A faint purring in the rocks—mingled with the whining from the cave.
It compared the purring with recorded memories. It remembered similar purrings. The sound came from a rolling object far to the south. It tried to send the pulses that asked “Are you friend or foe,” but the sending organ was inoperative. The movement, therefore, was enemy—but still beyond range of its present weapons.
Lurking anger, and expectation of battle. It stirred restlessly on the crag, but kept its surveillance of the cave. Suddenly there was disturbance on a new sensory channel, vibrations similar to those that came from the cave; but this time the vibrations came across the surface, through the emptiness, transmitted in the long-wave spectra.
“ Moonwagon Sixteen from Command Runabout, give us a call. Over.”
Then silence. It expected a response from the cave, at first—since it knew that one unit of enemy often exchanged vibratory patterns with another unit of enemy. But no answer came. Perhaps the long-wave energy could not penetrate the cave to reach the thing that cringed inside.
“Salvage Sixteen, this is Aubrey’s runabout. What the devil happened to you? Can you read fne? Over!”
Tensely it listened to the ground. The purring stopped for a time as the enemy paused. Minutes later, the motion resumed.
It awoke an emissary ear twenty kilometers to the southwest, and commanded the ear to listen, and to transmit the patterns of the purring noise. Two soundings were taken, and from them, it derived the enemy’s precise position and velocity. The enemy was proceeding to the north, into the edge of the demiworld. Lurking anger flared into active fury. It gunned its engines on the crag. It girded itself for battle.
“Salvage Sixteen, this is Aubrey’s runabout. I assume your radio rig is inoperative. If you can hear us, get this: we’re proceeding north to five miles short of magnapult range. We’ll stop (here and fire an autocyb rocket into zone Red - Red. The warhead’s a radio-to-sonar transceiver. If you’ve got a seismitter that’s working, the transceiver will act as a relay stage. Over.”
It ignored the vibratory pattern and rechecked its battle gear. It introspected its energy storage, and tested its weapon activators. It summoned an emissary eve and wailed a dozen minutes while the eye crawled crablike from the holy place to take up a watch-post near the entrance of the cave. If the enemy remnant tried to emerge, the emissary eye would see, and report, and it could destroy the enemy remnant with a remote grenade catapult.