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.”