"All right. But please keep your gun in your hand as well as your head on a swivel. I'd prefer to have Dr. Mitsuitei come down with us so we could stay together, but I know how he'd react to the interruption, and I realize you're not a kid. Just be careful."
Lampert promised; and the guide's manner had impressed him to the point where he was almost afraid to make the return journey, after reaching the flyer and packing his new equipment. He was rather surprised to get back to the site without being attacked, and McLaughlin's very evident relief at seeing him did nothing to ease his feelings.
He began to set up the machinery. This consisted of an assembly very similar to the drilling mole—a small delving robot drawing a slender tail behind it, the tail wound on a drum which surrounded the control unit. A dozen smaller cylinders reposed in attached clips.
"The attached borer," Lampert explained to the guide, "goes down to any depth I set, up to two hundred fifty meters. It can produce any of the three normal types of earthquake wave, singly or in any combination, with sufficient intensity to be detected at a range of over two kilometers in reasonably well-conducting rock. The small cylinders are detectors, equipped not only to receive and analyze the wave coming through the ground but to measure electronically their location with respect to each other and the main station. I can use as many of them as I please, up to the full dozen; but they can be planted only a little way below the surface. There exists equipment for getting readings at depths comparable to that of the transmitter, but I don't have it. As it stands, by spotting the receivers carefully I can get a pretty good picture of the formations for a radius of a kilometer and a depth even greater with ten minutes measuring—and ten hours computing."
"How far out do you plan to place these receivers?" the guide asked pointedly.
"Well—I hadn't made a detailed plan of that. I'd rather like to have them in radiating lines of three, the lines spreading about fifteen degrees, and the individual cylinders about two hundred meters apart."
"And just how were you going to place them? I gather that someone has to walk the best part of four kilometers—or do these things fly, in addition to their other abilities?"
"Er—someone walks. I thought perhaps, since you don't like the idea of my going alone through the jungle, that I might stand guard over Take in the pit while you set them out."
"Hmm." The guide did not explode, to Lampert's relief. It had not occurred to the scientist that the job of wandering around a hole in the ground waiting for animals which never came might get a little boring to a man of McLaughlin's background. "Let's go over first and see how Dr. Mitsuitei is getting along. I guess you could stand over him with a gun for half an hour. Of course, the cover runs dangerously close to the pit. Maybe we'd better burn it off to a safer distance—still, I guess that won't be necessary. You can stand out here where it's relatively clear, and see all the approaches to the pit. Something might jump in without your having time to hit it, and you'd at least see it and could get there fast enough to do any shooting necessary."
They approached the hole and looked in. Mitsuitei was working busily. A fair quantity of earth lay spread on the rock, and some two thirds of the length of the crack had been excavated to a depth of perhaps a quarter of a meter. The geophysicist attracted the little man's attention and told him of the plan; Mitsuitei nodded and bent once more to his work.