"I must admit it fits the requirements," Zircon agreed. "And we've seen no sign of an industrial plant. These caverns certainly would be no place for one." "We can soon tell," Scotty suggested. "Let's take a sample. When we get out, you can test it." "Quite right," Zircon said. "And let's be quick about it." It didn't take long to discover the reason for the odd little derricks on the barge. Each was equipped with a pulley and a reel of wire. Obviously, it was from here that the Nansen bottles were lowered. While Chahda and Scotty remained on shore, Zircon and Rick pushed the barge out into the lake. Rick got a Nansen bottle ready. The bottle was made of metal, each end equipped with a spring cap. The bottle was lowered on a wire with the ends open, permitting water to flow through it freely. When it reached the desired depth, a metal weight called a "messenger" was attached to the wire and dropped. The weight of the messenger released devices that closed the caps, thus trapping the water sample inside. A brass spigot on the side permitted the sample to be taken out easily when the bottle was hauled up again. They had brought four bottles from Long Shadow's stores. The first one was lowered to the very bottom, and it took a long time getting there. The reel of wire with which the barge was equipped ran out and out until a full seven hundred feet of it had disappeared into the dark depths of the lake. Rick was glad the reel of wire had a geared handle. Pulling that weight up would be no fun. Once the slackening of the wire told them that bottom had been reached, Zircon put the messenger on the wire and let it go. Seconds later, a tug on the wire told them it had struck and Rick reeled in. Other samples were taken at five, ten, and fifteen feet from the bottom. Zircon marked the bottles, then they paddled back to shore. Long Shadow spoke up. "Of course you have testing equipment?" "At our camp near Korse Lenken," Zircon assured him. "You'll find what you expect," the Eurasian said. "Thank you. And now, we'll also thank you to lead us out of here." "No," Long Shadow said. "You're beaten," Zircon said reasonably. "Why not admit it and co-operate? We've nothing against you even if there were law in Tibet. See us to the outside and open the barred gate and you're at liberty to go." Rick started to protest, then he realized Zircon was right. Law in this part of the world was the law of the rifle. There was nothing they could do to Long Shadow or Ko. Long Shadow considered. "I suppose you're right. My little business deal is over, at least for the time being." He raised his voice and yelled in Tibetan. The boys grabbed up their rifles as Tibetan heads showed from the caves, black eyes blinking in fear.