While the snow was melting, Alec had removed his skis and stuck them upright in the snow. He dropped his pack and unfastened a pair of mountain-climber's ice crampons and lashed them to his ski boots. In five minutes Troy had "burned" a sloping, ice-glazed ramp deep into the snow field, sloping down into a ten-foot deep chasm and terminating on bare wet soil. Sitting on the ground, slightly off center to one side of the original hole was the foot-round gray metal shape of radiation snow gauge P11902-87. A half-inch round tube projected upwards for three inches from the center of the round device. * * * * * Alec was down in the ice chasm, ski pole reversed in his hand. Standing as far from the gauge as possible, he dangled a leaden cap from the end of his ski pole over the projecting tube. On the third try, the cap descended over the open end of the tube, effectively shielding the radioactive source material in the gauge. Once the cap was in place, Alec moved up to the gauge and put a lock clamp on the cap and then picked up the gauge and moved back up the ramp. The wind was screaming across the top of the slot in the snow pack as he pushed the device over the edge and then heaved himself out into the teeth of the storm. He could barely make out the form of Troy fifty feet east of the original position of the gauge. The tall engineer had taken the replacement gauge from his pack and was positioning it into the snow on the surface of the snow pack. The replacement was bulkier than the defective unit and it was different in design. This was a combination radiation-sonar measuring gauge. Placed on top of an existing snow field, its sonar system kept account of the snow beneath the gauge to the surface of the soil; the radiation counter metered the fresh snow that fell on it after it was placed in position. The two readings were electronically added and fed into the transducer for automatic transmission. Troy hollowed out a slight depression in the fresh snow and pressed the gauge into the hollow, then packed the snow back around it to keep it from being shifted by the high velocity winds until fresh snows buried it. Satisfied that it was properly set, he removed the radiation cap lock and slipped his ski pole through the ring on the cap. He backed away, lifted the cap from the gauge and then quickly moved out of the area.