier in Chihuahua; I don't jest rightly recollect where," said Pete carelessly, as if the subject did not interest him much, as indeed it did not.

"I don't see what use a subterranean river is to anybody, anyhow," he went on. "If it was on top, now, it might be some use."

"But this is most interesting," protested the professor, while the boys lay about with their chins propped in their hands in intent attitudes. "Then, too, if this river exists, perhaps it is even navigable."

"Why, professor!" exclaimed Jack. "Is it not possible that it was to this river that those drawings of boats that interested and puzzled you so much had reference?"

"Quite possible, my boy," agreed the man of science.

"I wish we could find some way of getting down into it," said Ralph wistfully, poking at the ground, as if he thought he might force an entrance that way.

"Thar you go," laughed Pete. "Giv' you boys a cayuse, an' you'll ride him to death. I jes' mentioned that a lying, whisky-drinking old Injun had sprung a pipe-dream about a lost river, and thar you go navagatin' it in a Coney Island steamboat."

The boys could not help bursting into a laugh at the cow-puncher's whimsical way of talking. The professor joined in, too, for none realized better than he did that for a moment he, too, had been quite carried away by the idea.

"I expect that it is as you say, Pete," he agreed. "These Indians are most unreliable people. If anybody was to believe all the weird legends an Indian tells him, he would spend the best part of his life on wild-goose chases. Why, the Indians of the Mojave desert in California can even tell a circumstantial story about a buried city of Mojave. According to their contention, a great flood, occurring long ago, wiped it out and buried it in the sands of the desert."

"Has any one ever tried to find it?" asked Jack.

"Many expeditions have been fitted out for the purpose, my boy," was the rejoinder, "but so far no trace has ever been found of it, and it is, no doubt, like the lost river of which Pete was telling us, a mere myth."

"I didn't say it was a miff," protested Pete. "I jes' said I didn't believe it."

The remainder of that afternoon was spent in making more measurements and sketches of the interesting mesa, and the boys, on their own account, conducted a search for a possible entrance to the lost river. But, as may be supposed, they found none.

"I guess as romance-seekers we are not a success," said Jack, as at sun-down they prepared to quit. "Just think, what a proud bunch we'd have been if we could say we—The Border Boys—discovered the lost river of the mesa dwellers."

"We might be a sorry bunch, too," amended the practical Walt. "I tell you, Jack, I don't want anything to do with lost rivers, especially when they are underground."

"Walt, the spirit of adventure is lacking in you," laughed Jack. "You'd never make a Don Quixote——"

"A donkey who?" asked Walt innocently.

"Oh, you're the limit," chuckled Ralph, going off into a roar of laughter at the ranch boy's expense.

That evening the animals' pasture was changed to the opposite side of the mesa, where they could find fresh grass. The camp, however, was left as it was. After supper watches were assigned, as usual, the latter part of the night guardianship falling to Coyote Pete and Jack once more. When, soon after midnight, Walt and Ralph Stetson aroused them, there was nothing much to report except that One Spot had engaged in a spirited kicking match with his brethren. Outside of that, all had been, to quote Walt:

"Quiet along the Mesomac."

"We'll patrol round the whole mesa," said Coyote Pete, as he and Jack shouldered their rifles, "meeting by the stock on the other side."

After a few words more, the two sentries strode off into the darkness in different directions, meeting, as arranged, by the stock. Neither had anything to report, and in this way they kept up the night watch for an hour or more. They had met for the sixth time by the tents containing their sleeping comrades, when from the opposite side of the mesa came a shrill neigh of terror, followed by sounds of wild galloping and snorting.

"Something's up!" shouted Pete, as, with his rifle in readiness and followed closely by Jack, he tore around the mesa to ascertain the cause of the trouble.

As the two sentries emerged into view of the spot in which the stock had been tethered, they came upon a spectacle which, for a moment, caused them to recoil as abruptly as if a deep canyon had suddenly opened up before them.



CHAPTER VII.

WHAT CAME ACROSS THE DESERT.

That which brought the two—the plainsman and the lad—to such an amazed halt was nothing more nor less than the sight of the huge forms which had appeared to Jack in the sand-storm and which had given them such an alarm the night before, and which doubtless, as they now viewed it in a flash of intuition, had almost stampeded the stock while their owners were exploring the top of the mesa. But Coyote Pete was not the man to remain long rooted in astonishment.

With one quick jerk, he raised his rifle, and a vivid spatter of fire followed. As the report died out, one of the great forms sank to the ground with a scream that sounded almost human. The others glided off in the same direction as they had the night before, and vanished in the same mysterious way, before the thunderstruck Jack could get a shot at them.

"They're real, at any rate," exclaimed Coyote Pete, showing in his tone of relief, that until the great shadowy mass had sunk before his bullet, he had had some doubts of that fact.

"W-w-w-w-what is it?" came a frightened voice at their elbows, and, looking around, they saw the professor, in pajamas striped like a barber's pole, gazing apprehensively about him. Close behind him came Ralph Stetson and Walt, their weapons clasped determinedly, and evidently ready to face whatever emergency the sudden shot had betokened.

"Yes, what is it—Indians or bears?" demanded Ralph, entirely forgetful of the fact that bears are not wont, as a rule, to roam the barren desert.

"Dunno, but we'll see in a minute," said the cow-puncher, in answer to the excited questions. Followed by the rest, he made his way forward to where the great bulk that he had shot lay still and motionless on the ground. Even Jack owned to a slight feeling of apprehension as they neared the great form,—harmless as, whatever it might be, it had now become.

As for the stock, they were still plunging wildly about and snorting in a terrified fashion, and, had it not been for their stout raw-hide tethers, they would undoubtedly have stampeded.

Drawing a match, Pete held it high as he neared the stricken bulk outstretched before them. The next minute he gave an astonished cry:

"A camel!"

"A what!" gasped the entire group in unison.

"Jes' what I said, a backterian camel," reiterated Pete, striking another match.

They could all see then that he spoke the truth, astounding as it seemed. The creature that lay still before them, a bullet through its brain, was a veritable, undoubted specimen of the Bactrian species.

"But—but—great heavens!" cried Jack, hardly able to believe his eyes, "how,—what——"

"What on earth is a camel doing out here on the New Mexican desert?" the professor finished for him.

"Going eight days without a drink," suggested Ralph in an undertone; but none of the party was in a mood for humor just then.

It was Pete who solved the mystery.

"I've got it," he exclaimed, "and I'm a plum-busted idjut not to have thought uv it afore; I've hearn about 'em often enough. This here backterian camel must be one of that bunch of Circus Jesse's."

"Circus Jesse! Who was he, or she?" asked Jack.

"Why, he was a feller what owned a big eastern circus, but owned a ranch out here as well. It struck him one time that if camels was good for transportation purposes over the Sahara desert they ought ter be just as good here. So, what does he do but start a camel express from Maguez ter Amadillo over the border, with some of the backterians frum his circus."

"And didn't it work?" asked Ralph.

"No. That is, it did fer a while, till ther novelty wore off, and then folks went back ter ther old reliable mule or burro. Circus Jesse, he got so blamed sore, that one fine day he turned the whole shootin' match of his backterians loose, and packin' his trunk, let the country, and resolved in futur' ter stick ter his circus."

"Was that long ago?" asked Jack. "I shouldn't have thought the creatures would have lived long without being recaptured."

"It's about five years since Jesse got out, I reckon," rejoined Pete, "an' fer a while camel-hunting was a popular sport. By an' by, however, they got so wary no one could get near 'em, and, except fer a scare they'd throw inter a prospector now and ag'in, we never heard no more of 'em. I'd clean fergotten all about 'em, till I made this one inter cold backterian meat."

"I suppose they found food and water here and regarded the Mesa as their own property," declared Jack.

"That's about it. This is a place that's seldom visited, and I guess they just figgered out that they'd found a happy home."

"But what became of the rest of them?" asked Ralph, who had been apprised by Jack of the strange vanishment of the dead creature's mates.

"Must uv gone down that draw I noticed frum ther top uv ther mesa to-day," explained Pete. "Yer see, frum here, it would look as if they vanished inter the solid earth when they entered it, bein' as how you can't see there's any kind of a gully there till you get up high."

The next morning this was found to be the true explanation. Tracks on the bottom of the gully showed plainly how the strange desert wanderers had effected their disappearance in such a startling manner. But it was some time before Pete could sit down to a meal without being reminded of his "fire-spouting spook," which had cast such alarm into the camp the first night. The boys spent a week more at the mesa, during which time Professor Wintergreen obtained voluminous notes on one of the most interesting specimens of its kind in the south-west.

The days passed tranquilly, and, with the exception of the duty of removing the carcass of the dead camel, nothing to interrupt the routine of survey work occurred. The mates of the dead beast had evidently decided not to revisit their pasture grounds, for they did not put in a reappearance.

"Well, boys," said the professor one morning when they were all gathered at the summit of the mesa, "I guess that to-morrow morning we can say good-by to the scene of our rather tame adventures. My work is complete."

"How about the subterranean river?" asked Ralph, but a howl of derision from the others silenced him.

"Subterranean fiddlestick," burst out Jack, but the professor silenced him.

"The existence of such a stream is not so improbable as you seem to think," he said, "and Master Ralph is to be commended for his enterprising desire to locate it, but I think that our investigations have shown that if such a river ever did exist and the mesa dwellers had access to it, that the entrance, wherever it might have been, has vanished long ages ago."

Pete had taken no part in this conversation, but had wandered about the top of the mesa rather aimlessly, from time to time looking sharply at the surroundings beneath him in the alert manner of one whose life has been passed in the open places.

Suddenly he gave a quick exclamation and pointed off into the north-west.

"Look! Look there!" he exclaimed, riveting his eyes on something his keen vision had sighted, but which remained as yet invisible to the boys.

"What's coming—another storm?" asked Ralph.

"I don't know what it is yet," rejoined the other in a strangely uneasy tone, "it looks like—like——"

"A pillar of dust," exclaimed Jack, who had by this time sighted it, too, and had come to the aid of the unimaginative plainsman.

"So it does," cried the others, who now, with the exception of the short-sighted professor, could also see the approaching dust-cloud.

"What can it be?" wondered Walt, peering eagerly in its direction.

"Somebody riding. Several of 'em, I should say, by the dust they're raising," rejoined Pete bluntly.

The boys exchanged quick glances. Somebody riding across that arid waste? Their destination could only be the mesa, then, but who could it possibly be?

Had they been able to solve the riddle at that instant, they would have scattered pell-mell for their ponies, and made the best of their way from the Haunted Mesa, but, not being endowed with anything more than ordinary sensibilities, it was, of course, impossible for them to realize the deadly peril that was bearing down upon them in that dust-cloud.

"I can see things more clearly now," cried Jack, as for an instant a vagrant desert air blew aside the dust-cloud and revealed several riders, surrounding some cumbersome, moving object in their midst.

"There's a wagon!" he cried, "a big one, too, and surrounded by horsemen. What can it mean?"

"That we'd better be skedaddling as quick as possible," shot out Pete, brusquely.

The professor, who had wandered away from the group and was down inside the hollow altar, was hastily summoned and apprised of the strange approach of the mysterious cavalcade.

"Why, bless me, boys, what can it mean?" he cried, nimbly attempting a flying leap over the edge of the altar in his haste to ascertain for himself the nature of the approaching party.

Suddenly, however, as his feet touched the top, and he was scrambling over, he gave a sharp cry and fell back within the altar with a gasp of pain.

"Are you hurt?" asked Jack, running to the side of the ancient place of sacrifice.

The professor lay prostrate within. His face was white and set and beads of sweat stood out on his forehead.

"My—my ankle," he groaned. "I broke it some time ago, and in hurrying to clamber over the top of the altar I fear I have snapped it again. Oh!"

He gave a heartrending groan of pain. The boys stood stricken with consternation. It was going to be a long and difficult task to get the professor out of his present predicament, and there seemed need for haste.

"Here, put this under your head," said Jack, stripping off his jacket hastily, and throwing it within, "I'll tell Coyote Pete about your accident, and we can get remedies from the packs."

But when Jack turned, only Ralph and Walt stood beside him. The sturdy cow-puncher had vanished.

"He's gone to get the glasses," explained Walt.

Presently Coyote Pete, very much out of breath from his dash down the path and up again, stood beside them. He had the glasses in his hand, and lost no time in applying them to his eyes. He had not had them there two minutes when he gave a quick exclamation and turned hastily to the boys.

"Lie down; lie down, every one of you," he ordered sharply.

They lost no time in obeying, as they knew that the old plainsman must have an excellent reason for such a command. The next instant Pete himself followed their example. Crouching low, he once more peered through the glasses above the edge of the cup-like depression.

"Who are they?" asked Jack in a low voice, wriggling his way to Pete's side.

"I'm not sure yet, but they are all armed. I caught the flash of sunlight on their rifles. If they are Mexican insurrectos, we are in a bad fix."

"Mexicans! What would they be doing this side of the border?"

"That remains to be seen. But I don't like the looks of it."

"Suppose they are Mexicans, Pete, would they do us any harm?"

"That depends a whole lot on whether they are on lawful business or not."

"You mean——"

"That I don't like the looks of it. If there's an insurrection in Mexico, those fellows are after no good on this side of the border. They may be some band of cut-throats, who are taking advantage of the disturbances to raise Cain."

"Good gracious," exclaimed Jack, "and the professor's just injured himself so that we can't move him for some time anyhow."

Coyote Pete turned sharply on the boy.

"What's he done?"

"Broken his ankle, or, at any rate, seriously sprained it."

Pete's rejoinder to this was a long whistle of dismay. He said nothing, however, but once more applied the glasses to his eyes. Jack saw him gnaw his moustache, as he gazed out over the desert. The dust-cloud was quite close now—not more than a mile away. The boys, with their naked eyes, could easily catch the moving glint of metal.

"Well, Pete, what do you think?" inquired Jack eagerly, as the cowpuncher at length set down the glasses.

"That we're in Dutch," was the expressive rejoinder.



CHAPTER VIII.

THE DARK FACE OF DANGER.

"Are we in actual danger?"

It was Ralph who put the question. The Eastern lad looked rather white under his tan. Walt, however, seemed as imperturbable as ever, and gazed out at the approaching horsemen with no more sign of emotion than a tightening of the lips.

Coyote Pete's reply was a curious one. He handed the boy the glasses, and said curtly:

"Take a squint fer yourself."

Ralph gazed long and earnestly. Pete talked the while in low undertone.

"Do you recognize him—that fellow on the big black horse? I'd know that horse ten miles away, even if I didn't know the man. He's——"

"Black Ramon de Barros!" burst from the Eastern lad's astounded lips, while the others gave a sharp gasp of surprise.

"That's the rooster. Here, Jack; take a look."

The boy, as you may suppose, lost no time in applying the glasses to his own eyes. Viewed through the magnifying medium, a startling moving-picture swung into focus.

Surrounding a big, covered wagon, of the prairie-schooner type, were from ten to a dozen wild-looking Mexicans, their straggling elf-locks crowned by high-peaked sombreros, and their serapes streaming out wildly about them, whipped into loose folds by the pace at which they rode. As Coyote Pete had said, there was little difficulty for any one who had seen him once, in recognizing Black Ramon de Barros. His magnificent black horse—the same on which he had escaped from the old mission—made him a marked man among a thousand. The wagon was drawn by six mules, and driven by a short, stocky, little Mexican. The horsemen seemed to act as escort for it. Evidently they had no fear of being observed by hostile eyes, for, as they advanced, they waved their rifles about their heads and yelled exultingly.

Fortunately for the party on the summit of the mesa, their stock was tethered on the opposite side of the formation to that on which the cavalcade was approaching. Thus, Black Ramon and his men could not see that the mesa was occupied. Jack caught himself wondering, though, how long it would be before, and what would happen when, they did.

"Have you got any plan in your head?" he asked, turning to Pete, as he laid the glasses down. But for once, to his dismay, the old plainsman seemed fairly stumped. The danger had come upon them so suddenly, so utterly unexpectedly, that it had caught them absolutely unprepared. They had not even a rifle with them on the mesa summit, and it was now too late to risk exposing themselves by descending for weapons. There was nothing to do, it seemed, but powerlessly to await what destiny would bring forth.

"You boys get back to the altar. You can act as company fer the profusser, and it will be a snug hiding-place in case of trouble," whispered Pete. "I wish to goodness we'd brought the stock up inside the mesa, and then those fellows might never have discovered we were here. I don't see how they can help it, as things are, though."

"They'll be bound to see our footmarks in the assembly hall," said Jack.

"Not bound to, lad," rejoined Pete. "You see, they may be only going to make this a watering-place fer their stock, and then press right on."

"Press right on across that rocky range yonder?"

"Hum," resumed Pete, "that's so. They couldn't very well get that wagin across that, could they?"

"Whatever do you suppose they've got a wagon for, at all?" asked Jack.

"I've got my own ideas, lad, and I'll find out afore long if I'm right. Now, you and the other boys get back in that altar. If it gets too hot here, I'll jump in and join you. If the worst comes to the worst, we ought to be able to lay hid in there fer a while."

"In the meantime what are you going to do?"

"Keep my eyes and ears open. There's something mighty strange about this whole thing."

The boys knew that obedience to Pete's commands was about the best thing they could do at the moment, so they hastened to conceal themselves within the altar, which afforded a comfortable hiding-place, even if it was a trifle hot. The poor professor was in great pain from his ankle, but Jack, after as able an examination as he could give the injured member, was unable to find that it was anything more than a severe sprain.

It did not take the professor long to become acquainted with what had happened within the last fifteen minutes, and, in his anxiety over the outcome of their situation, his pain was almost forgotten.

"If we only had the rifles," he breathed in such a savage voice that had the circumstances been different the boys could have smiled at the odd contrast between his mild, spectacled countenance and his bloodthirsty words.

It seemed hours, although in reality not more than half an hour elapsed, before Coyote Pete returned. His reappearance was not an orderly one. Instead, he landed in the interior of the altar in one bound. His face was streaming with sweat, and he looked anxious and worried.

"What news?" asked Jack.

"The worst," was the rejoinder.

"Have they found our camp?"

"Not yet, but that's only a question of a few minutes now. At present they are unhitching and cooking a meal. Luckily the shade at this time of day lies to the north-west of the mesa, so that they may not explore the other side for some time."

"Let us hope not. But what have you found out about them? What are they doing here?"

"Just what I suspicioned. They are a part of a gang of gun-runners."

"Gun-runners?"

"Yes. From listening to their conversation, I have found out that this insurrection's a heap worse than we ever supposed. Half of Chihuahua is up in arms ag'in the government, and they are plotting to blow up railroad bridges, cut wires, and paralyze the country generally. Then they are goin' ter raid all the American mines and get the gold."

"Why, dad's mine's in Chihuahua, close to the border," gasped Jack.

"I know it. I heard that greaser ragamuffin, Black Ramon, mention his name. Your dad's the first one they're goin' after——"

"The scoundrels."

"They owe him a grudge, you know, and now's their chance to get even."

"Do they know that dad is in Mexico now?"

"I didn't hear that. All I found out was what I told you, and that, as I said, they are running guns across the border. That wagon's loaded up with machine-guns in heavy cases. They are labeled as agricultural machinery, and were taken off the train by white accomplices seventy miles or more from here. They chose this part of the border, I guess, as even Uncle Sam would never suspect any one of trying ter get guns over them hills yonder."

"Well, they can't take a wagon over those rocky, desolate places. How are they going to get them across, do you suppose?" asked the professor, his pain almost forgotten in the tense interest of the moment.

"That's just the funny part uv it," said Pete; "they never mentioned the mountains. You don't suppose there's any other way they could get 'em over the border, do you?"

"Maybe they have an airship," suggested Walt Phelps.

"Maybe," said Pete quite gravely, "I wouldn't put nothin' past a greaser."

"Hush!" exclaimed Ralph suddenly, "somebody's coming."

With beating hearts they sank into absolute silence. The three boys crouched at one end of the hollow altar, the professor and Coyote Pete bundled together into as small a space as possible at the other.

Voices, conversing in Spanish, could now be heard, and, from the inflection, the boys judged that whoever was talking was very much astonished over something.

"I recognize that voice," said Jack suddenly, in a low whisper, "it's Ramon de Barros."

The other two boys nodded. Ralph Stetson's heart beat so hard and fast that it fairly shook his frame. Truly the predicament of the party was a terrible one. Discovery by as wolf-hearted a band of ruffians—if they were all like their leader—as ever infested the border, was inevitable within the next few minutes. Taking into consideration their connection with Black Ramon in the past, it was unlikely in the extreme that any mercy would be shown them. Never had any of them looked so closely into the dark face of danger.

Suddenly the listeners, crouching in their hiding-place, heard a shout of astonishment from the Mexicans.

"They've seen our camp over the edge of the mesa!" exclaimed Pete in a low, tense voice; "in another minute they'll start looking for us."

As he spoke, the voice which Jack had recognized as Black Ramon's, uttered a crisp, curt command of some sort. The lads could hear footsteps hurrying hither and thither. Without doubt, the order that meant their probable doom had just been given.

"I can't stand this a minute longer," cried Ralph suddenly. The boy's eyes were blazing wildly. Clenching his fist, he sprang to his feet.

"Come back here, you blockhead," snapped Jack, tugging his friend down. Ralph came backward sprawling, and landed in a heap in Jack's lap, knocking Walt Phelps with him. Together the three boys were tangled in a struggling heap.

"Get up," whispered Jack. "They'll hear us. You——"

He stopped short. All at once an astonishing—an incredible thing—had happened. The floor beneath them,—the solid floor, as it had seemed,—began to tremble.

Before any of the amazed lads could utter a word, the foundation upon which they rested tipped, and, with a loud, ringing cry of terror from Ralph, they were plunged out of the sunlight into blackness as impenetrable as the pocket of Erebus.