The Tatars had arrived, swiftly and noiselessly, and a dozen of the warriors, still mounted, were surrounding him.  
His helpless condition aroused their curiosity, and while some of them hastily cut away his bonds and raised him to his feet, other plied him with questions in their own language. Rob shook his head to indicate that he could not understand; so they led him to the chief—an immense, bearded representative of the tribe of Kara-Khitai, the terrible and relentless Black Tatars of Thibet. The huge frame of this fellow was clothed in flowing robes of cloth-of-gold, braided with jewels, and he sat majestically upon the back of a jet-black camel.
 
Under ordinary circumstances the stern features and flashing black eyes of this redoubtable warrior would have struck a chill of fear to the boy's heart; but now under the influence of the crushing misfortunes he had experienced, he was able to gaze with indifference upon the terrible visage of the desert chief.
 
The Tatar seemed not to consider Rob an enemy. Instead, he looked upon him as an ally, since the Turks had bound and robbed him.
 
Finding it impossible to converse with the chief, Rob took refuge in the sign language. He turned his pockets wrong side out, showed the red welts left upon his wrists by the tight cord, and then shook his fists angrily in the direction of the town.
 
In return the Tatar nodded gravely and issued an order to his men.
 
By this time the warriors were busily pitching tents before the walls of Yarkand and making preparations for a formal siege. In obedience to the chieftain's orders, Rob was given a place within one of the tents nearest the wall and supplied with a brace of brass-mounted pistols and a dagger with a sharp, zigzag edge. These were evidently to assist the boy in fighting the Turks, and he was well pleased to have them. His spirits rose considerably when he found he had fallen among friends, although most of his new comrades had such evil faces that it was unnecessary to put on the Character Markers to judge their natures with a fair degree of accuracy.
 
"I can't be very particular about the company I keep," he thought, "and this gang hasn't tried to murder me, as the rascally Turks did. So for the present I'll stand in with the scowling chief and try to get a shot at the thieves who robbed me. If our side wins I may get a chance to recover some of my property. It's a slim chance, of course, but it's the only hope I have left."
 
That very evening an opportunity occurred for Rob to win glory in the eyes of his new friends. Just before sundown the gates of the city flew open and a swarm of Turks, mounted upon fleet horses and camels, issued forth and fell upon their enemies. The Tatars, who did not expect the sally, were scarcely able to form an opposing rank when they found themselves engaged in a hand-to-hand conflict, fighting desperately for their lives. In such a battle, however, the Turks were at a disadvantage, for the active Tatars slipped beneath their horses and disabled them, bringing both the animals and their riders to the earth.
 
At the first onslaught Rob shot his pistol at a Turk and wounded him so severely that he fell from his horse. Instantly the boy seized the bridle and sprang upon the steed's back, and the next moment he had dashed into the thickest part of the fray. Bullets and blows rained upon him from all sides, but the Garment of Repulsion saved him from a single scratch.
 
When his pistols had been discharged he caught up the broken handle of a spear, and used it as a club, galloping into the ranks of the Turks and belaboring them as hard as he could. The Tatars cheered and followed him, and the Turks were so amazed at his miraculous escape from their bullets that they became terrified, thinking he bore a charmed life and was protected by unseen powers.
 
This terror helped turn the tide of battle, and before long the enemy was pressed back to the walls and retreated through the gates, which were hastily fastened behind them.
 
In order to prevent a repetition of this sally the Tatars at once invested the gates, so that if the Turks should open them they were as likely to let their foes in as to oppose them.
 
While the tents were being moved up Rob had an opportunity to search the battlefield for the bodies of the three Turks who had robbed him, but they were not among the fallen.
 
"Those fellows were too cowardly to take part in a fair fight," declared the boy; but he was much disappointed, nevertheless, as he felt very helpless without the electric tube or the traveling machine.
 
The Tatar chief now called Rob to his tent and presented him with a beautiful ring set with a glowing pigeon's-blood ruby, in acknowledgment of his services. This gift made the boy feel very proud, and he said to the chief:
 
"You're all right, old man, even if you do look like a pirate. If you can manage to capture that city, so I can get my electrical devices back, I'll consider you a trump as long as I live."
 
The chief thought this speech was intended to express Rob's gratitude, so he bowed solemnly in return.
 
During the night that followed upon the first engagement of the Turks and Tatars, the boy lay awake trying to devise some plan to capture the city. The walls seemed too high and thick to be either scaled or broken by the Tatars, who had no artillery whatever; and within the walls lay all the fertile part of the oasis, giving the besieged a good supply of water and provisions, while the besiegers were obliged to subsist on what water and food they had brought with them.
 
Just before dawn Rob left his tent and went out to look at the great wall. The stars gave plenty of light, but the boy was worried to find that, according to Eastern custom, no sentries or guards whatever had been posted and all the Tatars were slumbering soundly.
 
The city was likewise wrapped in profound silence, but just as Rob was turning away he saw a head project stealthily over the edge of the wall before him, and recognized in the features one of the Turks who had robbed him.
 
Finding no one awake except the boy the fellow sat upon the edge of the wall, with his feet dangling downward, and grinned wickedly at his former victim. Rob watched him with almost breathless eagerness.
 
After making many motions that conveyed no meaning whatever, the Turk drew the electric tube from his pocket and pointed his finger first at the boy and then at the instrument, as if inquiring what it was used for. Rob shook his head. The Turk turned the tube over several times and examined it carefully, after which he also shook his head, seeming greatly puzzled.
 
By this time the boy was fairly trembling with excitement. He longed to recover this valuable weapon, and feared that at any moment the curious Turk would discover its use. He held out his hand toward the tube, and tried to say, by motions, that he would show the fellow how to use it. The man seemed to understand, by he would not let the glittering instrument out of his possession.
 
Rob was almost in despair, when he happened to notice upon his hand the ruby ring given him by the chief. Drawing the jewel from his finger he made offer, by signs, that he would exchange it for the tube.
 
The Turk was much pleased with the idea, and nodded his head repeatedly, holding out his hand for the ring. Rob had little confidence in the man's honor, but he was so eager to regain the tube that he decided to trust him. So he threw the ring to the top of the wall, where the Turk caught it skilfully; but when Rob held out his hand for the tube the scoundrel only laughed at him and began to scramble to his feet in order to beat a retreat. Chance, however, foiled this disgraceful treachery, for in his hurry the Turk allowed the tube to slip from his grasp, and it rolled off the wall and fell upon the sand at Rob's very feet.
 
The robber turned to watch its fall and, filled with sudden anger, the boy grabbed the weapon, pointed it at his enemy, and pressed the button. Down tumbled the Turk, without a cry, and lay motionless at the foot of the wall.
 
Rob's first thought was to search the pockets of his captive, and to his delight he found and recovered his box of food tablets. The Record of Events and the traveling machine were doubtless in the possession of the other robbers, but Rob did not despair of recovering them, now that he had the tube to aid him.
 
Day was now breaking, and several of the Tatars appeared and examined the body of the Turk with grunts of surprise, for there was no mark upon him to show how he had been slain. Supposing him to be dead, they tossed him aside and forgot all about him.
 
Rob had secured his ruby ring again, and going to the chief's tent he showed the jewel to the guard and was at once admitted. The black-bearded chieftain was still reclining upon his pillows, but Rob bowed before him, and by means of signs managed to ask for a band of warriors to assist him in assaulting the town. The chieftain appeared to doubt the wisdom of the enterprise, not being able to understand how the boy could expect to succeed; but he graciously issued the required order, and by the time Rob reached the city gate he found a large group of Tatars gathered to support him, while the entire camp, roused to interest in the proceedings, stood looking on.
 
Rob cared little for the quarrel between the Turks and Tatars, and............