The boys sat silent in their saddles and looked down at the queer tracks left in a place where the earth was soft. The marks were like two shallow depressions in the ground, about a foot across and separated by about eight feet. They looked to have been made by some rounded body, for in the center the depressions were more deeply indented than on the edge, and the marks, or tracks, curved and twisted this way and that, but always in almost an exact parallel.
“What do you make of them?” asked Ned, and both he and Bob glanced at Jerry.
“They’re queer,” said the tall lad at length.
“You’re right there,” assented Bob. “But what do they mean?”
“And have they anything to do with the disappearance of the professor?” went on Ned.
“You’ve got me there,” Jerry had to confess. “You see we don’t know whether the marks were made before or after he left us.”
“They can’t have been made very long though,”[175] declared Ned, sliding off his pony and getting down to feel the marks. “They’re comparatively fresh.”
“But what in the world made ’em?” asked Bob.
Neither of his chums could answer, and, at Jerry’s suggestion, they decided to follow the queer trail to see whither it led.
“It may have something to do with the disappearance of the professor, though I doubt it,” said Ned.
After following the queer marks for some distance, not knowing whether they were going toward the starting point or in the opposite direction, the boys encountered a difficulty. The marks came to a sudden stop at the edge of a stretch of land that was smooth shale rock. On that, if the object that made the marks had been dragged, no impression would remain.
“Now let’s go back and start over again,” suggested Ned. “The marks either end here—or begin.”
“More likely begin,” responded Jerry. “If they ended here it wouldn’t amount to a hill of beans as far as helping us is concerned. But let’s go back.”
So they followed the trail back to the spot they had first observed the strange lines in the soft earth. And when they reached this place Ned made another discovery.
“Look!” he cried, pointing to the space between the marks. “There have been horses along here.”
“Sure, we rode there,” said Jerry.
“No we didn’t!” said Bob, quickly. “We came over that way,” and he pointed to the left. “We haven’t ridden here at all. Those are strange horses.”
“Maybe you’re right,” Jerry admitted.
“I know I am!” Bob retorted.
An examination of the impressions left by the strange horses showed them to be unlike those made by the steeds the Motor Boys rode.
“Well, now that’s settled,” observed Jerry, “let’s keep on following the trail. We must find out what it all means.”
The queer marks went on for a little distance farther, and then were lost once more, at the edge of a stretch of ground so hard and rocky that it would have taken a small locomotive, running along without a track, to have made an impression.
“Nothing doing here,” said Jerry. “The mystery deepens.”
“The only two things we are sure of,” observed Ned, “is that the professor has disappeared, after calling for help, and that something has been dragged along here by horses. And they are both queer things.”
“The only thing to do is to keep on searching[177] and calling and shooting,” said Jerry. “And we don’t want to do too much of the latter, for we haven’t a big supply of cartridges, and we may need them.”
“What for?” Bob asked.
“Well, you never can tell what will happen,” was the answer. “It’s best to be prepared and well armed, especially in this region of cattle rustlers.”
“And we’re forgetting all about them!” exclaimed Ned. “We haven’t done the exploring up here we set out to do.”
“We had to drop it,” Jerry said. “The professor came first, of course.”
“Oh, sure,” Ned agreed with him. “I wonder,” he went on musingly, “if the rustlers are around here?”
“I only wish they were!” exclaimed Jerry, warmly. “They’re just the ones we’d like to see. They might put us on the trail of the professor. That is,” he chuckled, “if they didn’t feel hurt because we had caught them.”
“Do you expect to nab ’em?” asked Bob.
“Say ‘hope’ instead of ‘expect,’” suggested the tall lad with a smile.
“Well, the marks aren’t going to help as much as I expected,” Ned remarked. “We’ll just have to go it blind again.”
And they did, riding here and there, calling and[178] occasionally firing their revolvers. But as the day passed, and they received no answer, they became discouraged.
“Shall we go back to camp?” asked Bob, as night was beginning to manifest itself.
“Where else would we go?” asked Jerry.
“Well, I thought maybe we would go to the ranch. There isn’t much grub left——”
“Do you put eating ahead of the professor?” cried Ned.
“No, of course not. But I meant we could go back to the ranch, stock up and come back here prepared to make a long stay. Of course, I want to find the professor as much as you!”
“That’s all right,” returned the mollified Ned. “But we’ve got grub enough for a while yet, and he may come back as queerly as he went away.”
But Professor Snodgrass did not do so. The boys passed an uneasy night, listening for any sounds that might indicate the return of their friend, but his place in the tent was vacant when morning came.
Then they held a sort of council and decided it would be best to go back to the ranch and tell what had happened. They could come back the next day, with some of the cowboys and make a more thorough search.
It was a dispirited party of youths that took the homeward trail. They gave up, for the time[179] being, the plan of seeking for the cattle thieves.
“Maybe he’s here ahead of us,” suggested Bob, as they came in sight of the ranch buildings.
“Where?” asked Jerry.
Bob nodded toward the collection of buildings.
“He might have got away from whatever or whoever had him,” he resumed, “and wandered back here, not being able to find our camp.”
It was but a forlorn hope and it was not justified.
“Seen Professor Snodgrass? Why, no!” exclaimed the foreman, in answer to their question, as he greeted the boys. “What happened?”
They told him, and related what they had done in the way of making a search.
“Jumping tomcats! That’s too bad!” cried Mr. Watson. “We’ll get right after this! Here, Gimp, send up some of the boys!”
“What’s happened?” asked the cowboy.
“The cattle rustlers have captured the professor!” cried the foreman.

The boys started at these words. The professor in the hands of the cattle thieves!
“But—but!” stammered the surprised Ned. “If they took him, why didn’t they take us? We weren’t far away from where they made the professor a prisoner, to judge by his voice. It sounded very plainly.”
“Sound carries a good distance in this clear air,” said the foreman. “He might have been half a mile away.”
“Besides, they didn’t know you were there,” put in Gimp. “You say the professor went out of the tent?”
“Yes, to look for some moths. He’s been collecting them of late. And they grabbed him while we slept,” explained Ned.
“Well, that accounts for it,” went on the cowboy. “The rustlers were abroad that night on top of the mountain, maybe getting ready to make another raid on us. They came upon the professor, who probably didn’t notice ’em, and they[181] nabbed him before he knew what was going on. It’s as plain as a long-eared rabbit. But we’ll get after the rascals!”
“That’s what!” declared the foreman.
“You can’t do much there at night,” Jerry said.
“No. But we can get a start, which is something, and be on the ground bright and early in the morning,” replied Mr. Watson. “The more time we lose the worse for the professor. I know that trail in the dark as well as in daylight. Where’s Hinkee Dee?” he asked.
“Makin’ a new lariat the last I seen of him,” answered Gimp.
“Send him here, will you? I’m going to leave him in charge while I go off on this expedition with some of you boys. I’ve had enough of this business. I’ll get them rustlers or bust a leg! It’s bad enough to have ’em steal our cattle, but when they take to kidnappin’ a nice man, like Professor Snodgrass, it’s time something was done.”
A curious friendship had sprung up between the rough foreman and the gentle professor which accounted for the warmth of Mr. Watson’s talk.
“Hink,” he said shortly, when his assistant came in, “we’ve got bad news. More of those rustler’s doin’s. It’s got to stop! I want you to take hold here until I come back,” and he explained what had taken place and outlined his plans.
“Get off that shipment that’s to go to-morrow,”[182] he added, “and I’ll be back as soon as I can make it. I won’t come without the professor either, if I can help it,” he said grimly.
“We’ll be with you after we’ve had something to eat,” said Bob, for it was then near the supper hour.
“You’re not to go back to-night!” declared the foreman. “You’ve done enough and you’re tuckered out. Get a good night’s sleep and you can ride up and join us in the morning. Bring along plenty of grub, for we may have to stay a few days. We’ll prepare to camp out. You say you left your tent there?”
“Yes, for we counted on going back,” Jerry answered.
Arrangements were quickly made to get the cowboys, under the leadership of the foreman, off on their trip.
“I wish I was going along!” exclaimed Mr. Munson, as he limped around the room where the talk had been going on.
“Why aren’t you?” asked Hinkee Dee in some surprise. “They’ll need every man they can get, and the boss has signed up more of the cowboys to go with him than I like to see leave the ranch. It makes us short-handed.”
“I don’t see how I can go,” replied the cattle buyer. “My leg doesn’t seem to be getting on as well as I expected. It pains me a lot and if I go[183] up there, where the trail is steep, I might have to walk. I couldn’t do that very well now,” and he limped more than ever. “I’d be more of a hindrance than a help.”
“Well, I reckon there’s something in that,” agreed the assistant foreman. “Do as you think best.”
“Then I’ll stay until my leg gets better.”
“Hadn’t you better let the doctor look at it?” asked Jerry with a wink, seen only by his chums.
“Yes, I think I shall,” was Munson’s cool answer. “I’ll ride in to town and let the doc have a look some day if it doesn’t heal soon. It doesn’t hurt me to ride on the level.”
“What do you suppose his game is—playing off like that?” asked Ned of his tall chum when the three were by themselves.
“I wish I knew,” Jerry replied. “But I’m going to find out. He has some reason for wanting to stay around this ranch, and if it hasn’t to do with cattle stealing I’m very much mistaken.”
“That’s right,” chimed in Bob.
The little cavalcade of cowboys, headed by the foreman, left the ranch singing and shouting, one of the more excitable firing off his revolver.
Ned, Bob and Jerry kept pretty much to themselves that night, as Hinkee Dee was in charge. Even though the parents of the boys owned Square Z, the surly fellow might make it unpleasant for[184] them. He had not become at all friendly as had the others.
“Where are you going?” asked Bob of Jerry, as he saw the tall lad saunter outside.
“Just to have a look around,” was the answer. “I rather want to see what our friend Munson is up to.”
“Want any company?” asked Ned.
“Thank you, no. It will be better for one to do this. He might get suspicious.”
Jerry came back an hour later, shaking his head.
“Nothing doing,” he reported. “He just sat playing cards with the other cowboys for a while, and then took a walk around. I followed, but all he did was to saunter here and there, star-gazing as nearly as I could make out.”
“He’s up to some game,” decided Bob, and his chums agreed with him.
The night passed uneventfully, and after an early breakfast Ned, Bob and Jerry started for the mountain again. They made better time on this trip, and reached the site of the camp in mid-afternoon. No one was about, but another tent had been pitched near theirs, and through a note left in a conspicuous place by the foreman the boys learned that Watson and the others were off making a search. He advised the three boys to stay in camp until the return of the party.
The chums did not want to do this—they[185] wanted to be “on the job,” as Ned declared, but they decided it was best to obey the wishes of a more experienced person.
“We can be getting grub ready for them,” suggested Bob, who, to do him justice, was as anxious to have others partake of the good viands he so enjoyed as he was to eat them himself.
His plan was voted a good one by his chums, and, having had considerable experience in the way of preparing meals, they got up a good one, that was much appreciated by the tired cowboys who came in just before dusk.
“Well, this is a surprise!” exclaimed the foreman as he smelled the savory odors. “In a way it makes up for our disappointment.”
“Then you didn’t find a trace of him?” asked Jerry.
“Not a trace.”
“Did you see queer marks?” Bob queried.
The foreman nodded silently, his mouth full of bread and bacon.
“What were they?”
“Stone-boat,” sententiously replied Mr. Watson.
“Stone-boat?” repeated Bob.
“Yes. A stone-boat is a sort of platform of heavy planks nailed crossways to two logs. It’s easy to roll a big stone on this, as it’s up only a few inches from the ground. Then you hitch some[186] horses to the front end, and pull the stone-boat along. It’s an easy way of hauling heavy weights over dry ground. Of course, when there’s snow you can call it a stone-sled if you like. But that’s what made the marks you saw.”
“And did they drag the professor on a stone-boat?” was Jerry’s question.
“I think not,” and the foreman shook his head. “It was a pretty big stone-boat, to judge by the marks. Most likely someone has been building a sort of wall around a water hole, and had to haul the stone quite a way. I don’t think it had anything to do with the professor.”
The search was renewed early the next morning, and kept up for two days without success. There was no trace of the professor and none of the rustlers. A careful examination was made of the land lying to the west of the ravine, but nothing was revealed that would help solve the mystery.
“Well, I guess we’ll have to give up,” regretfully remarked the foreman after the third day, when their provisions were almost gone. “We’ve made a good search. They’ve either—well, done away with the poor professor somehow, carried him far off, or else they’re hiding with him in some cave in these mountains. And the land knows there are so many we’d never be able to search them all. We did go through a few.”
There seemed nothing else to do, and the cavalcade slowly wended its way down the mountain. The boys felt as though they were coming away from the funeral of their dear friend. It was like leaving him behind.
“But I’m not going to give up!” exclaimed Jerry. “We haven’t solved the cattle mystery yet, and we’re going to have another whack at that. Incidentally, we can look for the professor, too.”
“It does you credit, boys,” said the foreman. “But I don’t believe you’ll have any success.”
The mail was in when the boys got back to Square Z ranch. Each one had a letter, and when Jerry had finished his from his mother he looked at the faces of Ned and Bob.
“You don’t seem to have good news,” he remarked.
“We haven’t,” admitted Ned. “Dad wants us to come home!”

“What’s up?” asked Jerry, solicitously. “Someone ill?”
“No,” answered Ned. “But dad intimates that we’ve fallen down on the job, so to speak, and he thinks we might as well give it up and let him send on a real detective. He says he knows of one that used to be in the United States Secret Service and he thinks this fellow would succeed where we’ve failed.”
“I don’t admit we’ve failed yet!” Jerry exclaimed. “Of course, I don’t want to presume to dictate to your father,” he hastened to add, “but I wish he’d give us a little more time.”
“My father says the same thing that Ned’s father does,” said Bob, who had finished reading his letter. “I guess yours and mine must have had a confab, and decided on this move,” he remarked to Ned.
“It looks that way. But I’m not going home, fellows. I’m going to stick it out!” and Ned struck a defiant attitude.
“So’m I!” exclaimed Bob.
“Rebels!” remarked Jerry with a smile, though none of the lads felt in any gay mood since the disappearance of Professor Snodgrass.
“Well, you have to rebel once in a while,” went on Ned. “I don’t mean to say that I’d deliberately disobey my dad,” he added. “But he doesn’t understand. I suppose he’s a bit sore at losing so many cattle, and I don’t know that I blame him. But he doesn’t understand the situation here, and your father doesn’t either, Bob.”
“I’m with you there. But this letter says come home without delay, and let the detective take up the case. Dad says there are certain reasons for this.”
“What are they?” asked Jerry.
“Mine mentions ’em, too,” added Ned. “It seems that my father is rather sorry he bought a ranch, and got Mr. Baker to go in on the deal. Dad wants the money he put in it to finance some other matters connected with his store, though he doesn’t go into details.
“He says they had a chance to sell the ranch at a handsome profit, but the intending purchaser backed out when he heard rustlers were running off the cattle. The man said he wanted a ranch with some steers on it, not just grass,” went on Ned with a rueful smile as he referred to his father’s letter.
“Is the deal off?” asked Jerry. “It’s too bad to have your father lose money, Ned.”
“Yes. Though dad isn’t poor, still he is a good business man, and it must get on his nerves to see a waste in finances. The man who was going to buy the place hasn’t exactly given up all interest in it, but he won’t purchase until the rustlers are captured.”
“Then it’s up to us to get ’em!” cried Jerry. “We must do more and talk less.”
“I’m with you there,” agreed Ned. “But what can we do?”
“Especially when we’re practically ordered home,” put in Bob. “Told to give up and let a real detective take a hand! What can we do?” and he looked at his two chums.
Ned seemed to have a sudden inspiration.
“I know one thing I’m going to do!” he exclaimed.
“What?” cried his two chums together.
“I’m going to telegraph to dad.”
“And say what?” Jerry queried.
“I’m going to wire him that Professor Snodgrass has most unexpectedly disappeared, and that we can’t leave him here in this predicament, especially as he came out West with us as our guest. That will get my mother, anyhow,” he added with a twinkle in his eyes. “Mother’s great on that hospitable stuff, and she’ll get dad to let[191] us stay all right. She’ll argue that it would be wrong for us to come away and leave the professor in the hands of the rustlers—if that’s where he really is.”
“I think you’re right,” returned Jerry, after a moment of thought. “It’s only fair to him, and it will gain us a little delay in which we must work harder than ever before to solve the mystery.”
“Now you’re talking!” cried Bob.
This telegram was prepared and sent to Mr. Slade:
“Professor Snodgrass has disappeared. Probably captured by rustlers. Are on their trail. Impossible to leave now. Better wire us money for expenses. Letter follows.”
“Think that will do?” asked Ned.
“Pretty well gotten up,” Jerry assented. “You put it a bit strong, though, about being on their trail.”
“Well, it’s true enough. We are after them—on their trail—so to speak. I didn’t say we had caught them. But we will!”
“I hope so!” agreed Jerry.
The boys anxiously awaited the reply to their message, and to their gratification, it came the next day. They were told they might remain, and in a letter that followed a few days later funds were[192] sent to all three, while there were many expressions of concern from those in Cresville concerning the fate of Professor Snodgrass.
“Spare no expense in finding him,” wrote Mr. Slade. “Hire a couple of detectives if necessary.”
“I guess we can do as well at this business as the city detectives,” growled Ned.
His chums agreed with him.
“And we haven’t got to the bottom of the mystery of Munson’s fake leg,” remarked Jerry as, on the afternoon following the receipt of the letters, they were riding together toward a distant part of the ranch.
“No, that’s another secret we have to solve,” agreed Ned. “He said something about riding to town to-day to have the doctor look at it. He’s limping worse than ever.”
“He’ll never do it,” observed Bob.
“Do what?” asked Jerry.
“Let a doctor examine his leg. That would give the fake away right off the bat. That’s why he didn’t want to let the doctor look the time you were hurt, Jerry.”
“Oh, of course! But, it sure is a queer game.”
The capture of Professor Snodgrass—if capture it was—seemed to put a quietus on the cattle raids. The stock at Square Z ranch had not been molested since his capture, and the foreman and his cowboys were beginning to feel that perhaps[193] the operating gang had been frightened off because of the vigorous search made for them.
Meanwhile, Professor Snodgrass had not been forgotten. A systematic search was kept up for him, but without result. Circulars describing him had been sent through the mail to various ranches and to the neighboring cities. Cowboys from other ranges made trips to the mountain where he had last been seen and tried to find the little scientist. But he seemed to have disappeared completely. Ned, Bob and Jerry joined in these hunts, eagerly searching for some clue to the mystery.
Reports from distant ranches told that there had not been any cattle losses on them of late, though no other ranch had ever been so systematically robbed as had Square Z.
And then, like a thunderclap on a pleasant day, came a change. Two cowboys, who had been sent to bring in a bunch of choice steers for shipment to Omaha, returned without them but with worried faces.
“Well?” asked the foreman. “Where are they?”
It was short talk but to the point.
“How did it happen?” Mr. Watson demanded,[194] and when the cowboy admitted that the raid took place while he and his companion slept, the foreman became angry for one of the few times the boys had seen him in that condition.
“Get off the ranch! You’re discharged!” he called to the cowboys. “A tenderfoot could have done better!”
There was more than the usual buzz of excitement about the ranch when the news of the cattle raid became known. It proved, at least to Ned, Bob and Jerry, that the rustlers were still in the neighborhood and if they were, and had captured the professor, there was a chance to rescue him.
“Your father will feel still more greatly disappointed in us when he hears there’s been another raid,” said Jerry to Ned.
“I don’t intend he shall hear of it right away,” was the answer; and when Jerry pressed for an explanation his chum said he was going to ask the foreman not to telegraph word of the theft to Mr. Slade for a few days.
“I want to have an opportunity to see what we can do,” went on Ned. “It may be our last chance. A few days’ delay in letting dad know won’t do him any harm, and it will allow us to keep on trying to solve the mystery. If we can’t, in a reasonable time, I’m willing to quit, and let the New York detective try his hand.”
“Well, maybe it will be wise,” agreed Jerry. “But we’ll put in our best licks on this last chance. It does seem as though we ought to get some sort of clue to the thieves after all these tries.”
As the cowboys who had reported the raid did not know what time it took place, except at some hour during the night, it could not be said how much of a start the thieves had. It was seven hours at least, for the men had reached the ranch house about noon, and they had awakened at daylight to find the cattle gone. More likely it was ten hours, and that was a good start.
The trail of the stolen cattle was comparatively easy to follow. And, as had the others, eventually it led to the foot hills and to the ravine the boys had explored so ineffectually.
“The secret is here, and here’s where we’ve got to stick until we find it!” declared Jerry. “We’ll make a secret camp here, and not leave day or night. Can’t you plant a bunch of cattle somewhere, so they could be easily stolen?” he asked Mr. Watson.
“I s’pose I could. But why?”
“Well, we could stay near ’em and see who takes ’em. Then we could follow.”
“Oh, a sort of trap, eh?”
“That’s it.”
“Well, I’ll think about it.”
Search as they did, the rest of that day, no trace[196] of the missing cattle could be found. They returned to the ranch, tired and despondent. Mr. Watson had agreed to wait a few days before informing Mr. Slade of this latest loss.
“I’ll give you your last chance, boys,” he said. “Make the most of it.”
That night, when the three chums were out among the cowboys, listening to their talk, Munson came in. Hinkee Dee seemed to notice him at once.
“Where you been all day?” asked the assistant foreman.
“In town, having my leg treated.”
“Do any treating on your own account?”
“Why, no, I can’t say I did.”
“Oh, you weren’t around Jack’s place then?”
Munson looked up quickly at this persistent questioning.
“I don’t see that it is any of your business if I was,” he said slowly.
A flush mounted to the tanned face of Hinkee Dee.

Silence followed this rather insolent remark of the cattle buyer; and apprehensive looks were on the faces of his auditors. For in the free and breezy ranch life such talk usually was the preface to a stronger brand that ended in a fight.
“Well, in a manner of speaking, and casual like, maybe it wouldn’t be any of my business,” said Hinkee Dee, and it was noted that he was trying to keep his temper. “But this time I think it is.”
“Just what did you want to know?” asked Munson. Clearly he was not going off “half cocked.” He wanted a basis for his objections.
“I want to know,” and the assistant foreman spoke more slowly, “what you were doing with Pod Martin?”
“How do you know I was with Pod Martin?”
“You and him was seen going in Jack’s place together,” and Hinkee Dee banged his fist on a table.
“Go easy,” advised Munson. He seemed less[198] angry than at first. “Why shouldn’t I go with Pod Martin if I want to?” he demanded.
“Well, I’ll tell you why, Mr. Cattle Buyer, as you call yourself. Out here it ain’t healthy for folks visitin’ on a ranch where cattle are being stolen, to consort with a man suspected of being a cattle rustler!”
He fairly shot out the words, and there was a general murmur throughout the room. Everyone expected to see Munson spring to an attack on the assistant foreman, at least with his fists if not drawing a gun. But the visitor, who still wore his big diamonds, gave no sign of being insulted or accused.
“I don’t admit I was consorting with a cattle-rustler suspect,” he said gently.
“You don’t have to admit it. You was seen.”
“That doesn’t prove anything. How was I to know Martin is said to be a stealer of cattle?”
“Ain’t you heard it?” blustered Hinkee Dee.
“You heard what I said,” was Munson’s rejoinder.
“Well, if you ain’t heard that then you’re about the only one in these parts that ain’t—barrin’, maybe, these tenderfeet,” and he indicated the listening and interested boys.
“Isn’t Pod Martin suspected of being a cattle rustler?” demanded the assistant foreman of the Parson.
“Yep!” was the answer.
“Well,” rejoined Munson, coolly, “I suppose if he’s really a rustler he might have taken cattle from this ranch.”
“As like as not,” growled the assistant foreman.
“Then why don’t you have him arrested?” shot out the cattle buyer so suddenly that some of the cowboys jumped, steady as their nerves were.
Hinkee Dee paused for a moment before answering. Then he growled or grunted rather than replied:
“Huh! I would soon enough, if I could get the evidence against him. But he’s too slick. There’s nothing positive.”
“Oh!” exclaimed Munson, easily. Then he got up and went away. The incident ended so quickly and so unexpectedly that it left some of the auditors in a sort of gasping state. Hinkee Dee did not, apparently, know what to make of the way the wind had been taken out of his sails. He sat looking at the door through which Munson had limped and muttered, as he, himself, went out:
“I’ll get him yet!”
“Think there’ll be a fight?” asked Bob, apprehensively, of Gimp.
“Naw. It’s all talk. I’ve seen and heard lots like it before. But Hink was right; it was sort of brash for Munson to talk openly with Martin,[200] who people is beginnin’ to suspect of bein’ a rustler.”
All of this served to strengthen the suspicions that had been growing in the minds of the boys that Munson was, somehow or other, more or less connected with the cattle thefts.
True, there was no direct evidence against him. The only point that looked bad, aside from his talk to Martin, was the story of his having been shot while witnessing the raid of some rustlers. That part of the story was a fake, surely enough, as Jerry could testify. And Munson still kept up the fiction about his injured leg. In fact, for some time he had been going to town twice a week, saying he had to have it treated by a doctor.
“We could disprove that easily enough,” suggested Ned. “There’s only the one doctor and we could ask him.”
“We don’t need to,” Jerry declared. “I saw both his legs and there wasn’t a scratch on them.”
“It doesn’t seem as if we’d ever get to the bottom of this,” sighed Ned. “I’m plumb discouraged about that and the professor. Had a letter from dad to-day and he wanted to know how we were making out. I hate to tell him, on top of sending word about the latest cattle raid.”
“How much longer did Mr. Watson say he’d wait before sending word?” Jerry queried.
“The last of the week. Saturday was the last[201] chance he could give us,” he said. “He has to fix up his monthly accounts then and he’s got to make some report of the missing cattle. So, boys, we’ve got a few days more to make good.”
“It isn’t long,” suggested Bob, dolefully.
“It’ll be our first failure in a long while,” Ned admitted.
“And I’m not going to let it be a failure!” cried Jerry, eagerly.
“What are you going to do?” asked his chums. Somehow they always looked to the tall lad in an emergency, and one seemed to have arrived now.
“We’re going up in the airship,” said Jerry. “It’s a pity we couldn’t have used her more for this business as we would have except for the accident to the wheel. But from now on we’ll use our own little old machine. We’ll start to-morrow morning.”
“Doing what?” asked Ned.
“Making a search along the mountain ridge in the aeroplane,” was Jerry’s prompt answer. “This horseback business is too slow.
“Mountain climbing and searching around on top of a range is about the hardest work there is. Now what’s the matter with getting in our craft, taking along a week’s supply of grub—can we carry that much, Chunky?”
“That sounds good, coming from you. Well,[202] let’s go on a regular air expedition,” went on Jerry. “We can take it easy a thousand or so feet up in the air, and we can be looking down for signs all the while. We may pick up the trail of the stolen cattle, the rustlers, or even that of——”
“Professor Snodgrass!” cried Ned.
They set off early the next day, having packed a generous supply of food in the lockers of the airship.
“We’re off!” cried Ned, as the propellers whirred about.
Amid the cheers of the cowboys, who waved their hats and shot off their revolvers, the start was made.
Would the boys come back safely, having discovered the location of the rustlers’ camp, and perhaps having found Professor Snodgrass? Or would they be lost as the scientist had been, somewhere in the wilds of the mountain?
More than one asked those questions as they watched the airship becoming smaller and smaller in the blue sky.
“Our last chance!” murmured Jerry Hopkins. “Well, there’s luck in last chances.”

Below the boys in their airship there unrolled the fields and plains of Square Z ranch, as on some vast map. As the craft rose higher and higher the figures of the cowboys, gazing upward in wonder, became, to the eyes of the Motor Boys, first like dwarfs, then like a child’s dolls or toy soldiers. Then the men took on the similitude of ants, and were but tiny specks on a vast field of green.
“Wonder what will happen before we get back there again,” ventured Bob.
“No telling, but plenty, I hope,” said Jerry who was steering.
The airship was somewhat differently outfitted than when they had first used it in the West. A sort of cabin had been put on, it having been shipped to them from home, and this shut out much of the noise of the engine so that it was possible for them to converse without yelling at the tops of their voices in the ears of one another.
“Yes,” put in Ned, “if we discover the cattle[204] thieves and find the professor that will be enough to hold us for a while.”
“We may find them together,” suggested Jerry.
“Then you believe the rustlers got him?” asked Bob.
“I can’t imagine what else could have happened to him. Of course he might have fallen, and been fatally hurt that night when he went away alone, and his call that someone had him might have been a delusion.
“But I prefer to think otherwise. If the rustlers got him they’d keep him pretty close, so he wouldn’t have a chance to escape. If anyone else caught him, say a party of hunters or cattlemen who might think him an escaped lunatic, as he has been suspected of being more than once, by this time they would have let him go. But as not a word has come from him I believe he is a prisoner of the cattle thieves.”
After some talk, Ned and Bob were of the same opinion as was Jerry, and then they began to discuss ways and means of conducting the search in the airship.
“Where are you heading for, Jerry?” asked Ned, as he saw the tall lad change the course of the airship, which at the start had flown due north from the ranch buildings.
“I thought it would be a good plan to go to the site of our old camp, and make that our real starting[205] point. There’s a good landing place there, on top of the mountain, and there is just a possibility that the professor may have gone back there. We left a notice on a tree, you know, telling him, if he did come, to proceed at once to the ranch, leaving word on the reverse of our notice that he had done so.”
“Well, it’s a pretty slim chance, but let’s take it,” conceded Ned.
That the boys had not before used their airship to make an investigation on top of the mountain was due to the fact that in making a flight one day they had broken a wheel of the engine and had had to send to Chicago to have a new part made. The craft was now, however, in good running order.
The speedy airship was not long in reaching a point above the place where the camp had been made—the camp from which Professor Snodgrass had disappeared. Jerry, at the controls, sent the craft about in a spiral, bringing it lower and lower, for they had risen to quite a height.
“Nothing down there, I’m afraid,” said Bob, peering down through the celluloid window set in the floor of the cabin. “There’s not a sign of life.”
“We’re too high to see,” declared Ned. “Wait until we get a bit lower.”
“That’ll be in a few seconds,” said Jerry,[206] and he sent the machine down at a sharper angle.
“Hand me those glasses,” said Bob to Ned, who took a pair of powerful binoculars from their case on the cabin wall and gave them to his chum.
“See anything?” Jerry inquired, after waiting a few seconds.
“Take a look, Ned,” requested Bob, and there was that in his voice to indicate that he was laboring under some excitement.
“What’s this?” cried Ned, as he fixed the focus to suit his eyes. “I—I see smoke down there in the old camp!”
“Smoke!” cried Jerry.
“Yes—in little puffs—as though someone were signaling with a damp fire and a blanket—the way the Indians used to do. Here, give me the wheel, Jerry, and take a look yourself.”
As the two changed places there was a sharp metallic sound near the engine—a clang of metal that sounded above the noise of the explosions. And, just as Ned took hold of the wheel which Jerry relinquished, the motor stopped.
“Look out!” yelled the tall lad. “We’re falling! You’ll have to volplane down!”
“I know,” replied Ned, coolly. He and his chums had done this before, both in emergencies and when they had purposely shut off the engine.
Volplaning down in an airship is like coasting down hill on a sled, only in the former case the[207] hill is nothing more substantial than a bank of air. But by letting the airship slide down on slanted wings, and then by sending it sharply upward, by means of the vertical rudder, its speed can be nicely controlled, so that a landing can be made.
This was what the boys aimed to do. Ned was now at the wheel and controls in place of Jerry, who, seeing that his chum had matters well in hand, turned to look downward through the binoculars.
“Can you see the puffs of smoke?” asked Bob.
“No, I can’t,” murmured Jerry, not taking his eyes from the instruments.
“I wonder what made the engine stop?” asked Ned. “Did you have plenty of gas, Jerry?”
“Sure! Both tanks filled before we left. Wait, I’ll try the self starter.”
He set this in motion but it did not operate the engine. There seemed to be something broken, and as the motor was not readily accessible from the cabin the boys would have to wait until a landing was made.
This was in a fair way to be accomplished, and near the spot of their former camp. Ned was scanning the ground, which seemed coming up to meet them, for a smooth place on which to let the airship run along on its wheels.
“How about over there?” asked Jerry, indicating a spot to the left.
“All right,” assented Ned. “See any more smoke?”
Jerry resumed his observations, but shook his head to indicate that he saw nothing. They were soon near enough to see by the use of their unaided eyes, but the nearer they came the more it became plain to them that the camp was deserted.
“And now to see what it all means, and what happened to the engine!” exclaimed Ned, as he made the landing neatly and leaped out, followed by Bob and Jerry.
“Hello! Anybody here?” yelled Jerry as he looked about near the place where the shelter tent had stood. There was no reply save the echo of his own voice.
“Well, it couldn’t have been the professor, or he’d have been so glad to see us that he’d be jumping about here now,” commented Bob.
“But where is the fire that made the puffs of smoke?” asked Ned.
“I think there wasn’t any fire,” said Jerry.
“No fire? What do you mean? Didn’t I see smoke?”
“But smoke doesn’t always mean a campfire. Come on, let’s have a look at the engine.”
They went carefully over the machinery, the perfect working of which was so vital to their safety. It did not take Jerry long to discover what the trouble was.
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“Look!” he cried. “One of the carburetors is smashed.”
“Smashed!” echoed Ned.
“Yes. No wonder we couldn’t get any explosions, even when the self starter spun the propellers. She wasn’t getting any gas, and the spare carburetor wasn’t in service.”
“But what would make it break?” asked Ned.
“That’s what we’ve got to find out,” Jerry stated. “Did you hear a sort of click just before the machinery stopped working?”
“Yes,” assented Ned, “and I wondered what caused it.”
Jerry was looking with careful and eager eyes over different parts of the powerful motor.
“I think this caused it,” he said, and with the point of his knife blade he pried from one of the propeller blades, where it was not deeply imbedded, a bullet.
Silently he held it in his palm for the inspection of his companions.

“Well, for the love of guns! how did that get there?” asked Bob.
“Landed after it smashed our carburetor,” was Jerry’s reply. “At least that’s my theory.”
“But who shot it at us?” Ned demanded. “Some of those crazy cowboys, I guess, who got so excited when we made flights over their heads.”
“It wasn’t there when we started out this morning,” said Jerry, “for I went over the propeller blades with a fine tooth comb, so to speak. And certainly the carburetor was all right.”
“That’s so,” admitted Ned, scratching his head. “Then——”
“The puffs of smoke down below us!” interrupted Bob. “Was it someone shooting a revolver at us, Jerry?”
“Not a revolver, Bob. That wouldn’t carry as high as we were. This is a bullet from a high-powered rifle, and it’s lucky it smashed the carburetor instead of us.”
“But who in the world could have fired it?”[211] went on Ned. “If it was the professor, firing in the air signaling for help, he surely would have seen us and been a bit more careful.”
“It wasn’t the professor,” declared Jerry. “He hasn’t a rifle, and I doubt if he would know how to fire one if he had.”
“Then you think——” began Bob.
“I think, Chunky, that we’d better look about a bit,” was Jerry’s reply. “There may be some traces here that we could pick up which would help us solve the cattle mystery.”
“Good idea!” said Ned. “Let’s look about.”
They scurried about the site of their first camp, but it was not so easy to read any signs there as they had hoped.
“But there was certainly someone here firing at us from shelter, while we were up in the air,” declared Ned. “Those puffs of smoke Bob and I saw were from a rifle, and not a campfire.”
“My idea, too,” put in Jerry. “The question is who was shooting at us, why and where is he?”
“Three questions, and three of us to answer ’em,” remarked Bob. “For the first I’ll say it was one of the cattle thieves.”
“Probably,” agreed Jerry. “No one else hostile is in this neighborhood, as far as I know.”
“As for why,” mused Ned, “it must have been because he wanted to disable us, so we couldn’t continue the pursuit.”
“Probably that’s right,” assented Jerry. “And for the third question—where is he?—that’s for us to find out. I don’t imagine though, that he’s anywhere around here now. When he saw us coming down he probably ran away.”
“Or he might be in hiding within ten feet of us, watching us now, and hearing everything we say,” commented Bob, and at his own words he looked half-apprehensively over his shoulder.
The boys stood silent, thinking this last statement over. But as the place about them gave no sign of life they came to the conclusion that the unknown rifleman had made good his escape.
“But just to make sure we’ll have another look around,” suggested Jerry, and they scoured over the fields, penetrated a little way into the wood and looked behind clumps of bushes. No one did they see, however, and then Jerry remarked:
“Well, let’s look after our airship. We haven’t begun to do any real scouting in her yet. This is only the starting point of our search. We ought to cover a good deal of ground before night.”
“If we can go on,” supplemented Ned.
“Oh, there’s no serious damage done,” Jerry said. “We have a spare carburetor.”
“Will that bullet in the propeller weaken it any?” Bob inquired.
“Not in the slightest. The old machine will soon be as good as ever.”
It was not quite so easy to put in a new carburetor as Jerry had thought, however, for the bullet that put out of commission this very necessary part of the motor’s equipment had also smashed a feed pipe.
There was an extra piece in one of the lockers, however, and this was inserted after about an hour’s work. A test of the machine showed that it was again in shape for the duty required of it, and having rolled it to a stretch of level ground the boys prepared to set off once more.
Up and up rose the great bird-like affair of wood, steel and canvas and the deserted camp was soon but a speck below them.
“Now if that fellow takes it into his head to fire again, and smashes our other carburetor, we’re done for,” observed Ned.
“I don’t believe he will,” responded Jerry, and he proved a true prophet. For while the tall lad was at the wheel, Ned and Bob kept a sharp watch down below. There were no more puffs of smoke, and the airship was soon so high up that no ordinary missile could reach it.
“And now what’s your plan?” asked Ned of his tall chum.
“Well, I think we’ll fly over the mountain in a straight line west from the rocky defile, in which the disappearance of the cattle seem to have taken place. I have an idea there may be some way of[214] getting under the mountain, by means of a tunnel, perhaps.”
“It would have to be some tunnel,” observed Ned, for they were flying across the flat mountain top now, and could see that it extended for several miles.
“Well, it might be one made by nature. Probably is, if there’s one in existence,” Jerry said.
On and on they flew, now circling to the right, and again to the left in an endeavor to cover as much ground as possible. But they saw nothing that would lead to a solution of the mystery.
All that day was spent in flying about, peering here and there through the powerful glasses, the airship moving along at a low elevation so the boys might make more careful observations.
“Well, we don’t seem to have done much the first day,” observed Bob, as they descended to a level, sandy plain as night settled down. “All we can do is to get something to eat and go to bed.”
“There’s another day to-morrow,” remarked Ned, “so don’t eat up everything to-night.”
“No danger!” exclaimed Jerry. “Chunky brought along enough for a small army.”
“Well, I’m as hungry as half an army myself!” laughed the stout lad.
“Going to stand guard to-night?” Ned asked, as they proceeded to make the cabin of the earth-fast airship snug and comfortable.
“Well, I don’t know but that it would be a good idea,” agreed Jerry, after a moment of thought. “Of course we’re a good way from where that fellow shot at us, but that isn’t saying he hasn’t some confederates in this place. Yes, it wouldn’t be a bad plan to sit the night out in three watches. They won’t be such very long ones. I’ll take first, as I can always sleep better in the rear end of the night.”
“I wake up early, so I’ll take last watch,” volunteered Ned.
This gave Bob the middle watch, and he and Ned went to bed about nine o’clock, Jerry making a fire not far from the airship, so the blaze would serve to illuminate a space around the craft.
Somehow Jerry was distinctly nervous as he assumed his watch. There had been strenuous times since he and his chums had come to Square Z ranch, and there had been much to cause them worry. Of course, the disappearance of the professor was the most important. The loss of the cattle was serious, naturally, but both Mr. Baker and Mr. Slade were men of wealth and would not be ruined even if they lost the whole ranch. Still, Jerry and his chums felt an eager desire to solve the mystery. They felt the same excitement and determination as when trying to win a baseball or football championship.
Though Jerry kept eager watch, his vigil was[216] not disturbed save by the approach of timid animals of the night, which made off at the sight of the fire.
Nor were the watches of Bob or Ned fruitful of any results. Ned thought, just as the east was beginning to be light, that he heard a suspicious sound at the rear of the airship. He ran to the place immediately but all he saw was a small deer that was nosing the rudder and licking it, doubtless with the hope that it was coated with salt. The animal sprang away in alarm at the lad’s approach.
“Well, this is getting pretty close to our time limit,” observed Jerry as, after breakfast, they set off through the air once more. “If we don’t have any luck now——”
“It’s give up for ours!” declared Ned with a sigh.
It was toward noon, when they were flying over a small valley, that Bob, looking down through the observation window in the floor of the cabin, cried:
“Look, you fellows!”
Ned sprang forward, and Jerry, at the wheel, leaned to one side to look.
Down below, standing on a big rock, was the solitary figure of a man, and he seemed trying to signal to them.

“What shall we do?” asked Bob, greatly excited.
“Go down to him, of course,” answered Ned. “He may have some information for us.”
“I’m not so sure about that,” put in Jerry.
“Sure of what?” came quickly from Ned.
“Whether we ought to go down to him or not. He may be waiting for us with a gun, hoping to get us into range so he can take a pop at us.”
“We’re in range now, as far as that goes,” declared Bob, glancing at the barograph which gave their height. “We were up farther than this when we were hit before.”
“That’s so,” assented Jerry. “I didn’t think about that. He would have shot some time ago if that were his game. Well, we’ll take a chance.”
Nearer and nearer the aeroplane settled toward the great flat rock, on which the lone figure was now running to and fro. His clothes flapped in the breeze, as though in tatters and rags. He appeared greatly excited, and there was no question[218] now but that he was frantically beckoning to the boys to come to him.
“Who in the world is it?” murmured Jerry, trying to peer through the floor window, but not being able to get a good view because of his position at the wheel.
“He doesn’t look like a cowboy,” said Bob.
“Then he can’t be one of the rustlers,” observed Ned. “For they’re all cowboys—of a sort.” norfloxacin usp
“He looks like a tramp, as nearly as I can make out,” suggested Jerry.
“Maybe a grub-staked miner who’s lost his way,” came from Bob. “This is sure enough a lonesome place,” and he looked around the desolate valley of which the lone figure seemed to be the only occupant. Nor was there a habitation of even the most humble sort to be seen.
“Who is he, and what does he want?” murmured Jerry over and over again, as he manipulated the wheel and levers.
“Where are you going to land?” asked Ned. “You’ll knock him off that rock, if you don’t look out.”
“I think not,” returned Jerry, with a smile. “The rock is big enough to land on safely. And it will be a dandy spot to make a start from—it’s as level as a barn floor.”
They were now near enough to see faintly the unshaven face of the solitary man. His ragged[219] clothes, too, gave him a grotesque appearance, but for all his forlorn plight he seemed transported with joy as the airship, now moving about in big circles, came closer and closer.
“Who is he? And what does he want?” said Jerry, again.
And then, as the airship landed on the great flat rock, and came to a gentle, gliding stop, the strange figure rushed forward, crying hoarsely.
“Boys! Oh, boys! I never was so glad to see anyone in my life! Oh, boys, at last I’ve found you!”
For perhaps three seconds none of the lads spoke. They stood looking at the pathetic figure and then, as in one voice, they cried together in low, awed tones:
“Professor Snodgrass!”
“Yes. Oh, boys! No wonder you hardly know me. I haven’t had a shave in so long that I must look like Rip Van Winkle. And as for my clothes! Oh, I’ve had a terrible time. And I’m hungry!”
“Good!” cried Bob, but he didn’t mean it just that way. “We’ve got lots to eat!” he went on eagerly. “Come and have a square meal, Professor, and then tell us what happened. Did you get away from the cattle rustlers?”
“You mean the cattle thieves?” asked the professor.
“Well, thieves, rustlers—you can call ’em whatever you like,” laughed Jerry. “But never mind talking now. We are delighted to see you!”
“No more than I am to see you.”
“We’ve been looking everywhere for you,” added Ned. “We’d about given up. How’d you make your escape?”
“I hardly know. They kept me pretty closely guarded, for they took me for a spy, I guess. But finally they weren’t so careful, and after I had let pass several chances to leave their camp, they began to think I was content to stay there.
“I would have been, too, for there were a lot of the rarest bugs I ever saw. But I wanted to get back to my friends, and so I hid away one night and in the morning began a long tramp to find your ranch. But I can’t tell it all to you now.”
“Of course not!” cried Jerry. “We’re crazy to stand here making you talk when you’re starving.”
“I’ll get him something to eat!” volunteered Bob, hurrying toward the anchored airship.
“Yes, and I’d like to get rid of some of these whiskers and wash myself with soap,” said the professor, who was the most cleanly man imaginable. “I did manage to scrub with a little sand and water, but it wasn’t soap,” he cried.
“Come in then, and get fixed up,” urged Ned, laughing.
“Wait,” begged the professor. “I must not leave my specimens behind. They are too valuable.”
He hurried to the far end of the rock, where, in a niche, he had secreted several boxes and carrying cases made rudely from bark, held together with twisted fibers.
“I didn’t dare bring my regular specimen boxes away with me,” he explained to the boys, “or they would have suspected something. So I had to leave them behind. But I hid them well and we can get them again.”
“How?” asked Jerry.
“Oh, I can get them again if you’ll take me there, I’m sure. I can guide you to the secret camp of the cattle thieves, boys!”
“Hurray!” cried Ned. “Next to finding you this is the best news I’ve heard yet! Come on, Professor!”
They helped him carry his precious specimens in their rude cases, which he had fashioned himself, into the airship cabin. There Bob was busy with the meal.
“Sorry we haven’t got more,” said the stout lad, indicating the table which he had let down from where it had been folded up against the side wall of the cabin. “But we won’t be long, now, in getting back to the ranch.”
“Well, it isn’t such a small meal at that,[222] Chunky,” laughed Jerry. “Did you put on all there was in the locker?”
“No, there’s a little more left, but not much; so we’ll have to go back.”
“But you’ll return for my specimens, won’t you?” pleaded the little scientist.
“Oh, yes, we’ll come back after them—and the rustlers!” declared Jerry.
“Hope we can catch ’em,” sighed Ned.
“I think you can,” Professor Snodgrass said. “They are a bold but careless lot. They fancy themselves safe, but I know their secret.”
“What is it?” asked Jerry, and his chums waited eagerly for the professor’s reply.
“There is a secret way out of the rocky ravine,” was the answer. “I know how to find it. I’ll tell you about it after I eat.”
“Yes, for the love of horse-radish let him eat!” cried Bob. “He must be half starved.”
And the professor certainly seemed so, judging by the way he began at the food, after he had made a hasty toilet with soap and water, which he said was almost as great a luxury as the soup and meat Bob set before him. The boys ate with him, for they, too, were hungry.
“And now for the story of your disappearance!” cried Jerry, when appetites were satisfied, and they sat back on the lockers in comfort.

“Well,” began Professor Snodgrass, whose strange appearance on account of his ragged and unshaven condition was a source of fascination to the boys, “I suppose you know about how I went away?”
“Out of the tent, yes,” assented Jerry. “We were awakened by hearing you yell for help, and Bob here thought,” he added, grinning, “that one of the big moths might have carried you away.”
“Not so bad as that!” laughed the professor; “though some of the moths were very large and most beautiful specimens. I went out, without waking any of you, and I was moving about with my net, my lantern and my specimen boxes, when I suddenly felt myself grabbed from behind. I heard the sound of low voices and at once it flashed into my mind that the rustlers had me. I had no chance to use my revolver.
“I called as loudly as I could, and when I said ‘they’ had me I thought you boys, if you heard me at all, would understand.”
“We didn’t though, at least not for some time,” remarked Ned.
“But no sooner had I cried out for help than someone clapped a hand over my mouth and I couldn’t make a loud sound. Then I was bound and gagged and stretched out on something by which I was pulled along the ground. It seemed like a big sled.”
The boys uttered exclamations of surprise.
“What’s the matter?” Mr. Snodgrass asked.
“Nothing, only that we saw the marks of the log runners of the stone-boat on which you were carried away,” explained Jerry. “We tried to trace the strange marks,” he said, describing them, “but we failed.”
“Yes, a stone-boat,” agreed the narrator. “But they didn’t use it for hauling stone after they used it to give me an unexpected ride.”
“What did they use it for?” Ned asked.
“To haul cattle on.”
“Cattle!” cried the boys.
“Yes. They had a sort of fence built around the edge of the big, low, flat stone-boat. They would load it with cattle in the ravine and by means of pulleys and rope work it through the secret passage. That was done so the cattle would make no mark on the ground, telling in what direction they had been taken.”
“It sounds pretty complicated,” said Jerry.[225] “But maybe it’s easy when you come to the details. What about the secret passage in the ravine? We suspected one but we couldn’t discover it.”
“I’d better tell my story in sequence,” suggested the professor. “Throughout the night I was hauled along on this stone-boat, as I later discovered it to be, and I couldn’t see where I was going. When daylight came those who had captured me halted in a pleasant little, but well hidden, valley where hundreds of cattle were pastured. There was a sort of camp, around a group of rude buildings, and in one of these I was locked.
“To make a long story short I had been captured by the cattle rustlers as a spy. They had seen you boys come to camp and they guessed you were on their trail. They planned to get you all, but my going out in the night upset their plans, and they took me. Then events occurred to change their plans.
“That they were the cattle thieves who had me was soon proved to my satisfaction. A few days after I had been made prisoner I saw early one morning, some of the rustlers driving into the valley some of the steers from the Square Z ranch. I recognized the brand.”
“What did they do with them?” asked Ned, eagerly.
“Held them in the valley a few days, changed[226] the brand marks, and drove them away again. The valley was so well hidden in the mountains that I believe no one, save the thieves, knew of it.
“After about a week, during which time I was kept in the shack, I was allowed to go about at will. But when I tried to get out of the valley I found it was impossible. The sides were steep and dangerous to climb. There were but two entrances and both were guarded night and day. One was that by which the cattle were driven in, and the other where they went out. Both were well concealed by winding paths leading through dense forests, and though I found both, I could not get past the guards.”
“But you finally escaped,” said Bob.
“Yes. I’ll tell you how. As I said, after a while I was allowed to go about as I pleased, and when I found out I could not escape I began to collect specimens. And what wonderful ones there were in the valley!
“In time the rustlers paid little attention to me and, as I seemed engrossed in my collecting, they talked freely before me. It was in this way that I learned the ravine was connected with the valley by a secret passage.
“When they made a cattle raid they would drive the steers up near the V-shaped end of the gorge. There the cattle would be held together until, ten or fifteen at a time they were put on the stone-boat[227] and hauled through the secret opening, leaving no trace.”
“But how is the opening hidden?” asked Jerry.
“By means of a great wooden door covered with concrete on the outside, so that it looks like part of the rocky wall,” answered the professor. “I know about the location of it. It should be easy to find.”
“We’ll have a try at it!” murmured Jerry. “But how did you manage to get away, Professor?”
“By a stroke of good luck. The rustlers had brought in some of the choice cattle from Square Z, and as they had a market to which the steers must be sent in a hurry they decided to get them out of the valley after dark. I saw then my chance to escape. There were, lying about the camp, any number of old hides, taken off the cattle that had died or been slain for food. I wrapped one of these about me one dark night when the herd was to be driven out, and mingled with the cattle. It was taking a chance, I knew, but I managed to keep from being trampled on and went in the midst of the cattle through the woods to the secret outlet of the valley. Once outside I lay down under a bush to wait until morning. My one regret was that I had to leave behind my lovely specimens. But I dared not carry them.
“Since that night I have been tramping about[228] trying to find Square Z ranch. But I must have gone away from it instead of toward it for I became lost. My clothes and shoes began to wear out. I managed to get enough berries and roots to live on, for I had made a careful study of botany and knew what was best for me. But I was so hungry for a ham sandwich!” said the professor, pathetically.
“Have another!” begged Bob, offering one.
The professor munched it while concluding his narrative. He had wandered on and on, finally becoming so footsore, weary and ragged that he was the tramp the boys beheld him. But in his misery he did not forget his collection mania and made boxes of bark to hold his specimens.
Finally, he reached the great rock, not knowing where he was and scarcely able to go on. Then he had heard the hum of the aircraft engine above him, and had recognized the ship of his friends.
“You are to be congratulated on getting away from those rustlers,” said Jerry. “It wasn’t easy, I imagine.”
“Indeed it wasn’t,” said the professor fervently, and the boys admired him for his pluck.
Not that he had ever lacked it, but his was a restful life, compared to theirs, and he seldom had need to show what he could do in a strenuous way. Though once, when Jerry had been in danger from a wild animal on one of their trips, the[229] professor, armed only with a light gun which he used to bring down birds without injuring their plumage, rushed up and fired in the animal’s face, delaying the attack long enough for Ned to kill the beast.
“They watched me pretty closely,” went on the scientist. “But when I began collecting bugs and spiders, of which there is a wonderful variety in the valley, they began to think I was a bit out of my head,” he said with a chuckle. “Then, thinking me harmless and simple, they did not keep such a close espionage over me, and——”
“You fooled ’em good and proper!” exclaimed Bob, admiringly. “We couldn’t have done it half as well.”
“Not much!” declared Jerry. “We’d have probably tried to concoct some elaborate scheme to escape, and they’d have found it out right away. But the professor’s simple trick worked.”
“I didn’t exactly intend it for a trick,” said the scientist, who was the soul of honesty and fair-dealing. “I really did make a good collection while I was held a prisoner in the valley.”
“And have you really learned the secret of the mysterious ravine and just how the cattle rustlers work?” asked Ned.
“I think I have. Of course I haven’t seen the actual secret door, but I believe I can show you how to find it.”
“And the reason the marks of the cattle always stopped before the end of the gorge was reached was because they put the beasts on the stone-boat and dragged them over the remaining distance,” said Jerry. “It was a clever trick, but it’s been found out.”
“But not by us,” put in Ned, gloomily. “We have fallen down all along on this job.”
“Well, you found me, and that’s as good as finding the secret, for I can tell it to you!” exclaimed the professor. “If you hadn’t found me you might never have discovered what you wanted. So, you see, it is the same, one way or the other.”
“I wonder if we can catch the thieves?” mused Bob.
“I think you can,” the professor said. “They didn’t seem to have any idea of giving up their dishonest raids, and, doubtless, they’ll pay another visit to Square Z.”
“Then we must go back and get ready for a round-up!” exclaimed Jerry. “Are you sure you can lead us to the secret valley, Professor?”
“All we’ll have to do will be to go to the gorge, find the hidden door and go through a tunnel-like passage that leads through the base of the mountain. It is the dried bed of an ancient stream, I take it.”
The airship never made better time than in getting[231] back to the ranch, and the surprise created by the return of Professor Snodgrass, ragged and with bristly, unshaven face, was great. Everyone, from the foreman to the least of the laborers, was thrown into a state of excitement.
It was not until after Professor Snodgrass had been shaved by the ranch barber, and had put on some garments that were not in tatters because of his long tramp through forest and brush, that Watson really got at the facts of the professor’s abduction and subsequent escape.
“And so you have discovered the camping place of the rustlers!” exclaimed the foreman, gleefully.
“Well, the professor knows where it is,” Jerry remarked.
“You made good only just in time,” went on Mr. Watson.
“Why?” Ned inquired.
“Because there was another raid last night. The biggest yet. I was just going to send your father word. Instead, I’ll wait and we’ll round-up these thieves. It’s the best news I’ve heard yet! But we must be lively now.”
“Oh, if they have just taken some more cattle they will not move or dispose of them for some time,” said the professor. “They will have to change the brand and arrange for their sale.”
“That’s a part I’d like to know,” said the foreman. “How do they dispose of the stolen stock?”
But this the professor could not tell.
“All hands that can be spared for the round-up!” was the general cry the next morning, and Hinkee Dee was so busy seeing to the men that he had no time to be sarcastic or to sneer at the Motor Boys, in case he had been so disposed. In fact, he did not even notice them, though the other cowboys praised them warmly for their rescue of the professor—an act that would be, it was hoped, the means of wiping out the gang of outlaws.
“Where’s the Parson?” asked Hinkee Dee, as he was marshalling his forces, for he was to lead the party, the foreman having some business to attend to at the ranch that required his presence there.
“He rode to town,” volunteered Gimp.
“Huh! That’s a nice thing to do when he knew I wanted him on this round-up!” snapped Hinkee Dee. “Here, you Gimp, ride after him and tell him to come back at once. No, never mind. I’ll need you. Just tell him to follow us when he comes back,” he called to the foreman, who promised to do so.
“The Parson knew he’d be needed. I don’t see why he went away at a time like this without telling me,” fumed Hinkee Dee. “We’re short-handed as it is. Where’s Munson? He’ll be of some help, even if he has a stiff leg.”
“He went in to town right after Parson did,” someone said.
“Well, this is a nice thing!” stormed Hinkee Dee. “Why didn’t they make a regular party of it? But we won’t wait. Come on, and we’ll round-up this gang.”
It was arranged that the boys and the professor should go on ahead in the airship, to locate and open, if possible, the secret door. The cowboys would follow, go through the passage and surprise, if they could, the rustlers in their very possession of the stolen cattle. It would be good evidence against them.
“I wonder what made Munson and the Parson go off just before the time for the raid?” asked Bob, as he and his chums, with the professor, were in the airship, speeding toward the mysterious gulch.
“Oh, just a coincidence,” suggested Ned. Jerry did not give an opinion, but he had his own ideas. norfloxacin usp

“Better fly low,” said Ned to Jerry, who was guiding the airship. “If you go up too high,” he went on, as they were approaching the location of the mysterious gorge, “they may see you.”
As far as they could learn by looking down and sweeping the landscape through powerful glasses, they were not seen, and the airship settled down at the entrance of the defile, to give the boys and the professor a chance to find the secret door before the cowboys arrived.
“We’ve got about three hours,” Jerry said. “It will take them that long to ride here.”
They entered the V-gorge, and when they came to the place where, always before, they had been stopped by the lack of the cattle signs, they examined the ground with new interest.
“Look at those splinters of wood!” exclaimed Ned. “That shows where the big stone-boat was pulled along over the stones, laden with cattle.”
“That’s right,” agreed Jerry. “Probably those splinters were there all the while.”
“It’s queer we didn’t notice ’em!” cried Ned. “I don’t believe they were as plain before. I’m sure we would have taken some notice of them if they had been. More likely they put more cattle on the wooden drag this time, so as to hurry them through the passage, and because of the greater weight more splinters were rubbed off.”
“That’s right,” agreed Jerry. “Anyhow, the thing is plain now, and if we follow the splinter trail to where it ends it ought to bring us right to the secret door. Where the splinters end there is the entrance.”
“That was my idea,” said Professor Snodgrass with a smile.
They followed the “splinter trail,” as they called it, until it came to an end right where the two sides of the big stony V came together.
“Here ought to be the door—here or hereabouts,” the professor said as he drew a geologist’s hammer from his pocket, for he was a geologist as well as a botanist and a “bugologist.”
He began to tap gently on the walls of the defile. They were of rough stone, and so cunningly had the concrete coating been made for the wooden door that it could not be detected by an difference in hue or texture.
But suddenly the hammer, instead of giving back a sharp, thudding sound, produced a hollow boom.
“There it is!” cried Jerry.
“Right,” assented the scientist. “And you can see the outline of the door,” and he pointed to an irregular crack starting at the floor of the gorge, rising up about five feet, always irregular, then down again until it reached the rocky floor once more, the space between being roughly shaped like an inverted U with about ten feet distance between the two points.
“But how does it open?” asked Ned. “If we can’t get through we aren’t much better off than before.”
“It is only a light wooden door, covered on the outside with expanded metal lath and that, in turn, with concrete,” said the professor. “It was made in this irregular shape so that the crack, where it fitted into the opening of the tunnel, would look like a crack in the wall. But now we know what the crack means we can pry the door open.”
Ned ran to get the necessary tools, and while he was coming back with them Jerry and Bob looked at the secret door. It was so cunningly devised that from the gorge few would have guessed its existence. They, in their previous searches, had probably stared right at the crack but uncomprehendingly.
Ned returned with a short iron bar, sharp and flat at one end. With this, and an axe, they attacked[237] the secret door. As the professor had said, having gained his knowledge from overhearing the thieves talk while he was a captive, the portal was really but a shell. It was quickly forced open, the secret lock on the inside being broken.
Though they worked quickly they made as little noise as possible, for they feared, from what Professor Snodgrass had said about the two entrances being guarded, that someone would be stationed near the secret door.
But no alarm was raised, for while it was true that a guard was usually kept at the farther end of the tunnel, where it opened into the valley, on this occasion the man had been called away to help in re-branding the cattle.
So, thus favored by fortune, the Motor Boys and the professor were able, undetected by those whom they sought to capture, to force open the door. As it swung back on iron hinges set in the inner face of the rock, a dark tunnel was revealed. Hesitating a moment, to make sure none of the rustlers was there, they stepped in.
“Look! here’s the stone-boat and the ropes and pulleys they used to haul the cattle over a space so all trace of them would be lost,” exclaimed Bob, pointing to the contrivance that was at the opening of the tunnel, which, in reality was a large cave.
“Yes, that’s what I had my midnight ride on,” laughed Professor Snodgrass, who seemed to take huge delight in leading a raid on his former captors. “This is a new one they had just finished making in the woods when, unexpectedly, they caught me.”
“Hadn’t we better wait for the cowboys?” asked Bob, as Jerry and Ned seemed inclined to lead the way farther along the tunnel. “Besides, it’s so dark we can’t see more than a few feet,” and he pointed to the black void beyond.
“Yes, it is dark, and we’ll need lanterns,” said the scientist. “But we have time to go along a little way and explore. The raiding party won’t be here for some time yet.”
“We have plenty of electric flashes on the airship,” Jerry said. “We’ll get them and have a look.”
Presently they were going forward. It was new ground to the professor, as well as to the others, for he had never been in the tunnel. This latter was evidently a hollow shaft under the mountain, caused by an earthquake perhaps, or, more probably, by the erosion of an underground river.
The tunnel was about ten feet high and about as broad, being oval in shape. There was room to drive many cattle along it, and there were evidences that many had been so driven.
“Go a bit easy,” advised Ned. “We don’t want to burst out of the other end of this shaft into the midst of the rustlers.”
“Oh, the tunnel is about a mile long,” said the professor. “And the end is screened by bushes, so you’ll have plenty of chance to be on your guard.”
They hurried silently along the big rocky shaft, their electric flashlight casting queer, flickering shadows on the walls. The professor took the lead when they judged they had covered nearly the distance estimated, and presently he came to a halt.
“We’re near the end,” he said, indicating a glimmer of daylight. “Better put out your electrics.”
This the boys did. Then, proceeding still more cautiously, they presently found themselves looking through a screen of bushes at a curious sight.
Down in a sort of gigantic bowl of a valley, the presence of which they had not detected in their wanderings, as it was the depressed top of a big, deeply wooded hill, they saw a score or more of cowboys and a herd of steers, the latter being driven hither and yon in the process of having the brand of the Square Z ranch obliterated, and another substituted.
“The rustlers!” whispered Jerry.
“There they are!” murmured Bob.
“The secret solved at last!” cried Ned, in a suppressed voice. “Now dad will say we’re some pumpkins, I guess!”
“Only we haven’t got ’em yet,” remarked Jerry, cautiously.
“I guess they won’t get away,” came grimly from the professor. “And then I can get back my precious specimens I had to abandon. I hope they haven’t destroyed them.”
Marking the conformation of the valley, and noting the spot the professor pointed out as the egress, the boys and the scientist returned to the tunnel entrance. They had not long to wait before Hinkee Dee and the other cowboys came riding up.
“Are they there?” the assistant foreman asked eagerly, and he addressed Ned, Bob and Jerry in the most cordial tones he had ever used.
“All ready to go in and get,” Jerry replied.
“That’s good! Come on now, fellows!”
The situation was quickly explained, and plans for a rush made. The cowboys rode their horses into the tunnel, preceded by the boys and the professor with lights. At the far end they halted and then, after some whispered instructions from Hinkee Dee, the whole force went cautiously out and was posted behind the screening bushes.
“All ready now?” asked Hinkee Dee, as he scanned his waiting horsemen.
“All ready,” was the answer. Bob, Ned and Jerry had managed to get places in the front rank. The professor, as soon as he saw the preparations completed, went to one side in a quiet chase after some big bug he saw.
“Let her go!” said Hinkee Dee. “But don’t begin to yell or ride hard until they’ve seen us. Then rush ’em!”
This advice was followed. And so busy were the rustlers branding the steers that the attacking cowboys had ridden a quarter of the way toward them before the alarm was given.
And then it was too late to make a strong resistance. With a fusillade of revolver shots, with wild yells and waving of hats, while the ponies galloped on unguided by rein, the raiders rushed to the attack. The rustlers could not have been taken at a greater disadvantage. Not one of them was armed, all having laid aside their guns to work at the branding.
“Throw up your hands!” came the stern order from Hinkee Dee, his two guns pointed at the outlaws, and the order was sullenly obeyed. One rustler tried to make a dash for his horse, probably intending to seek the egress. But a shot fired over his head caused him to stop, and in a short time the whole gang was captured.
“Well, we’ve got you at last!” exclaimed Hinkee Dee, as he and his friends looked around the[242] discomfited gang, many of whom were known, at least by reputation, to the cowboys. “Caught you in the act, too.”
“Yes, I guess you’ve got the goods on us,” admitted one of the outlaws. “But I’d like to know how you found us.”
“I showed them the way!” exclaimed a mild voice at Hinkee Dee’s stirrup. “And now I’d thank you for my specimens. They’re very valuable. There’s one red bug that——”
“Jumpin’ molasses barrels!” cried Black Henderson, the leader. “It’s the bug-house chap! So you got away, did you?”
“Yes. And I came back again. Now for my specimens,” and the professor hurried off to the shack where he had been held prisoner, coming back presently with several boxes under his arms and a happy smile on his face. He had done his part to aid his friends, and the specimens he secured afterward proved to be of great scientific value.
“Got them—every one!” he called, and from then on he took no more interest in the raid.
The prisoners were bound and driven out of the tunnel and eventually to town where they were locked up. The stolen cattle were gathered together, and headed for their home range.
“Well, boys,” said Hinkee Dee to Ned, Bob and Jerry as they were on their way to the ranch[243] after the prisoners had been disposed of, “I want to congratulate you and say I was wrong in calling you tenderfeet. You’re one of us from now on. I was hopin’ to assimilate these rustlers myself, but you and the professor got ahead of me.
“Hello, what was the reason you didn’t come along with us, Munson?” he asked, as he dismounted at the corral and saw the cattle buyer standing near. “We needed all the help we could get.”
“I had business elsewhere.”
“Couldn’t have been more important business than roundin’-up the rustlers, to my way of thinkin’.”
“I was doing a little rounding-up myself,” was the smiling answer.
“You! Who’d you round up?”
“The Parson,” was the quiet answer.
“The Parson!” was yelled by a score.
“Yes, the head of the rustling gang, its prime mover and the man who gave them information when and where to make their raids on Square Z ranch.”
“Whew!” whistled Hinkee Dee; and the others expressed their surprise in different ways. “How’d you come to do that, Munson?”
“Peck’s my name,” was the quiet rejoinder. “Henry Peck, and I’m a detective. I was sent out here from New York.”
At this the boys started and looked at one another.
“I was sent on by your father,” said Mr. Peck, smiling at Ned, “to see what I could do. Evidently he didn’t take much stock in your efforts. But I shall tell him he was wrong. I did only a little end of it.”
“And you got the Parson,” murmured Gimp, amazed.
“Yes, I got the Parson! He is one of the most notorious cattle swindlers known, and the authorities have been looking for him a long time. I heard of him in Des Moines, and then I came on here. I guess you boys didn’t think much of me at first, did you?” Mr. Peck asked Jerry.
“No; not an awful lot. We thought you were a rustler yourself.”
“Especially after that fake about your leg,” added Ned.
“Well, that was a fake—part of it, anyhow,” admitted the detective. “I did see the rustlers drive off the cattle and they fired at me. They didn’t hit me; but I saw a chance to pretend to be wounded so I could have a good excuse for staying around the place here. That’s what I did, and in that way I got evidence against the Parson. I intercepted some messages he sent to the rustlers, made copies of them and they’ll be used for evidence. He was the real head of the gang.”
“Whew!” exclaimed Ned. “And we thought he was so good!”
“I guess you thought I was sort of mean, didn’t you?” asked Hinkee Dee.
“Yes,” admitted Jerry.
“But I want to say it wasn’t me who changed horses on you that time,” went on the assistant foreman. “I saw the Parson do it, but I wasn’t going to squeal. I didn’t know what his game was but I see now. He wanted to discourage you.”
“Of course not,” Jerry agreed. “I guess he had his reasons for trying to get us away from here.”
“The very best!” laughed Henry Peck. “And now I think you’d better send word home. The main credit belongs to you boys, for if you hadn’t rescued the professor you’d never have known where the rustlers’ headquarters were. I doubt if I could have forced the Parson to tell.
“I stayed away from the raid to-day to get the last bit of evidence against him I needed. And I got it—and him. He’s in jail with the rest of his gang now.”
There is little more to tell. The workings of the cattle thieves were revealed with the arrest of the entire gang. As has been related, they would run off a bunch of cattle when the signal was sent them by the Parson, who, working at the ranch, knew all its operations. Then the steers[246] would be held in the secret valley until a favorable time to send them out to innocent buyers.
The detective’s boast that he had bought Square Z stock under the market price was not a vain one, as he had done so in order to get evidence, though it was worthless at the time. Eventually, the lawless men received their punishment.
Mr. Peck, or Mr. Munson, a name he often went by, had been sent out to Square Z ranch by Mr. Baker as soon as the boys started. He traveled faster than they, and knew when they were to arrive in Des Moines. His attempt to make friends with them was more a joke than anything else, so as to be able to send word back to their parents that they were all right.
He learned of their arrival at the ranch, and, after having worked up some clues himself, he came on, surprising them at their airship. The detective tried to solve the mystery of where the stolen cattle were hidden, but was unsuccessful. He did, however, suspect the Parson, and with good reason, and laid his plans to trap him. The latter was a “slick” rustler, though, and, for a time, baffled the efforts of Mr. Peck.
It was soon learned that one of the rustlers, who had been sent by the others to spy on the deserted camp of the cowboys on the mountain top had fired at the airship.
“Well, I suppose we’ll have to be going back to[247] Boxwood Hall soon now,” said Bob one day, following the receipt of letters from home, in which were many congratulations on their achievements.
“Yes, but there are worse places,” commented Ned, and Jerry nodded.
“I’m glad that dad and Mr. Slade decided not to sell the ranch, and that Mr. Slade found funds for his new business enterprise somewhere else,” observed Bob.
“Well, while we have a chance, let’s take a trip in the airship,” said Jerry. “Want to come, Professor?”
“No, I’m going to stay on the ground to-day. I lost a valuable jumping spider from one of my boxes and I must search for it.”
And while the three chums are enjoying one of their last trips over Square Z ranch we will take leave of them for a time, to meet them again in the next volume, which will be entitled, “The Motor Boys in the Army, or Ned, Bob and Jerry as Volunteers.”
It was about a week after the capture of the rustlers that Ned, Bob and Jerry prepared to make their leisurely way back East in their big car. The airship, after a last wonderful flight, which was witnessed by a number of cowboys from neighboring ranches, had been taken apart and shipped to Cresville.
“Well, come again, boys,” urged the foreman,[248] as he shook hands with the travelers. “Always glad to see you, though I can’t offer you any more excitement like that you just went through.”
“We’ll be glad to see you, anyhow,” put in Hinkee Dee, and this was a great deal, considering the way he had formerly regarded the boys.
The ranchmen gave them a cheer as the big car moved away, and the last sight the boys had of Square Z ranch was the waving hats of their friends.
“Well, it turned out all right,” remarked Ned, after a period of silence.
“Yes, we succeeded better than I expected we would at one time,” agreed Jerry. “It looked as though we were going to fail. What are you thinking of, Chunky?” he asked the stout lad who had not said much.
“Something to eat!” challenged Ned.
“I was not! I was just thinking how the Parson fooled us all. No one would ever have taken him for a rustler.”
“That’s the reason—he was so different,” commented Jerry, as he guided the car over the trail toward the distant East.