"Ah, the Excellency is generous as a prince of the royal household!" cried Muhammed Bai. "It was on a stone--a boundary stone at the place I said--that I found the writings. See, here is the stone." He scrambled to his feet, bowing, and hastened to the rear of the stall. He cast off some rugs from the top of a pile, disclosing a piece of brown sandstone some three feet high and a foot in thickness. On the surface of the stone Gray saw characters engraved, characters that were strange to him. But not to Sir Lionel. The Englishman dropped to his knees with an exclamation, whipping out his eyeglasses. He ran his finger over the writing on the sandstone. "A form of Sanscrit!" he cried. "By Jove--three centuries old, at least. Four, I should judge. And here is the character corresponding to the Chinese word Wusun, the Tall Ones.' Remarkable! This evidently was one of the boundary marks of the Wusun land." He peered at the inscription intently, forgetting the American in his enthusiasm. "Hm--it was erected by one of the khans of the Tall People. _By a slave of the Chinese Emperor_. It speaks of the captive race of the Wusun. Plainly they were even then under the _kang_ of the Chinese priests. 'In the city of Sungan are the captive people ... greatly fallen since the age when they were conquerors ... they cling to their hearths and towers ... in the sand. There they will always be----'" He broke off his reading and glanced up at Gray. "Splendid! I must take a rubbing of this." He ordered Muhammed Bai to bring charcoal and a clean sheet of paper. The charcoal he rubbed over the stone. Then he pressed the paper firmly against it, beating the sheet with his fists until the outline of the inscription was imprinted on the paper. This he surveyed triumphantly. "Excellent! Captain Gray, I am indebted for your"--he smiled--"involuntary assistance. Will you dine with us? Mary will be glad of company, I am sure. I must place this where it will be safe." He hurried off, followed by the girl and Gray. Neither spoke during the walk to the outskirts of Ansichow. The American was regretting the bad fortune that had concealed the truth of his mission from the Hastings. He was in the position of a culprit obtaining valuable information from his rivals, without intending to do so. This information he was in duty bound to use to his own advantage. He had determined to set matters right by revealing to his host his purpose in seeking the Gobi. And the dinner would afford him an opportunity to do so. The camp of the Hastings was located in a garden which surrounded a spring near the caravanserai of Ansichow. Sir Lionel, disliking the filth of the caravanserai which bore evidence of much use by not over-fastidious Chinese travelers, had pitched his tents in the garden, making his own _dak_ bungalow, as he called it.