"Just that," Scotty agreed. "The guard must have been making a tour around the shot station. He got back just as we were taking off." "Funny he didn't hear the jeep when we came," Rick said. "Not very. Sound gets lost pretty fast in this heavy growth. You couldn't hear us a hundred yards away. Probably there's just the one guard, and he goes around the station in a big circle." "I'll buy it," Rick agreed. "But why? Why guard a chunk of jungle with nothing in it but some torn up yellow ground?" "When I find out," Scotty replied, "I'll let you know first thing." CHAPTER X The Volcanic Pipe Hartson Brant and Julius Weiss were still at work in the conference room when Rick and Scotty returned. David Riddle had gone, and the others had evidently not finished placing the tiltometers. The two listened to Rick's story in silence, then Hartson Brant sighed. "I don't know how you do it, Rick. But if there's trouble around, you and Scotty will find it. Are you sure the rifleman shot at you?" "We've got a bullet hole in the windshield and one just under the rear seat," Scotty said. "One might be an accident, but not two." "I agree." Hartson Brant nodded. "Let's see the samples of earth you brought back, Rick." He took both the yellow and blue pieces from his pocket and put them on the table. Hartson Brant and Weiss examined them with interest. "Unusual," Weiss said. "I think you are right in assuming that the yellow is simply an oxidized form of the blue, Rick. But I can't tell you what the material is. I've never seen anything like it before." "The grain is pretty fine," Hartson Brant added. "It could be igneous or sedimentary in origin. I'm not enough of a rock hound to know. David Riddle can tell us when he returns." "Connel would know, too," Scotty reminded. "He's a geologist. Wouldn't you think he would have mentioned an unusual formation like this when he found it?" "Perhaps it's not unusual to a geologist," Weiss pointed out. "Where is Riddle?" Rick asked. "He went to his room a few minutes ago. He should be back shortly. Rick, I think you'd better tell us the whole story. Why do you suspect Connel? Why was it important for you to look at his shot station?" Rick started at the beginning. "It wasn't any one thing, it was a series of little offbeat things. We thought it was funny he didn't even want company after Ruiz was hurt. Then he reacted so violently when we proposed swapping stations. It just seemed odd. The theft of the tracings bothered us, too. No ordinary thief would steal papers and leave Dr. Williams' wallet in his pocket, or leave his pocket transistor radio and stuff like that." "But you can't connect Connel with the theft of the papers," Weiss objected. "No, sir, we can't. But we almost got caught in the stolen dynamite, and he could have set that off. It was while we were on the way to his third station."