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.