thorn under your saddle. Of course, as soon as you sprang into your seat, your weight just drove one of these tough little points in deeper. And, as the horse jumped, every movement was so much more torture. Get onto it, Bob?"

"Sure I do; and I guessed all that while riding back. But tell me, why did he pick out my horse, instead of your Buckskin?" asked the Kentucky boy.

"Look back a little. Who was it gave Peg his little tumble when he was striking that child? Why, of course it was nobody but Bob Archer. I saw Peg standing on the porch of the tavern as I galloped after you; and give you my word, Bob, he had a grin on his face that looked as if it would never come off. Peg was happy—why? Because he had just seen you being carried like the wind out of town on a bolting nag. And I guess he wouldn't care very much if you got thrown, with some of your ribs broken in the bargain."

Bob proceeded to tell how he had figured on what caused the queer antics of his horse, and then what his method for relieving the pressure had been.

"Just what you should have done!" exclaimed Frank, enthusiastically. "Say, you're getting on to all the little wrinkles pretty fast. And it worked too, did it?"

"Thanks to the smartness of Domino, it did," replied Bob, proudly. "Some other horses might have broken away as soon as their rider dismounted; but he's mighty near human, Frank, I tell you. He just stood there, quivering with excitement, and pain, till I got the thing off. But do you know what kind of thorn this is?"

"I know it as well as you would a persimmon growing on a tree in Old Kentucky; or a pawpaw in the thicket. It's rank poison, too, and will breed trouble if the wound isn't taken care of in time.

"That's bad news, old fellow. I'd sure hate to lose my horse," remarked Bob, dejectedly, as he threw an arm lovingly over the neck of the black.

"Oh! I don't think it'll be as bad as that; especially since I happen to have along with me in my pack some ointment old Hank Coombs gave me at a time I fell down on one of the same kind of stickers, and got it in my arm," and Frank opened the smaller of the two packs he had fastened behind his saddle.

When the ointment was being thoroughly rubbed into the spot where the barb of the thorn had pierced the flesh of the animal, Domino seemed to understand what their object was. He gave several little whinnies, even as he moved uneasily when his master's hand touched the painful spot.

"Now what's the programme?" asked Bob, after he had replaced the saddle.

"Just what we decided on before," replied his chum; "a little rest before we make a start. Twenty-four hours will do Domino considerable good, too. How did you come out about the duffle you were carrying; any of it get lost?"

"None that I've noticed. I'll make a round-up and see, before we go any further," Bob remarked, examining the packages secured behind his saddle.

"How?" queried Frank, in the terse, Indian style, as he saw that the other had gone carefully over the entire outfit.

"Everything here, right side up with care. And now I'll have to mount again, a thing that may not appeal very much to Domino. But it's lucky I long ago learned the jockey way of riding, with most of the weight upon the withers of the horse. In that manner you see, Frank, I can relieve the poor beast more than a little."

Together they rode off slowly. Really, for one day it seemed that the big black must have had all the running his fancy could wish. Besides, neither of the boys knew of any reason for haste. As Frank had suggested, it would perhaps be just as well to allow a certain amount of time to elapse, before pushing their intended investigation of the mysteries supposed to hover around Thunder Mountain.

The afternoon had almost half passed when Frank's sharp eyes discovered a single horseman riding on a course that would likely bring him across their trail soon.

"Seems to me there's something familiar about that fellow's way of sitting in the saddle," he observed; and then, reaching for the field glasses which he carried swung in a case over his shoulder, he quickly adjusted them to his eyes. "Thought so," he muttered, and Bob could see him smile as he said it.

"Recognize the rider, then? Don't tell me now that it's Peg, or one of those slippery cowboy friends he has trailing after him," remarked Bob.

"Here, take the glasses, and see what you think," replied the other, laughingly.

No sooner had the Kentucky lad taken a single good look than he called out:

"Who but old Hank Coombs, the veteran cow puncher of the Southwest! I suppose your father has sent him on an errand, Frank."

"Just as likely as not, because he trusts old Hank more than any man on the entire ranch. You can see he's headed in a line that will fetch up at the Circle Ranch by midnight, if he keeps galloping on. Look there, he sees us, and is waving his arm. Yes, he's changed his course so as to meet us, Bob."

"But if we needed the glass to find out who he was, how does it come that an old man like Hank could tell that we were friends, at such a distance?" asked the young tenderfoot, always eager to learn.

"Because his eyes are as good as ever they were. Some of these fellows who have lived in the open all their lives have eyes like an eagle's, and can tell objects that would look like moving dots to you. Let's swing around a bit, so as to keep old Hank from doing all the going."

As he spoke Frank veered more to the left, and in this fashion they speedily drew near the advancing horseman. He proved to be a cowman in greasy chaps, and with many wrinkles on his weather-beaten face. But Hank Coombs was as spry as most men of half his age. He could still hold his place in a round-up; swing the rope in a dexterous manner; bring down his steer as cleverly as the next man; ride the most dangerous of bucking broncos; and fulfill his duties with exactness. Few men grow old on the plains. Most of them die in the harness; and a cowboy who has outlived his usefulness is difficult to find.

The veteran eyed the additional packs back of the saddles of the two boys with suspicion in his eyes. He knew the venturesome nature of his employer's son; and doubtless immediately suspected that Frank might have some new, daring scheme in view, looking to showing his friend from the East the wonders of this grand country, where the distances were so great, the deserts so furiously hot, the mountains so lofty, and the prairies so picturesque.

"Ain't headin' toward home, are ye, Frank?" was the first question Hank asked, as they all merged together, and rode slowly onward in company.

"Oh! not thinking of such a thing, Hank," replied the boy. "Why, we only left the ranch yesterday, you know, and meant to be away several days, perhaps a week. But I'm glad we ran across your trail right now, Hank, because you can take a message to dad for me."

"Glad to do that same, Frank," the veteran cowman replied, and then added: "but jest why are ye headin' this way, might I ask? It's a wild kentry ahead of ye, and thar be some people as don't think it's jest the safest place goin', what with the pesky cattle-rustler crowd as comes up over the Mexican border to give the ranchers trouble; and sometimes the Injuns off their reservation, with the young bucks primed for a scrap."

"Is that all, Hank?" asked Frank, turning a smiling face upon the old rider. Hank moved uneasily, seeming to squirm in his saddle.

"No, it ain't," he finally admitted, with a half grin; "that's Thunder Mounting about twenty mile ahead o' ye. None o' us fellers keers a heap 'bout headin' that-a-way. Twice I've been 'bliged to explore the canyons thar, arter lost cattle; but I never did hanker 'bout the job. It's a good place to keep away from, Frank."

"You don't say, Hank!" chuckled the boy. "Too bad; but you see that's just the very place we expect to head for to-morrow—Thunder Mountain!"

The old man looked closely at him, and shook his head.