Timothy Zahn - The Green And The Gray

There was a faint pop, but as far as Fierenzo could see nothing else happened. "Like I said, the shot picks up energy and momentum as it travels," Jonah said. "Right up close—" he fired into his palm again "—nothing much happens. A little farther away—"

Taking his hand away, he fired at one of the empty water bottles a foot away from him. The shot sent it skittering across the concrete. "—and you can start to feel it," he said. "Farther away yet—" he lifted the weapon to aim at an imaginary horizon "—and you could theoretically crack off a piece of a mountain."

Fierenzo shook his head. "Sounds pretty damn dangerous. I've never even heard of a weapon that doesn't work up close."

"That's probably because hammerguns aren't technically weapons," Jonah said. "They were designed as mining and stoneworking tools. Low-power at close range for delicate shaping; high-power farther away to give a kick to the ore vein or surface formation you're working."

"Uh-huh," Fierenzo said as something suddenly occurred to him. "Which means that when you shoved that thing in my face on the fire escape it was a hundred-percent bluff."

"Basically," Jonah admitted. "But what else could I do?"

"I suppose," Fierenzo conceded. "And that's why the second Green last night ran toward you instead of away. He was trying to move in to where you couldn't hit him as hard."

"That, plus the fact that the sonic nature of the Shriek means it gets stronger as you get closer to it,"

Jonah said.

"Tell me about it," Fierenzo said ruefully, rubbing his ear gingerly. "Was that Jordan up on the building playing target?"

Jonah nodded. "He was trying to hold their attention so I could get behind them." He grimaced.

"Though if I'd realized how strong the Shriek could be even at that distance, I'd never have let him do it. I guess I've never seen a Warrior in action before."

"So the Greens will always want to fight up close, while the Grays will always want to fight at a distance," Fierenzo concluded. "That'll make for some interesting battlefield tactics. Where exactly do these force bubbles get their energy?"

"They draw heat from the air molecules along their path and convert it into kinetic energy," Jonah explained. "That's why you usually see a white line, at least if the bubble's traveled far enough.

That's frost that forms where the air's suddenly had some of the energy sucked out of it and gone cold. Sometimes you can even get snowflakes drifting off the line."

"Sounds very festive," Fierenzo said. "What do you use to hang onto buildings?"

"Nothing but natural talent," Jonah said. "It has to do with van der Waals forces between our bodies and the metal in the walls, or some such thing. I'm a little vague on the details."

"Close enough," Fierenzo said. Physics had never been his strong suit, either. "Now, what about this tension line thing you mentioned earlier? How does that work?"

Jonah made a face. "What do you want, Fierenzo, a short course in Gray tech?"

"Humor me," Fierenzo said. "You're trying to convince me to keep my mouth shut, remember?"

"And there's no point in keeping quiet about one secret when you can have a hundred secrets to keep quiet about instead?"

"Exactly," Fierenzo said. "Come on, give."

With an exasperated sigh, Jonah reached beneath his coat to the side of his belt and pulled out a device about the size of a cigarette pack but flatter. "Fine," he said, tossing it into Fierenzo's lap.

"There it is. Go ahead—figure it out."

He leaned back against the wall, folding his arms across his chest. Picking up the device, Fierenzo gave it a quick study. It looked something like a tailless manta ray, with one side flat and the other smoothly curved, and seemed to be made of the same metal as Jonah's wristband. In the front, where the manta's mouth would have been, there was a finger-sized ring connected to a slender thread that disappeared inside the metal. Set into the concave top was a small round glass-like disk with a knurled bezel around it.

And that was it. No switches, no buttons, no controls of any sort that he could see. For all he could tell, it might have been the inner workings of one of the pull-ring talking dolls his sisters had played with when he was a boy.

He looked up. Jonah was watching him like a dog trainer with a new student. "You don't really want me to just start playing with it, do you?" Fierenzo asked him.

"Why not?" Jonah asked. "You can't hurt it."

"Come on, Jonah, I'm too tired for puzzle box games," Fierenzo said. "Give."

"Okay," Jonah said agreeably. "But if I do, show-and-tell is over. Deal?"

"I don't know," Fierenzo hedged. "There's still those radios of yours, and that invisibility trick—"

"Deal?" Jonah repeated.

Fierenzo sighed. "Deal."

"All right," Jonah said, uncrossing his arms. "Put the flat side against the wall, with the ring hanging downward."

Fierenzo set the device against the wall as instructed about a foot above the rooftop. "Now rotate the bezel around the eye a quarter-turn counterclockwise to loosen it," Jonah instructed.

Fierenzo did so, and found the glass disk now floating freely in its socket. "Aim it downward at an angle to the roof and tighten the bezel again," Jonah continued. "Now hold the projector against the wall so that your hand is away from the eye, pull the ring out an inch or so, and let go of the projector."

Carefully, Fierenzo got a two-fingered grip on the top of the device. Leaning as far back out of the way as he could without looking obvious about it, he took hold of the ring and pulled.

Nothing happened. Frowning, he let go of the projector. To his amazement, it remained firmly in place against the wall.

He looked at Jonah. The other had a faint smile on his face, the kind Fierenzo had often seen on amateur magicians. "Now what?"

Jonah gestured. "Wave your hand between the eye and the roof."

Frowning, Fierenzo eased a single finger downward—

And twitched it reflexively away as it hit something solid. "What the hell?"

"There's your tension line," Jonah said. "A thin line of force running between the projector eye and whatever solid object you've got it aimed at."

Carefully, Fierenzo eased his finger around the invisible line. The shape and feel were like a very tight, very slick rope. "How much weight can it handle?" he asked.

"You could hang a dozen guys from it without making the projector work very hard," Jonah said.

"We use them sometimes to travel between skyscrapers."

"Very impressive," Fierenzo said, sliding a finger up and down the line. "What kind of range does it have?"

"Like a hammergun shot, the line runs outward until it hits something solid," Jonah said. "I'm told it was once considered the quick and easy way to travel between mountains."

"And then, what, you just leave the projector behind?" Fierenzo asked, the discomfiting image of a thousand invisible wires crisscrossing Manhattan flashing to mind. "Or can you climb back up it?"

"Not a chance," Jonah said. "The coefficient of friction is way too low." He pointed to the ring Fierenzo was still holding. "That's what the ring's for. You slide it on over one of your fingers before you set off, and it feeds out thread until you reach the other end. Then you just give it couple of backand- pulls, and it shuts the line off and brings the projector back to you." He gestured. "Try it."

Sliding the ring onto his middle finger, Fierenzo pulled it out a couple of feet from the box. He paused, then backed it up and pulled it out; backed it up and pulled it out—

Without warning, the box detached itself from the wall and shot over to Fierenzo's hand, reeling itself in along the thread like a carpenter's tape measure. "And you're ready for your next trip," Jonah concluded, holding out his hand. "I'd offer you a ride, but you really need to be able to hold onto the side of your destination building for it to be a properly enjoyable experience."