Its appearance was not unusual. There was a power pack, consisting of batteries and a dynamotor, an amplifier, and a control panel. In the control panel was an oscilloscope. The probe looked like an aluminum pipe but was really a special tube built like a segment of coaxial cable. The sensing unit was in an inner core, surrounded by an atmosphere of pressurized helium. At the tip of the probe was the sensing element which looked very much like the Geiger tube of a radiation detector surrounded by a helical coil.
"Come on, you poor native, and I'll show you how it works," Rick invited.
"You not expect to find stuff here. You just testing?" Chahda asked.
"We want to get a standard pattern," Rick said. He pointed to the valley. "The terrace soil and rocks should be no different than those right here. So we'll get the typical response of these, and when we get to our location we won't have to take time—which could be important if we have Ifugao spear throwers shooting at us."
"What's typical response?" Chahda asked.
Rick showed him the helical coil at the end of the probe. "This coil is an antenna. It's shooting out electro-magnetic waves of very high frequency. When those waves hit anything, some are reflected. The reflected waves are picked up by the tube inside the coil. You with me?"
"Way ahead of you," Chahda said. "Not all things reflect these waves the same, huh? Maybe the more dense, the better reflect. So loose earth not reflect too good, rocks little better, metal very good, and stuff like crystals best of all."
"Poor native boy," Tony said chidingly. "You knew how it worked all along."
Rick shook his head. "He's never seen it before, Tony. It's just that he's pretty quick on the uptake for a poor native boy."
Chahda grinned. "Okay, chums, I'll drop the gag. Go ahead, Rick, I not know everything yet. Why you testing here?"