Captured by the Arabs

---

“THE Sahara Desert! Adventure! Exploration!” breathed Joe Lewis, as he sat with four companions on the deck of the steamer Sylvania, awaiting their first glimpse of North Africa.

“It’ll be wonderful!” muttered Bob Holton, who was also deeply touched. He, like his chum, had often pictured this mission into the heart of the vast expanse of sand. Soon it would be the real thing. Already the youth could feel his feet plod through the loose soil, could sense the delight of long traveling in a little-known land.

Dr. Kirshner, a noted archæologist, looked up from the book he was reading. His bronzed face took on a wide smile as he scrutinized the two young men.

“Got the old spirit, all right,” he said with twinkling eyes. “I suppose it came from that expedition in Brazil. Every explorer gets it sooner or later.”

“That’s right,” agreed Mr. Lewis, Joe’s father. “They say the main characteristic of a true explorer is his ability to sense the thrill of adventure.”

“Then we’re real explorers. Isn’t that right, Dad?” grinned Bob.

“‘We’?” asked Mr. Holton, trying to appear serious. “Where do you get that ‘we’ stuff? You and Joe have only bothered us on one expedition. We men have faced the scorching sun scores of times, and should by now have caught the true meaning of it all. But you boys——”

“Wait a minute,” cut in Bob, determined not to be beaten so easily. “Where would you have been if it hadn’t been for Joe and me? It was our ingenuity that brought about the success of the expedition.”

“Well, I must say I hadn’t thought of that before,” laughed Mr. Holton.

“It’s true, all right.” Bob stoutly defended himself and his chum. “If you say the word I’ll prove it.”

Mr. Holton smiled. He took a great delight in arguing in a friendly manner with his son, although at times he was forced to admit defeat. This time he was satisfied to drop the matter and turn his eyes to the western sky, where the sun, a great ball of red fire, was sliding into the bluish waters of the Mediterranean. Gradually the ball faded from view, leaving a soft blue sky, which a moment later became streaked with long gold streamers. At last these became molded into one great mass of color and light, crossed and dotted with every hue of the rainbow. Slowly the spectacle faded from view, and the sky became a warm blue, out of which came countless glittering stars.

It was a wonderful sight, and although the adventurers had witnessed it several times before, they never seemed to tire of it. Bob and Joe especially were deeply stirred.

“Now that we’ve seen our last sunset on this voyage, suppose we get our belongings together,” said Mr. Holton, getting up from his chair. “It won’t be long until we reach Algiers.”

“And if what we’ve heard is true, it’s a wonderful city,” added Mr. Lewis. “Has the most unusual blend of things Arab and European on the globe. Monuments, mosques, palaces, everything and more that characterizes the spirit of North Africa.”

He arose and led the way up the deck to the cabin, where already people were gathering to await the first sight of land. Among the passengers were brightly garbed Egyptians, Algerians, Arabs, and many others with quaint and picturesque costumes. Everyone was in a gay mood, laughing and talking merrily. That is, all but two tall Arabs, whose quiet gaze was fixed on Bob, Joe, and the others of the American expedition. That the men intended mischief was sensed by the boys, although their elders had caught no element of danger.

“Wonder what they want?” murmured Bob, in an undertone to his chum. “Fact is, I’ve noticed them before, but never said anything about it. They seem to follow us, for some reason or other.”

Joe nodded.

“I’ve thought the same thing,” he said quietly. “But as they made no move against us, I almost forgot about it till now.”

The youths said no more until they reached their stateroom, which was directly across the hall from that of their elders. As soon as their belongings were together, Bob decided to mention the matter to his father and friends.

“Ten to one they haven’t noticed these men,” he said to Joe, “and it might be best for us to put ’em wise.”

The youths found their companions preparing to leave for the deck and motioned for them to come in the room. Then Bob told of the actions of the two Arabs, pointing out that they probably had no good intentions.

The men listened closely, eager to get all the details. When the boys were finished, Mr. Lewis looked grave.

“They probably heard Dr. Kirshner mention the hidden treasure,” he said soberly, at the same time glancing about as if he expected to see the Arabs at the door.

“Hidden treasure? What treasure?” demanded Joe excitedly, while Bob looked up in surprise.

“It may only be a yarn,” replied Dr. Kirshner. “In fact I just heard about it this morning. An intelligent Arab with whom I made friends pointed out that he had definite information that there were great riches amassed in a cave in the heart of the Sahara Desert. It seems that they had been placed there by native tribesmen, or Tuaregs, who inhabited this region hundreds of years ago. Tuaregs even today are very fond of raiding caravans and small towns. Got it in their blood, I guess.” He paused a moment for breath, and Bob seized upon the opportunity.

“But why did the Arab tell you this?” he asked. “Didn’t he know——”

“I know what you’re thinking,” the scientist interrupted. “You’re wondering why I got in on this. I did too at the start. But as soon as he had finished with the details, he told me that he was not equal to making the expedition alone and had no relatives or good friends to accompany him. He went on to say that few expeditions are sent out into those remote regions, and that he would gladly share the treasure with us if we would go with him.

“Now as this treasure cave is supposedly in the region that we intended to explore, your dads and I could see no reason for not taking him up. His services as a guide will also be invaluable.”

“But—but how does he know where to search?” questioned Joe Lewis, his tone indicating that he was greatly puzzled.

“He has a map,” returned the archæologist. “Got it from an old tribesman who was about to die. Whether or not it is accurate, we have yet to see—if nothing prevents us,” he added significantly.

“Nothing will—if we can help it,” said Bob, delighted at such an opportunity.

A few minutes later they lugged their possessions out on deck. And they were none too soon, for it was scarcely ten minutes later that the lights of land became visible—dimly, of course, but they were there.

“At last,” sighed Mr. Holton, who, although he enjoyed the long voyage, was anxious to reach his destination.

Although land was a great distance away, the adventurers went to the prow to catch a first glimpse of that mysterious country on which they would soon set foot.

Bob and Joe watched closely as the myriad of lights grew more plain. A stronger beam flashed from the Cape Matifou lighthouse, and numerous lights from ships in and about the harbor were also visible. No more could be seen. But it was enough. Bob and Joe were convinced that Algiers was a charming city indeed.

“How large a place is it?” asked Joe, as the Sylvania neared the port.

“About two hundred and fifty thousand,” returned Mr. Holton. “And all different races, from Americans to Turks and Jews. Oh, we’ll see sights all right.”

Gradually the boat pulled into the harbor, reversed her engines, and stopped at a large dock. Then among lights the gangplank was lowered, and the boys and their elders soon found themselves among the many hurrying passengers. Lights were everywhere, almost as numerous as in an American city, and they had no trouble in finding their way to a hotel.

“Oh, by the way,” exclaimed Joe with a sudden recollection, “what became of your friend the Arab—the one who knows about the hidden treasure?”

“He’s at another hotel,” replied Dr. Kirshner. “I have his address on paper. We’ll go over there in the morning. He had already made reservations at this hostelry or would have put up with us.”

The remainder of that evening was spent quietly, for the explorers were tired after the long journey on the Sylvania.

Bob and Joe were up early the next morning, and after a small but satisfying breakfast they started out for a short walk. But they had scarcely covered a square when Joe, who had happened to glance back, stopped suddenly and nudged his friend.

Bob looked, and an answering expression of surprise and anger came on his face.

Walking slowly into the hotel were the two Arabs who had acted so suspiciously on the ship.

---

“WHAT do you suppose they want?” asked Joe, as the youths followed the movements of the Arabs.

“They’re not there for any good,” returned Bob, a look of anger, and at the same time anxiety, on his face. “Probably want to find that map that tells of the hidden treasure. Oh, of course it could be a coincidence that they picked the same hotel that we did, but it isn’t likely.”

The boys watched the suspicious characters until they disappeared into the hotel. Then Joe suggested that they cautiously follow.

“All right,” Bob agreed. “But we must be careful and not get too close. They might have guns and think nothing of using them, and they could probably get away in this country.”

Slowly the youths moved up to the entrance and peeped around the corner. Satisfied that there was no one in sight, they went inside.

“Nobody here but our dads and Dr. Kirshner,” observed Bob, glancing about. “I wonder if they noticed the Arabs?”

“Let’s ask them.”

The men had noticed the fellows, they said, but thought nothing about it. Why? Was anything wrong?

Bob explained that they were the two who had acted in a suspicious manner on the ship, and at once the scientists’ faces lightened.

“Come on,” urged Dr. Kirshner. “We can’t get there any too rapidly. When they find that we haven’t got the map, they’ll probably help themselves to money and anything else that happens to be lying about. They may even search other rooms.”

Hastily, and yet quietly, the boys and their elders went up the stairway. They were unarmed, their revolvers and other firearms having been left in their rooms. This might prove a handicap if the Arabs possessed weapons, but the Americans thought nothing of the risk they were taking.

“We’re five to two, even if we haven’t our guns,” said Bob, clinching his fists. “They’re likely to be shaken by numbers.”

But Dr. Kirshner, who knew the ways of these cunning natives, smiled grimly.

In a short time they reached the floor on which were their rooms and turned cautiously down the hall. With utmost care lest they be discovered, the explorers tiptoed up to their rooms.

Mr. Holton took the lead and glanced around the door into the room. A moment later his face scowled.

“What is it?” demanded Joe, in a whisper. “Are they inside?”

Mr. Holton shook his head.

“Worse than that,” he said solemnly. “Take a look.”

While the others are taking in the situation, it might be well to tell something about Bob Holton and Joe Lewis and, incidentally, their fathers.

Bob was a big, well-built youth of some eighteen years. He was particularly fond of adventure and life in the open, and always welcomed an opportunity that might bring about a realization of his desire.

Joe, who was about the same age, was of medium size and strength, with a naturally dark complexion that was now still further darkened by the tropical sun. He, like his friend, was fond of adventure, hunting and fishing and hiking whenever the opportunity presented itself.

The youths were together much of their time and agreed on practically every point. Their home was in Washington, D. C., where their fathers, Mr. Holton and Mr. Lewis, were employed as naturalists by a large museum.

A short time before, the youths were successful in persuading their fathers to take them on an expedition to unexplored Brazil. Here they helped the naturalists shoot and classify wild animals, birds, and reptiles and had many thrilling adventures with wild animals and savage Indians. How they fought hand-to-hand with a huge jaguar, barely prevented themselves from being crushed by a terrible anaconda, battled against rapids, and finally became lost and wandered for days in the world’s greatest jungle are told in the first volume of this series, entitled, Lost in the Wilds of Brazil.

The boys spent the following winter finishing up in high school, and scarcely was graduation over when their fathers were requested by the museum to make an expedition to the Sahara Desert to collect specimens of any animal life that might be present in the remote interior. Dr. Kirshner, of whom something has been said, wished to accompany the naturalists to investigate the remains of ancient civilizations. At once Bob and Joe requested that they be taken also, and after careful consideration their elders at last consented. What the boys were particularly looking forward to was taking motion pictures of the desert, for they had been engaged by the Neuman Film Corporation to get many unusual scenes.

Less than a week later the expedition sailed on the steamer Sylvania and made the long voyage without any special incident.

Now let us return to the boys, as they advanced into their elders’ room.

At once their mood changed, an expression of astonishment, later turning to anger, creeping over their faces.

Everything in the room was in the wildest disorder. Clothes, shoes, satchels, rifles, papers lay scattered about, the scene suggesting that a cyclone had visited the place. It was most deplorable, and the travelers stood for some time as if trying to catch the true meaning of it all.

Finally their anxiety caused them to move forward and inspect the belongings.

“Good thing we didn’t have the treasure map,” remarked Mr. Lewis, examining the contents of a small black bag. “It wouldn’t be here now.”

At the end of their inspection the explorers found that nothing had been taken from their belongings. It appeared that the crafty Arabs wished only the treasure map, and that, not being able to find it, they had left without any other spoils.

“They sure acted in wild haste,” observed Mr. Holton. “It’s almost impossible to see how all this could have been torn up so quickly. It wasn’t five minutes from the time that you boys told of seeing the men that we were up here.”

“Trust the Arabs to do that,” said Dr. Kirshner, with a dry smile.

The scientists’ possessions were placed back in their proper places, and then they went to inspect the room occupied by Bob and Joe.

“Probably nothing taken from here, either,” was the opinion expressed by Mr. Holton, and he proved right, as they later found.

“This shows that these Arabs are desperate characters, and will probably stop at nothing,” said Dr. Kirshner, after a moment of thought. “We must be extremely careful to lock everything up from now on. It may even mean that we’ll have to watch ourselves, too.”

“What do you mean?” asked Joe.

“Simply that they may try to kidnap one or all of us to get possession of the map,” he replied in a low voice. “I know these natives. I’ve seen some of their actions before and feel sure that if these two men thought there was a good chance to get the map, they would try to do it.”

“It may not be as easy as they think,” said Bob, although he was a bit uneasy.

No more time was spent in the rooms, for they were all desirous of seeing more of the strange city and country.

“It might be wise to call on our Arabian friend first,” said Dr. Kirshner. “The one who knows about the treasure, I mean. We haven’t seen him since we left the ship last night, and he may be anxious to know what plans we have in mind.”

“Yes,” agreed Joe. “And while there we can warn him against these crooks. They may come on to him for the map, since they found that we haven’t it.”

First, however, the boys’ fathers and Dr. Kirshner wished to breakfast.

“And while they’re busy eating, suppose we go out,” suggested Joe. “We don’t need to stay but a few minutes.”

Bob agreed. He, like his friend, was anxious to observe the strangeness of this unusual city. If what he had heard was true, it would be something to be long remembered.

Out on the street the youths were at once impressed by the wide variety of races and costumes. Frenchmen, Italians, Spaniards, Mahonese, and Maltese all walked side by side, the majority in European garb. Arabs, or rather those who are commonly called Arabs, for they are a very mixed breed, sauntered along, clad in their long gowns and hlafa, which hung down over the face and sides of the head. Occasionally a Negro could be seen, although this was the exception rather than the rule.

“Sure have variety here,” smiled Joe. “There’s about every race imaginable present.”

In a short time the youths reached the Place du Gouvernement, or central square, and the busy scene of life was very interesting. On one side of the forum was the Mosque of Djema-el-Djedid and the Grand Mosquée, and on the others were stores, hotels, and cafés. Stretching away in the distance were the four great streets of the city.

Bob and Joe spent some time in one position, watching the throng of Arabs, soldiers, Jews, and others peculiar to this metropolis. Strange, the boys thought, that the people paid little or no attention to them. But this was probably due to the fact that hundreds of tourists visit the city each year.

“I’d like to visit some of the stores,” remarked Bob. “But we’d better get back to the hotel.”

“Yes. Our dads and Dr. Kirshner will probably be waiting for us.”

Reluctantly they made their way back and found that the scientists were ready to leave for the Arab friend’s hotel.

“We’ll trust that we’ll find him in his room, or in the lobby,” said Mr. Holton, as he and the others followed Dr. Kirshner.

“He’ll probably be there,” returned the archæologist. “He’s expecting us over this morning to talk over the best procedure to find the hidden treasure.”

The hotel in which the Arab was staying was but a short distance up the street and around the corner. The explorers were barely within sight of the building when a figure rushed madly out of the door and came toward them.

“Something the matter with that fellow?” asked Bob, surprised to see such haste from the native.

“Looks that way,” returned Mr. Holton. “He’s——By George! It’s our Arab friend. Wonder what has happened?”

A moment later the man was up to them, his face white, his hands trembling.

“The treasure map!” he cried in poor English. “It is gone!”

---

AT the Arab’s dread remark it seemed for a moment that the explorers were going to sink through the street. Dr. Kirshner reeled, and the perspiration came out on Mr. Holton’s face. Mr. Lewis and the boys were spellbound.

Gone! Hundreds of dollars—yes, thousands. After all this anticipating the good fortune of finding the supposedly hidden treasure. The explorers could hardly believe it.

At last Dr. Kirshner got a grip on himself.

“Do you have any idea where the thieves went?” he asked of the Arab, whose name was Fekmah.

“No,” was the reply. “They have complete disappeared. I try see where they go, but could not. They gone when I got to my room.”

“When did you first notice that the map had been taken?” inquired Bob in an anxious voice.

“No more than ten minutes ago,” Fekmah answered. “I had gone out to stay but a moment, and when came back to my room the door open and map gone. I run around to back and look out, but they gone.”

“Gone!” echoed Mr. Lewis. “We should have warned Fekmah to be on the lookout. If Bob and Joe had discovered the suspicious actions of the rascals sooner, it would have given us time to do so. But the fact that nothing strange was noticed till the night we were to reach port gave us no time to tell it.”

“So you knew?” asked the Arab friend. “You knew that robbers were after the map?”

Dr. Kirshner nodded.

“They broke into our rooms this morning, but when they couldn’t find the map they left without taking anything else,” he said. “We were just going over to warn you to be on the lookout and guard the map closely when we saw you.”

The Arab scowled and gritted his teeth.

“Allah curse them!” he exclaimed, vexed all the more because of almost but not quite knowing in time. “It’s too late now to find them, and they prob’ly gone by now.”

“Gone where?” asked Mr. Holton.

Fekmah spread his hands apart in a wide gesture and then pointed to the south.

“To get treasure,” he said quietly.

“Then we’ll get there first!” exclaimed Dr. Kirshner. “No thieves will get ahead of us. I think it might be well to start on the journey at once—that is, if you can go that soon,” he said to the Arab, who nodded.

“But how will we know where to go without the map?” asked Mr. Lewis.

“I have general idea,” Fekmah returned. “I studied it so much that know about where go. And I can leave any time.”

“Fine!” blurted out Dr. Kirshner. “We’ll get our belongings together and leave tomorrow. But first let me introduce my friends. I don’t believe you’re acquainted with them,” and he proceeded to introduce the Arab to Mr. Holton, Mr. Lewis, and Bob and Joe.

“Now let us all come up to my room,” said Fekmah. “We can talk over plans for the treasure search. There are much things you should know.”

They walked on up the street to a comparatively large building and were led in the door and up the stairs by Fekmah.

“So this is the hotel where he’s staying,” said Bob, casting eager eyes about the place.

“Sure is luxurious,” remarked Joe. “It’s the best in town.”

The Arab’s room was halfway down the hall, and to it they went.

“Now sit down,” directed Fekmah, “and we will talk things over.”

They did so and then made ready for what the Arab had to say.

There was a short silence. Then Fekmah resumed the conversation.

“Like Dr. Kirshner said, we should leave at once if expect to find the hidden riches before the thieves get ahead of us,” he began, showing an unusual ability to speak English correctly. “There are two routes we can take to get to the edge of the desert. We can take the railroad to Oran and then to Figuig, or can get on train to Wargla.” He moved over to a small satchel and took out a cloth map, which he unfolded and laid on a small table that was in the middle of the room. The map was French, and although the naturalists and their sons had a slight knowledge of that language, Dr. Kirshner and Fekmah were the only ones who knew it thoroughly.

“I think we can make out enough to satisfy ourselves, though,” said Mr. Holton.

The Arab traced the one route and then the other, pointing out the possibilities of each one. The object was to take a train to the farthest point in the desert possible and start the expedition from there on camelback.

“Now,” continued Fekmah, “our destination is the Ahaggar Mountains. They are about seventeen hundred kilometers (about a thousand miles) from here. From what we measured, the best route is to go to Wargla and get camels from there. What you think?”

“I believe you’re right,” returned Dr. Kirshner. “That route is much shorter, and we’ll have less difficulty in finding our way from Wargla than from Figuig. Nearly all expeditions depart from Wargla, and there are numerous small settlements on the way to the Ahaggar Mountains. Can we get a train in the morning?”

The Arab nodded.

“There about three trains a day out,” he said. “I believe one leaves in morning, so we can get there easy.”

“Fine!” exclaimed Mr. Lewis. “Then we’ll leave now and get packed and be here for you early in the morning.”

Fekmah bowed.

“And I will make the stolen map over again from memory, as near as can,” he said.

They bade the Arab good-bye and left the hotel to get their belongings together. If they were to leave for the Sahara the next morning, a great deal of packing would have to be done.

“Don’t suppose there’s any use trying to find the thieves, is there?” asked Joe, as they approached their hotel.

Dr. Kirshner laughed unwillingly.

“They are probably halfway to the Sahara by now,” he returned, although he knew this to be an exaggeration.

When the explorers arrived at their rooms, Dr. Kirshner directed the preparations for the expedition, and the remainder of the day was spent in doing this. It seemed that the archæologist had forgotten his duties as a scientist and was thinking only of finding the hidden riches.

“If we are fortunate enough to find our objective, we will be paid many times the cost of the expedition,” he said.

“If those crooks don’t get ahead of us,” added Joe, with a grim smile.

“They won’t—not if we can help it,” blurted out Bob, fumbling his automatic.

At noon the adventurers stopped only a few minutes for a meal, so eager were they to finish the task of preparing for the expedition. They found it necessary to purchase much that they did not have, and the bazaars of Algiers were visited often for the unusual in the way of luxuries.

At last the work was completed, and all sat down to rest after the strain. Bob and Joe had had the experience once before of helping to make preparations for an expedition and knew what was expected of them.

“I wish we could take motion pictures of this city,” remarked Bob that evening. “But we’ve been instructed to wait till we start the journey in the Sahara.”

The next morning the explorers were up early, and after a bountiful breakfast they made their way to Fekmah’s hotel.

The Arab was expecting them and had finished making a second map. It was none too accurate, for he did it from memory, but it promised to be the only means between defeat and failure.

“You may wonder why I bothered to make more map,” he said to his friends. “But it possible that I forget some of the landmarks when we are on way, and this will——”

“Come to the rescue,” interrupted Joe, smiling.

“And also,” Fekmah went on, “you may have this if anything should happen me.”

“Let’s hope nothing will,” said Bob.

“And now,” began Dr. Kirshner, “I’m going down to the railroad station and find out if we can get a train this morning. I’ll be back in a short time.”

“While he’s gone, suppose we go out,” suggested Joe to his chum. “There’s a lot we can see around here before we leave.”

“All right,” Bob replied. “But we don’t want to stay too long. There might be a train out in an hour.”

The youths decided to see the old section of the city, as they had heard from Dr. Kirshner that many points of interest were to be found there. It was but a few minutes’ walk to their objective, and they turned their eyes about.

As they were passing a café, Bob motioned for his friend to look inside.

A gray-haired, shriveled old man in torn clothing was strumming a guitar and walking from one end of the café to another, holding out a hand for money. But no one seemed inclined to give him any. Evidently this was a common occurrence, for the people paid little or no attention to the old beggar.

“I’ve half a mind to give him a break,” started Bob, but Joe pulled him back.

“If we want to see any of this town we’ll have to be at it,” Joe said, leading the way down the street.

The narrow ways were lined with shops and bazaars, offering the shopper a wide variety of commodities.

“But most of the things they sell you don’t want,” smiled Bob, glancing at a counter laden with coarse native food.

The youths noticed that certain streets were devoted to the selling of certain products. For instance, one avenue was lined with shops displaying brassware.

“It ought to be easy to find what you want,” grinned Joe. “Just walk down one street and you will have a large choice of the same thing.”

The boys spent nearly a half-hour in the native quarter. Finally Bob suggested that they get back to the hotel, and his friend was also in favor.

In a short time they were back in the hostelry and proceeded to go to their rooms. But they were scarcely at the doors when the sound of footsteps came to their ears. The next moment Dr. Kirshner came into view.

“Hello,” greeted Bob, and then his jaw dropped.

That something was wrong was evidenced by the frown that was on the archæologist’s face. His usual smile was absent.

“There’s been a wreck,” he said in an anxious voice. “The train has been wrecked. I guess we can’t get to Wargla so soon after all.”

---

BOB and Joe gasped in astonishment.

“The train wrecked!” muttered Bob and then started. “What caused it?”

“I imagine you’re thinking the same as I,” the archæologist said quietly. “That those thieves were responsible for it to prevent us from getting to Wargla at once.”

Joe’s face glowed with anger.

“The dirty beggars!” he cried. “Was anyone hurt?”

“No. It happened that no one was. But the locomotive was derailed and lodged in a ravine, and the work of getting it back on the track and repairing it won’t start any too soon in this country. It may be two or three days before order will be restored. It looks like those robbers have won out after all.”

They walked on into the room, where they were met by the boys’ fathers and Fekmah.

“Is there anything wrong?” asked Mr. Holton, as he noticed the sober faces of his friends.

The situation was explained, and the men frowned. Fekmah especially was agitated.

“May the black monsters of Tidihet feast on them!” he exclaimed, running his fingers through his white hair. “Allah will punish them—they will not go free!”

“But that won’t help us any,” said Mr. Lewis dryly. “We’ve got to figure out some way to stop them, if it’s at all possible. The question is, what will it be?”

“There’s no way of telegraphing,” said Dr. Kirshner, gazing thoughtfully at the floor. “If we had any idea where they went—that is, what route they took—we might overtake them on fast dromedaries. But the chances even then would be slight.”

“We might——” began Joe but was interrupted by a knock at the door.

For a moment the adventurers looked at one another in surprise. Then Mr. Holton moved over and cautiously opened the door.

The figure that stood in waiting was a tall, powerful Arab, with dark, piercing eyes that were none too pleasant to look at. He towered several inches above Mr. Holton, who was himself nearly six feet. Around the man’s shoulders and reaching nearly to the floor was a white gown, and on his head was the conventional hlafa.

For several moments he stood looking at the occupants of the room, as though forming a rapid opinion of the situation. Then he again turned to Mr. Holton and muttered something in the native tongue.

That Bob’s father understood was evidenced by the look of surprise that came on his face. A moment later he turned to his friends.

“He says Fekmah is wanted by a friend,” Mr. Holton said. “Won’t say any more. I don’t know what to make of it.”

“A friend?” Fekmah gasped. “Why, I know no person here. What could it mean?”

Again the stranger said something in Arabic and motioned for his objective to come out.

For a moment Fekmah was thoughtful. Then he decided to investigate.

“I will be back in short minutes,” he said and walked toward the door.

“Wait a minute,” called Dr. Kirshner. “I’m going with you.”

“And I, too,” cried Bob, getting up from his chair.

Joe also put in a request, but the archæologist shook his head.

“Two more are enough,” he said quietly, as he and Bob followed the Arab down the hall.

“Be careful,” warned Mr. Lewis, as they reached the stairs. “There’s no telling what that fellow may want.”

They reached the street and were directed around the corner and up a narrow byway, the stranger remaining several yards in the van.

“Keep a ready hand on your automatic,” whispered Dr. Kirshner to Bob. “Something may happen in a short time now.”

“Do you believe Fekmah is really wanted by friends?” the youth asked, glancing about as if he expected any minute to be confronted by a band of desperate characters.

“Beyond me,” was the reply. “But I believe it would be safer to say no than yes. But there is a possibility that he met someone and has forgotten about it.”

“What could they want of him? It all seems funny to me.”

On they went, now upward by a gently sloping street that was so crooked it seemed to have no outlet.

Suddenly the street stopped at a narrow, winding stairway that led almost straight up. All about were crowded houses of clay, dirty and weather-beaten and suggesting that only the very poorest of Arabs lived there.

Having made sure that the others were following him, the stranger led the way up the stairs. At the head was a small door, and this was opened for them to go inside.

But they hesitated.

“Ask him what he wants,” directed Bob. “There could be anything in there.”

Dr. Kirshner turned to the Arab and in a stern voice put the question before him.

The latter surveyed the American closely, then said in the native tongue:

“I wish nothing of you. It is Fekmah who is wanted. But if you and your friend must intrude, you may come in.”

The man’s attitude did not win the friendship of the explorers, but chiefly because they were at a loss to know what to do next they followed him inside.

A moment later the door was closed and they found themselves in a sort of twilight.

As soon as their eyes became accustomed to the dim light, they made out four figures sitting in the corner of the room. The bare floor alone served the place of chairs, and the men seemed comfortable. Bob at once formed the conclusion that these Arabs were of the same type as the stranger who escorted them here, and felt a bit uneasy. He would have felt much better with a hand on his gun, but this would have aroused the suspicions of the natives. Nevertheless he kept on guard for any treachery. If it came to a fight, he knew that it would be two to five, for Fekmah was, in his age, not capable of taking part.

None of the Arabs was able to speak English, evidently, but Dr. Kirshner knew the native language from his previous visits to North Africa. And he promised to translate occasionally to Bob.

But a moment later it was plain that there was little translating to be done, for one of the Arabs said something to Fekmah and motioned for him to come into the next room. The Americans were to remain where they were.

“I don’t like this,” muttered Dr. Kirshner, as he and Bob were told to be seated on the floor. “Anything may happen to him in there.”

“Suppose we go with him,” suggested Bob.

The archæologist nodded. He arose from his chair and started to follow, but one of the Arabs gently pushed him back.

“It is Fekmah who is wanted,” the fellow said in a queer bass voice. “You will wait here. It will only be a moment.”

Dr. Kirshner had half a notion to push through and follow his Arab friend, but he changed his mind and sat down with Bob on the floor.

“What’s the big idea of all this?” the youth asked in a puzzled voice. “They trying to double-cross us or something?”

The archæologist did not answer, for he felt all too sure that something serious was wrong. But what was there to do?

There was no conversation between the archæologist and the natives, for each seemed busy with his thoughts. Bob was extremely grave, and he wondered what was taking place in the adjoining room. Perhaps the Arabs wished to sell Fekmah something and did not wish to be thwarted by the whites. Or perhaps they wanted to engage themselves as guides on the coming expedition and knew they would have a better chance with Fekmah than with the Americans. But whatever it was, Bob felt uneasy. If their friend did not return before long he would go after him, the youth thought.

“We’ll wait a few more minutes,” said Dr. Kirshner. “Then——”

“Listen!” commanded Bob. “What was that?”

“I didn’t hear anything. What——”

“There it is again. Sounds like a muffled cry for help. It’s—it’s Fekmah!”

---

BOB was on his feet in an instant and dashed toward the door to the next room. But two of the Arabs were there first. With a catlike quickness they drew knives and advanced on the Americans. The other two natives came at them from the side.

“What does this mean?” demanded Dr. Kirshner, looking from one to the other, his black eyes snapping with anger.

“You are going to die!” was the grim answer from an evil-looking, flat-nosed fellow. He moved forward a step or two.

Bob did not understand the man but sensed that something sinister was to take place. He noticed the look of anger and anxiety on the scientist’s face.

With a sudden movement he drew out his automatic, at the same time stepping back several feet. His action was so quick that the Arabs were taken by surprise and stood for several moments trying to grasp the true meaning of it all.

“Now get back!” he commanded, flashing the shining pistol in their faces. “Take away their knives,” he said to Dr. Kirshner. “I’ve got them covered. Tell them I’ll shoot the first man who makes a forward move.”

The scientist did as directed and found that, beyond a vicious-looking knife, they were unarmed.

“You stay here and guard them,” said Bob. “I’m going in and see what’s happened to Fekmah.”

He moved over to the door and opened it. Holding the pistol in readiness, he walked slowly in the room. One glance told him that no one was in sight. But there was a door leading into a large alcove, and it was possible that he could find someone there. Perhaps the Arabs were in hiding, having sensed that they were in danger.

Tiptoeing as quietly as possible, Bob made his way to the closed door. He stood for several moments wondering what to do next. Then he decided to make a bold move.

Clutching his tiny automatic tightly, he took hold of the knob and with a sudden twist threw open the door.

The next instant he shrank back, for a tall Arab was almost upon him. The man held a vicious-looking knife in his uplifted right hand and was apparently ready to open the door when Bob did so first.

During the next few seconds Bob’s brain was in a whirl. He had half a mind to shoot the fellow outright and take no chances. But a moment later he thought better of it. He did not want to be guilty of murdering even this cruel Arab. If he had been as good a shot with a pistol as he was with a rifle, he would have shot the knife from the fellow’s hand. But as it was, he knew this could not be done.

Suddenly the Arab lowered the knife and, scowling cruelly, he rushed at the youth furiously.

Realizing that he must act quickly, Bob aimed at the man’s leg and fired. But his hand was unsteady from the terrific strain, and the bullet missed and lodged itself in the wall.

With a hoarse bellow the Arab came forward with terrific force, muttering angrily. He had the knife in readiness now, and was about to plunge it into the youth’s body when something unexpected happened.

Seeing a good chance, Bob pushed his foot forward with all his strength, bringing the man down with a thud that resounded through the little room. The Arab was taken completely unawares, and the knife went sliding across the floor.

The next instant he was on his feet, and, showing his black teeth wickedly, he darted toward his young enemy, his large hands ready to grip anything they might rest on.

Now was the time to act, Bob thought. Leaping forward, he sent his fist crashing into the Arab’s nose with all the strength in his powerful young body.

The man reeled, backed up, and then fell against the wall. Another victim of the youth’s boxing ability had gone to his fate.

Perspiration was dripping from the boy’s brow. His leg ached from the twist he gave it in bringing the Arab to the floor. Every muscle in his body seemed fatigued. For a brief moment a sensation of nothingness crept over him, and he felt slightly numb.

With a start he regained his composure and, with one glance at the still limp Arab, he dashed through the door, the shining automatic still in his possession. One thought stood out in his mind above all others. He must find Fekmah.

No one was in the alcove, but another door led out into a sort of hallway, and casting aside all thoughts of personal danger, Bob passed through it.

The next instant he found himself in a narrow passageway, with no windows or other means to admit light. The semidarkness was tantalizing, overcoming, but the boy went bravely on. Occasionally he stopped to listen. But no sound reached his ears. Could it be possible that Fekmah had been....

The thought was not a pleasant one, and Bob dismissed it from mind. Here was a door. Perhaps this would reveal something.

As quietly as possible he turned the latch and peeped in the room.

In the darkness he could make out no one at first. Then his eyes almost burst from his head as he saw, lying on the floor in the corner, tightly bound and gagged—Fekmah!

For a moment Bob stood spellbound. Then he rushed over to the unfortunate man.

“Fekmah,” he cackled gently and then bent over and felt of the Arab’s heart. It was still beating, and with a swift motion of a small knife Bob cut the ropes that bound the man. Then he removed the gag and stood back to see if his friend had been injured.

The Arab’s eyes opened, and he sat up with a start. A moment later the look of fear vanished from his face as he saw Bob.

“Praise be to Allah!” he murmured, getting feebly to his feet.

“Are you hurt?” the youth asked.

“No—not yet,” was the grim reply. “But the evil-doers were going to come back and kill me if I not tell where to find treasure. It is time now that they come. Let us go in haste, or they will stab us.”

“Treasure?” cried Bob. “You mean they wanted you to tell where the hidden riches in the desert are?”

“Yes. They were going torture me if I not tell. They are demons. Allah curse them!”

“But how did they know?” demanded Bob. “How did they find out about it? They’re not the same ones who wrecked the train, are they?”

Fekmah shook his head.

“How they find out, I not know,” he said.

Cautiously they made for the door and opened it. Satisfied that there was no one in sight, they walked through the hallway and into the alcove.

“Now we must be careful,” Bob warned. “I knocked a man out a while ago, and he may have come to by now.”

But when they reached the place, they found the fellow still limp.

At sight of the Arab, Fekmah looked at Bob with admiration. It was evident that the youth had gone beyond his expectations.

In a short time they reached the door into the first room and found that Dr. Kirshner was still guarding the Arabs. The scientist looked up in relief when he again saw Bob and Fekmah.

“I feared something had happened to you,” the scientist said. “I shouldn’t have allowed you to go in there,” he said to Bob. “But I see you’ve done your duty and brought back Fekmah.”

“But what shall we do now?” Bob asked. “Are there any officers to take charge of these crooks?”

“Yes,” the archæologist returned. “You and Fekmah stay here and guard these men and I will go after them. It is best not to take them down to the police station for fear of attracting too much attention. Other Arab friends might charge us in a large band.”

The next moment he was gone, after having promised that he would be back with officers in a few minutes.

“There ought to be some way to get the fellow I knocked out in here,” Bob thought, as he guarded the Arabs closely. “But I’d better not risk letting Fekmah have the gun. I’ll trust the fellow is still out of his senses when Dr. Kirshner and the officers arrive.”

The Arabs whom the youth was guarding were silent, but their evil faces suggested what they would do if given the chance.

Bob was in a position where he could also watch the door in the next room. He was taking no chances on an attack from behind.

“I bet Dad and the others are worried,” the boy thought. “We’ve been gone a long time.”

Inside of ten minutes Dr. Kirshner was back with three native policemen, who handled the crooks roughly. Each man was handcuffed and made to walk in front of the officers.

“Now,” said Dr. Kirshner, “suppose we get back to the hotel room. Our prolonged absence has probably caused a great deal of anxiety among our friends.”

“Yes,” Bob returned. “We——” He stopped suddenly and then dashed into the next room for the crook whom he had previously knocked out.

But he was not surprised to find the man gone. An opened door revealed that he had escaped.

“No use looking for him,” the youth thought, as he retraced his footsteps back to his companions.

Bob was forced to explain to Dr. Kirshner, who was puzzled at the youth’s sudden dashing away. When he had finished, the scientist regarded him admiringly but warned him against taking unnecessary chances.

“Those fellows would think nothing of stabbing you to death,” he said, shaking his head gravely.

They went on up the street and arrived in a short time at the hotel in which were their friends. Up at Fekmah’s room they were given a hearty welcome.

“What kept you so long?” asked Mr. Holton, seeing at a glance that something was wrong.

Dr. Kirshner related the details of the previous happenings, laying stress on the pluck and bravery of Bob.

The naturalists and Joe listened closely, eager to get an account of everything. They did not seem unduly surprised, for at the start they felt that something was wrong. But that their friends would be in such grave danger was not in the least anticipated.

“It’s lucky that you’re here to tell it,” said Mr. Lewis, with a shaking of his head. “Such desperate characters know nothing else but to rob and kill.”

“But as it is,” smiled Joe, “you came out all right, and had an unusual experience at that.” Secretly he was sorry he had not taken part in it.

“And that is the second time Bob brought in criminals,” said Mr. Lewis, recalling an incident that happened the summer before.

“I’d rather you wouldn’t take such risks, though,” urged Mr. Holton. “If one taxes good fortune too much, he is sure to come to a tragic end some time.”

There was a short silence. Then Joe ventured to touch upon the matter that concerned them before the abrupt interruption of a short time ago.

“What will be our next move?” he inquired.

“Hmm,” hesitated Dr. Kirshner, “that is hard to say at present. I suppose, though, that the logical thing to do is wait and take a train to Wargla as soon as possible. When the track will be cleared is hard to say. It might be a day, or it might be several. I can see no other way of getting to Wargla, can you, Fekmah?”

“No,” replied the Arab. “Of course there are good roads part of way, and might ride automobile some of way, but train could get there sooner, even if we wait.”

“I guess you’re right,” agreed Joe, thoughtfully. “There’s no use wasting time trying to do a thing that can’t be done. Have you made inquiries as to about when we can expect the train to be ready?”

“Yes,” answered Dr. Kirshner. “The station agent said inside of two days, but it probably won’t be that soon.”

“Let’s hope it will,” said Bob. “I’m anxious to get started into the desert. How long will it probably be before we reach our destination, once we get started on camelback?”

“That all depends,” replied the archæologist. “If we see fit to use dromedaries, or the one-hump camel, we will make much better time. They can travel from ninety to a hundred miles a day with ease, and if forced, can do much better than that.”

“But the jolting is most uncomfortable,” Mr. Lewis reminded him, and Fekmah nodded.

“Soon get used to it, though, don’t you?” asked Joe.

Fekmah laughed.

“No, never,” he said. “But not feel it so bad after many days of riding.”

“But getting back to your question,” resumed the archæologist, speaking to Joe, “if we have good luck we should cover the thousand miles to the Ahaggar Mountains inside of two weeks, considering, of course, stops at oases, small towns, and the like. Then how soon we can find the hidden riches would be a mere guess, because without the map Fekmah will probably have much more difficulty in recognizing various landmarks.”

“But you must remember that our main object was to work for the good of science,” Bob’s father said. “Mr. Lewis and I were to get specimens of any animal life that exists in the far reaches of the desert, and you were to look up the remains of ancient civilizations. Incidentally, though, we’ll search for the hidden riches.”

“And Joe and I were to take motion pictures when we get started on camelback,” said Bob proudly.

“Speaking of animal life,” began Mr. Lewis, “suppose in the morning we get out in the open country and see if we can collect any specimens. From what I’ve read and heard, I guess it is necessary to go at least as far as Arba before we would find a region that is worth hunting in.”

“I’m with you,” said Mr. Holton. “We’ll engage an automobile to take us the fourteen miles or so to Arba, and then foot it from there. It will be funny if we can’t bag a few worth-while specimens, at least.”

“Of course Joe and I can go, can’t we?” grinned Bob.

“You bet. And Dr. Kirshner and Fekmah, if they care to.”

But those persons announced that they would remain in Algiers and further discuss the coming expedition.

“Then too,” the archæologist remarked, “I’d like to keep posted on the progress made in getting the train ready for the journey to Wargla.”

It was well past noon, and the explorers now realized for the first time that they were extremely hungry. The strain of the eventful morning had stimulated their appetites to a high degree, and they felt they could devour almost anything in the way of food.

“Lead me to the café and watch what happens,” said Joe, making for the door.

The others followed, and although not as emotional they were no less hungry.

The meal tasted good, despite the fact that they were ignorant of its composition. Fekmah tried to explain one of the dishes, but the foodstuffs used in its preparation were unknown to the Americans, and they were as much in the dark after he had finished the explanation as before he had begun it.

“We’ll trust there isn’t anything repulsive in its make-up,” smiled Mr. Holton.

“At any rate the taste isn’t so bad,” came from Bob. “I’ve seen stuff much worse.”

“Referring to the delicacies of the South American Indians, I suppose,” laughed Mr. Lewis, and the boys nodded.

“We were forced to eat almost anything for a while,” reflected Joe. “Getting lost in the Brazilian jungle was a serious thing, and we realized it. Then when we got in with those savages, we accepted their offer of food at once, even though we weren’t sure it was all right.”

“That was a great adventure, boys,” remarked Mr. Holton, his thoughts going back to the countless days of river traveling in unknown South America. “The more I think of it the more convinced I am that we should be extremely proud of that exploit. Mr. Lewis and I have had many adventures in unknown lands while collecting specimens for the museum, but none surpasses that one.”

“I’d like to go there some time,” said Dr. Kirshner. “But so far, my work as an archæologist has not called me into that region. When it will, if ever, I do not know.”

After the bountiful meal the explorers took it easy in the hotel, and Fekmah returned to his room.

“Since we haven’t anything in particular to do, we might as well rest up for the hunting trip tomorrow,” said Mr. Lewis, as he and the others sat in the lobby of their hotel. “We’ve had a hard day of it and deserve to be idle for a while.”

The others agreed, and the remainder of the day was spent in quiet.

But early the next morning the boys and their fathers were busily preparing for the hunting expedition. By seven o’clock they had their rifles and other necessities in readiness, and with a farewell to Dr. Kirshner, who wished to talk over the Sahara journey with Fekmah, they left the hotel.

Mr. Lewis had earlier made arrangements for a car to take them to Arba, whence they would go on foot into the forests and desert. The automobile was parked in a small garage not far away, and they reached the place in but a few minutes. It was a low, dirty structure, with few windows.

A swarthy native came out to meet them and at once recognized Mr. Lewis. He led the way through a small door and into a room that served as the garage.

“Here we are,” said Joe’s father, as they rounded a corner.

He pointed to something that at once caused Bob and Joe to burst out with laughter.

---

“THAT a car—an automobile?” asked Bob, holding back his laughter.

“You don’t mean to say that thing will take us fourteen miles!” cried Joe, no less moved than his chum.

The naturalists smiled. They had apparently not expected this.

“It’s about the best we can do here,” confessed Mr. Lewis. “Of course there are better automobiles, but none of them seems to be for hire. You see, this drive-yourself idea doesn’t appear to be very popular here. I suppose it’s because there is so much danger of being attacked by bands of nomads who would think nothing of robbing the occupants and stealing the car. But this car, although not beautiful to look at, has a good motor and good tires, and that’s about all we could expect. Remember, we’re not in America now.”

The object of their remarks was indeed not anything to be especially proud of. A well-known American make, it had undoubtedly been of great service in its time, and was still capable of covering many more miles. It had no top, and nothing to show that one had been present, but the seats were in fair condition, and a well-shined windshield promised to keep away the formidable dust of the desert.

“Well, I suppose we could do much worse,” sighed Joe, taking his place in the back seat.

After a few more remarks with the keeper of the garage, the adventurers started the motor and pulled out into the street, Mr. Lewis at the wheel. The chug of the engine was almost deafening, but, as Bob remarked, they would probably get used to it.

“Ought to be some new springs,” said Joe, with a wink at his chum.

“And there could be new upholstering,” added Bob. “Of course it needs new——”

“All right, boys,” smiled Mr. Holton, cutting off their capricious suggestions. “If you don’t like it, you know what you can do.”

“I guess we’d better shut up,” grinned Bob. “We may get thrown out on our ear.”

Mr. Lewis had studied the map of Algiers and had no difficulty in finding his way out of the city and to Maison Carrée, which might almost be called a suburb of the metropolis. From here they went almost straight south and soon came to a narrow river, which was spanned by a small bridge.

“Scarcely any curves from here on,” said Mr. Lewis, as he increased the speed of the car.

The road remained good, and in a short time they reached Arba, their destination. Here for the first time they caught a glimpse of a camel caravan, for they are never seen as far as Algiers. It was composed of about ten dromedaries, with only three riders. Strapped on the brutes’ backs were packs containing probably dates and other products of the desert.

Bob and Joe took in the scene with intense interest, for soon they would be fitted out in a like manner for the long desert journey. The youths were particularly anxious to observe the manner in which the brutes are ridden. They had heard that to straddle a camel and be able to bounce freely along was an art that came only of long practice. Whether this was true they did not know but resolved to find out sooner or later from Fekmah.

“I’ll bet it’s harder than it looks, though,” remarked Joe.

A little later they saw other caravans of donkeys, the usual beast of burden used near the coast.

“The Arab, unlike other natives, never carries his load,” explained Mr. Holton. “I guess he thinks it lowers himself too much.”

They drove on into the town and had more trouble finding good streets than in Algiers.

Luckily it was Wednesday, and the market was in full swing. Traders were swarming everywhere, buying and selling the queer native goods and foodstuffs.

“Suppose we park the car where we can and look about a bit,” suggested Joe. “It’s no special hurry to begin the hunt, is it?”

The others were more than willing, and as soon as possible the automobile—if it could be called that—was stopped at a convenient corner.

“Sure feels good to get out and stretch,” smiled Bob, taking advantage of the opportunity to relax his cramped legs.

They left the car and made for the business center of the town, intent upon spending a half-hour or so in watching the busy scene of interest.

It was soon discovered that except for the large market there was little of interest to be seen. In many respects the town resembled Algiers, although on a much smaller scale and not nearly as modern. The streets were narrow and, in many cases, curving, and the houses were far from attractive. But the hustle and bustle of the natives clearly indicated that Arba was of considerable importance commercially.

This was especially noted in the city market, where every article imaginable was for sale. Bakers, vegetable dealers, butchers, shoemakers, wine venders, and many others did their best to convince the buyer of the worth of their products.

“And over there in that tent is a physician,” pointed out Mr. Lewis. “How good he would be considered in the United States is hard to say, but the Arabs seem to have confidence in him. Look at the patients going in.”

“For my part, I’d rather trust nature to cure my illness,” smiled Bob, as he noted the rather blank expression of the native physician.

The explorers spent nearly a half-hour in the city, taking in the various sights so strange and interesting to a visitor from a far-away land. At last Mr. Holton moved that they go back to the car and get their rifles and begin the hunt, and the others were in favor of doing so.

Their lunch, cartridges, binoculars, and other hunting necessities were packed in lightweight ruck sacks, which required but a minute to strap on their backs.

The car was to be left where it was, as probably no better parking place could be found.

“Guess we’re ready,” said Mr. Lewis, picking up his rifle.

It required but a short walk to reach the edge of the town, and one glance revealed that the country here was wild and uncultivated. Mountains were but a short distance away, and some of the peaks were rather impressive.

“Those forests look like there might be anything in them,” observed Joe, directing his glance at the towering wooded slopes.

“We’ll see in a short time,” said his father, fumbling his rifle.

The foothills over which they were passing were, for the most part, bare and devoid of heavy vegetation. But a little later they came to a region that gradually sloped upward, and less than an hour’s traveling brought them to the base of a high, sloping mountain, which was covered with a dense forest.

With renewed efforts they began the task of climbing, keeping a sharp lookout for any wild animals that might dart out in front of them.

“About all the wild animals to be found here are rabbits, jackals, hyenas, panthers, and a very few lions,” said Mr. Holton, as they trudged up the hill.

Luckily there were no sharp cliffs to be scaled. Instead, the way was gradual, unbroken.

“I’d like to get a glimpse of one of those queer creatures that have been reported to exist in these woods,” remarked Mr. Holton with a smile.

“What’s that?” asked Joe.

“Another Arabian myth, most likely. At any rate I know of nobody who has ever been fortunate enough to see one. It is supposed to be about the size of a badger and is a very peculiar combination of six or more well-known animals. The face, eyes, tail, abdomen, and other body regions are supposed to be taken from other creatures; and all the details are very accurate and convincing, to hear the Arab tell it. Again arises the question of where such queer conceptions get into his head.”

As they hiked on, Bob and Joe began to get behind their elders. There was much to be seen in the way of odd plants and colorful flowers, and their attention was continually diverted from one thing to another.

“I suppose when we get as seasoned in the art of exploring as our dads we’ll not notice such minorities,” said Bob. “But right now——”

He stopped suddenly as he caught sight of something that made his blood turn cold.

Not five feet away was a huge wild boar, showing its terrible tusks savagely as it prepared to rush at the youths.

---

“WHAT is it?” cried Joe, as he noticed the look of anxiety on his chum’s face.

For answer, Bob pointed to the wild boar, and as Joe glanced around he shrank back in consternation.

“Quick!” he cried. “It’s going to charge!”

There was no time to lose. The animal, angered because cornered, was getting ready to stand its ground savagely. And the boys had heard of the wild boar’s terrible ferocity.

Almost in unison the youths raised their rifles and took careful aim. The guns were of only twenty-two caliber, not any too powerful for the occasion, but the chance had to be taken.

“Now,” murmured Bob, holding his rifle in a steady position.

Bang! Bang! Two shots rang out, and each found the mark.

But the small bullets did not stop the beast’s charge, and it came on with horrible atrocity.

“Run!” cried Bob, his nerve completely gone. “Let’s go up a tree!”

As the youths darted to one side, a shot rang out; another; and still another. A moment later the wild boar sank to the ground in a crumpled mass, gave a convulsive twitch, and then lay still.

Mr. Lewis and Mr. Holton came running up, on their faces a look of apprehension.

“A narrow escape!” said Joe grimly. “It’s a good thing you came across with those high-speed bullets. They sure did the job, all right.”

“We just happened to glance around in time,” explained his father. “We didn’t know you boys were so far behind. Why didn’t you bring larger rifles?”

“Weren’t expecting to meet such a creature as this,” replied Bob. “I had an idea that this was a tame country, but I see I’m wrong,” with a glance at the wild boar.

“You certainly are,” smiled Mr. Holton, shaking his head. “And this incident may be the beginning of a series of adventures with wild animals. Where there’s one of a thing there’s likely to be another. So stick close, boys. I’d hate to have to rely on those twenty-twos again.”

The wild boar was shattered by the bullets and was no good as a specimen. The naturalists especially wanted one of these terrible beasts and were put out to think that this one had been made worthless by the rifles, but they were thankful that they had been able to come to the rescue of their sons.

With one last look at the creature they resumed the hike, this time keeping a closer lookout for any other formidable beast.

As they penetrated deeper into the forest, signs of life began to increase in numbers. Small rodents darted out, only to be brought down by the guns of the naturalists; lizards of grotesque and ugly shapes were all about; birds of many colors flew overhead, their plumage showing brightly in the sunlight. It was a sight that the youths never grew tired of.

Suddenly a jackal ran out, and Mr. Holton lost no time in firing at it. It was carefully but quickly skinned and placed in the burlap bag for the specimens.

“This forest certainly is untrodden,” observed Mr. Lewis, unable to discern the faintest traces of human tracks. “It has probably been a long time since anyone broke into its fastness.”

“Which is all the better for us,” said Joe. “Animals here probably have never heard the sound of a gun before.”

Along toward noon they picked out a small grassy area and got out the kit of lunch. The sandwiches were spread on a paper, and thermos bottles of cold lemonade were opened. To the tired adventurers it promised to be a feast fit for a king.

“No meal in the most luxurious café tastes better than a bountiful lunch in the heart of a forest,” said Mr. Lewis.

Bob’s father nodded.

“It has been said that no one but an explorer really knows what an appetite is,” he remarked. “And in times when I’m working in the museum at home and not doing any strenuous work I can fully realize the truth of it.”

They ate the lunch in quiet contentment, taking it easy on the soft grass. It seemed good to be out on the trail again, feasting on the wonders of nature. Bob and Joe were impressed by the stillness of the great forest.

“This is about the only kind of a woods you can get through,” remarked Bob, his eyes on the numerous cork-oak trees. “A tropical jungle has so much undergrowth and vines that it keeps you busy cutting them away with a machete.”

An hour or two after the repast was spent in resting their tired limbs and chatting merrily. Then Mr. Lewis suggested that they continue the hunt.

“We won’t have so very much time left,” he said. “And we’d like to get several more specimens.”

A little later they came to a narrow valley between two high mountains. A tiny spring trickled from beside a large rock, and they welcomed the taste of the refreshing liquid. It was quite cold, showing that it probably came from an underground stream.

“Drink all you want,” said Mr. Lewis. “It’s likely the last water we’ll see till we get back to Arba.”

All the remainder of that afternoon the explorers trudged on, bringing down several small animals and birds. None of them happened to be dangerous, however.

The hunters had described a wide circle that took them by sundown within a mile or two from Arba, and the accuracy of the naturalists’ calculations was greatly appreciated, for they were very tired and did not feel that they would care to have to hike a great distance to get to the automobile.

“Wonder if the old car’s still there,” mused Bob, as they came to the limits of Arba.

“Don’t know why it shouldn’t be,” returned his chum. “Nobody’d want it for anything.”

It required but a short time to reach the main part of the town. Then they turned off on the street where the car was parked.

“It’s there!” cried Joe, making out its ancient shape in the distance.

The others shared in his enthusiasm. They had had an uneasy feeling about its safety all day, despite the fact that the ignition had been locked.

In a short time the explorers were in the seats, and Joe, who had asked to drive, began the task of starting the engine. It finally responded to the sluggish self-starter.

“Now let’s hurry and get back to Algiers,” urged Mr. Holton. “We don’t want to be out after dark, for there’s no telling how good these lights are.”

During the next half-hour Joe pulled the throttle as far down as possible, and then complained because he could only do forty-five. However, it was not long before they saw the lights of Algiers in the distance.

“Now to get something to eat,” said Mr. Holton, sitting up in the seat in anticipation. “It will be good to see the old hotel again, won’t it?”

“Sure will,” replied Bob. “I’ll bet Dr. Kirshner expected us long before this.”

“He’s probably conversing with Fekmah,” was the opinion expressed by Mr. Lewis. “You know,” he went on, “that Arab is a strange contrast to these worthless fellows around here. It all goes to show what anyone can do if he wants to.”

“He’s educated, too, isn’t he?” inquired Joe.

“Yes, highly,” the naturalist replied. “Was graduated from the University of Algiers and received a degree. What he doesn’t know isn’t worth knowing.”

“Where is his home?” asked Bob. “He doesn’t live in Algiers, does he?”

“No. He lives in Oran; that’s about a hundred and twenty-five miles or so west of here. Quite a prosperous city, I guess.”

“But,” questioned Bob, thoroughly puzzled, “what is he doing here in Algiers?”

“It all goes back to Dr. Kirshner’s conversation with him on the ship,” Mr. Holton explained. “You see, Tom”—referring to the archæologist—“met him on the last day of the voyage and recognized him to be a very intellectual man. As soon as Fekmah found that he could trust Kirshner, he confided this secret about the hidden riches. Well, then, when he found that we would accept his proposition and make it one of the objects of the expedition to search for this treasure, Fekmah put up at a hotel in Algiers in order to accompany us into the Sahara. See?”

“Sure. I don’t know now why I didn’t before.”

They were now among the lights of Algiers, and Joe headed straight for the business section, where the car was to be returned to the garage.

They reached the place in a short time and left the automobile. Then they hurried around to their hotel.

When they came to their room, they found Dr. Kirshner and Fekmah in earnest conversation. When the two heard their friends in the hall, they arose, wreathed in smiles.

“We have good news for you,” announced Dr. Kirshner joyously. “The train is leaving for Wargla in the morning.”

---

“HURRAH!” burst out Joe, overwhelmed with delight. “We’ll get ahead of those crooks after all.”

“When did you find out?” asked Mr. Holton, as overjoyed as the youth.

“Late this afternoon,” was the response. “We intended to make frequent trips to the railroad station in order to know as soon as possible. The agent there informed us that the track had been cleared last night and the locomotive repaired this morning. He didn’t give the impression that there are other trains on this route, but I suppose there are.”

“That’s fine!” exclaimed Mr. Lewis, as excited as a boy. “We’ll get a meal at once and then complete preparations for the journey. Have you two eaten?”

“Yes,” returned Fekmah. “It is getting late. Six, seven o’clock.”

The naturalists and their sons made their way to the café and did full justice to a delicious meal. Then they went back to their room and finished packing their possessions.

“Do you know,” remarked Joe that night just before retiring, “we were, in a sense, responsible for that train wreck?”

Bob looked up in surprise.

“If it hadn’t been for our proposed expedition, those two Arabs would have had no cause to wreck the train,” Joe explained.

“Oh. Indirectly, huh? Well, you’re right.”

Very early the next morning the explorers were up making last-minute preparations. The train was to leave for Wargla at eight o’clock, giving them three hours or so to use to best advantage.

“When do we reach our destination?” asked Bob, as he snapped the catch on his handbag.

“At about noon day after tomorrow,” answered Dr. Kirshner. “You see, it’s a three-hundred-and-seventy-five-mile journey, and the train won’t go any too fast through the mountains.”

“Mountains? Do we go through mountains?” queried Joe, a little surprised.

“Yes, twice. Through these around here and then in the more lofty Aures. And the scenery is said to be wonderful.”

“What cities do we pass through?” Bob asked.

“Setif, Batna, Biskra, and Tuggourt are the principal ones,” the archæologist replied. “But there are a number of smaller towns. Get a map. There’s one in the pocket of that bag over there.”

The boys took out the guide to Algeria and studied it closely. They found that the railroad did not make a straight run but curved considerably in order to pass through several important cities and towns. The map was not strictly up to date and consequently did not show the new stretch from Tuggourt to Wargla.

“It’s been constructed only recently,” explained Mr. Lewis. “At present the French have proposed building a trans-Sahara route. When they will begin it, if ever, we don’t know.”

“Perhaps not in our lifetimes,” smiled Joe. “Large enterprises like that come very slowly.”

An hour before train time everything was in readiness, and it was Mr. Holton who suggested that they go down to the railroad station.

The others were in favor of doing so, and as it was but a short distance away they were content to walk and carry their belongings. There was a good-sized load, but it was distributed evenly without anyone being overtaxed.

At the station they checked the things securely and safely. Even then they had a leisure half-hour.

“You may be surprised at sight of the train,” said Fekmah.

And they were. The Americans had expected to see rickety wood coaches attached to an incapable locomotive, but instead they saw a large, fine train of the French design.

“All due to the influence of France, I suppose,” remarked Dr. Kirshner, as he followed the others up in the coach.

A few minutes later they felt a slight jerk and the train began moving slowly away from the station. Gradually it picked up speed, and before long Algiers disappeared on the horizon.

“We’re off!” said Joe enthusiastically. “Before long we’ll see the great Sahara Desert!”

It required but a few minutes to reach Maison Carrée, and after a short stop they began the journey in earnest. Rapidly they passed through cultivated fields, orange groves, and vineyards, heading for the mountains. Small farmhouses were left behind, their owners laboring in the fields. Villages inhabited largely by whites were passed, and occasionally a five-horse cart loaded with swarthy Arabs could be seen winding slowly along the shaded roads.

Finally they came to the Djurdjura Mountains, after having passed through the dense forest of La Reghaia. Through numerous tunnels and around scenic gorges they went, and finally came to Palestro, a small town on the banks of the Isser River. Here the train stopped for a few brief minutes.

Again it took up the journey, speeding through the beautiful mountain gorges. In the narrow valleys farmers could be seen laboring with primitive implements. The next stop was Beni-Mansour, where the railroad branched.

Still on they went, the mountainous country gradually growing wilder and more beautiful. Occasionally they found themselves in a narrow gulch between high walls of rock, and a curious sensation of being hemmed in crept over them.

After passing through a long tunnel, the train sped out on a barren plain, with little vegetation and few or no people. Another stop was at Setif, a modern city populated by Americans and Europeans as well as natives.

Resuming the journey, they passed over another great stretch of level country, and then finally a mountain range could be seen in the distance. But just when the explorers were anticipating the change of scenery, the train pulled into El Guerrah and stopped.

“Here we must get off,” announced Fekmah, getting his belongings together. “We must change trains for Biskra. This one goes on.”

The explorers lugged their belongings out on the platform and into the station.

Darkness was fast approaching, and as it would be necessary to remain in El Guerrah overnight, the adventurers stepped into the hotel, which was the only structure in sight.

“The town is some distance away,” declared Fekmah. “We not have time to see it.”

At the hotel they engaged rooms and lost no time in getting to them. Sleepiness was rapidly overpowering them, and they went to bed at once.

The next morning they awaited the train to take them on the remainder of the journey. At eight o’clock it was there, and the explorers climbed aboard, eager to get started on the last stretch.

“What’s the next stop?” asked Bob, as he stretched out on the comfortable seat.

“Batna,” his father returned. “Quite a prosperous place, I guess. And it is the starting point for tourist excursions to several Roman cities that are of considerable interest historically.”

Inside of an hour that city was reached. A short stop and then they were off for Biskra, at the very edge of the Sahara.

“We are now three thousand five hundred feet above the level of the sea,” declared Fekmah, as the train sped over the last few miles of level country.

Soon they came to the Aures Mountains, and between high walls of rock they sped. At last the short range of peaks was passed, and they found themselves once more on comparatively level ground.

Suddenly Fekmah pointed to a high ridge of rock:

“The Sahara Desert!” he exclaimed. “We have come to it at last.”

---

AT the Arab’s welcome remark, Bob and Joe sat up with a start.

“At last!” murmured Joe. “Though I’ll admit it doesn’t look much like a desert to me.”

“There’s still quite a bit of vegetation,” said Dr. Kirshner. “But nevertheless, that rocky wall is classed as the mark of the desert’s edge.”

Another small town was left behind. Then, almost without knowing it, they reached Biskra, a modern city that is much frequented by tourists. The train came to a stop at a small but well-built station.

“Here we must get off again,” said Dr. Kirshner. “The train does not leave for Wargla in the daytime because of the excessive heat.”

They found much to interest them the remainder of the afternoon. For Biskra, with its picturesque natives, lanes of dirty houses, quaint cafés, and modern buildings held their constant attention.

That evening the train arrived for Wargla, and the explorers were glad to continue the journey.

For the next eight hours they sped along barren country, only the outline of which could be seen in the darkness. At last they stopped at Tuggourt, formerly the last stop on the railroad.

“It won’t be long now,” sang Joe, as he sat up in his seat expectantly.

The train covered the fifty-mile journey in less than an hour, and then, after gradually moving downhill, it passed through a cluster of mud houses and pulled up at a modern station.

“All off!” said Mr. Holton. “Here’s Wargla, our destination.”

They got their bags off the train, and then stood for some time taking in their environment.

The sun was just beginning to peep from behind a high sand dune, and it was rather easy to make out the landscape. Over to one side was a high minaret of earth, the tallest sun-dried clay mound in existence. Scattered about were numerous clusters of date trees, and to their left was Wargla, glittering with many lights.

“Now what?” inquired Bob, rousing himself.

“Better get to the hotel,” answered Dr. Kirshner. “From what I’ve heard, it has been built but recently, and we’ll have everything of the latest design.”

A sign told them that the hotel was only a short distance away, and picking up their belongings, they walked over to it.

It was all that could be asked for, with modern conveniences that the explorers had not dreamed of enjoying in such an out-of-the-way place.

“Better turn in right away,” suggested Dr. Kirshner. “It isn’t advisable to start the desert journey without having had any sleep.”

After the train trip it felt good to stretch out on the comfortable beds. Despite their youth, Bob and Joe were very tired.

“We must wake up at dawn tomorrow,” Bob reminded his chum. “We’ll have to get our stuff together early.”

Notwithstanding this, the youths’ deep slumber made it necessary for their elders to awaken them. They felt rather sheepish as they arose and noticed that the sun was well up in the sky.

“Guess we haven’t developed our mental alarm clocks yet,” grinned Joe, slipping hurriedly into his clothes.

“Now, boys,” said Mr. Holton, opening the door of their room, “we’re going out to find a guide and camels. You had better come along, so you can practise riding. It isn’t easy to get used to a dromedary’s trot. First, though, go and get your breakfast.”

When the meal was finished, they joined the men in the hotel lobby. Fekmah, as the best-informed concerning the Sahara, acted as the leader.

“The man in charge of hotel told me of worthy man who will be our guide on the expedition,” he said. “He lives at edge of town, not far away.”

“Fine! Then we’ll go there at once.” Mr. Lewis walked over to the door, followed by the others.

The fellow lived in a small, low structure of clay, and although not pleasing to the eye, it probably lessened the intense heat of the fierce desert sun.

Fekmah knocked at the door. A moment later a tall Arab greeted them, his face thin but not indicating that he was possessed of a weak constitution.

“Are you Tishmak?” Fekmah asked.

The Arab nodded.

Fekmah then conversed rapidly in the native tongue, and although the Americans could not catch the meaning of most of the words, they gathered that their friend was succeeding in employing the man to act as a guide. A moment later he confirmed their suspicions.

“He will go,” Fekmah said delightedly. “And his price is right.” He then proceeded to introduce the Americans as best he could in his own language, for the guide could not speak English.

“Now,” began Dr. Kirshner, “what about the camels? Can this fellow, Tishmak, get them? How many will we need? Ask him, Fekmah. I’m afraid I can’t get along very well with his mixed dialect.”

Their friend put the question before the guide, and he at once gave them an answer.

“He says he can get them,” Fekmah translated. “And how many we will need depends on our own taste. But he makes suggest that we use twenty. That is seven for us to ride and thirteen to carry food and other things.”

“All right,” said Dr. Kirshner. “Have him lead us to them now, so that we can practise riding.”

Fekmah again turned to the man, who a moment later nodded and motioned for them to follow him.

Ten minutes later, after having wound through many narrow streets, the explorers found themselves in a large open field at the edge of the town. About them were grazing a hundred or more camels.

“Here we are,” declared Fekmah, his eyes on the idle beasts.

Tishmak had a moment before left for the house. Now he returned with a thin, lithe Arab, who was evidently the owner of the camels.

A short conference between Fekmah and the stranger took place. Then Fekmah turned to the Americans.

“We can have the dromedaries,” he said. “And he is asking only a fair amount. Come and I will pick them out.”

The others followed him over the field, where he singled out twenty of the best-looking beasts.

“Now,” said Mr. Holton, “we want to practise riding before we start on the real journey. Perhaps we’d better do that this afternoon. Then we can load up in the evening and get started in the morning.”

Fekmah nodded.

“We’ll go now and come back this afternoon,” he said.

Shortly after the noon meal the explorers left the hotel, intent upon trying their skill astride the ponderous humps. None of them but Fekmah had ever had the experience of riding on camelback.

“Wonder how it’ll be?” mused Joe.

He soon saw. Aside from a most uncomfortable jerking it was a novel and enjoyable experience, for the time being, at least, surpassing horseback-riding.

“But you’ll soon get tired of it,” said Mr. Holton. “At least Fekmah says so.”

“Dad might say we’ll get fed up on it,” remarked Bob, when they were ready to start back to the hotel. “But I haven’t yet.”

“Nor I,” put in Joe. “But of course, after several days——”

There was much to be looked after that evening, and it kept the explorers busy. Tishmak acted as leader in securing the food supply, which, however, was also to include canned goods. The naturalists and Dr. Kirshner attended to last-minute preparations, while the youths kept their time busy in helping the others.

Early that night they retired, eager to get all the rest possible.

“Sleep well,” said Mr. Lewis, as the boys jumped in bed. “We’ll have it rough from tomorrow on.”

At four o’clock the next morning Bob and Joe were awakened by Mr. Lewis, and despite the fact that they were still very sleepy, they began the task of getting their belongings together. It took them the better part of an hour, although they worked like beavers.

“We’re ready to leave, boys, if you are,” called Dr. Kirshner, opening the door to their room. “The provisions are on the dromedaries, and Tishmak is ready.”

The youths’ hearts were in their mouths. Leave! Leave for the great Sahara Desert, with its mysteries and thrills and tragedies! They could hardly come to a full realization of the true situation.

“It’ll be great, Joe, old boy,” said Bob, deeply touched. “At the end of this expedition we’ll be full-fledged adventurers.”

The youths went down to the hotel lobby and found their fathers, Dr. Kirshner, and Fekmah. Tishmak, the newly engaged guide, had left for the camels, which he promised to have in readiness.

Fekmah had made arrangements for a mule cart to take their belongings to the spot where the dromedaries were grazing. Bob and Joe had scarcely got the last of their bags down when it arrived, driven by a short, fat native who looked to be a cross between an Arab and a Negro.

The paraphernalia was placed in the wagon. Fekmah climbed up with the driver to direct him to the camels.

“Guess we’ve attended to everything,” said Dr. Kirshner. “Let’s get started. It’s a good ten-minute walk.”

When they reached the place they found Fekmah and Tishmak awaiting them. The packs had been strapped on the dromedaries’ backs, and the ropes had been harnessed from the back of one animal to the head of another, keeping them in single file.

“Well, let’s go,” urged Mr. Holton, after one more glance to make sure that everything was in preparation for the long desert journey.

The explorers got astride the ponderous humps, and then, while the master of camels gave them a cheery farewell, they moved out for the unknown.

The great desert journey had begun.

---

BEFORE long the little town of Wargla vanished from the horizon, and a sense of dread crept over Bob and Joe at the thought that they were now shut off completely from the outside world. What tragedies might befall them before they would again see the United States? There were all sorts of dangers out on that vast stretch of wasteland. Would their lives be threatened—and possibly lost?

Bob glanced back and saw the worried look on his chum’s face. That Joe’s thoughts had been the same as his was evident.

“Snap out of it, Joe, old man!” he said, rousing himself. “Think of the fun we’ll have. And the strange sights we’ll see. It’ll be great. And behind it all lies adventure.”

Joe nodded. His face took on a smile as he anticipated the coming events.

“Wonder what adventures we’ll have?” he mused. “But I suppose we’ll soon see.”

The boys were at the end of the little caravan, keeping an eye on the pack camels. Although ropes had been fastened from the back of one animal to the head of another, keeping them in single file, it was best to guard them closely, for anything might happen on the desert.

Tishmak, acting as the guide, was in the lead, followed by Dr. Kirshner and the youths’ fathers. Fekmah was in the middle of the line. The twenty dromedaries were spread out over perhaps a quarter of a mile and trotted at a speed that promised to cover many miles in a short time.

“I guess dromedaries don’t compare with camels when it comes to fast traveling,” remarked Joe, recalling something that Fekmah had said some time before. “The one-hump animal makes four times as much speed.”

In the early morning, as it was, the atmosphere was chilly. Bob and Joe welcomed the warmth of their tight-fitting coats.

“I never thought I’d need a wrap on the desert,” smiled Bob, fastening the collar around his neck.

“We’ll need more than coats at night, if what Dr. Kirshner said is true,” said Joe. “Gets cold as Greenland’s icy mountains.”

“Seems strange, doesn’t it?”

“Yes. But you remember it was the same way in Brazil. And that’s about as hot a country as there is anywhere.”

Soon the flat hill of Gara Krima, dominating the sandy plain, could be seen, its smooth surface tinted with many colors. Then it was left behind, and the explorers came to a region of loose sand. The dromedaries found it more difficult to plod through, and slackened their rapid pace somewhat. Although their feet were specially adapted for traveling on sand, they made much better time on hard surfaces.

“Look at the dust they’re making,” observed Bob, as a dense cloud of fine sand particles arose, making it necessary for the youths to ride a short distance to one side of the pack animals.

“They don’t believe in kicking it up, do they?” Joe said dryly.

After a while the sun came out in full splendor, sending its dazzling rays down on the scorched sand. Bob and Joe soon perspired freely, and were glad to remove their coats.

“Whew!” gasped Joe. “I’d give anything for a drink of water.”

“So would I,” his friend replied. “I’m going to ride on up and ask for one.”

“Remember me while you’re there.”

It was a good distance to the other end of the caravan, but the sure-footed dromedary trotted along briskly. Fekmah waved as Bob passed.

“How about a drink of water, Dad?” asked Bob, coming up to his father’s camel.

“Go to it,” was the answer. “We’ll come to a well before long, and refill the canteens.”

The third and fourth animals back were the water carriers, and Bob lost no time in filling his container. Then he drank freely of the refreshing liquid, and felt new life creep into him. Although warm, the water did wonders in quenching his thirst.

Again he filled the container and rode back to his friend, who was delighted.

“I was afraid they wouldn’t let you have it,” Joe said, wiping the perspiration from his brow.

“Wouldn’t have, only there’s a well not far away, and we’ll have a chance to refill the tanks.”

“Well, huh? Wonder if they’re this close together all along?”

“Let’s hope so.”

A little later the explorers passed a scattering of bones and skeletons that were partly covered with sand. They were dry from age, having probably been uncovered by a sandstorm.

“Camels’ bones, I suppose,” remarked Joe. “They’ve become overcome with thirst, most likely.”

“Who knows but that the skeletons of their riders are there some place, too,” said Bob, his face sober.

The sight was not a pleasant one, for it brought to mind the fact that it was altogether too possible that their little caravan might perish for want of water also. Some time elapsed before the boys resumed their cheerful mood.

As they traveled on, the ground became strewn with small red pebbles that shone brightly in the dazzling sunlight.

“I guess most of the rocks here are red,” remarked Bob, who had studied books on the Sahara.

“Burned that color by the sun, huh?”

“Seems reasonable, doesn’t it? Come to think of it, though, the ground in the Land of Thirst is black.”

“The Land of Thirst?”

“Yes. I heard Fekmah talking about it this morning. It’s a region where there are few or no wells, and you have to be very careful to have a good supply of water in the tanks before you plunge into it.”

“Looks like even then it would be dangerous. What if a storm or something would hold you back for a long time?”

“Have to take that chance,” Bob replied. “Wouldn’t doubt that quite a few caravans come to a tragic end there.”

“Will we go through it?” Joe asked.

“Fekmah said we might,” was the response.

Finally they came to the well that Mr. Holton had told about. There was a steady flow of water, which was comparatively cool.

“Drink all you want,” said Dr. Kirshner. “Tishmak says we won’t see another for a long time.”

The explorers drank and drank, until they could hold no more. Then they began the task of replenishing the tanks. But as little had been taken out, this was finished in a very few minutes.

“Now let’s get on,” urged Mr. Lewis. “We want to cover a good many more miles yet before we stop for the noon meal.”

Another hour brought them again to a region of hard soil, and the dromedaries increased their pace several miles per hour.

“Wish it would stay like this all the way,” said Joe, noting that ground was being covered much faster.

“Won’t though. But we’ll have stretches of it here and there.”

As the minutes passed, the glare from the sand became more intense, and the temperature went steadily up. The boys had dark-colored glasses but hesitated to put them on so soon.

“Wouldn’t a good cold drink come in fine now?” asked Bob, keeping his hands off his canteen with difficulty.

“Sure would. But we must fight the temptation to drink too often,” returned Joe. “Remember, we’re on the desert now, and not in the mountains, where there are plenty of springs.”

They rode rapidly on, the country remaining about the same. The red pebbles, however, grew more numerous, some of them glowing like rubies.

Joe remarked that they were gradually ascending, and Bob nodded.

“There’s a line of high dunes over there,” he said, pointing to the distant horizon. “Fekmah said when we reach those we’ll have climbed a good many hundred feet. We should get to them tomorrow.”

In a short time they passed beyond the stretch of hard soil and again plodded through loose sand. From all indications, it was heated to a high degree by the fierce sun. How the dromedaries stood it was a mystery to the boys.

“I wonder how Tishmak can find the way to the Ahaggar Mountains?” mused Joe, glancing up ahead at the guide. “He isn’t using a compass.”

“Does seem strange,” Bob agreed. “But I suppose he’s been over the route so much that he knows all the landmarks by heart, though it looks like a sandstorm or something else would change the surface of the land.”

Mention of the Ahaggars brought to mind the possibilities of finding the hidden riches. Bob and Joe wondered if the two thieves who had caused the explorers so much trouble would, with the aid of the stolen map, locate the treasure first. Perhaps they had already found the place and were gloating over the success of their wicked scheming. The youths said nothing, but the expression on their faces told what they would do to the men if given the opportunity.

“We’ll finally have a chance to square things,” thought Bob, gritting his teeth. “And oh, how those fellows will look when we’re through with them!”

A little later they came to a deep valley between the mounds of sand. In order for the camels to cross it they would find it necessary to climb the steep sides of the dune.

Mr. Lewis rode back to the boys.

“Have to be careful here,” he warned. “It’s rather steep near the top. Don’t let your mounts get out of control.”

The next instant he was on his way back to the front of the caravan.

The climb was hard and not a little dangerous, but the sure-footed dromedaries did not even threaten to slip.

They had barely reached the top when a cry of delight from Joe mingled with the scarcely less emotional exclamations of the others at sight of a small oasis not far away down the opposite slope. A number of tall date palms towered above the green grassy area, an indication that water was to be had for the taking.

“Hurrah!” cried Bob. “Water at last!”

“And if I’m not mistaken, we’ll find dates there, too,” put in Joe.

“You’re right,” affirmed Mr. Lewis, coming up from the side. “And this seems to be a good spot to stop for the noon meal. We’ll have it shady this afternoon when we take our midday rest.”

Nearer and nearer they were coming to the oasis, when suddenly, from behind a low dune of sand, appeared a small caravan of Arabs—possibly bandits.

---

“KEEP your hands on your guns,” called Dr. Kirshner, as he gazed at the approaching party of Arabs.

There were ten of them, and each armed with a short range rifle, which, although inferior to the guns of the Americans, could do a great deal of damage. In addition to the mounts of the Arabs, there were six or seven pack camels that trailed.

As the caravan came nearer, Tishmak waved and shouted a friendly greeting, but he did not receive the same in return. Evidently the men had no friendly intentions.

Tishmak chattered a moment to Fekmah, who then turned to the Americans.

“They are probably nomad bandits,” Fekmah said excitedly. “Tishmak says we might have fight.”

“A fight!” cried Joe. “Why? Are they going to try to rob us?”

Fekmah nodded.

“Worse, perhaps,” he replied.

“Those fellows would think nothing of killing all of us,” said Mr. Lewis gravely. “So we want to be ready for anything that might happen.”

As the Arabs came nearer, their leader shouted something to Tishmak, whose jaw dropped in surprise and astonishment.

Tishmak turned to Fekmah and conversed rapidly. Then Fekmah translated to the Americans.

“They want two of our camels,” he said nervously.

Dr. Kirshner gasped in amazement.

“Want two of our camels?” he cried, his voice indicating a high state of anger.

“What for?” demanded Bob.

“They say theirs are too much loaded,” Fekmah answered. “Want to spread out packs on more camels.”

“Well, of all the nerve!” exclaimed Mr. Holton. “Tell them to get out of here—and get out quick, or we’ll fill them full of holes!”

Fekmah turned to the Arabs and put Mr. Holton’s command before them. Then an answer came.

“They say they go, but we will be sorry,” interpreted Fekmah, as the men turned their camels in the opposite direction.

A moment later they disappeared behind a low dune, leaving a cloud of dust at their heels.

For a moment there was silence among the explorers. Then Mr. Lewis spoke up.

“I don’t like this,” he said, greatly annoyed. “Those men are likely to slip up on us when we’re not expecting them. And such desperate characters would lose no time in shooting us.”

“But what can we do?” questioned Bob.

“Keep on the lookout is all,” returned Mr. Holton. “But I’d feel much safer if this hadn’t happened.”

The explorers rode on into the oasis and dismounted. It seemed pleasing to see green trees and grass again. They were delighted that good fortune had enabled them to find an oasis at a time when it was wise to stop for a meal and rest.

There was good water not far away, and they drank all they wanted, glad of the chance to quench their rapidly overpowering thirst.

“Now,” began Mr. Holton, “we’re going to have something to eat. But first let’s put up the tents. It isn’t wise to be in such a sun as this.”

The bags of supplies were removed from the camels. Then the tents were taken out and put up by Bob and Joe. Mr. Lewis and Mr. Holton got out the food and soon laid out a delicious meal of canned goods and native products.

“Eat all you want, but don’t gorge yourselves,” cautioned Mr. Holton, as they sat about the tent. “There’s plenty of stuff, but still we must be careful. If we’re to be gone any length of time, we’ll have to use our provisions sparingly.”

They ate quietly, taking it easy in the shade of the tent. The heat of the fierce African sun was somewhat abated by the heavy canvas, which would also serve as a shelter from sand storms, should any come up.

When the meal was over, they sat for a few minutes talking. Then Fekmah got up and went over to the corner of the tent.

“Let us sleep for two or three hours,” he said, curling up on the soft soil. “The sun will soon get so hot that we cannot travel without making sick.”

“Suits me,” agreed Joe. “I feel like I could sleep for two or three days.”

“One of us had better stand guard, though,” said Mr. Lewis. “That bandit caravan might return unexpectedly.”

“I’ll do it,” volunteered Dr. Kirshner. “I’m not sleepy. I’ll just take it easy here and read.”

For the next three hours Bob and Joe slept soundly, forgetting that they were under a scorching desert sun. They were not tired, but were extremely drowsy from the heat.

Then suddenly they were awakened with a start. They looked about wonderingly.

Dr. Kirshner stood over them, holding his rifle in readiness.

“The bandits!” he exclaimed excitedly. “I believe they’re coming!”

Mr. Holton and Mr. Lewis jumped to their feet and grabbed their guns. Cautiously they peered out, holding the flap but a few inches up.

“Where are they?” demanded Bob’s father, while Tishmak and Fekmah ran forward.

“I’m not sure that it’s they,” the archæologist said. “But I heard camel steps a moment ago, and in this country it is best to investigate before it’s too late.”

A second later Tishmak stopped still and listened. He held up a hand for silence. Fekmah had also caught a sound.

“It’s they,” he whispered. “Camels! They’re coming this way!”

The swishing sound increased, and Dr. Kirshner called his friends together for a plan of defense.

“Chances are those bandits were planning on surprising us while we slept,” he said quietly. “They figured that the time to get the camels they wanted was during our afternoon siesta. But it apparently didn’t occur to them that we would set a guard.

“Now the thing for us to do is get together and give them a real welcome with bullets. They’ll probably come around the back of the oasis, where our dromedaries are grazing. We’ll go around there and hide beside that sand dune. Then when the robbers—and I think that’s who the newcomers are—come, we’ll fire a volley of bullets into the air. If we find we can’t frighten them away, we’ll shoot their camels from under them. Then if that fails, we’ll have to shoot the men.”

The others thought this good advice.

“We must act cautiously, though,” warned Mr. Lewis, as they made their way to the back of the oasis.

When they came to the dune, they crouched down and waited. Tishmak glanced around the corner.

A moment later he drew back, his face scowling. He mumbled quietly to Fekmah.

“They’re coming,” the latter said. “And they are the robbers.”

The swishing of footsteps grew louder, indicating that the Arabs were coming nearer.

“Now!” said Mr. Lewis. “Fire in line, aiming at the sky. Then we’ll see what happens.”

Seven rifles spoke up in rapid succession, a dense cloud of smoke arising.

That the robbers had been totally surprised was certain, for a loud chattering followed. Then the sand was thrown up, and they rode off at lightning speed.

Joe peeped around the corner of the dune.

“They aren’t going far,” he announced, following the Arabs’ movements closely. “They’ve stopped behind that sand hill over there.”

“By George!” exclaimed Mr. Holton. “They’re going to plant a battery, are they? Well, just let them waste their ammunition. We won’t fire until necessary.”

“We may need our bullets to use on those two thieves who stole Fekmah’s map,” said Bob to his chum, smiling.

The explorers waited ten minutes for the robbers to take the aggressive, but they did not.

“Well,” said Dr. Kirshner, turning about, “I’m going over and get our things packed back on the dromedaries. If nothing prevents, we want to get started in a short time now. It is much cooler, and we should cover a good distance by night.”

“We’ll stay here and guard a few minutes longer,” declared Mr. Lewis. “There’s no telling what those fellows may do.”

Suddenly a sound from the opposite direction caused them to turn about. Then their expressions changed.

Not fifty feet down the slope were the robbers, riding at full speed toward the explorers. The Arabs had their rifles in position to fire, which they were undoubtedly intending to do when slightly nearer.

“Quick!” cried Bob, his voice cool but determined. “Fire at them before they get us!”

A moment later he took careful aim and pulled the trigger.

His rifle cracked, and the foremost camel went down, sending its rider sprawling over the ground.

Bang! came the sound of Mr. Lewis’s gun, and another camel fell.

The eight Arabs who were still mounted wheeled about and galloped back hurriedly. As quickly as possible they formed a wide line, one beside the other, until it stretched several rods.

“They’re going to charge!” observed Dr. Kirshner. “Have your rifles in position, and make every shot count.”

When the bandits were confident of their formation, their leader gave the command, and bending low over their camels, they dashed with all speed toward the explorers.

Shots rang out from the Arabs’ pistols, but they were too unsteady to cause any damage.

The explorers’ rifles spoke out, and those of Bob and the naturalists found their marks.

Again the rifles cracked. Three more camels went down simultaneously. Now only two of the animals remained on foot, but they were halted abruptly by their panic-stricken riders.

“Luckily we downed the leader,” remarked Mr. Lewis. “And now,” he added, “suppose we get away from here at once. There will be no danger of those men starving, for this oasis will furnish them with food and drink. They can wait for another caravan to furnish them with more camels.”

Without hesitation the party placed the packs back on the dromedaries and rode off, Tishmak in the van.

A few pistol bullets whizzed past uncomfortably close, but soon they died down as the Arabs saw the futility of their efforts.

“Whew! That was some experience,” remarked Bob, when they were well out of sight of the oasis. “I hope we see no more such fellows.”

“And you’re not the only one,” said Dr. Kirshner, shaking his head. “But the desert swarms with bandits, and it will be strange if we don’t have another such encounter.”

“Maybe we won’t have such good luck the next time,” mused Joe.

“Nonsense!” Bob retorted. “We’ll drive them off the same as we did these men.”

“But you got that wrong,” corrected Mr. Holton, smiling. “They made us get away.”

Bob looked a little sheepish as he saw where he had been caught.

“Well, anyway,” he grinned, “they didn’t get us.”

As they plodded on, the sand became looser than ever before. The dromedaries, however, did not seem to notice the change. They plodded on with the same stiff steps.

After two hours of constant traveling, the adventurers found themselves in a narrow valley between two high sand dunes. The country was gradually losing its level character and was steadily becoming more hilly.

Suddenly Mr. Holton gave a cry of delight and pointed to something not far away.

---

“WHAT is it?” asked Bob, slow to catch sight of the object.

“Gazelles,” returned his father. “A small herd of them.”

In a moment the agile animals came running out in full view of all, their beautiful coats showing clearly in the bright sunlight.

The creatures were about a hundred yards away, not any too near for an accurate shot, but the naturalists were much in desire of several as specimens.

Their long-distance rifles were equipped with telescopes, making it much easier, according to the naturalists, to sight an object at a hundred yards or more. Bob’s gun, however, did not have this convenience.

Mr. Lewis prepared to take aim.

“You take the animal to the extreme right, Howard,” he said to Mr. Holton. “Bob, you pick the one in the middle, and I’ll try to get one at the left. Tom,” he said to Dr. Kirshner, “suppose you count to three. When you say three we’ll all fire together. Let’s go, now.”

“One, two, THREE.”

Bang! Three rifles spoke as one.

Mr. Holton cried out in delight.

“Hurrah!” he said. “Got all of the ones we aimed at. Good work.”

The report of the guns caused great disorder in the herd, the graceful creatures leaping about at a speed that did their thin, muscular legs full justice. Before long they had disappeared behind the sand dunes.

“Now we’ll ride over and see what the ones killed look like,” said Mr. Lewis.

As the dead gazelles were not in a direction that would take the explorers off their steady course, the pack camels were driven along also.

When they reached the spot, Joe cried out in amazement at sight of the gazelles’ sleek skin. It was of a yellowish brown color, and the abdomen was as white as snow. The legs were long and thin, narrowing down to a finely shaped hoof.

“As beautiful an animal as one can find,” declared Mr. Lewis, who with Mr. Holton had been everywhere and knew what he was talking about.

“Two males and a female,” observed Bob’s father, noting the curved horns of the former.

“Look at the eyes,” said Joe. “They’re almost jet black.”

The naturalists began at once the task of removing the skins, for it was best not to leave them on too long under such a sun.

As soon as this was completed they were placed in a solution of alum that had been prepared by Dr. Kirshner under the naturalists’ directions.

“In our opinion, that’s the best preservative there is,” remarked Mr. Holton, “although there are many others in use.”

It required the better part of two hours to complete the task. The sun was just beginning to sink behind the distant mounds when they were ready to continue the journey.

“Be dark before long,” predicted Fekmah. “Then we will have to stop and wait for the moon. If you have not before traveled on desert under moon, you have much to see.”

They plodded continually on, Bob and Joe occasionally taking motion pictures. As the heat gradually became less intense, the youths felt a thrill of exultation run through their veins. Now there was nothing to worry about, no fierce sun to sweat under, no cares or anxieties to occupy their minds. Life—life on the boundless Sahara—seemed great.

“The folks back home are sure missing something,” smiled Bob. “Though I suppose a lot of them wouldn’t care for doings of this kind.”

Slowly the darkness came. At last, when the little caravan was in a notch between two unusually high dunes, Tishmak called a halt and conversed with Fekmah. Then the latter turned to the Americans.

“Tishmak says it is not thing to go on through darkness,” he told them. “Might come on to something bad. We’ll wait here for moon to come out, then go on.”

“Now’s a good chance to get our suppers,” said Dr. Kirshner, commanding his dromedary to lower.

By the aid of flashlights a limited but satisfying meal was prepared on paper, and the adventurers all ate heartily.

“Too bad there’s nothing for the camels,” said Mr. Lewis.

“No need of worrying about them,” returned Fekmah. “They can have no food or drink for good many days. Soon we come to region of thin vegetation. Then they eat.”

After the meal the explorers stretched out on the now cool sand, glad of a chance to rest their tired limbs. The constant jolting of the dromedaries had contributed much toward fatiguing them.

“Now’s the time when a coat comes in handy,” said Bob, reaching into his bag on the camel’s back.

“Wait till dawn, if you want to see real cold weather,” came from Dr. Kirshner. “Isn’t that right, Fekmah?”

The Arab nodded.

“Temperature often gets down to thirty-five degrees,” he said.

Before long the moon came out in full splendor, flooding the vast expanse with enchanting light and creating a scene beautiful beyond description. The sand looked white all about, broken only by an occasional ripple caused by the wind. The brilliant moon was surrounded by a large white circle, which seemed to throw silver darts on the dunes. In the distance were groups of luminous clouds, whose ragged edges were transparent. It was a wonderful sight, and the explorers sat for some time as though transfixed.

“Never saw anything like it in my life!” exclaimed Mr. Holton, his breath almost taken away by the magnificent spectacle.

“Wonder if we’re dreaming?” mused Joe, also fascinated.

Fekmah and Tishmak had been out to witness such a spectacle before, but seemed to think no less of it.

“I guess here’s a case where familiarity doesn’t breed contempt,” laughed Mr. Lewis, his eyes on the Arabs.

Bob got out the movie camera, intent upon taking several scenes that would be “really different.”

“Moonlight always makes a good impression on a motion-picture audience,” remarked Joe. “And away out here on the Sahara—well, it’ll seem wonderful!”

Tishmak made signs that they move on, and the others were glad to do so. Since there was so much light, it would be easy to find their way.

They were now in a region of high sand hills, with still no rocks other than the small bright-colored pebbles that were scattered about. Vegetation began to be more numerous in the form of had, drinn, and other plants, which were occasionally eaten by the dromedaries.

“I wonder if Fekmah is sure he’s headed right?” said Bob, as he and his friend again took their places at the end of the caravan.

“He doesn’t seem to be having any trouble yet,” was the reply. “You remember he made another map from memory after the first one was stolen. Chances are he knows where he’s going.”

“If he doesn’t, we probably won’t find the hidden riches,” was Bob’s return.

They trudged on, up and down the sand hills, until about ten o’clock. Then Tishmak called a halt.

“We camp here for night,” announced Fekmah, after a short conference with the guide. “It not wise to go any farther tonight. We get a sleep; then start on in morning.”

“I was just thinking it’s about time,” laughed Dr. Kirshner.

Tishmak had purposely picked out a deep gulch between the mounds as the stopping place. This would be a fair precaution against the nomad bandits who were reputed to be in this region.

“Takes a guide to know what’s best,” remarked Bob, observing the high walls of sand all about them. “The country in this vicinity is so rough that a caravan wouldn’t come anywhere near it, especially later on, when it will be pitch dark.”

The explorers dismounted and got out the tent. The poles were put up, and in a short time everything was in readiness for the night’s sleep.

“Curl up tightly in your blankets,” advised Mr. Lewis, as he prepared to occupy a corner of the tent. “It will be very cold along toward dawn.”

“And will we sleep!” said Bob, throwing himself down in relaxation.

Bob’s prediction proved right. The boys enjoyed the deep slumber that only an explorer can experience. It was wholly unexpected that they be awakened at dawn by their elders.

“It’s a dirty trick!” grinned Joe, as his father urged him to fully awaken.

“I know,” the naturalist said sympathetically. “But we must be on our way before the sun gets so hot that traveling will be dangerous.”

But once up, it was easy to forget sleepiness and enjoy the early-morning air.

“Talk about cold!” cried Joe, shivering in spite of the fact that he was wrapped in a heavy coat. “I’ll bet the old mercury is down to thirty degrees.”

“Not quite that bad,” laughed Dr. Kirshner, holding up a thermometer. “It’s thirty-eight.”

“Even that is cold for the desert,” said Bob. “I always had the impression that it is hot all the time.”

“There are some places that way,” returned Mr. Lewis. “But certainly not the old Sahara.”

Mr. Lewis and Mr. Holton got out the provisions and began preparing the breakfast.

“And while they’re doing that, suppose we go up to the top of this mound,” suggested Bob to his chum. “It’s rather high. Maybe we can get a view of the country ahead of us.”

“Don’t be gone long, boys,” called Dr. Kirshner, as they made their way to the edge of the hill.

The sand under their feet was, in many places, loose and unstable, but they found sufficient hard spots to make safe footholds. It was not a little difficult to estimate where they could safely climb higher. Perspiration was dripping from them when they at last reached the top and turned their gaze toward the horizon.

A cry of astonishment came from Joe at the scene that was spread out before them. The dunes that stretched away in the distance were tinted with many colors, showing strangely in the early-morning light. Some were pink, others blue, still others green, while the ones farther away paled away into nothingness.

“That’s a new one on me,” remarked Bob, highly puzzled. “I never expected anything like this.”

“Nor I. Wonder what causes it?”

“Beyond me.”

They stood for some time gazing at the varicolored mounds. Then Joe turned about.

“Better get back to camp,” he suggested. “Breakfast may be ready.”

They were about to retrace their footsteps when they heard a rustling sound but a few feet away.

“What’s that?” muttered Bob, sensing that danger was at hand.

The youths glanced around—and then shrank back in horror!

---

“A horned viper!” exclaimed Bob fearfully, recognizing the long, sinister body that was coiled almost at their feet.

“And it’s going to strike!” cried Joe. “Get your pistol—quick! We’ll both fire at it. Oh, how I wish we had our rifles!”

The snake was preparing to lunge forward, its terrible head swaying slowly from side to side. Whether or not the fangs contained poison, the boys did not know, but they knew they could not take a chance.

Neither Bob nor Joe was an outstanding shot with a revolver, and they felt rather panic-stricken as they raised the weapons and took aim.

After a few seconds that seemed to the youths like hours, Bob pulled the trigger.

A moment later the cold sweat burst out on his forehead, as he saw that he had missed. Before he could take another aim, the reptile would be upon him, a mass of scaly ferocity.

Bang!

Joe’s pistol spoke out, and the bullet caught the snake in the neck, just as it was about to strike.

Another shot from Joe’s automatic struck in a vital spot. The fiendish head turned violently, then fell to the ground with a thud. The tail twitched about momentarily, and as life passed out, the horrible body lay still.

It was some time before Bob and Joe could regain their natural peace of mind, for the strain had been great. Their hearts were beating rapidly from the unusual mental exertion.

“A narrow escape!” breathed Joe, putting his gun back in its holster.

“Thanks to you, old boy, we came out alive,” praised Bob, giving his friend an affectionate pat on the back. “It was your coolness and determination that sent those bullets in the right place. I was too nervous, I guess.”

“But say,” began Joe, turning aside the commendation of his friend, “our dads might want this fellow as a specimen. Do you suppose they would? Those bullets didn’t shatter it as a rifle cartridge would have.”

The youths were not particularly anxious to handle the long, scaly body, but they felt it their duty to do all they could for their fathers.

“What say we take it to the edge of the hill and roll it down?” suggested Bob. “The way is gradual and there are no protruding crags to tear it.”

“All right. We never can carry it without falling ourselves.”

The reptile was pushed over the side of the dune, and the boys made their way down. They slid more than climbed, but reached the bottom uninjured.

Mr. Lewis came out to meet them, on his face a look of anxiety.

“What kept you so long?” he asked.

“That over there,” replied Joe, pointing to the snake, which lay but a few feet away.

The naturalist ran over to it. Then he straightened up in surprise.

“A horned viper,” he pronounced. “Where’d you find it?”

Bob related the narrow escape at the top of the dune, not forgetting to point out Joe’s part in killing the reptile. When he had finished, Mr. Lewis shook his head gravely.

“Never leave camp without your rifles,” he warned them. “In a strange land anything is likely to happen.”

During breakfast the youths’ experience with the viper was the chief topic for conversation. Tishmak looked at the boys with a new respect as he heard the account of their daring deed.

As soon as the morning meal was over, the tent and provisions were packed back on the dromedaries, and the explorers continued their journey.

“How much ground did we probably cover yesterday?” asked Dr. Kirshner of Fekmah, as they followed a narrow way between the rolling sand dunes.

“At least a hundred miles,” the Arab answered. “Perhaps many more. Dromedaries trot rather rapid.”

“Then, at that rate, it shouldn’t take us so very long to reach the Ahaggaras, should it?” asked Joe, who with Bob had not yet taken his place at the end of the caravan.

“No. But something could keep us back. Maybe storm, or could be bandits. Never know about that.”

As the explorers moved on, they occasionally saw small animals and birds. The naturalists were constantly on the lookout, shooting any creature that came within range of their guns. Among the victims of their marksmanship were desert larks, rats, hares, lizards, and a small animal called the ferrec.

Bob and Joe kept their time occupied in taking motion pictures of the country they were passing through. By the time that their caravan had stopped for the midday meal, the boys had “rolled off” a good many hundred feet of film.

“Here’s hoping our moving pictures here prove to be as successful as those that we took in Brazil,” said Joe, as he took out a bag of rations from a camel’s pack.

“If they do, the Neuman Film Corporation may give us a job on every future expedition we might make with our dads,” came from Bob.

Thus far the day’s traveling had not yet brought them to an oasis. Tishmak informed them that water would probably not be found until late the next night. The containers, however, held a large supply, making it unnecessary for the explorers to worry.

“It’s a good thing the dromedaries don’t need it often,” said Mr. Lewis, as he went about preparing the meal.

“Four or five days is often enough for them,” put in Mr. Holton. “They can go much longer than that, but it isn’t wise to risk it.”

It was about eleven o’clock, the time advisable to begin the usual afternoon rest. Bob and Joe were glad of the chance to escape the heat of the fierce sun. Even in the morning it was too hot for comfort, although nothing compared to the baking atmosphere of the afternoon. The youths were tanned so dark as to resemble Arabs.

“Funny,” smiled Joe. “Back in the United States we fellows wanted to get burned by the sun. Here we try to keep out from under it.”

“All goes to prove that circumstances alter cases,” laughed Dr. Kirshner.

The tent was again pitched, and the meal eaten. This time, however, water was used sparingly. The adventurers did not wish to run the risk of getting dangerously short.

It was thought best to set a guard again while the others slept or idly rested on the cool sand. Mr. Holton took the job, sitting in the shade of the tent facing the resting dromedaries.

“Chances are nothing will turn up, though,” he said, and proved to be right.

Sharply at three o’clock Dr. Kirshner was up stretching himself and suggesting that they continue the journey.

“It isn’t the thing to wait too long,” he reminded his friends, “even if we are drowsy. By night we want to have covered another hundred miles or more. I’m especially anxious to reach the mountainous region and see what I can find in the way of records of ancient peoples who might have lived there before the desert became a desert,” he added, laughing.

The others were more than willing to start on. When sleepiness or drowsiness threatened to overpower them at the wrong time, the thought of the two thieves who had stolen Fekmah’s map spurred them on to action.

“I don’t know that it is necessary to set a guard while we take our afternoon rests,” remarked Fekmah casually, as they packed the tent back in its place for the journey.

The Americans looked at him wonderingly.

“The dromedaries will give us warning,” he explained. “They are much uneasy if stranger come near camp. They jump up and make noise.”

“A bit like watchdogs, are they?” said Mr. Holton. “Well, we’ll give them a tryout the next time.”

They again took up the journey, winding in and out among the rolling sand hills. Occasionally they would come to a dune several hundred feet high. They seemed to be gradually mounting higher, for the camels did not move as rapidly as before.

Vegetation increased still more, giving the dromedaries an opportunity to nibble often on the various plants and shrubs. A few scattered trees began to be seen, their sharp thorns protruding threateningly.

“Camels don’t bother with thorns,” remarked Bob. “They know just where to take a mouthful without cutting their mouths.”

“And they aren’t particular about their diet, either,” Joe added, remembering what Fekmah had told him some time before. “Leather, paper, wood—almost anything will satisfy their appetites.”

At last they came to the region of high sand dunes that were visible the day before. Many of the hills towered five and six hundred feet, and a few were much higher than that. The explorers were lucky in finding a narrow lane that passed between the mounds. How long the good fortune would continue, they did not know.

“Getting to look more like the dunes in Indiana, back in the United States,” remarked Joe. “But of course these stretch a hundred times as far.”

In some places the ground was hard and brittle, while in others it was strewn with loose sand.

At last the lane stopped, and the adventurers found themselves face to face with a high hill.

“Guess we’ll have to climb it,” said Mr. Holton, looking about. “There is no other way out. The sand seems to be hard and safe enough. And it could be a great deal steeper.”

“Let dromedaries go slowly,” cautioned Fekmah. “Do not hurry them.”

They began the dangerous ascent, keeping their eyes glued to the ground. Slowly the camels trudged up, feeling their steps carefully.

They were almost to the top when suddenly the ground gave way from under Joe’s dromedary. The animal fell to its knees, struggled for a moment, and fell backward.

With a wild shout Joe plunged from the animal’s back and went rolling helplessly down the hill!

---

DOWN the steep slope Joe went, powerless to catch himself. There were no shrubs or stalks to grip, no hard soil to cling to.

His mind was in a whirl. Where would he land? How far had he yet to go? He comforted himself in the thought that there were no rocks or tree trunks to dash against, but if the soil at the bottom of the hill happened to be hard, his doom might be sealed. Already he could feel the jar and pain of suddenly coming to an abrupt stop on unyielding ground.

Down, down he went, past the pack camels that were still slowly climbing the steep side of the mound, lucky enough to have been missed by the falling camel.

Joe caught a momentary glimpse of his own dromedary, which was also rolling rapidly down.

Suddenly he felt a severe jar and gradually came to a stop in the soft sand at the foot of the dune.

A moment later he glanced up fearfully, as he saw his dromedary coming down at him with lightning rapidity.

He tried to rise and dash to one side, but his feet failed to respond to his efforts. They had been numbed by the jar of striking the ground.

The falling camel was almost upon him now. Something must be done at once!

Summoning all his strength, he threw his body to the right of the oncoming animal. It was an act of desperation, and he felt sure that it would fail. But a moment later there was a rush, the sound of swishing sand, and the animal whisked past, stirring up a dense cloud of fine soil.

Joe gave a sigh of relief and for a brief period sank back down on the sand, as though waiting for his strength to be restored. Then he was up, looking for the fallen camel.

It had come to a stop in a drift of loose sand and appeared to be uninjured. But it was snorting and kicking furiously, its anger visibly heightened to a high degree.

Joe ran over to it and attempted to give aid, but the furious dromedary kicked at him in a rage.

Mr. Lewis and Bob came running down, finding footholds with difficulty.

“Wait!” cautioned the naturalist. “Don’t hurry the camel. Let him take his time. His fit of anger will be over in a few minutes,” and then added: “That was some fall! We were afraid you’d be hurt seriously. No bones broken, are there?”

“I guess not,” Joe replied. “Just shaken up a bit. I’m afraid the dromedary is hurt more than I. Don’t see what could prevent it.”

“You may be right,” his father said solemnly. “We’ll find out in a minute.”

Before long the animal’s anger lessened, and it tried to rise. But its legs refused to move, despite the frantic efforts.

Mr. Lewis’s face took on an expression of anxiety. He bent down and felt of the struggling legs. Then he straightened up and shook his head hopelessly.

“Broken,” he muttered in a tense voice. “Two legs are broken.”

“What!” cried Mr. Holton, who, along with the others, had managed to scramble down the hill.

“Look for yourselves,” Mr. Lewis said gravely. “The camel’s weight was too great to come continually against the rather fragile limbs, and the hind ones snapped in two.”

The explorers’ faces were greatly sobered by the dread discovery. Now there was but one thing to do. The unfortunate beast must be left to die a slow and torturing death. There was no other way out, for the legs could not be set, and the beast could not be taken on.

Mr. Holton unstrapped his rifle from his shoulder.

“I’m going to put an end to it,” he said with a sudden decision. “It seems only humane, for otherwise death will come slowly and horribly.”

He walked over to a small elevation along the side of the dune, while his friends moved away to a safe distance.

After a moment of careful aim, he pulled the trigger.

The high-velocity bullet sped true, penetrating the brain.

There was but one spasmodic movement; then the camel rolled over, dead.

For some time the explorers were silent. It was not pleasant to see the useful dromedary come to such an end. Finally Joe began the ascent of the dune.

“It’ll seem strange without that camel,” he said. “How will I manage to have a mount?”

“You’ll have to take one of the pack animals,” returned Dr. Kirshner. “We’ll divide the supplies among the others and get along some way. If we do the right kind of scheming, I don’t believe the other camels will notice the extra load.”

It was difficult work climbing the treacherous slope of the dune. Many times their feet would scarcely find a foothold when the sand would give way, making it necessary for them to sprawl out or clutch one another in order to prevent rolling down.

At last they reached the top and began dividing the provisions among nine of the ten pack dromedaries. It required over an hour to complete the task, for it was difficult to find places for all their belongings.

“Now you may find it hard to get used to the strange camel,” said Mr. Holton, as Joe straddled the kneeling animal. “He may act up and threaten to throw you, but stick to it. It won’t take long to show him you mean business.”

“He’s been broken in some,” remarked Fekmah. “Though it may been good time since he had rider.”

Much to their surprise the dromedary responded to Joe’s commands at once, resigning himself over to his new master.

“And am I glad!” the youth exclaimed, as the little caravan prepared to resume the journey.

“That’s rather an exceptional piece of luck,” smiled Mr. Holton. “Usually it takes a good while for a camel to get used to its new rider.”

The explorers continued the journey, although they realized that they could cover but a few more miles before dark. Already the sun was beginning to sink behind the distant hills, tinting the dunes many colors.

“Didn’t get as far today as we did yesterday,” observed Bob, as the boys waited for Tishmak to find a suitable stopping place.

The guide found the place he wanted between two large dunes, which were spread out over a large amount of ground.

“Tishmak say we wait here and get supper,” said Fekmah, after a moment of conversation in the native tongue. “Then when moon come out, we go on and try to make up for lost time.”

“That suits me,” agreed Dr. Kirshner. “Almost anything would satisfy my appetite right now.”

The explorers dismounted and prepared the meal, which after the strenuous hours of constant traveling tasted delicious. Then they sat quietly in the semidarkness.

At last the moon came out, and the desert was again seen to take on a new appearance. The sand was even more beautiful than the night before, white as it was from the soft light.

Tishmak motioned for the adventurers to mount their dromedaries and get under way. If they expected to get over much more territory, it would be necessary to hurry.

“Here’s hoping we can come up to our hundred-mile minimum,” said Joe, urging his camel to trot faster.

It was nearly ten o’clock when they finally stopped for the night’s slumber. Fekmah was well satisfied with the distance they had made that day.

“Tomorrow we will come to Tudemait Plateau,” he said, after conversing with Tishmak. “It is a rocky region, with large black boulders.”

“Then we won’t see any more sand dunes?” asked Bob.

“No. The country will be rather level, but we will have to go many kilometers out of way to avoid rocks.”

“That’ll suit me,” put in Joe. “I’m tired of seeing nothing but sand.”

That night they trusted to good fortune and did not set a guard. Tishmak informed them that there was little danger of robbers in that region, and the alertness of the camels would be an added precaution.

“We are nearing the country of the Tuaregs,” explained Fekmah. “These natives are friendly, but drive away nomad robbers. We probably be safe tonight.”

And they were. The next morning they had completely regained their natural liveliness and pep, feeling thoroughly refreshed and ready for anything the day might bring.

Breakfast over, the long journey was resumed.

As Tishmak had predicted, the country gradually began to change. The sand dunes that had recently been high slowly became smaller and lower, and vegetation increased still more. Small rocks were everywhere, their color a dark gray or black. In the distance the sharp crags of the Tudemait Plateau could be seen.

As the explorers neared a low long mound, Tishmak’s dromedary suddenly halted and sniffed nervously. A moment later the animals of the other explorers also came to a stop.

“What’s this!” exclaimed Mr. Lewis, looking about wonderingly.

“Guess they heard something,” said Dr. Kirshner. “What it was, we’ll see in a moment. They have an uncanny power of detecting noises that we men can’t catch.”

Tishmak unstrapped his rifle and motioned for the others to do likewise.

“Wonder if it’s bandits,” muttered Joe, holding his gun in readiness.

The sound of camels’ footsteps now reached the adventurers’ ears. Then from behind a hill appeared a long trading caravan of Arabs, who also had their rifles in readiness.

Tishmak rushed forward, throwing his hands apart in a gesture of friendliness. He was followed by Fekmah and the others.

As soon as the Arabs saw that the whites meant no harm, they stopped and talked freely. Much to Dr. Kirshner’s delight, he could understand the men easily, their language differing greatly from that of Tishmak.

The Americans learned that the caravan was on its way to Wargla, loaded with a large supply of dried dates, grapes, and many other products of the desert oases. It was made up of over seven hundred camels, which were in a line several miles long.

“Look at the leader,” said Joe to his chum, referring to the head camel. “It’s decorated with about as many colors as there are.”

“Want to make a good showing,” smiled Bob. “From what I’ve heard, a caravan is judged by how well the first camel is engulfed by colors.”

Much as the explorers would have liked to talk with the Arabs, they did not stop long. Time was too valuable to be wasted, especially when they were literally running a race with the two thieves who had stolen Fekmah’s map.

But before they left, Bob and Joe took motion pictures of the caravan at several distances. Especially were the youths pleased by the friendly attitude of the Arabs when the camera was held before them.

“Doubt if they know what it’s all about,” smiled Bob. “But that doesn’t keep the pictures from being good.”

“Wouldn’t they be surprised if they could see themselves on the screen!” laughed Joe. “They’d probably think something supernatural was taking place.”

With a cheery farewell the American expedition left the Arabs at the head of the trading caravan and again took up the journey. But it required nearly a half-hour to pass the last of the pack camels, which were guarded at intervals of every fifty animals by an armed Arab.

“Seven hundred camels is a good many,” remarked Bob, as the youths rode at the rear of their own pack animals. “Their owner must have a good bit of money.”

“Many of those Arabs are wealthy, I guess,” said Joe. “Fekmah said some have as many as two thousand camels.”

As the explorers moved on, they saw other signs of small game. Occasionally Mr. Holton and Mr. Lewis displayed their skill with a rifle by shooting creatures from a great distance.

“Seems to be getting a little darker,” remarked Joe, as they descended into a little valley.

“Darker? Couldn’t be.”

Then, as Bob gazed ahead at the opposite slope, he uttered an exclamation of bewilderment.

“It is getting darker!” he cried. “Why—why, it’s impossible. Dark at nine in the morning! Something’s wrong somewhere!”

A second later Mr. Holton rode up to the boys anxiously.

“Get out your goggles!” he directed them. “We seem to be riding into a fog of black dust. Tishmak thinks we may have to stop for the day.”

---

“WHAT!” cried Bob excitedly. “Stop for the day! We—we can’t. Our time is worth too much!”

The naturalist laughed unwillingly.

“This time it’s a question of what we have to do,” he said dryly. “If the blackness increases, it will be suicide to plunge through it with so many rocks and walls of stone near.”

The boys and Mr. Holton rode on up to the front of the caravan, where Tishmak and Fekmah were visibly moved with fear.

The darkness was becoming more intense with every minute. Soon the explorers could not see one another.

“It might be well to get off our dromedaries,” suggested Mr. Lewis. “If this is to continue long, it won’t pay to remain mounted.”

“This is likely to mean a loss of several hours,” said Fekmah gravely. “Then again, the fog of dust might pass away in but few minutes.”

“Worst thing about it is the difficulty to breathe,” pointed out Dr. Kirshner. “Tragedy has been known to come upon caravans in this manner.”

It was indeed stifling, but the adventurers managed to get air through the dust. They feared every minute that time would bring about an impossibility to breathe.

Much to their relief, that dread moment did not come, and after a half-hour the blackness gradually thinned out until it again became light.

“Thank goodness!” breathed Mr. Lewis. “Now let’s get on our way again.”

Still more the country was changing. The rocks became more jagged, taking on many shapes and forms. Small trees and plants became more abundant, causing the region to resemble certain areas of the American desert. And along with this plant life came numerous traces of wild animals.

“Wish we would run across a fox,” said Joe. “I’m anxious to shoot anything.”

“Probably will,” returned Bob. “I guess there are not only foxes but jackals and other small game. There should be much more here than in the sandy section.”

The party stopped at eleven o’clock for the meal and midday rest. This time the dromedaries alone were to be the guards, for they had already proved their efficiency in detecting unusual noises.

At two they were again on their way, climbing a gentle slope widespread with sharp rocks.

“Seems strange to get away from the sand dunes,” remarked Bob. “It hardly is like a desert now.”

As they passed up a rocky hill, Fekmah called a halt.

“We have come to the Tudemait Plateau,” he announced, getting out the map that he had made from memory. “That sharp peak in the distance is one of the landmarks. Now we pass through this plateau for rest of today and part of tomorrow; then come to another sandy stretch.”

“Then what?” inquired Mr. Holton.

“Get to Ahaggar Mountains,” the Arab replied. “We have to follow compass more close from now on, because must see peak called Illiman. Then we know we near treasure.”

“And here’s hoping those two thieves haven’t gotten there first and taken everything away,” said Joe.

That afternoon they came to a small well and refilled their containers, which were beginning to get low. Despite the fact that the water was exceedingly warm, it was greatly welcomed by the explorers.

A high hill was before them, and Bob suggested that they climb to the top afoot and make out the character of the land ahead of them.

The others were in favor of doing so, for Fekmah might catch sight of something that would be recognized as a landmark on the map.

The climb was tiresome but easy, the many boulders offering footholds. Finally they reached the top and turned their gaze toward the horizon.

“What’s that ’way over there?” asked Joe, pointing to a narrow valley walled closely by high rocks.

Mr. Lewis and Mr. Holton had their binoculars strapped over their shoulders. They took them out and peered into the distance.

Suddenly Mr. Holton started.

“It’s a village!” he exclaimed, and Mr. Lewis nodded. “A village of Arabs. Look at the low huts of sun-baked mud,” handing the binoculars to Fekmah.

“Yes,” said Fekmah, gazing out through the glasses. “Suppose we go over there and see them. They treat us all right. It not take much of our time.”

“All right,” returned Dr. Kirshner. “I’m anxious to make a casual study of them. They might have some primitive implements that belonged to their remote ancestors.”

The adventurers made their way down the hill and mounted their camels. Then they rode off toward the distant valley. It was a good distance away, and perhaps hard of access, but the explorers were determined to find it.

In less time than they had expected, they came to a spot that would probably afford an opening into the valley. For a few minutes they wound in and out among the rocks. Then they came within sight of the village.

A crowd of Arabs ran out to meet them, uttering hearty greetings. It was evident that expeditions rarely passed within sight of their dwellings, for they were very excited.

Tishmak and Fekmah conversed with the people in a very friendly manner and then introduced the others of the American expedition.

Dr. Kirshner and the naturalists found it almost impossible to understand the language, and they were satisfied with Fekmah’s translations.

“A good chance to take some movies,” said Bob, getting out the camera.

“Don’t suppose the Arabs would object,” added Joe. “At any rate, we’ll risk it.”

The youths cranked off several scenes of the Arabs and their village. It was clear to the explorers that the people had never seen a motion-picture camera before. The strange purring box was an object of curiosity, and they crowded around like so many children.

To the Americans, these people were of great interest. The men and women dressed almost alike, in a long, white robe that reached to the ankles. A tight-fitting cloth was wound around the head, and the back of the neck was protected from the sun by a black veil. They were of a naturally swarthy complexion, which was still further darkened by the fierce desert heat.

“Not very pleasant to look at,” said Bob to his chum. “But they sure are giving us a hearty welcome.”

“That’s probably because they’re so unused to seeing strangers,” Joe remarked. “Nearly all friendly natives are that way.”

The Arabs led the explorers into the main part of the village, where there was a large open space before the chief’s, or sheik’s, hut. Suddenly the head native stopped and pointed to a distant large rock. He babbled animatedly to Tishmak and Fekmah, whose faces took on a look of disgust.

“Sheik say over there is a place where they bury those guilty of witchcraft,” Fekmah explained to the Americans. “They put to a terrible death, and then their bones taken over there.”

Mr. Holton shook his head repulsively.

“Ignorance is the root of evil,” he said. “These people are even worse off than the Negroes of the Congo. They so infrequently come into contact with civilization that they have degenerated into a state of almost nothingness.”

“With even more respect for Fekmah and Tishmak, the Arabs in many remote sections of the Sahara are a bloodthirsty, treacherous, and immoral people,” put in Dr. Kirshner. “They do not at all compare with their brothers in Algiers and other places nearer the coast.”

Fekmah nodded.

“Praise be to Allah that I was not born here,” he muttered.

The sheik invited the explorers to stay for dinner, but Fekmah politely refused, saying that they must hurry on.

“We have many miles to go yet,” he told them in the native tongue. “If we are to get far today we must be going now.”

The explorers left the village for their camels, the Arabs shouting warm farewells.

“Professor Bigelow ought to be here,” smiled Joe, referring to a famous anthropologist who had accompanied them on their expedition in Brazil.

“Wouldn’t he be tickled,” laughed Mr. Lewis. “But then—maybe he’s already been here. He has been about everywhere else studying primitive people.”

Soon the adventurers were out of the narrow valley, again taking up the journey. They were glad to get started again, welcoming any new sight in the way of oddly shaped rocks, deep valleys, and other formations of nature.

Darkness was rapidly falling, but they kept traveling until it became impossible to see ahead. Then Tishmak held up his hand for them to stop.

Again they waited for the moon, not continuing the trip until it came out.

“Tonight we must make up for the lost time at village,” said Fekmah. “We can stand to stay up an hour later.”

It was not until eleven o’clock that they finally came to a stop in a wild, rocky region. The tents were put up for the night.

The next morning the explorers were barely up when Joe happened to notice something crawling toward him as he sat near the tent.

He was up in a moment, looking about fearfully.

“A scorpion!” he cried excitedly.

---

THE creature that was slowly moving toward Joe was as large as his hand, with long, powerful legs that were doubled ready to spring. And Joe well knew what that spring would mean.

The youth viewed the hideous scorpion with a terrible awe, fearing to move lest it become angered and charge. What was he to do? He knew he could not get up in time, for his terrible enemy would be upon him. Yet if he should remain sitting, he would surely feel the hairy mass upon him in a very few seconds.

Slowly Joe reached into his holster for his pistol. He was a poor shot with such a weapon, but the chance had to be taken. Still there was a possibility that he might kill the huge spider by throwing the gun at it.

With a sudden movement the youth drew out the automatic and carefully but hurriedly threw it with all his strength.

Then his heart sank as he saw the gun whiz past the scorpion and roll across the hard ground. The sudden movement angered the creature still more, and it crouched as if to charge.

Suddenly, as a last resort, Joe sprang to his feet and dodged to one side, just as the scorpion left the ground. As the result the charge was unsuccessful, the huge spider alighting several feet to the youth’s left.

The next moment Joe was in the tent, looking about nervously. He picked up his rifle and dashed back outside.

The scorpion was slowly crawling toward the entrance to the tent when Joe took careful aim and fired.

His aim was true. The small bullet caught the creature squarely, shattering it into pulp, which flew in several directions.

After watching the remains of the scorpion for a moment, Joe turned about, to find Dr. Kirshner and Bob standing beside him with small rifles.

“That was a wonderful shot, Joe,” praised the archæologist. “Bob and I happened to have our rifles and would have taken a shot at the scorpion if you had missed.”

“So you saw, did you? Well, I don’t mind saying that I was frightened stiff for a few minutes. Thought sure I was a goner.”

He was forced to tell of the entire experience, and in the end his listeners looked grave.

“A very narrow escape,” said Dr. Kirshner, who, along with the naturalists and Fekmah, had listened breathlessly.

“Scorpions are terrible adversaries,” said Mr. Holton soberly. “The fluid they inject is extremely poisonous! From now on we’ll have to watch more closely.”

After breakfast the explorers continued on the dromedaries. They were to reach another stretch of sand dunes late that afternoon, Tishmak told them.

“Sand hills will seem good after these endless miles in the Tudemait Plateau,” remarked Joe. “But there won’t be any shade, and there is a little here from the rocks.”

“Wait till we get to the Ahaggars, if you want shade,” smiled Mr. Lewis. “Some of that region resembles the mountainous part of Arizona. There are deep ravines, narrow valleys, high peaks, unknown caves, and many other remarkable phenomena of nature.”

“That is where our journey comes to an end, isn’t it?” asked Bob.

“Yes. In the southern part of the Ahaggar range. Thus far, Fekmah hasn’t had much need of the map, because he has directed us more by compass. But when we see the mountains, it will be necessary for him to consult it frequently. Whether or not it will prove accurate, made from memory as it was, we have yet to see.”

The way now led through a dry river valley, which wound through the many black rocks. Some of the rugged hills near by towered to two and three thousand feet, their perpendicular sides gray or deep black.

There was sparse vegetation, but a few gum trees were scattered about over the hard soil.

Tishmak had informed them that they would come to a well some time that afternoon. The water, he said, would be very cool, for it came from far underground.

“I’d like to see that Land of Thirst you were talking about,” remarked Joe to Fekmah, as the Arab mentioned the well of cool water that lay ahead of them. “It must be an interesting region.”

Fekmah shook his head.

“Caravans avoid it much as can,” he said grimly. “Too much danger of falling dead. Then, too, it is supposed to be inhabited by evil spirits.”

“Evil spirits?”

“Yes. Superstitious natives near there never see parts of it. I much glad we not have to go through it, because we sure to get very much thirsty.”

Shortly after the explorers had passed around a large hill they heard camel steps from behind a sharp corner in the river bed.

“Quick!” directed Dr. Kirshner. “Let’s hide in back of these rocks. It may be more bandits.”

The adventurers drove their dromedaries out of sight and then followed, looking about cautiously.

The sound of footsteps grew louder, and soon a small caravan of natives came into view, looking very strange indeed with their faces tightly covered with black veils.

“Tuaregs!” exclaimed Dr. Kirshner, who had made a study of the peoples in the Sahara. “Tuaregs at last!”

He rode out from behind the place of hiding and shouted a friendly greeting in their own language. The people at once called back and moved on up to the archæologist.

“Guess we might as well go out,” smiled Mr. Holton, urging his camel to move forward.

Soon the others joined Dr. Kirshner, who seemed to be having no trouble in understanding the people.

“They live in the Ahaggars,” explained the archæologist, after a few minutes of conversing with them. “They’re on their way north to In Salah. That’s a town of considerable importance.”

The natives did not stop long, and the American expedition was also anxious to be going.

“I didn’t know Tuaregs were found this far north,” said Mr. Lewis, as the people disappeared from view. “Their home is in the lower Ahaggars, and they seldom ever, if what I’ve heard is true, wander far away.”

The explorers stopped before noon for the meal and rest. Then, at two o’clock, they continued on their way, anxious to leave the plateau behind.

Suddenly, as they gradually ascended a long grade, an agile form darted out to one side of Bob’s dromedary, its red coat showing brightly in the sunlight.

“A fox!” Bob exclaimed and raised his rifle to his shoulder.

Glancing along the sights, he pulled the trigger. There was a howl of pain as the bullet struck the animal broadside. Another howl; then silence.

“You got him!” cried Joe, delighted.

“A big specimen, too,” declared Mr. Lewis, getting out his knife.

The animal was carefully but rapidly skinned and the hide placed in the solution of preservative.

“Already we have a large number of specimens,” said Mr. Holton, as they left the skinned body behind. “And we hope to see a good many other animals and birds as we pass on.”

Late that afternoon the adventurers came to the well that Tishmak had told about, and found the water very cool. It reached the surface in a shady spot among the many high rocks.

All drank with a thirst that came from long traveling in a dry, hot region. Bob and Joe especially welcomed it, the latter declaring it better than flavored beverages.

“That’s right,” agreed Mr. Holton. “One can drink many things, but water is, after all, the old stand-by.”

When the containers were filled, the explorers rested in the shade of the rocks. There was something about that spot that made them hesitate to leave it behind. Perhaps it was the cool water, or it might have been the wall-like formations of stone all about.

Finally Tishmak got up and mounted his dromedary, motioning for the others to follow suit.

All the remainder of that afternoon they trudged on over the Tudemait Plateau. Slightly to their surprise, they had not yet reached the region of sand that lay at the south of the plateau. Fekmah especially was very restless, saying that he could not understand why the rocky region had not been left behind shortly after the midday rest.

“It supposed to be only about a hundred and seventy kilometers [about one hundred miles] across, and we have traveled at least that far,” he said, very much perplexed.

“Perhaps we have followed the arc of a circle,” suggested Mr. Lewis. “Suppose you ask Tishmak.”

The guide was also in the dark, not being able to give an explanation.

“Well,” said Bob, “it might be well to keep going awhile longer. We’ll surely come to the sandy region before long.”

The others thought this good advice, but late that evening they were still on the plateau.

They retired that night with high hopes that the morning would bring good fortune. During the last few hours they had had an uneasy feeling that their efforts to find the region of sand were in vain.

The next day they were off early, after a hurried breakfast.

“We’ll get out of these rocks some time this morning,” predicted Mr. Lewis with a smile.

And he was right. Gradually the boulders they passed grew smaller and the soil more loose. By the time they had stopped for the noon meal they were again among sand dunes.

The heat was now terrific. If it had been warm before, it was scorching now. Everywhere they went they were under the blaze of the fierce sun. How the camels managed to keep from burning their feet was a mystery to the youths.

Their throats were parched, their tongues numb. Water, water! If they could only drink and drink and drink! But only small amounts were allowed to be taken, for this region was many, many miles across, and there was no well or oasis anywhere near their path of traveling.

“If we have much more of this I’m afraid I’ll fall off my camel,” said Bob with a grim smile.

“Not quite that bad off, are you?” laughed Dr. Kirshner. “Dying of thirst is a rare occurrence in this part of the Sahara. But it does happen sometimes, and it is a tragic death indeed.”

“Worst thing is,” explained Mr. Holton, “there is a time when the victim of thirst would die should he touch water. In that case, water is virtually a poison.”

The sand hills that they were passing over were much lower than those in the country below Wargla. The desert stretched away to the horizon in endless waves, which, as far as the travelers could see, were unbroken.

Vegetation was scarce, only a scattering of yellow plants dotting the dunes. This promised to be a disadvantage to the dromedaries, for previously they had occasionally nibbled on the trees and shrubs that were clustered about.

“Look at the sky,” said Joe, turning his gaze upward.

“Funny color, isn’t it?” Bob returned. Then, as he peered into the distance, he uttered an exclamation of surprise and fear.

But the others had seen also and were equally as excited.

Away to their right a heavy mist had risen and was rapidly turning reddish.

“A sandstorm!” cried Fekmah in great anxiety. “A sandstorm is coming!”

---

THE explorers, particularly Tishmak, knew the danger of a sandstorm. It was not infrequent for large caravans to be completely engulfed by the heavy veil of sand, leaving only the dead bodies of the camels and their riders. The Americans remembered a tale that Fekmah had told them about a trading caravan of five hundred dromedaries coming to a tragic end in this region. Would their little caravan also perish?

“Get your goggles,” commanded Fekmah, his tone indicating that he was calm even in the face of danger.

“And be sure they fit tightly!” warned Dr. Kirshner. “Even then we’ll get some of the sand.”

The atmosphere was rapidly becoming extremely dry and hot, and at intervals a fierce wind brought minute particles of sand into the explorers’ faces.

“Now,” began Fekmah, after conversing briefly with the guide, “we must get dromedaries in group, so they not get fright and run away. Then we crouch down behind them.”

The camels were drawn up together and fastened in a circle with ropes.

“It might be wise to put up our tent, mightn’t it?” asked Mr. Lewis, but Fekmah shook his head vigorously.

“No, no,” he said. “Then we get in trap and not get out. If sand very heavy, we want to be in open.”

The dense mist was thickening and spreading, until it soon covered the whole horizon. The sky in the distance was not visible for the heavy cloud of fine particles.

The explorers got out blankets and wrapped themselves tightly. Even then, said Fekmah, the small bits of soil would get through to their skins.

They had scarcely finished preparations when the first breaker suddenly came with all force, striking the adventurers in the face and penetrating the blanket.

It was blinding, smothering, but they managed to get air and fought with a determination that was born of adventure. Crouching behind the sturdy dromedaries, they held their heads low to avoid as much of the fury of the storm as possible.

It was with great difficulty that the camels kept their positions together, but they succeeded admirably.

“Doesn’t seem right for them to have to stop the sand for us,” said Joe, shouting in order to make himself heard.

“It’s a shame,” Bob shouted back. “But they can probably stand it better than we can.”

Slowly they found themselves enveloped in a heavy opaque atmosphere, so dense as to seem almost as a wall. The thought of being completely covered up was constantly in their minds, bringing about almost a feeling of despair.

The burning wind was constantly lashing them in the face, until it seemed that they could stand it no longer. Indeed, if their heavy goggles had not been of unbreakable glass, the furious particles of sand would have smashed them in the explorers’ eyes. Even as it was, some of the sand found its way in.

“This is terrible!” moaned Joe. “Awful—simply——”

He stopped suddenly, as his mouth became filled with sand. Another gust of wind had come, bringing with it an enormous quantity of the burning sand.

The explorers’ eyes were smarting, their lips were cracked and bleeding. They felt that they would smother. Nothing could have been worse, it seemed.

They could hear the dromedaries snorting with fear and irritation. What if the brutes could not stand?

Conversation was now impossible, for they dared not open their mouths for fear of swallowing some of the stinging sand. Even when they breathed, the fine particles filtered through the net that hung over their faces.

The sky above was of a bright red color, and a weird light trickled through the fog of yellow. It was the most unusual happening that the Americans had ever witnessed.

“If it just wasn’t for this terrible wind!” muttered Mr. Holton, when there had come a slight lull.

“Yes,” agreed Fekmah. “Then it not be so hard to stand it.”

He had scarcely finished when another gust of hot sand struck them cruelly, making their faces sting anew.

Suddenly Tishmak noticed that they were nearly engulfed in a heavy pile of sand. With a quick motion he drew himself out and drove the dromedaries to another spot.

For a brief moment the explorers were exposed to the full violence of the storm. Then they again took places behind the newly located camels.

“Not taking any chances on being covered up, are you?” said Dr. Kirshner to Tishmak.

The latter did not understand the words, but he caught the meaning and smiled.

How long the terrific onslaught of sand lasted, no one knew. They had lost all sense of time, and the heavy atmosphere completely hid the sun.

It was only gradually that the terrible storm subsided, and then the air was exceedingly hot and dry, promising to remain that way for some time. Slowly the cloud of sand about them grew thin, until it finally cleared away completely. Now only an occasional hot wind annoyed them, but it was scarcely anything compared to the previous bombardment of sand.

“No more of anything like that for me!” muttered Bob, as he worked his feet loose from the high pile that strove to bury him alive.

The dromedaries, too, had their legs embedded in the sand so deeply that it required several minutes of constant digging to relieve them.

“Suppose we rest awhile before going on,” suggested Bob. “It has been a great strain for all of us, standing against that terrible rush of sand.”

The others readily agreed, and all thoughts of continuing the journey at once were dismissed from mind.

“At least,” Joe said, “we got out alive, and that’s more than you can say of many caravans.”

“Yes,” returned his father. “Perhaps under this very spot are the bones of men and camels that were not as lucky as we were.”

“That storm rather short lasting,” remarked Fekmah, glancing at his watch. “Many times storm last several hours.”

Joe sighed.

“I’d hate to have had to stand much more of it,” he said.

It was nearly noon, and the tent was pitched for the midday rest. All were very weary after the terrific strain.

“Let’s have our lunch,” suggested Mr. Lewis. “I’m very hungry, and I’m sure everyone else is.”

The noon meal and rest followed, the explorers not continuing until after three o’clock.

Late that afternoon they came to one of the largest uninhabited oases that they had yet seen. It was situated snugly on a narrow stretch between high dunes.

“It’s a wonder a small town hasn’t sprung up around here,” remarked Bob, drinking greedily of the refreshing water that gushed from the large spring.

Dr. Kirshner nodded.

“With all these palm trees and the abundance of water it is surprising,” he said. “But I suppose there are so few people, even among the natives, who would live here that it wouldn’t pay.”

The containers were hurriedly filled.

“It might be well to stay here for the night,” said Fekmah. “It is getting late, and we all need sleep very bad.”

He turned to Tishmak and put the question before him in the native language.

The guide at once gave his approval, more than glad of the chance to stop.

“He say he wanted to stay here for night, but thought we in big hurry,” Fekmah told the Americans.

“We are,” returned Mr. Holton. “But here is a very good place to camp, and I think we’d better take advantage of the opportunity.”

The tent and provisions were unpacked from the camels, which seemed more than glad of the chance to relax.

“Funny,” remarked Mr. Lewis, “that camels don’t care to lie in the shade when there is an opportunity. You would think the terrible sun would be avoided as much as possible, but that is not the case.”

“Either they like the heat or they are too lazy to move,” said Joe.

For some time the two youths sat with their elders. Then Bob got up and stretched.

“Suppose you and I get on our dromedaries and ride over to that distant hill,” he said to Joe, pointing away to the horizon. “I’d like to see what’s beyond there. This seems to be very high ground, and we might get a view of the distant mountains from the top of that dune.”

“Be sure and take your rifles, boys,” warned Mr. Lewis. “And don’t stay too long.”

The boys slung their guns over their shoulders and rode off, waving to their friends.

The hill that Bob referred to was at least a mile away, and the ground on the way was of loose sand. The boys urged their mounts to trot faster, however, and they would probably cover the distance in a very short time.

“I wonder if we could get a glimpse of the Ahaggar Mountains?” said Joe.

“Might. But you must remember that we are still a great distance away.”

As the boys had expected, they came to the hill in but a few minutes. It was very high and steep, but the soil was hard. The dromedaries had no difficulty in climbing steadily up.

At last they came to the top and gazed out into the distance.

“Look!” cried Joe. “The mountains! We can see them!”

Sure enough, the Ahaggar range was visible, stretching miles and miles to either side. A few sharp peaks protruded high above the others, but for the most part the line of mountains was rather regular.

“Suppose that high peak is Illiman?” asked Joe, pointing to a high crag that towered above the other mountains.

“You mean the one Fekmah was talking about? It might be. He would know if he saw it, I suppose. And of course Tishmak would.”

The youths spent nearly a half-hour peering out at the mountains, greatly impressed by the wonderful view.

“How far away do you suppose they are?” questioned Joe.

“Fifty miles, at least; maybe more. It will probably take us another half-day to get to them.”

Finally the youths turned and rode back down the hill to tell their elders of the magnificent view. Fekmah particularly would be pleased, Joe thought.

But the boys were not overly anxious to get back to the oasis at once. There were many other high sand dunes that they would like to ride over.

“We won’t stay much longer,” said Bob. “Just ride around a bit.”

To their right was another high hill that might afford a view in another direction. The youths rode over to it and climbed the gradual side.

Then, when they came to the top, they cried out in surprise and fear.

In the distance appeared to be a whole regiment of galloping horsemen coming toward them!

---

FOR a moment the youths were taken completely aback in surprise. That they would see anything like this away out on the Sahara was not in the least expected. They stood for some time in sheer amazement and not a little fear.

“An army coming at us!” muttered Bob, staring at the distant spectacle.

“An army, yes. Must be five hundred cavalrymen.”

“But—but it can’t be! It’s impossible. What would soldiers be doing away out here on the desert? Something’s seriously wrong somewhere. If just one of us should see such a thing it might indicate that the old brain wasn’t working just right, but for you and I both——”

“Come on,” suggested Joe, giving his dromedary a slight kick. “Let’s get out of here. I’m greatly worried.”

The youths turned their camels back to camp for a short distance; then they urged them on to a fast trot.

They were not a little relieved when they finally reached the oasis, where they found their friends awaiting them.

“Where have you been so long?” inquired Mr. Lewis, his face not a little serious.

“We thought maybe something held you back,” added Dr. Kirshner.

“It did,” replied Bob, trying to remain calm.

The men sat up quickly, sensing that some misfortune had come upon the boys.

“What was it?” demanded Mr. Holton tensely.

“An army,” Joe returned soberly.

For a second there was silence. Then the men broke out in laughter. Evidently they thought the youths were joking. Even Fekmah joined in, his dark features drawn together in mirth.

“Nothing to laugh at,” said Joe, vexed because the men thought their experience funny. “It nearly scared Bob and me out of our wits.”

Mr. Holton grew more serious.

“Come, now,” he said. “Tell us what you mean.”

Joe told of seeing the phenomenon from the top of the hill, saying that there appeared to be at least five hundred horsemen coming toward them.

When he had finished, the naturalists and Dr. Kirshner jumped up in wonder and not a little fear, but Fekmah only laughed.

“W-what’s humorous!” demanded Mr. Lewis, greatly perplexed.

“Everything,” said Fekmah, laughing still harder. “What the young men saw was only an illusion or mirage. There no army on Sahara. Only look like army.”

“You mean it was a trick of nature, like the more common mirages of lakes on the desert?” asked Dr. Kirshner with great interest.

“Yes,” the Arab answered. “Caused by the bending of the rays of light when they strike the hot sand.”

“Well, that’s a new one on me!” confessed Bob. “I was aware of the fact that mirages of lakes are common, but that I should see an army——”

It was now rapidly becoming dark. The explorers thought it best to sleep all through the night and not wait for the moon, for they greatly needed the rest.

“Tomorrow morning I’d like to see that mirage that you boys thought was an army,” said Mr. Holton, when they prepared to retire.

“And I, too,” put in Dr. Kirshner. “As it isn’t out of our way, we can all ride over there.”

“It’ll be a good chance to take some motion pictures,” said Bob. “A scene as unusual as that is sure to attract the curiosity of an audience.”

Tishmak informed them that they would be out of this short sand stretch early the next morning. Then they would come into the Ahaggar Mountains, the real home of the mysterious Tuaregs.

“And I expect to begin my work in this region,” announced Dr. Kirshner. “Perhaps if I put legend and history together, I can locate something that will prove of great value to the world of archæology. I have in mind at present the tomb of a great king who reigned in those mountains many thousands of years ago. He is said to be an ancestor of the Berbers, who are related to the Tuaregs. When we come to the many Tuareg villages, I intend to make inquiries as to their ancient legends.”

They were up early the next morning, anticipating the exploration of the mountains that lay ahead of them.

But in order to get to the Ahaggars, it would be necessary to continue for a short distance over the sand dunes.

After breakfast they rode over to the distant hill to get a view of the mirage seen by the boys the day before. Sure enough, the army of horsemen appeared to be riding toward them, and the details were rather plain.

Mr. Lewis shook his head in bewilderment.

“Sure is strange,” he muttered. “Why should the horses and the riders be so clearly defined? I can easily understand the mirage of a lake, but this sure gets my goat.”

They stood for some time staring at the distant spectacle, Bob and Joe taking motion pictures. Finally they rode on up the hill to catch a glimpse of the Ahaggars.

“I rather think that peak not Illiman but Oudane,” said Fekmah to the youths, in answer to their question asking the name of the distant high mountain. “Mount Oudane very high, and much nearer than Mount Illiman.”

More movies were taken by the youths. Then they rode down the opposite side of the dune in the direction of the mountains.

“Ahaggars very strange,” said Fekmah to the Americans, as they rode in a group at the back of their pack camels. “There are high cliffs, tall needle-like peaks, deep caves. There are canyons, ravines, underground passageways. We see much, and we too be in great danger.”

“Danger?” Joe looked up in some surprise.

“Yes. Very great danger. Wild Tuaregs roam about, and when on a raid, think only of robbing travelers. Then, too, we be in region where the two thieves who stole my map are. They perhaps be waiting for us and shoot us quick without giving warning. Many other dangers we might see.”

Fekmah sobered the Americans a little. They had not anticipated any great peril, although they knew the two thieves might, should they have arrived at the hidden riches first, give them trouble.

“But we’ll come out all right,” predicted Bob, again becoming cheerful. “We’ll show those fellows that we’re capable of attending to any crisis.”

A little farther on they reached the wall of rock that had previously shut out the view of the mountains. It stretched many miles to their right and left, but there were numerous breaks that afforded openings into the country beyond.

They had barely reached the other side of the wall-like formation when Joe caught sight of a group of tents quite a distance to the east. He motioned for his friends to look in that direction.

“Probably Arabs,” pronounced Fekmah, after Tishmak had chattered rapidly for a moment. “They nomads, who wander about the desert taking their flock of goats with them.”

“Suppose we go over and see them,” suggested Mr. Holton. “Perhaps they can give us a description of the country ahead of us. There may be many more wells than we think, and it will do us no harm to know of them.”

The others were in favor of carrying out Mr. Holton’s move. But Fekmah warned them to be on the lookout for treachery.

“They probably not do us harm, but can never tell,” he said, as the dromedaries were turned in the direction of the tents.

They reached the encampment in a very short time and were about to look up some of the Arabs when a savage growl made them wheel around in surprise and fear.

“Look!” cried Joe, laying his hand on his rifle.

Two large, savage dogs were making toward them with all fury, showing their terrible teeth in anger. The enraged creatures were probably owned by the Arabs in the tents and were acting as guards against all marauders.

The foremost dog was almost upon Mr. Lewis’s camel. In another moment the beast would sink its teeth in the dromedary’s throat.

Displaying the quickness of a cat, the naturalist unslung his rifle, took hasty aim, and fired.

The report of the gun was followed by a longdrawn howl from the huge dog.

“Quick!” cried Bob. “The other dog!”

The second beast was rushing forward angrily.

Mr. Lewis again took aim. The others, trusting in his marksmanship, made no move to get their rifles.

Click! There was no report this time. His magazine was empty!

Mr. Holton tried vainly to get his rifle out in time. Something must be done at once, for the savage dog would be at the camels in but a moment.

Suddenly Joe leaped from his camel directly in the path of the oncoming animal. The dog stopped for a second, then rushed at the youth with terrible ferocity.

“It’s now or never!” Joe thought and brought the butt of his rifle down with all his strength on the dog’s head.

There was a cry of pain, and the next moment the beast rolled over in a dazed condition. At last the terrible enemies had been overcome.

“Great work, Joe!” praised Mr. Holton. “We weren’t expecting to see you act so quickly.”

“I didn’t know whether I could hit him at the right time or not,” the youth said, wiping the perspiration from his brow. “But I thought I’d take a chance. It——”

He stopped fearfully as a rifle shot rang out. Another report followed the first, and Tishmak fell from his dromedary.

“Back!” cried Dr. Kirshner. “It’s the Arabs shooting from the tents. Hurry or we’ll all be hit!”

Tishmak was rapidly picked up and placed on his camel, and then the explorers retreated behind a formation of rock near the high wall of stone that was to their right.

“You look after Tishmak,” said Mr. Holton to Dr. Kirshner. “Meanwhile we’ll keep these Arabs away. We certainly aroused their tempers when we put those dogs out.”

A volley of shots came from the Arabs’ tents, and the Americans at once answered with their own rifles. Wherever a shot was heard, Mr. Holton directed his friends to fire at the spot.

Suddenly Mr. Lewis caught a glimpse of a large one-armed Arab who emerged into full view to send a bullet at his white enemies. Without hesitation the naturalist fired, bringing the man down with a thud.

“Look!” cried Bob. “They’re backing up. That fellow you shot must have been the leader.”

“Does seem that way,” agreed Mr. Lewis. “But we must remain on guard. These are treacherous characters.”

Only an occasional shot rang out. Then finally there was silence.

“Now we’ll see how Tishmak is,” said Mr. Holton, leaving his position at the end of the rocky crag.

They found that Dr. Kirshner had bound and treated the wound, which was in the left arm. The Arab seemed in high spirits, despite the fact that he was evidently in pain.

“It doesn’t appear serious,” said the archæologist. “With the right kind of attention it will probably be all right in a few days.”

“Lucky that he wasn’t killed, or that more of us weren’t hit,” remarked Mr. Lewis gravely. “The Sahara is a dangerous place for explorers.”

They waited several minutes for any more rifle shots from the Arabs, but none came. Finally Mr. Holton mounted his dromedary.

“Let’s get on our way,” he suggested. “I don’t think there’s any danger now. The Arabs have retreated to a distance beyond their tents, and I believe they’ll stay there awhile.”

Tishmak was helped on his camel. Then, when the others had also mounted, they rode off.

They were now rapidly leaving the region of low sand dunes behind. Rocks of all sizes and shapes became more numerous, and vegetation was more abundant. There were, however, stretches of coarse sand plains, which were now and then dotted with boulders.

Suddenly, as they ascended a long low hill, Bob and Joe cried out in delight and pointed to something a half-mile or so away.

“A lake!” exclaimed Joe happily. “A lake of water!”

---

“NOT a lake,” said Fekmah, shaking his head. “Only another mirage. They are rather common all through this region, and we may see much more short time.”

“Well, if there was a real lake there beside that mirage, I wouldn’t know which to pick,” confessed Joe. “And look! Even waves are there. And foam caps!”

“Wonderful facsimile, all right,” remarked Dr. Kirshner. “Old Nature is capable of playing mighty big jokes on us sometimes.”

For over a half-hour the illusion was visible to the explorers; then, when they rounded a large pile of rocks, it could no longer be seen.

“And I’m glad,” said Bob. “Now maybe I can get my mind away from thinking only of water. It wasn’t very pleasant to see what looked like it and not be able to have it.”

“When do we come to another oasis?” inquired Joe of Fekmah.

“Tishmak say within next fifty miles,” was the response. “It be very small, but there be much water to drink.”

Late that evening they came to the foothills of the Ahaggars. Majestic Mount Oudane was directly before them, and the whole Ahaggar range appeared to be only a few miles away in the clear desert air.

They at last reached the small oasis among the many red boulders. After filling their containers, they continued toward the mountains, greatly refreshed and ready for action. But darkness was rapidly falling, and it would be necessary to stop before long for the night.

Tishmak, however, thought it best to travel in the moonlight. The others were more than willing to do this, for now that they were so near their goal they hesitated to lose any precious time.

“We can go on for a while,” said Mr. Lewis, as daylight rapidly faded. “Then we’ll turn in and get a few hours of sleep.”

Soon it became dark, making it necessary to stop. But before long the moon came out in full splendor, flooding the rocky vastness with enchanting light. The distant needle-like peaks took on a strange appearance, like mysterious towers of a fairyland.

The scene was unusual and slightly weird, resembling the rough surface of the moon. For some time the Americans were silent, absorbed in thought. Finally Bob roused himself.

“Those mountains seem rather intangible, or ghost-like,” he remarked, as he and Joe rode at the rear of the caravan.

Joe nodded.

“It’s like we’re the characters of an Arabian Nights story,” he muttered. “No vegetation, no life of any kind around anywhere. Gets under my skin a little.”

Through the early part of the night they rode ever on, on toward the mysterious Ahaggars. One question stood out in the minds of all. What did the future hold in store?

Finally Tishmak brought his dromedary to a halt beside a huge boulder. He motioned for the others to follow suit.

“We’ll stop here for the night,” announced Fekmah, after conversing with the guide. “But we must be up very early in morning and get on way to mountains.”

That night everyone slept soundly, anxious to refresh themselves thoroughly for the tiresome march through the Ahaggars.

“Let’s go,” urged Joe, as he dressed the next morning at dawn. “We can’t get to those hidden riches any too soon for me.”

Mr. Holton laughed unwillingly.

“Who ever heard of fast traveling in the mountains?” he asked. “If we make ten or fifteen miles in a day we’ll be lucky.”

“There are stretches of smooth country, though,” Dr. Kirshner put in. “And when we get to the central plateau of the Ahaggars, it won’t be so hard to cover territory.”

A breakfast of limited food but a bountiful supply of water was prepared by Mr. Lewis, and then camp was broken.

In the early-morning light the peaks ahead looked pale purple, but, said Fekmah, this color would gradually change to mauve and blue as the sunlight became more radiant.

As they rounded a tall, red boulder, Tishmak suddenly halted his camel and pointed to a little crevice between the rocks.

“Well, as I live!” murmured the archæologist in surprise. “Camels—dead, mummified camels.”

The beasts had evidently been dead a long time, for their skins were extremely dry and cracked. The fierce desert sun had preserved their bodies for an indefinite period.

“And look, they’ve got their mouths down to the ground, as if they were searching for water,” observed Joe.

“They were,” affirmed Fekmah. “There once a well here, but it dried up just before camels got to it.”

“Perhaps they wandered for days searching for it, and then finally found it—dry.” Bob shuddered.

It was a pitiable sight, particularly to the Americans. They half expected to come across the mummified body of some unfortunate explorer who had died a tragic death from thirst.

“We must be doubly careful to have the containers filled with water,” warned Mr. Holton. “This is a dangerous region, and disaster could easily come upon our little expedition.”

They trudged on in the rapidly rising temperature of the terrible sun, keeping their eyes off the ground as much as possible to escape the glare. They could easily have worn sun glasses, but hesitated to do so because of the rather obstructed vision.

“What’s this!” cried Dr. Kirshner, as they came to a huge rock that was directly in their path.

“Some kind of an inscription, isn’t it?” inquired Bob.

“It is that!” came the excited reply. “An ancient Libyan record, perhaps of a noteworthy event that took place in this vicinity. If you will give me a few minutes I’ll copy this down. It may prove of great interest in my future study of early Sahara peoples.”

The others waited for the archæologist to transcribe the writing. It proved very difficult to read offhand, but that a full translation would eventually come to light was not in the least doubted by the other Americans. In fact they had come to regard Dr. Kirshner as a wonder among men of his profession.

At last he put the paper back in its place and made a sign to Tishmak that he was ready to continue the journey.

“Now let’s make time,” said Bob anxiously. “We ought to get over a good many more miles before time for the noon rest.”

And they did. The country had not yet become rough enough to hinder the progress of the dromedaries, even though huge boulders were strewn about. By ten o’clock they had reached the base of the Plateau of the Mouydir, a thousand-foot-high wall of solid stone.

“Tuaregs have many superstitious legends about this rock,” said Fekmah, after talking several minutes with Tishmak. “They believe evil spirits up in great caves come down and kill travelers. They too think sandstorms and whirlwinds are caused by spirits hiding up in large cracks there.”

“How interesting,” said Dr. Kirshner, getting out his small portable typewriter.

Bob and Joe had taken motion pictures along the journey, and now they saw another opportunity to film a scenic wonder.

“I’d like for you to do a little acting,” said Bob to Fekmah, as the youth turned his camera in the direction of the mammoth wall of rock.

The Arab looked up in some surprise.

“I want you to point to the Plateau of Mouydir and talk to Dr. Kirshner,” the young man explained. “Tell him about the legend of the Tuaregs. Meanwhile I’ll be photographing you. Too bad this can’t be a talking picture. All right. Let’s go.”

Fekmah understood and smiled. Dr. Kirshner was also willing to assist the young photographers in their work.

The Arab and the American engaged in conversation, while Bob took movies of them pointing to the high rock. When it was finished, Bob and Joe smiled in satisfaction.

“That’s the kind of scenes we ought to have more of,” Joe said. “They’re different from the usual monotony of ‘shooting’ the country alone.”

“Gives a sort of individuality, huh?” laughed Mr. Holton. “Well, any time we can be of use to you, let us know.”

Camp was made at the very base of the huge rock. Then the usual meal was prepared.

“Use water sparingly,” cautioned Mr. Lewis, as they sat down on the cool sand in the shade of the tent. “Tishmak says we will not come to another well till tomorrow afternoon.”

“That’s a long time to wait,” said Dr. Kirshner gravely. “Can we make what we have hold out?”

“We’ve got to,” Joe’s father returned. “We’ll have to restrain from taking any undue exercise in the heat of the sun.”

“Hum-m!” Dr. Kirshner looked disappointed. “That seems to want to spoil my plans for this afternoon.”

“How’s that?”

“I had intended to do a little exploring up on top of that wall of stone.”

There were exclamations of surprise and anxiety.

“What!” cried Mr. Lewis. “Why, you couldn’t scale that steep cliff with ladders and ropes!”

“Maybe not in some places,” the archæologist smiled. “But I have noticed that there are large fissures that would offer footholds with comparative ease, and I’m going to chance it. There’s no telling what I may bring to light from up on that lofty rock.”

There was a period of silence, finally broken by Bob.

“May Joe and I go with you?” he asked.

There were loud protests from the youths’ fathers, who thought it almost madness to attempt to climb the steep slope. But Dr. Kirshner held up a hand for silence.

“Wait till we finish this meal and I’ll show you a place where it will be more or less easy to get to the top,” he said.

“If it’s there, I’d like to see it,” came from Mr. Holton.

When the noon meal was over, the archæologist led them to a point perhaps a quarter of a mile from the camp. He pointed up and smiled.

“Doesn’t that look like an easy climb?” he asked. “Plenty of safe footholds and cracks to grasp. I’m going up.”

Bob and Joe put in a request to their fathers to accompany the scientist and were finally given permission.

“But be careful,” warned Mr. Lewis. “And don’t wander too far away.”

Dr. Kirshner led the way up the side of the cliff, followed by Joe and Bob. The climb was in some places difficult and a little dangerous, but they plodded surely up.

At last, panting and perspiring, they came to the last foothold and pulled themselves up to the top. Then they turned to take in the view below.

Cries of astonishment came from all at the wonderful panorama that stretched out before them. Hundreds of feet down and to their right was the camp, and a short distance away were Mr. Holton and Mr. Lewis. The dromedaries were tethered beside a large rock near the cliff.

“I suppose Fekmah and Tishmak are in the tent,” remarked the scientist, scanning the landscape.

With the aid of his powerful binoculars the camp was made to appear quite near, and the features of the naturalists were easily made out.

At last Dr. Kirshner turned about.

“A fine view,” he said. “But let us not spend too much time here. I want to explore the roof of this cliff.”

The rocky surface was in most places flat, but there were a few huge fissures that apparently extended far into the rock.

They had come to one unusually deep crack when Dr. Kirshner stopped and slid down the steep side, desirous of seeing the unusual.

He reached the bottom some fifteen feet below, sending a score of small rocks down the side of the crevice.

“What’s there?” Joe called down, bending over the side.

“Nothing, I guess. There is—— Wait a minute!”

The next moment he was all excitement, having evidently come across something on the side of the rock.

“Drawings!” he cried animatedly, pointing to the wall about him. “Prehistoric drawings of—of elephants!”

---

“ELEPHANTS?” asked Bob, almost bursting out in laughter.

“Come on,” suggested Joe, moving slowly down the side of the fissure. “Let’s have a look at the strange drawings.”

The youths slid to the bottom, where Dr. Kirshner stood staring at the wall.

Bob nodded.

“Drawings of elephants, all right,” he said, his eyes on the etched rock. “And look how plain they are.”

The archæologist took out his notebook and copied the sketches as best he could. Then he turned to the youths.

“Here is proof that the desert was not always a desert,” he said, his eyes becoming bright with interest. “Thousands of years ago this region was green with tropical vegetation, like the dense forests of East Africa. It was probably inhabited by tribes of people much different from the Arabs and Tuaregs who now live here. Then came a gradual dry spell, and in time the luxurious growth gave way to a hot desert of sand and rocks.”

“Those drawings of elephants, then, were made while this region was covered with forests?” questioned Joe, becoming as interested as the scientist.

The latter nodded.

“Elephants and other wild game probably roamed about here in great numbers,” he explained.

After one last look at the strange sketches, the explorers began the task of climbing up the side of the ravine. It was not easy to pull themselves up out of the steep crevice, but the rocky walls were solid, not even threatening to give way.

Then followed an hour of exploration about the top of the cliff, during which time the archæologist came upon the remains of many other ancient drawings and inscriptions. By the time that they were ready to begin the descent of the cliff, he had filled his notebook.

“But when we get to the Ahaggars we’ll undoubtedly find many more,” he said, slowly leading the way down.

After what seemed a long time, they came to the bottom of the precipice and lost no time in getting back to camp.

“Have any luck?” asked Mr. Holton, looking up with interest as the three explorers moved toward the tent.

“Did we!” laughed Joe and proceeded to tell of the many drawings and inscriptions.

“You boys should have taken the motion-picture cameras with you,” Mr. Lewis said. “They would have furnished proof to the outside world.”

“Perhaps we can yet,” said Joe.

“No, you can’t,” protested Mr. Holton. “We must not waste any time here, if we are to find the hidden riches. Right now,” he added, “you three had better turn in and take your afternoon rest. That sun is terrible!”

Dr. Kirshner and the youths did as suggested, glad to rest their tired limbs. But they were up promptly at three, packing the tent and provisions on the dromedaries.

Now, as they continued farther toward the barren mountains, they began to realize what thirst really meant. As Tishmak had told them, no well would be reached until late the next afternoon, and their water containers were none too full. Their throats were parched, and their tongues began to feel numb. The fierce sun seemed all the hotter, greatly stimulating thirst.

All through that day they rode onward, the Ahaggars gradually becoming nearer. It was late that night when they finally stopped and camped in a wild region of large red rocks.

The next day their thirst became almost overpowering, even though they did not exercise. It seemed that they could stand it no longer, but they rode continually on toward the well that was located at the foot of the mountains.

The noon meal was almost without water. They did, however, sip a small amount of the precious fluid.

“Oh, if we could only drink all we want!” groaned Joe, hesitating to eat the beans that had been prepared. “Everything is so dry without water.”

But although the explorers were extremely anxious to come to the well, they gave full consideration to the midday rest. It would have meant destruction to ride under that terrible desert sun.

“Before long we’ll come to the well,” said Fekmah, as they prepared to continue the journey. “In an hour it be seen.”

“And how glad we’ll be,” muttered Bob, anticipating the pleasure of drinking a large quantity of the refreshing fluid.

The hour passed slowly. They were looking about now, searching among the many huge rocks.

Suddenly Tishmak halted abruptly, and the expression of hope that had been on his face changed to one of fear. He motioned for the others to move on up to where he was.

No translation of his excited words was necessary to the Americans. They understood his anxiety. The well was dry!

For a moment the explorers sank back, and fear—stark fear—seized them. Thoughts of disaster haunted their stricken brains—stories of how large trading caravans had been brought to a tragic end because of no water. It was torture unthinkable!

“And after all this waiting,” groaned Bob, his hope almost gone.

The others were equally touched. Now that they had met with defeat, they felt at a loss to know how to carry on.

As a last resort Tishmak had fallen into a convulsion of motions asking Allah that they might be delivered from the jaws of death. His enthusiasm grew more intense with every moment, becoming almost disgusting to the others. Even Fekmah, although he was a devout believer in Mohammedanism, thought the actions of his fellow countryman detestable.

“Come, now,” urged Dr. Kirshner, using his knowledge of the native language to console Tishmak. “We’ll come out all right. This isn’t the only jam we’ve been in.”

The guide finally became his natural self, although still a bit panicky.

“You’d think after all the expeditions he’s led into the Sahara he would be calm in the face of danger,” remarked Bob.

“Danger, yes. But not in the face of tragedy!” thought Dr. Kirshner, although he said nothing. He feared all too much that this might be the end.

“Where is the next well?” asked Mr. Lewis calmly.

Fekmah put the question before the guide, who replied that there was no water within a distance of fifty miles. And mountains lay directly before them, hindering travel. It might mean a several days’ journey before they would come to the well, and then there was a possibility that it, also, was dry. Disaster seemed almost inevitable!

“But let’s hurry on,” said Mr. Holton. “Perhaps if we make time we can get to it much sooner than we think.”

The camels were urged forward at a fast trot. But before long they were entering the mountains, and the rapid pace was necessarily slackened somewhat.

During that desperate ride against time, the explorers hardly thought of the scenic wonders that lay before them. Indeed if they had not been in such anxiety, they would have seen much to interest them greatly.

Tall, needle-like peaks were all about, grotesque rocks dotted the irregular plateau before them, deep gulches and ravines were everywhere. It was a wonderful view, that beheld by the adventurers, and could have been enjoyed to the fullest had they not been in such terrible plight.

Luckily there was a full moon that night, lighting the vast expanse with a weird brightness. Countless stars shone down from the clear sky, appearing so close that they could seemingly be touched.

“Like we’re in another world,” breathed Bob, as he and his chum rode rapidly at the rear of the pack camels.

“Does seem strange, doesn’t it? I wonder if we’ll live to find the hidden riches?”

“Of course we will.” Bob cheered his friend as best he could, and himself felt much the better for it.

Luck was with them that night. The plateau remained open and free from peaks and rocky crags that would have delayed progress. It was, however, very unlevel, and the dromedaries often found it necessary to slow down to a difficult walk.

It was very late when they finally halted and made camp under the beautiful mountain sky. After a brief supper, at which almost the last drop of water was used, they fell asleep, not to awaken until the sun was well up in the sky the next morning.

“You know,” remarked Fekmah, “it seems strange that that well was dry. I been thinking about it since we left it behind. Tishmak too thinks it strange.”

“Why?” questioned Mr. Lewis, sensing that something was in the wind.

“Because,” Fekmah said gravely, “it a large well, and should not go dry much easy. Tishmak think it been covered up.”

There were exclamations of surprise from the Americans.

“You mean,” began Mr. Holton, beginning to catch the point, “that someone did it to keep us from continuing the journey?”

“Yes. I think it might have been the two thieves who stole my map. They did it to keep us away from hidden treasure.”

There were cries of astonishment from the others. For the past few days the thought of the thieves had been absent from their minds. Now they began to realize that at last they had probably come into the region in which were the hidden riches.

“Then the rascals must be around here some place,” said Joe, looking about sharply. “Perhaps they’re right around here.”

Fekmah got out the map he had made from memory after the original one had been stolen. He studied it closely for a few minutes.

“Hidden treasure still great distance away,” he said at last. “We not find it till several days pass. I think the two thieves not here but somewhere near treasure.”

“What’s the next landmark?” inquired Mr. Lewis, as the camels were made to move forward.

“The gorge of Arak,” Fekmah returned. “It quite a distance from here, but Tishmak lead us to it quickly.”

All morning they trudged on without coming to the well that Tishmak knew was somewhere in the first range of mountains. Although it seemed impossible, their thirst rapidly increased still more.

“Say,” cried Bob, as a sudden thought struck him, “if those two thieves could cover up the first mountain well, they might do the same to others. Wouldn’t it be possible?”

“Not the next one,” returned Fekmah. “It too large. Take many, many men to stop it. But there are several small ones farther on that could be covered.”

At an hour before noon it was necessary to stop for the daily rest, even though they would have liked to continue in search of water.

They were in a narrow valley between tall, sharp peaks. A ribbon-like dry river bed wound in and out among the brightly colored rocks, suggesting that once a rushing stream had forced its way through the mountains.

“How I wish the river were still here,” said Joe with a sigh.

As soon as camp was made, the explorers took it easy in the shade of the tent, more than glad to escape the terrible heat of the sun.

But before long Bob and Joe became restless. At last Joe got up and stretched. He sipped a very small quantity of water; then motioned for Bob to get up.

“What’s up?” the latter asked.

“Come on,” said Joe, picking up his rifle. “Let’s go out awhile. I’m anxious to explore these mountains around here. There’s no telling what we may come across.”

Bob was willing, and as the sun was slightly less hot, they started out in the direction of a large mountain that had tall, sharp points reaching up into the sky.

“What’s that over there?” asked Bob, pointing to a wall of rock some two hundred feet away.

“Don’t know. Let’s go over and see.”

The youths walked over to the precipice and then halted before a small crack that looked to be the entrance to a cave.

“Shall we go in?” asked Joe.

“I’m game. Come on.”

The hole in the rock was so small that it was necessary to crawl on their hands and knees for a short distance. Then the cave became larger, and they could stand.

Bob had his flashlight in his pocket and at once switched on the light.

“We’re in a large cave, all right,” observed Joe, casting eager eyes about. “There’s another opening away over there,” pointing to the far side of the cave. “Let’s go through it and see where it leads us.”

The hole was so small that the boys barely got through crawling on their stomachs. But at last they reached the other side, and Bob turned the light ahead.

“Just another cave,” said Bob. “Chances are——”

“Wait!” started Joe, gazing at the darkness before them. “Let’s have some light over there.”

The beam was turned in the direction indicated by Joe, and the next moment the boys gave startled exclamations.

“A narrow passageway,” observed Bob. “Come on. We’ll see where it takes us.”

Suddenly, as they rounded a sharp corner, the youths came face to face with something that made them cry out in delight.

There, directly before them, was a large underground pool of sparkling water.

With a word of thanksgiving the young men rushed over and gulped up large quantities of the precious fluid.

“At last!” cried Bob, too happy for words. “At last we’ve found water!”

---

TO the two boys, who had hoped against hope that their parched throats could be relieved, the priceless water tasted like nectar. They had felt sure that grim tragedy was near. Now their spirits were restored to a new high level, and they considered themselves equal to anything.

At last, when they had fully quenched their thirst, they glanced about the cavern.

Near the edge of the pool were the tracks of wild animals, which had evidently made this place a frequent haunt. The youths did not recognize all the imprints, but Joe stoutly declared that gazelles had been there.

“Doesn’t seem pleasant to know that we’ve been drinking after wild animals, does it?” laughed Bob.

“No. But we won’t think of that, especially since our thirst was so great. Then, too, it’s not likely that many germs are to be found away out here in the desert mountains.”

The youths stretched out on the cool white sand beside the pool. The atmosphere in the cavern was such a departure from the fierce outside heat that they were content idly to while the time away, despite the fact that they should be getting back to camp. At times they bent over to drink of the refreshing water, delightfully knowing that they could have all they wanted.

Then they grew drowsy and gradually fell asleep, a thing that they should not have done.

At last they were awakened—suddenly! Every nerve in their bodies seemed tense. Something told them not to move.

Slowly they edged around and looked toward the back of the cave. Then they started, as a savage growl rent the air. A fierce tiger cat was crouched ready to spring. It had evidently come to the pool for water when it had discovered the youths.

There was no time to take aim with their rifles, for the beast would be upon them.

Slowly Bob reached for his pistol, and Joe followed suit. At last the boys were ready for action.

With a quick motion Bob whirled about and took hasty aim; then fired. A second later the report of Joe’s gun rang out.

“Missed!” cried Joe in horror. “Both shots missed!”

“Well, we won’t miss again,” said Bob, gritting his teeth. “We’ve got to stop him.”

Bob jumped to his feet and took aim. Five shots followed in rapid succession. Joe continued the defense with his revolver.

When the deadly fire ceased, the tiger cat was literally riddled with bullets. It gave a convulsive twitch and rolled over, dead.

“Finally stopped him,” muttered Joe, his face wet with perspiration. “And a powerful fellow, too.”

“One can do a lot of things if he has to,” remarked Bob, putting his gun back in its holster.

The youths lost no time in getting out of the cave. They would have liked to remain in its cool retreat much longer, but they realized that it was necessary to get back to camp.

“Won’t our dads and the others be tickled beyond words when we tell them we’ve found water!” smiled Joe, as they crawled through the narrow passageway.

“Tickled is too weak to describe it,” said Bob. “I bet old Tishmak will hug us to death.”

At last they reached the outside and turned their footsteps toward camp. It was but a short distance away, beyond the tall precipice at the entrance to the cave. The youths put unusual energy into their legs and in but a few moments were met by all of their friends. Their fathers, in particular, rushed forward anxiously.

“Where have you been so long?” demanded Mr. Holton, vexed to the utmost that the young men should stay away from camp for an indefinite period without giving an explanation of where they were going.

Joe’s father’s temper was also wrought up.

“Did something hold you back?” he asked.

“Yes,” Joe answered quietly. “Several things kept us from returning sooner. But it may interest you more if we tell you that we’ve found water.”

“Water!” Mr. Lewis was all excitement. “You mean—you actually have located a well?”

Mr. Holton and Dr. Kirshner listened breathlessly. Fekmah translated joyfully to Tishmak.

“Not exactly a well,” returned Bob, “but something just as good. An underground pool. And how cool it is! Come on,” he added. “I know you’re all dying for a drink.”

Hastily the men followed their young companions over to the large cliff. Then, after crawling through the small opening, they found themselves at the edge of the pool of bubbling water.

For a moment the men could hardly believe their eyes. At last! Water!

Suddenly, as though urged on by some unseen power, they bent down and drank until they could hold no more. It was pleasure unthinkable!

At last Dr. Kirshner straightened up.

“I’ve never had such enjoyment in years,” he said happily, and then added: “Lucky that our thirst was no worse than it was, or it would have been necessary to restrain ourselves from drinking too much at once.”

When the men had finished drinking, they glanced about the cave. Their flashlights fell on the body of the tiger cat, and they looked up in surprise.

“What’s this?” inquired Mr. Lewis, pointing to the bullet-riddled carcass.

Bob and Joe smiled.

“That old boy tried to make us remain for dinner, but we fooled him,” explained Bob. “We had to empty our revolvers to stop him, though.”

There was a clamor of excited questions, and the youths were forced to relate every detail of the encounter. When they had finished, the naturalists bent over to examine the striped skin.

“Too bad, but I’m afraid you’ve put too many bullets in him for us to use the skin,” said Mr. Holton regretfully. “And a large specimen, too. But then,” he went on, “we won’t think of that when your lives hung in the balance.”

The explorers spent a few minutes sitting in the cool white sand. Then they went back outside to get the water containers.

They had had an uneasy feeling that perhaps the camels had been molested during their stay in the cavern, and gave a sigh of relief upon seeing them sitting peacefully near the tent.

As it was getting late, camp was broken, and the dromedaries were led to the entrance of the cave. The water containers were carried in to the pool and filled to capacity with what stood between the explorers and death.

“Now that everything is in readiness, I suppose we must be getting on our way,” said Dr. Kirshner. “But I must admit I hate to leave that pool behind. Somehow I’ve become greatly attached to it.”

“Does seem too bad,” Mr. Lewis agreed. “But I suppose we will find other wells and sources of water. Where is the next one, Fekmah?”

“Many miles away,” the Arab returned. “But come to think of it, Tishmak says one around here near. If it very far away, we go to it.”

When the question was put to him, the guide replied that the well was but a few miles away. He considered it unnecessary to find it, as another was a day’s journey in their direction. He informed them that since it was very large, it could not be easily covered up by the two thieves.

With one last look at the high precipice, the explorers turned the camels back on the lane between the mountains. With the right kind of luck they would come to the gorge of Arak some time the next day, and another landmark on Fekmah’s duplicate map would have been noted.

As they penetrated farther into the mountains, the scenery became more beautiful. There were many wonders that caused the explorers to gasp in astonishment.

“The Ahaggar range is of larger extent than the Alps,” said Dr. Kirshner, as they circled about among the rugged cliffs. “And although not of extremely high altitude, these Saharan mountains have many show points that cannot be found elsewhere.”

“And they are comparatively unknown to the outside world,” put in Bob. “Why, the average person doesn’t even dream of mountains being in the heart of the old Sahara.”

All along the way Bob and Joe took motion pictures of the many strange marvels of nature. They photographed the tall peaks, the deep gorges, and the narrow valleys. They turned the cameras on the many ancient inscriptions that were of so much interest to the archæologist.

“We’ve run off a good many hundred feet of film,” remarked Joe, after the cameras had “purred” for an unusually long period as the youths filmed a deep canyon through which they passed. “In fact, if they had given us twice as much film we could easily have used it all.”

Bob nodded.

“And there’s less danger of losing it in a hot, dry region like this,” he said. “Isn’t at all to be compared with the damp, tropical climate of Brazil.”

Slowly the country became more rough, until that evening, after the meal, the adventurers found it very difficult to pick out a way between the many large rocks. On one occasion they passed through a dark tunnel-like passage beneath high, overhanging peaks, and had literally to feel their way through. There was not the faintest ray of moonlight to lighten the deep passageway.

When they finally came to the other end they gave sighs of relief that at last the moon could again be seen. But now something else hindered progress. A peculiar desert plant, with sharp, poisonous needles and a rather disagreeable odor, had been known previously to the explorers. Now, as they emerged from the dark recesses of the tunnel, they came upon large clusters of these plants. Everywhere the dromedaries went, it seemed, they were forced to tramp through these formidable shrubs.

“It’s a wonder they can stand it,” said Joe, shaking his head. “Their feet are already swollen almost double.”

“Be tragedy if the animals would have to stop,” the other youth said. “It would mean our end, I guess.”

“They’ll make it all right,” put in Mr. Lewis, who was riding at the rear with the boys. “But, needless to say, we couldn’t walk on them.”

Suddenly, as they came to the edge of a dry river bed, Dr. Kirshner halted his camel and looked about on the ground. The others waited a moment to see what he had discovered.

“An ancient tool of flint,” he announced, commanding his camel to kneel.

The archæologist picked up the instrument and examined it carefully with the aid of a flashlight. It was about a foot long and shaped to resemble a crescent. The inner edge was as sharp as a razor.

“Doubtless some kind of a knife,” Dr. Kirshner said, as the others crowded around him. “Shaped out of flint by people of the Neolithic age. Perhaps it was used to harvest crops.”

“Crops? In the desert?” Bob was amazed.

The scholar nodded.

“It is firmly believed that primitive people lived in what is now the desert rather than along river valleys of more modern prominence. Of course the Sahara was at that time much less arid, or dry, than it is today.”

Dr. Kirshner searched about for other relics, but found none.

“It is strange how that tool got on the surface of the ground,” he remarked, as they turned the dromedaries ahead. “Other expeditions have penetrated into this region, and it is quite obvious that they would have found it had it been in sight.”

“Perhaps a rainstorm washed it out of the ground,” suggested Mr. Holton.

They rode until late that night, for they were anxious to come to the gorge of Arak some time the next day.

“We should see it tomorrow afternoon,” predicted Fekmah.

Notwithstanding this, they rode all the next morning without coming to the landmark. Finally Tishmak gave up in disgust and stopped in the shade of an overhanging rock. It was nearly noon, and the necessity to get a meal was becoming more apparent.

When they had finished eating they continued to rest in the tent. At this high altitude the sun was less hot than it had been on the plateaux, and it would have been possible to ride farther. But they had become accustomed to the usual afternoon rest and were loath to depart from this regularity.

But Dr. Kirshner had sat only a few minutes before he got up and stretched. Mr. Holton and Mr. Lewis were asleep, but Fekmah and Tishmak remained awake. Bob and Joe sat in one corner of the tent, sleepily gazing out at the distant peaks.

“I’m going out and look around,” Dr. Kirshner said to them. “Care to go along?”

Bob replied in the negative, but Joe arose and walked over to his rifle.

“Don’t stay too long,” advised Bob, as Joe and the archæologist started out.

They were familiar with the country in the immediate vicinity of camp. As there was nothing of new interest to be found there, they hiked farther to the south. The scientist wished particularly to find more ancient inscriptions, and, if possible, other evidences of ancient civilizations.

“What’s this?” cried Joe, slapping his hand to his face. “Well I’ll be—— Some kind of a fly.”

“It is a wonder we haven’t come across insect pests long before this,” Dr. Kirshner said. “They are very common all through this section.”

The flies had been discovered while they were trudging through a long, hot passageway between two high wall-like rocks. Now, as the two adventurers passed farther on, they came into more of the insects, which swarmed about as if thirsty for human blood.

“Ought to have some kind of a spray,” remarked Joe, pushing them away in great numbers.

“We have, in camp,” his friend said. “If the pests bother us much we’ll have to make use of it.”

After an hour’s hike they came to another dry river bed, and again Dr. Kirshner found flint implements scattered about. Joe had a small motion-picture camera with him, and at the scientist’s request he filmed the half-buried primitive tools as they lay hardly visible in the sand.

“I want proof that these antiquities came from the Sahara,” Dr. Kirshner said, placing them in the small box he carried over his shoulder for the purpose.

A little later Joe started to take a motion picture of a small animal that darted across the river bed, but cried out in disgust.

“A pesky fly got in front of the lens,” the youth explained. “Looked as big as an elephant.”

“One scene ruined,” laughed the archæologist. “But you’ll have to get used to that.”

The adventurers stopped here and there to rest and sip a small amount of water. Then they would hike on, always on the lookout for the unusual.

They had just rounded the corner of a tall, cone-shaped peak when Joe stopped and pointed to the sand near by.

Dr. Kirshner’s jaw dropped in surprise.

“Footprints!” he cried. “Human footprints!”

He had hardly uttered the words when there came a chorus of yells from behind a large rock. A moment later ten or twelve rough-looking Arabs darted out and surrounded the Americans. The natives at once disarmed the whites by sheer force and then displayed long knives threateningly.

The Arabs chattered ominous words, which caused Dr. Kirshner to start in alarm and fear.

“We are being captured!” he exclaimed excitedly. “These Arabs are hired by the two thieves who stole Fekmah’s map!”

---

AT Dr. Kirshner’s dread explanation, Joe cried out in surprise and fear.

“Captured!” he mumbled in a strange voice. “Find out how long they are going to keep us.”

The scientist put the question before the Arabs, who laughed mockingly.

“Until the treasures have all been taken from the hidden cave,” they replied in the native language.

Dr. Kirshner could hardly believe his ears.

“Then—the riches have been found?” he demanded.

“Yes. And we are to keep you away. We know not how long it will be. If you act right, we will treat you well. But if you try to get away you will be severely punished.”

“Where are you taking us?”

For answer the Arabs only laughed.

“What do you think of it?” asked Joe, after his friend had translated the natives’ words.

Dr. Kirshner shook his head.

“Looks like we’re not going to get back to camp today,” he said gravely. “Worst thing is, these rascals may hunt out our friends and capture them also. If we could just leave some word that would give them a hint to be on the lookout——”

The two Americans were forced along the narrow edge of a deep canyon, and more than once they felt that they were but an inch from death. Their tempers were thoroughly aroused, but they knew that they had no chance against such a horde.

“These fellows are a bit different from American roughnecks,” Dr. Kirshner said. “Arabs would not hesitate to stick a knife through you if not satisfied with your actions, but our own countrymen would ordinarily think twice before doing such a thing.”

The two explorers were in the midst of the group, with swarthy natives on each side of them. To attempt to break loose would indeed be futile.

“I wonder if we will be taken near the hidden riches?” muttered Joe, gazing ahead at the distant country.

“Hard telling,” the archæologist replied. “Of course it is possible, but I doubt it. Still they might purposefully show us the treasure to let us know how much we are missing.”

A half-hour’s traveling brought them to the base of an unusually high peak. It might, thought the Americans, be Mount Oudane or Illiman, as it was every inch of ten thousand feet.

There was a small well in a crevice between the rocks, and much to their great delight the prisoners were given the opportunity to drink to their hearts’ content. The water was unusually cool, protected as it was from the heat of the sun.

But only a few minutes’ rest was allowed, even though the Americans were very tired after the ceaseless afternoon tramp.

Another hour of hiking over the rough country brought them to a high hill, which Dr. Kirshner said led to the central plateau of Atakor. For a great distance it was almost flat country, with little or no vegetation.

The prisoners were forced to climb a narrow ledge and came at last to the top of the mountain. To their right was a large entrance that led undoubtedly into a cave.

The Arabs motioned for the whites to stop and turn into the cavern. Dr. Kirshner and Joe hesitated for a moment then did as directed.

At first they found themselves in utter darkness. As their eyes became more accustomed to the blackness, they saw that a long, narrow tunnel stretched away from the back of the cave. Whether it led to any place in particular they did not know.

“Well, I guess we’ve come to the end of our tramp,” observed Joe, looking about to see what the Arabs intended to do next.

There were no chairs or boxes to sit on, but slabs of rock invited the newcomers to sit down.

As soon as it became evident that the Americans had settled themselves, the Arabs stationed themselves at the entrance of the cave. Before long, however, all of the men but three departed.

“Looks bad for us,” remarked Dr. Kirshner. “We were fools to start out alone in this country when we knew we were getting near the hidden riches.”

“Too late now,” mourned Joe. “We’ll have to make the best of it, I guess. But I’d feel a lot better if we had some way to warn Dad and Bob and the others. Perhaps they’ll walk right into a trap set by those Arabs.”

The cave in which they were guarded was in the side of a wall of rock, which was several hundred feet above the surrounding mountains. From their lofty positions the Americans could look out over scores of miles of rugged country.

Dr. Kirshner had his binoculars strapped over his shoulder and took them out to view the distant panorama. The binoculars were of very high power, made by a well-known firm.

Suddenly his eyes fell on something that made him gasp in astonishment.

“The cave of riches!” he cried. “I can see it! And there are five or six Arabs walking inside!”

---

DOWN a little valley between two high mountains rode four explorers, their eager eyes penetrating every crevice and notch in the mountainous country about them. High-power binoculars were turned upon every level stretch, rifles were fired at regular intervals, voices were brought to new swells. It was a search that under ordinary circumstances would have brought Dr. Kirshner and Joe back in a very short time.

Finally, after the searchers had been out several hours and darkness was beginning to fall, Mr. Lewis stopped and buried his face in his hands. He realized that defeat was staring them in the face.

“Guess they’re really lost,” sighed Bob Holton, his face extremely sober.

“Or else something has happened to them,” added Fekmah in a voice that he tried to keep steady.

Mr. Lewis said nothing, but he feared all too much that the Arab was right. And yet, he reasoned, they were likely to be very careful and not take chances. Still that would not prevent nature or wild tribes from harming them.

Mr. Holton, however, was very optimistic. He believed that, despite the length of their stay, the two were safe. Perhaps they had fallen asleep from exhaustion or had wandered farther away than they had intended and were forced to spend the night in the mountains.

Tishmak had been left at the camp, as it was thought best to have someone there in case the archæologist and Joe should return while the searchers were gone.

“We’re a long distance from camp,” said Mr. Lewis, as the searchers sat on their camels at the brink of a deep gully. “Shall we try to get back tonight?”

“I’m in favor of it,” returned Mr. Holton impatiently. “Of course we left word with Tishmak that we might spend the night away, but he may be greatly worried. Then, too, he might not be safe there alone.”

The others thought this good advice, and turned the dromedaries back up the lane. They could possibly get half of the way there before the darkness would halt them. Then the moon would probably furnish sufficient light to continue.

“Here’s hoping they will be at camp when we get there,” said Bob.

But Tishmak was the only one who greeted them when finally they rode wearily up to the tent.

The guide had fully expected to see the lost ones return with the others, and his face wore an anxious look when he saw that their search had been in vain.

Fekmah immediately related their past experiences, concluding by asking what Tishmak thought had happened to them.

The guide replied that, as Mr. Holton had said, perhaps they had wandered farther away than they had intended and were forced to spend the night away. Of course, he went on, tragedy might have come upon them, but he doubted this very much. The Tuaregs who inhabited this region were friendly to strangers, showing excellent hospitality. And both Dr. Kirshner and Joe he considered able to take care of themselves. He finished by saying that, through his guiding numerous expeditions into the Sahara, he believed himself capable of judging a true explorer.

When Fekmah translated this to the Americans, they were much relieved. Especially was Mr. Lewis hopeful. He had confidence in Joe and believed him equal to taking care of many tight situations.

Notwithstanding this, there was little sleep for any of them that night. When at last the sun began to peep through the distant mountains they were up ready for action.

“We’ve got to find them today,” said Bob, gritting his teeth.

“We will, if they are anywhere around here,” Mr. Lewis added. “Let’s hurry and have breakfast.”

As soon as the meal was over, they again started out on the search, this time taking Tishmak and leaving Fekmah. The latter thought this the best procedure, as the guide could render more assistance in searching the mountains.

Taking the opposite direction from the one they followed the day before, the explorers rode off, bidding warm farewells to Fekmah.

For several miles they rode over the smooth surface of a dry river bed. Then they turned and followed a path around a small mountain.

“Wonder how this path got here?” said Joe, as they plodded up the hill.

“Wasn’t made by nature,” concluded Mr. Holton, observing the regularity that was persistent with every step.

He resolved to use his limited knowledge of the native language and inquired of Tishmak, for surely the guide would know.

When finally the latter understood, he replied that the lane had been made by Tuaregs who inhabited this region. Perhaps the path would lead them to a village.

But the searchers trudged on around the hill without seeing any signs of natives. However, they finally broke away from the narrow way and emerged on level country.

They were now on a high plateau, with towering peaks on all sides of them. As far as the explorers could see, there were no breaks or ravines anywhere about.

Rifles were discharged at intervals, and hoarse shouts often rent the air. At every few steps the searchers stopped to look about, almost expecting eventually to find the lost ones nearer than they thought.

Once Bob thought he heard footsteps, but several minutes of listening convinced them that no one was about. Perhaps it had been his imagination.

“Sounded like someone was coming toward us,” the youth said. “But I guess I just thought so.”

“We’ll have to keep our ears and eyes wide open,” Mr. Lewis reminded them. “If Joe and Dr. Kirshner are anywhere around here, it might be possible to hear them.”

“Isn’t likely that they fell into the hands of Tuareg raiders, is it?” asked Mr. Holton.

“Tishmak said not,” Joe’s father returned. “He thinks that the Tuaregs around here are friendly and peaceful.”

A little farther on they passed several large slabs of rock that were covered with ancient inscriptions and drawings. Dr. Kirshner would surely throw a fit of delight if he could see them. But, thought Bob, perhaps he had already come to them and was searching for more, quite forgetful of the necessity to get back to camp. But no, this could not be, for Joe would realize that necessity if the scientist did not.

At noon they stopped for lunch under a large crag that resembled an inverted hook. There was plenty of water in their containers, giving each the opportunity to satisfy his thirst.

There was not much conversation during that rest, for they were all busy with their thoughts. And those thoughts were anything but cheerful. But they refused to give up hope so soon, for another half-hour might see the two lost ones back with their friends.

Scarcely ten minutes were spent in the shade of the rock. Even then Mr. Lewis felt that that time had been wasted.

“Something might have happened to them during that time,” he said, greatly worried.

Mr. Holton laid a hand on his friend’s shoulder.

“Snap out of it, Ben, old man,” he begged. “I’m willing to bet that they are safe and well. And I firmly believe we will find them before another day will pass.”

Mr. Lewis did resolve to cheer up and be hopeful; but still he possessed a haunting fear that perhaps tragedy had come upon them.

The sun blazed very hot that afternoon, scorching the already baked soil. This did not hinder the progress of the searchers, however, who trudged constantly on.

Suddenly, as they passed over a wide valley strewn with rocks and dotted with cracks and ravines, Bob stopped and looked about expectantly. The others had also caught a sound.

The next moment the explorers were seized with fear, for ten or twelve evil-looking Arabs darted out on dromedaries and rushed toward the explorers.

“What’s this!” cried Mr. Holton, as one of the men caught hold of his camel.

There was no chance to use their guns. The Arabs were on the lookout for any treachery.

Suddenly Bob saw a chance and, drawing the reins of his dromedary, he dashed away at full speed for a short canyon between the rocks.

---

URGING his dromedary on to the utmost, the youth was carried over the narrow valley at a pace that ate up the distance surprisingly. In fact, never had he traveled so rapidly on camelback.

When he was several hundred feet away, he glanced back, to see that two of the Arabs were pursuing him desperately. At the start he had put a good distance between himself and his enemies, but now the latter were gaining swiftly. They were more familiar with the country and knew better how to command their camels to move fast.

“If I can only make that little canyon,” the youth thought, bending low so as to lessen the wind resistance.

The canyon was near now, but a hurried look over his shoulder told Bob that the Arabs were near also. If he could only get there!

He lashed the dromedary with a new determination and entered the narrow way between the mountains just as the Arabs passed over a small grove of low shrubs some two hundred feet away.

Bob knew that this was a very short canyon and that there were numerous large rocks and crevices at the opposite end. Perhaps he could successfully evade his pursuers by hiding in one of these openings in the mountainsides.

Sharp jagged crags protruded from all sides of the thread-like passageway between the high walls. It was very dangerous to ride with much speed in such a place, but the chance had to be taken.

He reached the other end of the passage with but a moment to spare. Immediately his dromedary was cut over to the right behind a barrel-like rock. But the youth did not stop there; he wound in and out among the many huge boulders.

At last he came to a stop in a large crevice between two imposing slabs of stone. With every nerve on edge, the young man listened.

“They’re coming!” he thought, getting out his revolver. “But they won’t get me if I can help it!”

But he was in a very secure hideout, and it was unlikely that the Arabs would locate it. Still he realized that they probably knew this region better than did he.

As Bob waited breathlessly, his mind was in a whirl. Who were these Arabs? What did they want? Why had they descended upon the little exploring party so mysteriously? Bob did not know what to make of the situation, but he knew that danger was at hand. What further added to his perplexity was the fact that Arabs did not normally inhabit the Sahara so far south as this.

Suddenly he started, as a thought struck him. Was it—the two thieves who stole Fekmah’s map? Entirely possible, of course.

Then a strange thing happened. As though informed by some unseen power, Bob grasped the whole situation. He saw Dr. Kirshner and Joe in the clutches of the two thieves, being held as prisoners. He visioned his father, Mr. Lewis, and Tishmak riding away under the guard of the Arabs.

“Those thieves did it, then, to keep us away from the hidden treasure,” thought the youth, and he could not have had a more accurate realization.

For some time he listened closely for any sound from the two Arabs who had pursued him. He thought once he heard the footsteps of camels, but was not sure.

What was he to do next? He was now doubly glad that good fortune had enabled him to escape from the would-be captors. If the Arabs had been nomad plunderers, he would probably not have suffered much by remaining with his father and the others. But as it was, there was a possibility of bringing rescue to his friends.

“How am I to do it?” the youth mused, trying to remain calm.

Suddenly the far-away noise of footsteps came to his ears, and he knew that the two Arabs who had followed him had given up and were abandoning the chase to join their friends back in the valley.

After several minutes of waiting, Bob got off his camel and tethered the brute to a small protruding rock. Then he walked over to some distance beyond the mountain near which he had been hiding.

He glanced up to the top of the peak and saw that it was unusually high. The sides stretched almost straight up.

“If I could only get to the top of some tall mountain,” Bob thought, his eyes scanning the landscape. “Then I might be able to see where Dad and the others will be taken.”

The peak before him offered no footholds and therefore could not possibly be scaled. He looked about for other sky-piercing hills. At last his eyes fell on one about a hundred yards away, and he resolved to inspect it.

“Looks like there might be a chance there,” the youth thought and then walked over and untied his dromedary.

He rode over to the mountain, every step bringing new hope. The peak, rocky as it was, was rather gradual and not straight up, as were many others in the vicinity.

Once more the camel was tied by the rocky side, and Bob moved over to gaze up to the top. The dizzy height almost took his breath away. But he saw at once that it would be possible to climb to the very summit of this imposing peak of rock.

Bracing himself to the task that was before him, Bob began the dangerous ascent, slowly, at first, and then climbing faster. It was exhausting, fear-inspiring, but he went bravely up. There was no option in this case. He must observe where his father and the others would be taken by their Arab captors.

“If I can only get up in time,” the young man thought, as he sought out a means to ascend a five-foot plate of smooth stone that was directly above him.

To do this, it was necessary to edge on around the mountainside until he came to a rough, gradual section. Then climbing became comparatively easy.

Once, when he was but a third of the way up, he glanced back over his shoulder to the ground below and almost lost his balance. But he caught himself with a quick motion, and after resting a moment from the terrific strain, continued the climb. That glance to the ground had revealed that he was several hundred feet up. How easy it would be to slip backwards!

Another hundred feet and he found himself on a wide shelf, which seemed to encircle the peak. A short rest was taken here, and in the end he felt much better for it.

“Wonder if I can get down from here?” the boy mused, again taking up the climb. “I’ll find some way, though,” was his conclusion.

For a few more hundred feet the way was very gradual, with many rocks of different sizes affording footholds. But as he came to a sharp break in the side of the mountain, the lofty pointed crag shaped up straighter and more jagged. Once he thought he had gone as far as possible, but finally managed to get to the brink of a slab that had threatened to hinder his progress.

“On to the top,” he thought, bringing his foot up another notch with difficulty.

At last, panting and perspiring, he ascended the last stretch and took his position on the flat surface of a platform-like formation. Then he turned to look below.

A cry of astonishment came from his lips as he saw that he was hundreds and hundreds of feet in the air. Far, far below, he could dimly make out his dromedary by the outermost side of the mountain. The beast seemed no larger than an ant.

“I wonder if Dad and the others can be seen,” he mused, turning his gaze in the opposite direction.

“Yes!” he muttered excitedly. “There they are.”

He had caught sight of his father and friends being led up the valley by their Arab captors. The camels on which they rode seemed only crawling, so small did they appear.

As usual, his binoculars were strapped over his shoulder, and he took them out to get a closer view. Through them he could see the worried expressions on his friends’ faces, and the surly grins of the Arabs.

There was a sort of narrow ledge that passed up the little valley and around the mountain. It was up this that the captives were being led.

“There’s probably a hideout somewhere around here,” the youth thought, shifting his eyes from the camel procession to the rugged country ahead.

From his lofty perch it might be possible to get a glimpse of the hidden cave in which were the riches. Bob scanned the landscape about him but finally gave up and again followed the movements of his friends and the Arabs.

“If it’s anywhere around here, it’s concealed from view,” he thought.

The youth was crouching low behind a flat shelf of rock, so as to be invisible to the Arabs if they should happen to look up in that direction. He knew that their seeing him would spell his doom.

As Bob watched the line of camels and their riders, it seemed that they were making no time at all; yet he knew that they were winding around the mountain as fast as possible.

Up, up, up they went, but always in sight. Bob noticed that they were gradually moving away from him, and he wondered if he would be able to follow their movements to the end.

“If I can’t, I’ll have to change peaks,” he thought, although he realized that this would be difficult and dangerous.

The Arabs and their captives were now nearing a high wall of rock that would prevent them from being seen. But it would be for only a short time—if they did not stop opposite it.

After what seemed like hours to Bob, they emerged again into view, this time at the brink of a high cliff.

“Hope they don’t step off of there,” the youth breathed, his heart in his mouth.

At last, just as the sun was beginning to sink behind the distant peaks, the camels and their riders came to a stop at an opening in a mountainside that evidently led into a cave.

Hardly able to hold the binoculars steady, Bob watched breathlessly, almost expecting to catch sight of Joe and Dr. Kirshner. But those individuals did not make an appearance. Bob did not doubt, however, that they were in the cave.

A moment later, captors and captives dismounted from their dromedaries and walked through the opening out of sight.

Bob waited silently for another half-hour, thinking that it might be possible that this was only a temporary prison. But when at the end of that time no one had left the cave, he was convinced that this was a permanent hideout.

“Now I suppose it’s up to me to get down from here right away,” Bob thought, gliding silently off the shelf and onto a narrow ridge that was directly below.

Carefully he felt his way down with great difficulty. As he had surmised, the descent would prove much harder than the ascent.

Once his heart sank, as he saw that a five-foot wall of stone was directly below him. But then he suddenly remembered that a little to his right there were protruding rocks that would offer footholds. He edged around, and in a short time was again climbing steadily down.

The minutes passed. When he was a third of the way to the bottom, darkness began to fall rapidly. He realized that he could not get to the base of the peak before pitch darkness would envelop him.

“But I’ve got to keep going down,” he told himself, frantically feeling his way among the rocks.

For the past five minutes he had been getting drowsy, sleepy. The day’s strain was beginning to tell on him. With an effort he kept himself awake. He knew the grim consequences if he should suddenly fall asleep while making the dangerous descent of the peak.

He was half of the way down; now two thirds. But a few more hundred feet remained, and he braced himself and continued his slow, careful movement.

“Not much more now,” he observed, glancing down. “Ought to make it in a few more minutes.”

Long before, darkness had come upon him, making the frequent use of his small flashlight necessary. Even then it was a hard task.

“Must be almost to the bottom,” he thought, when another fifteen minutes had passed.

He flashed the light downward and saw that fifty feet still remained. Again he bent his efforts upon the descent that was still before him, and in no time had covered most of the distance.

But just when he prepared to use his flashlight, a small rock gave way from under his left foot. He tried vainly to catch hold of a sharp crag, and then felt himself falling!

---

WHEN Bob reached the ground, he was sore from numerous bruises, but to his great joy his legs and arms responded to his efforts to move them.

He glanced up the side of the peak, but the darkness veiled his vision.

“Wonder what became of the old flashlight?” he mused, feeling about on the soft ground.

Finally his hand came upon something hard, and a thrill of delight ran through him as he realized that he had found the electric torch. But his heart sank as he saw that it had been damaged by the fall.

“Lens wasn’t broken, though,” he observed. “Must be the bulb.”

Without the light there was no way of knowing how far he had fallen. But he readily guessed that it was not over eight or nine feet.

The moon was just beginning to show itself from behind the thin clouds, and it might be possible to travel in its light. Whether to do so or not, Bob could not easily decide. He knew that Fekmah would be extremely worried if no one returned to camp that night, but he doubted if he could keep awake long enough to direct his dromedary over the right way. He finally made up his mind to stretch out beside the mountain and surrender himself over to sleep.

“I hate to treat Fekmah that way, but I don’t believe I could make it back,” the youth thought, closing his eyes.

A second later he fell asleep, not to awaken until the sun was well up in the sky.

“Eight o’clock!” he cried, looking at his watch. “By George! I bet Fekmah is throwing a dozen fits.”

Bob at once jumped up and untied his dromedary. He was on the animal in a moment and rode back toward camp.

“I hope I know the way,” he thought, as he was carried to the spot where his father, Mr. Lewis, and Tishmak had been captured.

But the youth had carefully observed the landmarks as they left camp on the search, and had no difficulty in recognizing the way.

First, however, Bob had made a small sketch map of the distant cave in which his father and friend were being held captive. He was positive he could locate it, perhaps without the use of the map.

Bob was now passing up the path that Tishmak had believed made by Tuaregs. For a good distance it would be necessary to follow this lane; then he would turn off on a level stretch.

Suddenly, as Bob made a sharp bend in the path, his jaw fell in surprise and horror.

Not twenty feet away sat a native, a Tuareg, with his back against a low rock. The man was terror-stricken as he watched a long reptile move toward him with a slow, terrible fascination.

That the man knew not what to do, Bob rightly guessed. If he should make the slightest move, the reptile, a deadly horned viper, would strike.

“It’s up to me to come to his rescue,” thought Bob, and, raising his rifle, he took steady aim.

The report of the gun was followed by a terrible twitching of the snake. Meanwhile the Tuareg had jumped in surprise at the sound of the gun and was now looking at his benefactor thankfully.

Bob rode on up to the man and dismounted, to be met by the Tuareg. The latter was of unusual height, towering several inches above Bob, who was himself six feet.

The man quite promptly threw his arms around Bob and hugged him, too thankful for words that he had escaped a terrible death. It was rather embarrassing for the young American, but he smiled modestly and passed the thanks aside as best he could.

Finally the Tuareg stood away and motioned for Bob to follow him up the path. The youth did as directed, even though he was anxious about getting back to camp.

As Bob followed his newly made friend up the lane, he took note of the man’s dress. He was garbed in a loose black robe, which reached almost to his feet. On his chest were numerous decorations that distinguished him as a man of some importance among his people. What seemed most unusual was a black veil that covered his face, leaving little more than his eyes visible. On his head was a strange high cap of black and white.

“Quite a specimen,” thought Bob. “And evidently a chief or nobleman.”

Ten minutes of walking brought them to the top of the hill. Then, as they moved around a large rock, Bob caught sight of several tents placed about a hundred yards apart on a vast plain.

Several natives came running out, followed by a score more. They rushed forward as they caught sight of Bob and his friend.

The latter at once spoke excitedly to his fellow people, and Bob rightly guessed that he was telling of being saved from the snake by the white youth.

When the man had finished, the Tuaregs looked at Bob with gratitude and admiration. They asked him by signs to come into their tent village, and he did so.

“Wish I could speak some of their language,” he thought, as he was being shown the various things about the tents.

It now became apparent that the man whom Bob had saved from death was the chieftain of the tribe, as he was held in high esteem by all. And no one else wore such decorations as did he.

Suddenly a thought struck Bob, and he smiled in renewed hope. Perhaps it would be possible to engage the aid of these Tuaregs in rescuing his friends from the Arabs. Could it be worked?

Bob was now extremely anxious to get back to camp, for he knew that Dr. Kirshner had prepared a paper with many Tuareg words on it for reference. The youth would get that paper and then come back and ask for help in rescuing his father and the others. Perhaps they would be willing to give aid.

As best he could, Bob told the Tuaregs by signs that he must be leaving, and it was evident that they understood. With a last farewell, the youth turned his dromedary away.

His hopes were high as he rapidly covered ground toward camp. Before coming across these Tuaregs, Bob was in doubt as to whether he could tackle so many of the Arabs alone in order to rescue his father and friends. Now, with the prospects of getting aid from the Tuaregs, the future looked brighter.

“Still they might not be willing to help,” he thought. “But at least I can ask them.”

After winding in and out among the huge rocks and peaks for well over an hour, Bob turned his camel up a little hill and came in sight of camp.

How good it looked! Since his friends had been captured by the Arabs, the youth had had an uneasy feeling that perhaps he could not find his way back.

“Where’s Fekmah, I wonder,” he mused, looking about.

A moment later the Arab came running up, delighted beyond words at again seeing him alive and well.

“What kept you away so long?” Fekmah asked. “And where are the others?”

Bob’s face darkened. He told of his father, Mr. Lewis, and Tishmak being captured by the Arabs, and of his own good fortune in getting away.

“But,” he said, “I have a plan to bring about their rescue.”

“What is it?” Fekmah waited breathlessly.

“On the way back to camp this morning, I came upon some Tuaregs who live in a tent village several miles from here. They were very friendly and wanted me to stay longer, but I told them I had to get back.

“Now Dr. Kirshner has a paper with a good many Tuareg words on it. I remember hearing him tell about it several days ago. If we can find that, everything will probably be all right. We’ll take it with us to their village and ask them in their own language to help us. How does it sound?”

“Very good,” Fekmah returned. “But do you think they will?”

“Won’t do any harm to find out,” Bob said, going in the tent.

Dr. Kirshner’s large satchel was on a box, and the young man at once took it down and searched its contents for the paper of Tuareg words. His nerves were on edge with a terrible fear that perhaps it would not be there.

Papers and books and pamphlets were all taken out and hastily read. Scarcely would the youth glance at one sheet when he would pick up another. Under ordinary circumstances, Dr. Kirshner would not have permitted anyone to go through his belongings, but now it was a case of necessity.

Suddenly Bob straightened up in great relief. He had at last found the object of his search.

“Here it is,” he said to Fekmah, who was standing beside him. “A translation of about three hundred Tuareg words. Now I guess we’ll fool those Arab crooks.”

Bob had had nothing to eat that morning, and he was very hungry. He lost no time in preparing a satisfying breakfast. When he had finished eating, he turned to Fekmah.

“Now,” he said, “I’m going to that Tuareg village and ask for aid in rescuing Dad and the others. You had better stay here with the camels and supplies, hadn’t you? It would probably mean tragedy for us if anything should happen to them.”

“Yes,” the Arab returned, “I will stay. And I not afraid that you will fail.”

“I’ll try not to,” Bob said, getting on his dromedary.

With a warm farewell the youth rode off at a rapid pace. His mind was desperately set upon a purpose. He would rescue his father and friends if he had to do it himself.

The Tuareg village was several miles away, but his fleet-footed camel covered the distance in no time.

“Here’s where I get busy with this new dialect,” Bob thought, getting out the paper of native words.

A score or more Tuaregs came running up, led by the chieftain, whom Bob had saved from death previously. The people shouted sincere welcomes.

Bob glanced down at the paper and found a few words for casual conversation. They were not difficult to pronounce, and the effect upon the natives was astounding. They were indeed surprised to find that this white youth could speak any of their language.

But before long Bob got to the purpose. There was one word that stood out in his mind more prominently than any of the others. It was reeskra (help).

As best he could, the young American picked out several words and put them in sentences. He outlined briefly and simply that his father and friends were being held captives in a cave not a great distance away. If the Tuaregs would give aid, they would be rewarded. Would they help?

The result of his request was instantaneous. The Tuareg men, nearly all six-footers, waved their guns in the air and commanded Bob to lead them to the cave where the whites were being guarded.

A thrill of joy ran through Bob’s veins, and he ordered his dromedary to move forward. At last his father and friends would be released.

---

FOR a distance of several hundred yards the country remained comparatively level, although dotted with huge rocks. Then mountains loomed up before them, and they found it necessary to travel slower.

Bob was followed by about fifteen Tuareg warriors, all magnificent specimens of “desert knights.” Each man was armed with a rifle which, although inferior to Bob’s high-velocity type, could do much damage.

Bob was almost certain he could find the way without the small sketch map he had made from the top of the tall peak the night before. But he had the map in his pocket and intended to consult it if necessary.

Breathlessly he led the way through the rough country and at last came to the spot where his father and friends had been captured by the Arabs.

From then on, finding the way would be easy, the youth thought, for he had only to move toward an odd formation of twin peaks that loomed up above the other mountains in the distance. The cave in which those captured were probably being held was along the side of those tall double peaks.

To make sure of this, Bob got out the map and scrutinized it closely. Then, satisfied that he was right, he dashed forward, the Tuaregs at his heels.

The way now led up the side of a large hill. There was a break just to one side of the path, and the rescuers could look down to the foot of a deep gorge. Bob kept his dromedary as far away from the brink as possible, to do away with the grim possibility of the ground giving way from under his camel’s feet.

Finally, after trudging over a high plateau, they began climbing the base of the twin peaks. At first the ascent was very gradual, but in a short time the path curved upward around the side of the mountain.

“Getting there, all right,” observed Bob, as he noticed that they were now several hundred feet above the plateau.

At last they came to the top of a wide ledge, from which they could look out over scores of miles of rugged country. As the shelf began to narrow, Bob called a halt.

He took out the paper of native words and told the Tuaregs that they were now near the cave in which were his father and friends. It would only be necessary to round a corner before coming to its entrance.

But first he divided the group of natives into two sections. One, under the command of the chieftain, was to move on around the ledge to the cave from the west. The other, led by himself, would climb the steep side of the mountain and walk on above to the other side of the cavern. Then they would meet at the entrance and surround the Arabs and release the prisoners.

When Bob gave the word, the Tuaregs swung into action. Those in his group followed him up the cliff to the brink, while the men under the chieftain began moving around the ledge.

It was a dangerous climb up the steep side of the mountain, but at last Bob pulled himself up to another ledge about fifty feet above the lower one. Then he led the way several rods along its surface. When he thought they had passed beyond the entrance to the cave, he led the descent to the lower shelf.

A moment later he saw that he had miscalculated. He had not gone far enough beyond the cavern to escape the wary eyes of the Arabs who were stationed as guards.

“Caught!” he exclaimed. “Caught square!”

Four Arabs were sitting out in front, and they were on their feet instantly as their eyes fell on Bob. The latter was no more than twenty-five feet away from them, much nearer than he had expected to be.

The Arabs’ rifles were standing against the wall of rock near the cave. But before the men could get to them, Bob rushed forward. With a wild shout he kicked the rifles away and dashed into the cavern.

Startled exclamations—exclamations of joy, surprise, happiness—came to the youth’s ears, and he realized that he had at last found his father, Joe, and the others.

“Bob! You here!” cried Mr. Holton in wild excitement.

“You old rascal! I knew you’d get us out!” came from Dr. Kirshner.

But there was no time for that. Danger was at hand.

“Quick!” he commanded. “Hide. Here, take my rifle, somebody. I’ll use my pistol. There’s no time to lose!”

The words were scarcely out of his mouth when the four Arabs darted inside the cave and made for the captives and their new enemy. They would not be beaten so easily!

With a terrific crack to the chin, Bob sent the foremost Arab to the ground. The other three men were making for the prisoners in the back of the cave.

Mr. Holton had taken Bob’s rifle and was by the youth’s side looking for other Arabs.

Suddenly Bob noticed that the man whom he had knocked down was getting to his feet and making for the rifles not far away.

Without hesitating a moment, the youth dashed out of the cave and directed a stinging blow to the Arab’s nose. The latter staggered a moment at the edge of the cliff, and then, to the horror of the two Americans, fell backwards over the cliff.

Bob gave a cry of regret. Despite the fact that the Arab was an enemy, the young man did not wish to send him to his death.

Mr. Holton had also been touched deeply.

“You—you shouldn’t have done that,” he muttered. “But—it couldn’t have been helped.”

Now a chorus of shouts and yells rent the air, and the Tuaregs rushed into the cave. To the surprise and relief of the Americans, they had captured the two thieves who stole Fekmah’s map. Where had they found them?

Mr. Holton, Dr. Kirshner, and the other former prisoners were taken aback at sight of the natives. At first they thought them other enemies. Bob soon gave an explanation.

The thieves were searched for Fekmah’s map, but the latter was not found.

Meanwhile a struggle was taking place at the rear of the cave.

Joe in particular attracted Bob’s attention. The former youth was grappling with a large, powerful fellow, who was vainly trying to choke his young enemy.

“Joe’s sure a fighter,” remarked Bob, as he and his father looked on for a moment.

“We had better help him, though,” Mr. Holton said. “Come on.”

But a second later they saw that this would be unnecessary, for Joe had suddenly jerked away and sent his fist with all force into the Arab’s jaw, knocking him out.

“Great work!” commended Mr. Holton. “That fellow was dangerous.”

The two remaining Arabs saw that they had no chance against so many, and they surrendered without a struggle.

“Now tell us all about it,” urged Dr. Kirshner, speaking to Bob. “We want to know how you managed to engage the aid of these Tuaregs.”

Briefly the youth outlined his adventures since escaping from the Arabs the day before. He told of climbing to the top of the peak, of saving the Tuareg chieftain from death, and of getting the paper of Tuareg words.

“That’s all,” he finished. “Only these natives came up here with me to get you out of the clutches of these Arabs.”

“A wonderful demonstration of ingenuity,” breathed Mr. Lewis. “We expected you all the time. Knew you’d find some way.”

“But our greatest work is yet before us,” Bob said. “We must drive the Arabs from the hidden treasure—if we can locate it.”

“No,” came from Mr. Holton, “we won’t need to do that.”

---

BOB looked at his father in surprise.

“What do you mean?” he asked.

“Simply that no one is there to drive away now,” was the reply. “We have captured all of the Arabs—even the two thieves who stole Fekmah’s map. And I might add that we have located the hidden treasure.”

“What! You’ve been there?”

“No, but we’ve seen the cave in which it is. In fact, it is possible to see it from here.”

Mr. Holton took out his binoculars and handed them to his son.

“Look away over there,” the naturalist said, pointing to a distant wall of rock that was many hundred feet high. “That small shelf on the side of the cliff is an opening into the cave in which are the hidden riches.”

Bob scanned the landscape ahead. Then he cried out in surprise and amazement.

“A cave away up in that cliff? Seems impossible. How can you get to it?”

“Must be an entrance on the other side,” Dr. Kirshner replied. “Fekmah’s map no doubt points it out. Whether he remembered to put it on the duplicate after the original was stolen, we have yet to see. Where is he now?”

“Who, Fekmah? I left him at camp this morning.”

“Let’s go there now.”

First, however, Dr. Kirshner engaged in conversation with the Tuaregs in their own language. He told them, among other things, of how grateful he and the other former prisoners were for their help in releasing them from the clutches of the Arabs.

The natives were very courteous and friendly, inviting the archæologist to their village. He returned that he would be delighted to visit them, and concluded by saying that they would be given a reward for their generous services.

“Now let’s get out of here,” he said, turning to his friends. “I’m particularly anxious to get back to camp and see Fekmah. I wonder if any misfortune could have come upon him and our camels.”

The Americans, Tuaregs, and Arab captives left the cave behind and trudged down the mountainside. But before they did so, they carried out the food supply that had been in the cave for the prisoners and their guards. It consisted of simple native food, but was welcomed by the Americans and Tishmak.

“There is much more in the cave where the hidden treasure is,” remarked Joe, as he walked beside his chum, who was leading his camel. “We won’t need to worry about not having enough to eat for many weeks.”

“Doubt if we’ll stay here that much longer,” Bob said. “But I imagine it’ll come in handy all right.”

The Arabs were ordered to walk in front of the Americans and Tishmak. The Tuaregs rode on to their village, after asking their newly made friends to visit them the next morning.

It required several hours for the explorers and their captives to get back to camp, going on foot as they did. But when they finally came within sight of the tent and camels, all gave sighs of relief.

Fekmah came running out to meet them, his face showing an intense thankfulness at again seeing his American friends and Tishmak alive and apparently none the worse for their experience.

“So Bob got you from Arab demons,” he muttered and then added: “I knew he would do it.”

Nothing would satisfy him but a complete detailed account of their experiences, and it was Mr. Lewis who related all of the happenings since they had last left camp.

“Howard [Mr. Holton] and Tishmak and I were sure greatly relieved when our captors took us to the cave where Joe and Dr. Kirshner were being held,” Mr. Lewis finished. “Funny, but we had not dreamed of them being prisoners.”

“And I see you’ve brought the rascals with you,” observed Fekmah. “What are we going to do with them?”

“I’m sure we’ve all been thinking about that,” Dr. Kirshner returned. “There are no police so far south as this, and we can’t very well take them with us back to Wargla. I wonder how it would be to take them to an oasis fifty miles or so from here and leave them? There would be no danger of them starving, because dates and water would furnish food. And they couldn’t get away without camels.”

“Sounds all right,” Mr. Holton said. “Do you know where there is such an oasis?”

“No, but I’m sure our Tuareg friends do. I’ll ask them in the morning. Until then we’ll have to keep our eyes on these Arabs. It might be well to tie them up.”

This was thought good advice, and the captives were bound together so tightly that they could not escape.

The remainder of that day passed idly, and the explorers retired shortly after the evening meal.

“But we must be up early in the morning,” Mr. Holton told them. “We have a big day before us.”

They all slept the sleep of exhaustion and did not awaken as early as they had intended.

Breakfast over, Dr. Kirshner and Bob got on their camels and started for the Tuareg village. The others put in a request to go also, but the archæologist stoutly refused, saying that no time must be wasted.

“We only want to make arrangements to take these Arab crooks to an oasis and leave them,” he said. “If more of you go, it will necessarily keep us longer.”

It did not take the two long to get to the natives’ village. The chieftain at once came out to meet the newcomers, and Bob introduced Dr. Kirshner to them.

After a few casual remarks the scientist got to the point. He told the natives of his desire to banish the Arabs to an oasis, if any were near. He also asked if enough camels could be borrowed to take the crooks there.

The chieftain at once replied that he knew of an oasis a half-day’s journey from the village, and that he would gladly let them have the camels.

“Fine!” Dr. Kirshner said in the native tongue. “We’ll go there at once.”

The chieftain insisted upon leading them to the oasis, for, he said, they could not find it alone.

Dr. Kirshner consented, and the head native at once herded enough camels to take the prisoners away. Then the Americans and the Tuareg chieftain started for the explorers’ camp to get the Arabs.

“Be glad when this job’s over,” remarked Bob, as they rode toward camp. “I’m anxious to see the hidden treasure.”

They arrived at camp and placed each Arab on a dromedary. After preparing a lunch to last them until they would return, Dr. Kirshner, Bob, and the Tuareg chieftain began the journey to the oasis, riding behind the prisoners and guarding them closely.

The oasis was about forty miles away, situated on a barren sand plain surrounded by mountains. The Tuareg explained that there was no other well near and that the prisoners would be forced to stay there for an indefinite period, for no caravans passed along that way.

In order to get to the place it was necessary to go through the mountains, and traveling was not any too easy. But they rode with a determination and finally arrived at the oasis.

The Arabs were commanded to dismount and walk forward. Then, after filling their canteens with water, the Americans and the Tuaregs started the return journey, herding the dromedaries ahead of them.

“Now that that’s over, maybe we can rest easy,” said Dr. Kirshner. “Those Arabs can’t get away because of not having camels, and the monotony will punish them greatly.”

Bob, the scientist, and the Tuareg made good time that afternoon, arriving at the explorers’ camp just before sundown. The chieftain lost no time in getting back to his village, after being thanked warmly for his services.

“We’ll see that those Tuaregs get a reward,” said Mr. Holton. “Just as soon as we get to the hidden treasure we’ll give it to them.”

The natives had not been told of the cave of riches, however, for fear that their age-old desire to raid might get the better of them.

Very early the next morning the explorers got their belongings placed on the dromedaries and started out for the cave of treasure. Although it would mean only a few hours’ journey, they were extremely impatient.

“Wonder if those Arabs carried any of the riches away?” asked Bob, as they rode toward the high wall of rock, in the side of which was the cave.

“No,” Mr. Holton returned. “They hadn’t started yet. Were just looking over everything. At least that’s what our guards told us. It seemed that they intended to carry the stuff out in a day or two.”

“Wanted to catalog everything first, huh?” asked Bob. “Well, it’s a good thing we stopped them when we did.”

Fekmah found it necessary to consult his duplicate map very frequently, and he wondered if he had remembered to put in all the details accurately.

Finally, after they had passed the tall wall of rock and were following a narrow trail up the mountain on the opposite side of the cliff, Dr. Kirshner turned to Bob.

“You asked the other day how we were to get into the cave,” he said. “Of course it would be impossible to scale that lofty cliff. Fekmah’s map points out a narrow opening in the rock somewhere in this vicinity, and we ought to find it in a very few minutes now.”

He had scarcely uttered the words when Fekmah cried out in delight and pointed to a peculiar rock formation not far ahead.

“There it is,” he declared joyfully. “There is where we enter mountain to get cave of treasure.”

The explorers, led by Fekmah, moved on up to the spot.

“Here’s an opening!” cried Joe, pointing to a small crack that was barely large enough to let them in.

Getting out their flashlights, they followed Fekmah through the crack and into a narrow tunnel. The air was damp and heavy from the breath of ages, but they trudged on through.

After what seemed like hours, the passageway gradually became lighter, and the explorers found themselves in a large cave.

Suddenly Joe stumbled and fell, unable to catch himself.

“What’s this!” he mumbled.

Then, as his light was turned to the floor, he gave an exclamation of joy.

“The hidden riches!” he said excitedly. “I’ve found them!”

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AT Joe’s welcome declaration, the others ran over in a high state of excitement.

There, directly at their feet, was a huge chest of metal, the lid of which was pushed back. Piled up to the top were emeralds, diamonds, and a myriad of other precious stones. There were gold coins, rifles of ancient design, small silver boxes, and a hundred or more other valuable trinkets.

For several minutes no one could speak. They were too amazed at the value of the treasure. Finally Dr. Kirshner looked up.

“Thousands and thousands of dollars’ worth,” he muttered, as though he could hardly believe his eyes. “And it has all survived through the ages. In addition to the gold and precious gems, those rifles and coins will be of enormous value as relics.”

“Relics?” asked Joe.

“Yes. They date back to the Middle Ages. You see,” he went on, “the Tuaregs have always been fond of raiding caravans and cities. Whenever they see an opportunity to take possession of riches, they go out at once on a raid. The treasure in this cave was undoubtedly collected many hundreds of years ago. That is why there are guns and implements of the seventeenth century.”

“How interesting!” exclaimed Mr. Lewis. “I suppose now you are doubly glad we searched for this cave, because these relics will fit right in with your work as an archæologist.”

A thorough search of the cave was made, and the explorers discovered many other articles of great worth.

“Now we’ll carry this stuff out to the dromedaries,” said Mr. Lewis. “It isn’t wise to leave it in here too long.”

They had brought several large burlap bags, and the treasure was divided into these. There were eight of them, each filled to capacity.

“Guess we’ll have to make two trips,” said Bob. “It’ll be too much for us to get it all out at once.”

“We won’t mind that,” smiled Mr. Lewis. “The more there is the better.”

They carried out five of the sacks and then went back for the other three. When finally everything had been taken from the cave, they rested in the shade of the rocks.

A lunch was prepared of canned food that had been taken from the supplies. All ate heartily, their eyes remaining much of the time on the bags of riches.

“We may have to have more camels to get this stuff back to Wargla,” remarked Mr. Holton. “I wonder if there is a chance of buying them from the Tuaregs?”

“Probably is,” Dr. Kirshner returned. “We’ll see when we get these riches back to camp.”

The explorers thought it best to get the bags of riches to their camp before going to the Tuareg village for camels. Despite the fact that the natives were friendly, they might have the desire to raid the American expedition for their precious find.

Camp was made several miles north of the Tuareg village. Then Bob, Dr. Kirshner, and Joe started out to the habitation.

“Do you think they’ll let us have the camels?” Joe asked, as they moved out of sight of their camp.

The archæologist nodded.

“I’m inclined to think they will,” he said. “We’ll pay them a good price for the animals, in addition to rewarding them for helping get us out of captivity.”

At last they rode into the village, to be met by the chieftain.

Dr. Kirshner told the native that he wished several more camels, and that he would pay a good sum for them. He finished by presenting the man with a number of large coins, treasured so highly by Tuaregs. These, he said, were in return for the services of him and his people in capturing the Arabs.

The chieftain was delighted and at once said that they could have the camels. He walked out beyond the village to a large plain, where several hundred meharii, or native dromedaries, were grazing on the sparse vegetation. These were huge white animals, towering many inches above the mounts of the explorers.

The Tuareg said the Americans could have the brutes for a very nominal sum, and Dr. Kirshner at once accepted his offer. Secretly he knew he was getting a bargain.

“Now to get back to camp,” the scientist said, after bidding the tall native good-bye.

When the three Americans rode within sight of the tent, their friends were indeed surprised at sight of the large camels.

“You sure brought something back this time,” observed Mr. Lewis. “Never in my life have I seen camels of that size and strength.”

“Just what we need,” laughed Joe. “I don’t know how we could have managed without them.”

They took it easy the remainder of that day. In the evening, Dr. Kirshner called his friends together.

“I make a motion that we start back to Wargla,” he said. “You naturalists have collected scores of specimens of animals, Bob and Joe have exposed hundreds of feet of motion-picture film, and I have made numerous archæological observations. And to cap it all, we located the hidden treasure. If there is anything else to keep us any longer, I don’t know what it is.”

“You’re right,” agreed Mr. Holton. “We should be getting back home. On the way, however, we can keep our eyes open for anything else that might interest us.”

It was decided not to leave until after a rest of two days. The explorers were greatly fatigued after the eventful week, and were content to do nothing but sit idly in the tent.

But when the morning set for their leaving arrived, they were refreshed and ready for action.

“We’ve had a big time of it here,” remarked Bob. “But somehow I’m anxious to get back home.”

After attending to last-minute preparations, the explorers got on their dromedaries and turned the animals toward the north.

It was slow traveling through the Ahaggars, with the numerous jagged rocks and peaks standing in their way. They were glad indeed when finally they reached the end of the mountain range and rode over a rocky plain.

“Now let’s make time,” said Mr. Holton. “We’ll have it comparatively easy from now on and should get to Wargla inside of a few weeks.”

“And we’re likely to have many more adventures before we again see civilization,” remarked Joe.

Notwithstanding this, the journey back to Wargla was made without important incident, except that in a region of deep ravines Mr. Lewis’s camel missed its footing and came near plunging down a twenty-foot crevice.

At Wargla the explorers remained for several days, boxing and crating their specimens and antiquities. Here Fekmah divided the treasure among himself and his friends. They begged him to take much the largest share, but he firmly refused.

“If it had not been for you Americans, I would not have had any of the hidden riches,” he told them, as they sat in the station awaiting the train to take them to the coast.

“It was Bob who did it,” said Dr. Kirshner loyally. “It was he who got us out of captivity and brought about the success of the expedition!”

THE END

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Across the Sahara, by Hanns Vischer—E. Arnold, London.

Across the Sahara by Motor Car, by Haardt—D. Appleton Co.

Sands of Sahara, by Sommerville—J. B. Lippincott.

Camping in the Sahara, by Hull—Dodd, Mead & Co.

The Spell of Algeria and Tunisia, by M. S. Mansfield—L. C. Page Co.

Encyclopedia Britannica.

Wood’s Natural History—A. L. Burt.

Elements of Zoölogy, by Holder—American Book Co. (D. Appleton.)

The World and Its Peoples—The Thompson Publishing Co., St. Louis.

 

 

 

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