“Adding the sine oscillator now,” came Sully’s voice. “I’ll raise the frequency, 880 hertz.”
“Goose the decibels,” Marshall called over his shoulder.
The sound grew louder still, until the metal walls of the corridor seemed to vibrate with noise. “Passing the threshold of pain!” shouted Sully. “At 120 decibels!”
The maelstrom of sound, overlaid with the fullness in Marshall ’s head, threatened to grow maddening. The creature took a step backward. Its haunches jerked slightly, as with involuntary tremors. It shook its shaggy head: once, twice, violent shakes of obvious pain.
“Just the sine wave now!” Sully cried. “It’s working!”
And then-suddenly-the creature gathered itself into a crouch, preparing to spring.
A dozen things happened simultaneously. Phillips and Sully cried out in dismay and fear. The volume of the device spiked still further, broadening and swelling. Gonzalez gave an almost inaudible command to fire. And then bullets were singing past Marshall ’s head, ripping down the corridor in strafes of gray smoke as they whined off walls and tottering piles of surplus equipment. Marshall raised his own gun and depressed the trigger. He could see his bullets running true; see them impact the creature, then ricochet off; watched fresh streaks of chitinous obsidian appear on the beast’s withers and flanks as the slugs exposed more exoskeleton. At this moment of crisis, of absolute extremity, time seemed to slow and reality fade: it was as if Marshall could almost see each individual bullet fly down the corridor on its violent, futile journey.
And then the beast charged. Instantly, Marshall flung himself toward the hatch in a desperate attempt to shut it, heedless of the fire being laid down by Gonzalez and Phillips. But the creature moved with remarkable speed. In a heartbeat it was past the hatch and through, knocking Marshall aside, throwing him against the wall with a sickening impact, leaping over the sonic weapon and overturning it in the process as-with single-minded ferocity-it seized Sully in its forepaws and, with two savage twists of its head, tore his arms from their sockets.
52
Marshall raised himself onto one elbow, momentarily stunned by the force of the blow. The central corridor of the science wing had been transformed into a bedlam of sound and violence: the beast, ripping into the shrieking Sully; blood, spraying from the climatologist’s ruined limbs, spraying the walls and floor in a maelstrom of crimson; Gonzalez and Phillips, scrambling backward, trying to get in a clear shot at the creature; the tray that held the sonic weapon lying on its side, wheels still turning; Usuguk, stepping forward past the soldiers, shaman’s charm held out before him as his chanting rose in pitch and urgency.
As Marshall watched, ears ringing with the impact, he saw the beast bat Sully-still screaming-into the air with one powerful swipe of a forelimb. A second swipe knocked the scientist through a doorway and into the forward office. The creature bounded in after him, disappearing from view. An enormous din-the crash of furniture, the impact of a body slamming against walls-erupted from inside. Sully’s screams grew ragged.
Marshall tried to rise to his feet, staggered, pulled himself up. It was too late-Sully was going to die. They were all going to die. For a second he wondered if there was time to get them out of the science wing, to close the hatch on the monster, but he quickly dismissed the thought. There was no time. It was over, the thing would kill Sully and then it would turn on them, one at a time, and-
His eyes fell on the sonic weapon, its pieces in disarray on the hallway floor. And yet it had worked. That last waveform Sully had tried, the sine-it had clearly affected the creature. He tried to drown out the ferocious din, the shouts of the soldiers, the painful pressure in his head. Tried to think, to concentrate, in the few seconds he had left. Why would a sine wave work when a sawtooth wave or a square wave didn’t?
He stopped. Maybe it wasn’t the waveshape at all. Maybe it was something else entirely…
He dashed toward the cart, righted it, and frantically began picking up the electronics that had shaken free and reassembling them.
“What are you doing?” Logan cried. Sully’s screams had now stopped but the terrible crashing and banging in the forward office continued.
“Trying again.” Marshall checked the connections from the amplifier to the drivers, snapped a loose potentiometer back into place. “It’s the harmonics; it has to be. That’s the only answer. But we need proper acoustics if we’re going to maximize-” He looked around wildly a minute. “Come on, give me a hand. That thing will be back out any second. We have to get this into the echo chamber.”
“You don’t have time for that shit!” Gonzalez said. “What’s the point of moving it?”
“It’s like adding poison to an arrowhead. We’re maximizing the payload.”
With Logan ’s help, Marshall wheeled the cart down the corridor, slipping repeatedly on a floor made slick with Sully’s blood. Usuguk followed in their path, still chanting, shaman’s rattle in one hand and a bone fetish in the other. With difficulty the two men trundled the cart past the control room, past the corridor intersection, and through the rear hatch into the echo chamber itself.
“Gonzalez!” Marshall cried. “I’m counting on you to slow it down!”
Motioning to Phillips, Gonzalez fell back to a spot just outside the echo chamber and took up a defensive position.
The crashing and banging from within the forward office stopped.
“We’ll need to set it up in the center to get the greatest effect,” Marshall told Logan.
Together, they pushed the cart to the middle of the catwalk. The electrical cables stretched taut, and for a dreadful moment Marshall thought they would not reach. But there was just enough play in them to position the weapon precisely in the center of the chamber, a spot marked on the floor of the catwalk with a label reading “0 dB.”
Marshall glanced at Usuguk. “You might be safer in that monitoring booth,” he said, gesturing to the glass- enclosed landing at the rear of the catwalk.
The Tunit stopped his low chant, shook his head. “Do you forget already what I taught you? If you are going to walk on thin ice, you might as well dance.”
“Your call.” Marshall turned the cart so the drivers were facing down the corridor, checked the connections, snapped the machine back on. No response. Frantically, he reseated vacuum tubes, tightened leads, and tried again. This time a low hum sounded from the massive woofer. He scanned the device, recalling the basics of sound generation on a synthesizer, reacquainting himself with the controls for amplitude, frequency, oscillator waveshape, filter envelope. He grabbed the amplitude knob, turned it sharply right. The cart began to tremble.
He noticed Logan was looking at him. “I calculate I’ve got about three minutes left to live,” the historian said. “If I’m lucky, it’ll happen quickly. In that case, I’ve probably only got two minutes. I’d like to die knowing what it is you tried to do.”
“That last waveform Sully tried,” Marshall replied, eyes back on the controls. “The one that caused the creature to react. It was a sine wave. That’s the purest sound wave possible. No harmonics, no overtones. So I’m going to pick up where he left off-I’ll use Fourier addition to complicate the pattern. Maybe it’ll hurt the creature enough to drive it away. If we can keep it away long enough, maybe we can create more portable-”
He fell silent. The creature had emerged from the forward office. Now it slowly turned to face them. Its forelegs and paws were sop-ping with blood, and its fangs and vibrissae were flecked with gore.
Marshall took a deep breath, tried to steady his shaking hands.
The creature took a step toward them. Quickly, Marshall set the waveform of the first oscillator to sawtooth, the frequency to 30 hertz, verified the amplitude of the master output was at 100 decibels. He pressed the tone button. The room rumbled with a low tone just above the threshold of hearing.
The creature sprang forward.
Marshall did a frantic mental calculation. A second note, overtone free, several octaves higher…
Even as he did so, the creature picked up speed, coming toward them at great leaps down the corridor. He set the second oscillator to sawtooth, dialed its frequency to 800 hertz.
“Christ!” Logan shouted.
Gonzalez and Phillips were firing now. Over the whine of the speaker, Marshall could just make out Phillips’s ragged cry, his weapon firing wildly, up and down and side to side as he lost the last remnants of his shattered
