Despite the heavy loads that the cars carried, they moved along with gratifying speed. There was no attempt to let them out to the limit, as safety was the watchword. There would be plenty of time for speeding if there should be need for haste, after the drivers had learned what they could do with the cars and had become familiar with the character of the going.

In the immediate vicinity of Tuggurt, the sand in many places was loose and shifting. But before long the travelers came to a region where the sand was as smooth and almost as hard as a floor, so hard indeed that as they looked behind them, they could scarcely detect any trace of their passage.

“Nothing the matter with this as a road,” exulted Brick. “Why, it’s almost as good as a speedway track. It’s like some of those Florida beaches you read about, where they hold auto races.”

“Don’t crow too soon,” counseled Kyle, as he devoted all his attention to the steering. “This is velvet, all right, but there’ll be plenty of tough places to make up for it.”

He spoke with some difficulty, for he had not yet become accustomed to the litham that he wore. This was a thin blue veil that covered almost all his face except his eyes, the latter being protected by huge blue sun glasses. The litham is an absolute necessity to prevent the wearer being choked by the clouds of sand that are constantly blowing about the Sahara. Then, too, Alam had told them that the use of it prevented thirst to a remarkable extent.

“Gee,” chuckled Brick, who was similarly accoutered, “we must look like something that the cat dragged in.”

“I guess we do,” laughed Kyle, as he gave the wheel a twist and cleverly avoided a hillock. “Neither one of us would take a prize in a beauty show.”

Before long, the town of Tuggurt vanished below the horizon. Its disappearance seemed to mark the severance of all ties with civilization. All about them nothing was to be seen but desert, an apparently boundless ocean of sand, compared with whose immensity the three cars seemed like so many black ants creeping over its surface.

The sun was like a ball of burnished brass in a cloudless sky as it came up from the east and flung its fierce rays on the sands beneath. The ground shimmered with the heat waves that rose quiveringly above it and wrapped themselves about the travelers.

“It’s lucky that we can make our own breeze as we go along,” remarked Brick.

“That will be one incentive to make good time,” replied Kyle. “The faster we go, the better the breeze. Though we’ve got to admit that the breeze doesn’t bring much refreshment with it. It feels as though it came from the mouth of a fiery furnace.”

A little to one side of the path they traversed they noted a collection of bones and skulls of camels.

“Alam says the whole desert is strewn with them,” remarked Brick, as their glances met. “Sometimes they just give out and die in their tracks. At other times, a whole caravan is overwhelmed by a sand storm.”

The sight sobered the boys a little, and gave them some idea of the perils that attended the journey on which they had embarked. It was full of romance, to be sure, but also full of danger. Just as the floor of the sea was strewn with wrecks, so this ocean of sand had many times claimed the lives of those who defied it.

“Oh, for a drink of water!” murmured Brick, as he passed his tongue over his dry lips. “Now’s the time that I envy the camels who can go a week on a stretch without it.”

“We’ll have to get used to being thirsty,” rejoined Kyle. “But that will make the water all the more refreshing when it comes. That won’t be long now, for Uncle Frank said that we’d stop and pitch camp after we’d been riding for a couple of hours.”

“We’ll have to camp right in the open,” remarked Teddy, as his eyes roved over the boundless plain that lay baking in the sun, with not a tree to break the monotony all the way to the skyline.

“The tents will give us shelter enough from the sun,” replied Kyle. “Then, too, the cars themselves will cast a shadow, and we can follow the shadow around and so get the best of old Sol.”

At that moment, however, there was no denying that the sun had the best of it. Its rays beat down with fury on the top of the cars. Brick’s hand inadvertently came in contact with one of the metal parts, and he withdrew it with a startled “ouch!” as though he had touched a red-hot iron.

But those in the party were game, and whatever discomfort they experienced they took as all in the day’s work. The novelty of the situation atoned to a great extent for whatever unpleasant features accompanied it. They had not come on a holiday jaunt, but had embarked on a great adventure, and they were willing to pay the cost.

What secrets did the desert hold? How many of those secrets was it going to yield up to them? These were the questions that made their blood tingle with eager anticipation.

The sun had mounted high in the heavens when the leading car slowed up and a loud blast from its horn signaled for a halt.

Kyle turned off the engine and came to within a few feet of the captain’s car where he stopped, being joined in a moment more by the rearguard machine driven by the professor.

All jumped out and stretched their limbs, grateful for the release from their cramped position, while Alam and Abdullah, with the dexterity born of long practice, unrolled the tents and set them up, sheltered by the cars as much as possible from the fierceness of the sun.

“Well, Kyle, how do you like your first taste of driving in the desert?” asked the captain, as he threw his arm affectionately over his nephew’s shoulder.

“First rate,” was the quiet reply. “Though I’d like a taste of something else still better.”

“Meaning water, I suppose,” replied the captain. “I guess you’re not alone in that. Just now you can have all you want, for there are good wells at Wargla, and we can fill the tanks again. You’ll find it rather warm, but you won’t mind a little thing like that.”

He took some cups out of their kit, filled them from one of the aluminum tanks, and passed them around. The water was warm, as he had predicted, but to their parched throats it tasted like nectar. They drank and drank until they could drink no more.

“And now for a little grub,” said the captain. “That is,” he added, with a twinkle in his eye as he looked at the boys, “if you don’t object.”

“Object!” cried Brick. “Lead me to it.”

“The only thing I object to is the word ‘little.’” And Kyle grinned as he settled himself on the sand.

Sandwiches were handed out to begin with, and they ate them with avidity. The captain opened some canned goods that provided an abundant meal.

“All the comforts of home,” murmured Kyle, when at last he had satisfied his clamorous appetite.

“Not quite,” objected the professor. “I could do without some of this sand that goes with every mouthful.”

“That’s part of the menu in the desert,” affirmed the captain. “The sand sifts in everywhere. The very air is full of minute particles of it. We’ll breathe and we’ll eat it until we get back to civilization. But the Arabs seem to thrive on it, and I guess it won’t hurt us. They say, anyhow, that everybody has to eat a peck of dirt during his life. Here’s where we get our peck.”

“How long do we camp here?” asked Kyle.

“Until about five this afternoon,” was the reply. “Until we get used to the heat, it would be simply suicide to try to travel in the middle of the day. The moon rises early to-night, and we can do a good deal of traveling by its light. If we have luck, we’ll get to Wargla, our first stop, by nine or ten o’clock.”

“In the meantime,” suggested the professor, “it would be well to get as much sleep as possible. We can get some of the blankets from the cars and use them as pillows.”

“Seems odd to talk of blankets in this oven of a place,” laughed Kyle.

“There’ll be plenty of times when we’ll be mighty glad to have them,” replied the professor. “When the weather gets down to zero, we’ll bless our stars that we brought them along.”

“Zero!” exclaimed Brick incredulously. “In this desert?”

“Just so,” was the rejoinder. “We’ll feel many a bitterly cold blast before we get out of here. Sometimes the thermometer drops sixty points in an hour.”

They stretched out and slept soundly for hours, and the sun was well on its way to the western horizon when they opened their eyes. The heat was sensibly abating, and they moved about with renewed vigor, enormously refreshed by the intermission.

The road still continued hard and good. Every mile of such traveling they regarded as clear gain or, as Brick phrased it, “velvet,” for they well knew that there were many stretches to be encountered that would test all their own skill and the strength and endurance of their cars.

They journeyed over vast expanses strewn with little brown and yellow pebbles, glistening like gems in the rays of the sun. Just before dark a small caravan passed them, coming from the other direction. That the desert nomads were greatly excited and impressed by the sight of the cars was evident by the suddenness with which they came to a halt, talking wildly and vociferously among themselves and pointing to the strange invaders of a domain that hitherto had belonged to them alone. But the cars plunged along without stopping, though their inmates waved their hands in friendly fashion to the Arabs, and soon the caravan was lost to sight.

Darkness came suddenly, and it was now that the searchlights with which the cars were provided stood the drivers in good stead, flinging their powerful beams into the night and lighting up the way for a long distance ahead.

Soon, however, these became unnecessary, for, as the captain had remarked, the moon rose early and flooded the vast expanse with splendor. Then the Americans saw the desert under a new and witching guise. The scene was beautiful beyond description. The sand under the brilliant rays of the moon looked like a white sheet. All the aridity of the landscape was transformed by the dazzling sheen into fairyland. It was as though the travelers were voyaging in another sphere. The strange effect was heightened by the silence that enveloped them, broken only by the chugging of the cars as they ploughed along.

The spell was broken by an exclamation from Brick.

“Look!” he said eagerly, putting his hand on Kyle’s arm. “See those lights. We’re coming to a town.”

In the distance gleamed a multitude of tiny lights that told of human habitations.

“Good!” blurted out Kyle. “I guessed we must be near it. I just saw from the speedometer that we had nearly covered the hundred and twenty-five miles that lie between Wargla and Tuggurt. Pretty good work for the first day, considering how much time we spent in resting.”

They were descending now, for the town of Wargla that they were approaching lay in a low basin, surrounded by sand hills. They soon reached the outskirts and quickly made their way to the French Residency, a spacious, handsome building, very similar to the one in Tuggurt. There was no hotel in the town, but they received a hearty welcome from the French Resident and his staff, who had been apprised of their coming and had extended an invitation to the party to be their guests during their stay.

A bountiful repast had been prepared for them, and their hosts outdid themselves in their hospitality. What the travelers enjoyed most of all was the cold bath with which they regaled themselves before retiring to their rooms. Never before had one been so grateful, the more so because they knew that probably many days would pass before they could expect to have another.

But quite as important as food and bath to the professor, was the opportunity he found at the post to add to his collection. There was a large aggregation of minerals of the desert, secured by the officers from the caravans that passed through the place. Rare curios, specimens of ancient pottery, brasswork, weapons, gathered from the ruins of cities that once had flourished in that vast expanse, were there in abundance.

For the most part the articles had been purchased for a mere song, and the professor was able to obtain some of the rarest specimens at a nominal cost. Some of them he could never have hoped to get had he not embarked on the present expedition, and he already regarded himself as well recompensed for the risks he might incur. And in the distance the Cave of Emeralds still beckoned.

The Americans had expected to leave the next morning, but some minor troubles had developed with the cars, and it was necessary that repairs be made before they again ventured into the desert. These occupied the major part of the morning.

Shortly before noon, Kyle and Brick sallied forth into one of the date groves for which the place was famous. The shadow of the trees furnished a soothing refuge from the heat, and the fruit itself, fresh from the trees, was delicious.

They sat down under one of the date palms, Brick with his back against the tree and Kyle near him, idly toying with a stick he had picked up from the ground.

Suddenly Kyle saw something on a little projection of the tree directly over Brick’s head that made him give a quick start.

“What’s the matter?” asked Brick, noting the intent look on his friend’s face. This look slowly turned to one of horror.

“Don’t move, Brick!” came the tense warning. “Don’t move—for your life, don’t move!”

[Chapter 09 Maze: Help Kyle Escape]