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