"The what?"

"The fund made up of donations from various professors and firms who have a vested interest in keeping the Science Shop running smoothly. Hell, it's all just grant money. In the egalitarian system we had before, nobody got anything done."

"Look." Casimir shook his head and sat back down. "I don't want even to hear all this. You know, all I've ever wanted to be is a normal student. They won't let me take decent classes, okay, so I work on the mass driver. Now I come here to get your help and you start talking about local law and free enterprise. I just want some estimates from you on getting these electromagnets wound for the mass driver. Okay? Forget free enterprise." Casimir dropped a page of diagrams and specifications on Virgil's desk.

Virgil looked it over. "Well, it depends," he finally said. "If we pretend you're just a normal student, then I will charge you, oh, about ten thousand dollars for this stuff and have it done by the time you graduate. Now, unofficially, I could log it in as something much simpler and charge you less. But you can't put that into a formal budget proposal. Very unofficially, I might do it for a small bribe, like some help from you around the Shop. But that's really abnormal to put in a budget. Looks like you're stuck."

"It wouldn't really take you three years."

"It would take me." Virgil waved at the door. "Zap could do it in a week. Want to ask him? He's not hard to wake up." Casimir brooded momentarily. "Well, look. I don't really care how it gets done. But it's necessary to have something on paper, you know?"

Virgil shook his head, smiling. "Casimir. You don't think anyone pays any attention to those budgets, do you?"

"Aw, shit. This is too weird for me."

"It's not weird, you're just not used to it yet. Here is what we'll do. We work out a friendly gentlemen's agreement by which I make the magnets for you, probably over Christmas vacation, in exchange for a little of your expert help around the Science Shop. When I'm done with the magnets I put them in an old box and mark it, say, 'SPARE PARTS, 1932 AUTOMATIC BOMBSIGHT PROTOTYPE.' I dump it in the storeroom. When budget time comes around you say, 'Oh, gee, it happens I've designed this thing to use existing parts, I know just where they are.' Ridiculous, but no one knows that, and those who understand won't want to meddle in any arrangement of mine."

"Okay!" Casimir threw up his hands. "Okay. Fine. Ill do it. Just tell me what to do and don't let me see any of this illegal stuff." "It's not illegal, I said it was legal. Hang on a sec while I Xerox these pages."

Virgil opened the door and was met by a clamor of voices from several advanced academic figures. Casimir looked around the room: a firetrap stuffed with books and papers and every imaginable variety of electronic junk. A Geiger counter hung out the window into a deep air shaft, clicking every second or two. In one corner a 1940's radio was hooked up to a technical power supply and wired into the guts of a torn-open telephone so that Virgil could make hands-off phone calls. An old backless TV in another corner enabled Virgil to monitor the shop outside. Electronic parts, hunks of wire, junk-food wrappers and scraps of paper littered the floor. And in three separate places sat those little plastic trays Casimir saw everywhere, overflowing with tiny seeds— rat poison.

"Damn!" spat Casimir as Virgil reentered. "There's enough of that poison in this room alone to kill every rat in this city. What's their problem with that stuff anyway?"

Virgil snorted. Everyone knew the rat poison was ubiquitous; the wastebaskets might go a month without emptying, but when it came to rat poison the B-men were fearsomely diligent, seeming to pass through walls and locked doors like Shaolin priests to scatter the poison-saturated kernels. "It's cultural," he explained. "They hate rats. You should read some Scythian mythology. In Crotobaltislavonia it's a capital crime to harbor them. That's why they had a revolution! The old regime stopped handing out free rat poison."

"I'm serious," said Casimir. "I've got an illegal kitten in my room, and If they keep breaking in to spread poison, they'll find it or let it out or poison it."

"Or eat it. Seriously, you should have mentioned it, Casimir. Let me help you out."

Casimir rested his face in his hand. "I suppose you also have an arrangement with the B-men."

"No, no, much too complicated. I do almost all my work at the computer terminal, Casimir. You can accomplish anything there. See, a few years ago a student had a boa constrictor in his room that got poisoned by the B-men, and even though it was illegal he sued the university for damages and won. There are still a lot of residents with pets whom the administration doesn't want to antagonize, because of connections or whatever. Some students are even allergic to the poison. So, they keep a list of rooms which are not to be given any poison. All I have to do is put your room on it."

Casimir was staring intently at Virgil. "Wait a minute. How did you get that kind of access? Aren't there locks? Access checks?" "There are some annoyances involved."

"I suppose with photographic memory you could do a lot on the computer."

"Helps to have the Operator memorized too."

"Oh, fuck! No!"

Casimir, I am sure, was just as surprised as I had been. The Operator was an immense computer program consisting entirely of numbers— machine code. Without it, the machine was a useless lump. With the Operator installed, it was a tool of nearly infinite power and flexibility. It was to the computer as memory, instinct and intelligence are to the human brain.

Virgil handed Casimir a canister of paper computer tape. The label read, "1843 SURINAM CENSUS DATA VOLUME 5. FIREWOOD USAGE ESTIMATES AND PROJECTIONS."

"Ignore that," said Virgil. "It's a program in machine code. It'll put your room on the no-poison list, and your cat will be safe, unless the B-men forget or decide to ignore the rule, which is a possibility." Casimir barely looked at the tape and stared distantly at Virgil. "What have you been doing with this knowledge?" he whispered. "You could get back at E13S."

Virgil smiled. "Tempting. But when you can do what I can, you don't go for petty revenge. All I do, really, is fight the Worm, which is really my only passion these days. It's why I stay around instead of getting a decent job. It's a sabotage program. It's probably the greatest intellectual achievement of the nineteen-eighties, and it's the only thing I've ever found that is so indescribably difficult and complex and beautiful that I haven't gotten bored with it."

"Why would anyone do such a thing? It must be costing the Megaversity millions."

"I don't know," said Virgil, "but it's great to have a challenge."

Sarah and I were in her room with my toolbox. Outside, the Terrorists were trying to get in. I sat on her bed, as she had commanded, silent and neutral.

"When did they start calling themselves the Terrorists," she asked during a lull.

"Who knows? Maybe Wild and Crazy Guys was too old-fashioned."

"Maybe the hijacking of that NATO tank yesterday gave them the idea. That got lots of coverage. Shit, here they are again." Cheerfully screaming, another Airhead was dragged down the hail to be given her upside-down cold shower. The original Terrorist plan had been to drag the Airheads to the bathroom by their hair, as in olden times, but after a few tries they were convinced that this really was painful, so now they were holding on to the feet.

"Terrorists, Terrorists, we're a mean, sonofabitch," came a hoarse chant as a new group gathered in front of Sarah's door. "Come on, Sarah," their leader shouted in a heavy New York accent. He was trying to sound fatherly and patient, but instead sounded anxious and not very bright. "It'll be a lot better for you if you just come out now. We're tickling Mitzi right now and she's going to tell us where the master key is, and once we get that we'll come in and you'll get ad-dition-al pun-ish-ment."

"God," Sarah whispered to me, "these dorks think I'm just playing hard-to-get. Hope they enjoy it."

"Give the word and I'll shoo them off," I said again.

"Wouldn't help. I have to deal with this myself. Don't be so macho."

"Sorry. Sometimes it works to be macho, you know."

Their previous effort to flash her out of her room had failed. "Flashing" was the technique of squirting lighter fluid Under a door and throwing in a match. It wasn't as dangerous as it sounded, but it invariably smoked the victim out. Powdering was a milder form of this: an envelope was filled with powder, its mouth slid under the door, and the envelope stomped on, exploding a cloud of powder into the room. Three days earlier this had been done to Sarah by some Air-heads. A regular vacuum cleaner just blew the powder out again, so we brought my wet-dry vacuum up and filled it with water and had better results, though she and her room still smelled like babies. She had purchased a heavy rubber weatherstrip from the Mall's hardware store and we had just finished installing it when the flashing attempt had taken place. From listening to the Terrorists on the other side of the door, I had now become as primitive as they had— it was no longer a negotiable situation— and was itching to knock heads.

"Why don't you stop bothering me?" she yelled, trying too hard to sound strong and steady. "I really don't want to play this game with you. You got what you wanted from the others, so why don't you leave? You have no right to bother me."

At this, they roared. "Listen, bitch, this is our sister floor, we decide what our rights are! No one escapes from the rule of the Terrorists, Terrorists, we're a mean, sonofabitch! We'll get in sooner or later— face up to it!"

Another one played the nice guy. "Listen, Sarah— hey, is that her name? Right. Uh, listen, Sarah. We can make life pretty hard on you. We're just trying to initiate you into our sister floor— it's a new tradition. Remember, if you don't lock your door, we can come in; and if you do lock it, we can penny you in."

The Airheads had once pennied Sarah in. The doors opened inward and locked with deadbolts. If the deadbolt was locked and the door pushed inward with great force, the friction between the bolt and its rectangular hole in the jamb became so great that it was impossible for the occupant to withdraw the bolt to unlock the door. One could not push inward on the door all the time, of course, but it was possible to wedge pennies between the front of the door and the projecting member of the jamb so tightly that the occupant was sealed in helplessly. Since this maneuver only worked when the owner of the room was inside with the door locked, it was used discourage people from the unfriendly habit of locking their doors. Sarah was pennied in just before a Student Government meeting, and she had to call me so that I could run upstairs and throw myself against the door until the pennies fell out.

"Look," said Sarah, also taking a reasonable tack, "When are you going to accept that I'm not coming out? I don't want to play, I just want peace and quiet." She knew her voice was wavering now, and she threw me an exasperated look.

"Sarah," said the righteously perturbed Terrorist, "you're being very childish about this. You know we don't want that much. It doesn't hurt. You just have one more chance to be reasonable, and then it's ad-dition-al pun-ish-ment."

"Swirlie! Swirlie! Swirlie!" chanted the Terrorists. "Fuck yourselves!" she yelled. Realizing what was about to happen, she yanked my pliers out of my toolbox and clamped their serrated jaws down on the lock handle just as Mitzi's master key was slid into the keyhole outside.

She held it firm. The Terrorists found the lock frozen. The key-turner called for help, but only one hand can grip a key at a time. The handle did rotate a few degrees in the tussle, and the Terrorists then found they could not pull the key from the lock. Sarah continued to hold it at a slight twist as the Terrorists mumbled outside.

"Listen, Sarah, you got a good point. We'll just leave you alone from now on."

"Yeah," said the others, "Sorry, Sarah."

Looking at me, Sarah snorted with contempt and held on to the pliers. A minute or so after the Terrorists noisily walked away, an unsuccessful yank came on the key.

"Shit! Fuck you!" The Terrorist kicked and pounded viciously on the door, raging.

After a few minutes I got on my belly and pried up the rubber strip and verified that the Terrorists were no longer waiting outside. Sarah opened her door, pulled out the master key, and pocketed it. She smiled a lot, but she was also shaking, and wanted no comfort from me. I was about to say she could sleep on my Sofa for a few days. Sometimes, though, I can actually be sensitive about these things. Sarah was obviously tired of needing my help. I felt she needed my protection, but that was my problem. Suddenly feeling that dealing with me might have been as difficult for her as dealing with the Terrorists, I made the usual obligatory offers of further assistance, and went home. Fortunately for what Sarah would call my macho side, I was on an intramural football team. So were all of the Terrorists. We met three times. I am big, they were average; they suffered; I had a good time and did not feel so proud of myself afterward. The Terrorists did not even understand that I didn't like them. Like a lot of whites, they didn't care much for blacks unless they were athletic blacks, in which case we could do whatever we wanted. To knock Terrorist heads for two hours, then have them pat me on the butt in admiration, was frustrating. As for Sarah, she had no such outlets for her feelings.

She lay on her bed for the rest of the afternoon, unable to think about anything else, desperate for the company of Hyacinth, who was out of town for the weekend. Ultra-raunch rock-'n'-roll pounded through from the room above. The Terrorists figured out her number and she had to take her phone off the hook. She ignored the Airheads knocking on her door. Finally, late in the evening, when things had been quiet for a couple of hours, she slipped out to take a shower— a right-side-up, hot shower.

This was not very relaxing. She had to keep her eyes and ears open as much as she could. As she rinsed her hair, though, a klunk sounded from the showerhead and the water wavered, then turned bitterly cold. She yelped and swung the hot-water handle around, to no effect, and then she couldn't stand it and had to yank open the door and get out of there.

They were all waiting for her— not the Terrorists, but the Airheads in their bathrobes. One stood at every sink, smiling, hot water on full blast, and one stood by every shower stall, smiling, steam pouring out of the door. With huge smiles and squeals of joy, they actually grabbed her by the arms, shouting Swirlie!, Swirlie!, took her to one of the toilets, stuck her head in, and flushed.

She was standing there naked, toilet water running in thin cold ribbons down her body, and they were in their bathrobes, smiling sympathetically and applauding. Apologies came from all directions. Somehow she didn't scream, she didn't hit anyone; she grabbed her bathrobe— tearing her hand on the corner of the shower door in her spastic fury— wrapped it around herself and tied it so tightly she could hardly breathe. Her pulse fluttered like a bird in an iron box and tingles of hyperventilation ran down her arms and into her fingertips.

"What the fuck is wrong with you? Are you crazy?"

They mostly tittered nervously and tried to ignore the way she had flown off the handle. They were leaving her a social escape route; she could still smooth it over. But she was not interested. "Listen to me good, you dumb fucks!" She had let herself go, it was the only thing she could do. In a way it felt great to bellow and cry and rage and scare the hell out of them; this was the first contact with reality these women had had in years. "This is rape! And I'm entitled to protect myself from it! And I will!"

She had stepped over the line. It was now okay to hate Sarah, and several took the opportunity, laughing out loud to each other. Mari did not. "Sarah! Jeez, you don't have to take it so serious! You'll feel better later on. We've got some punch for you in the Lounge. We were just letting you in to the wing. We didn't think you were going to get so upset."

"Yeah."

"Yeah."

"Yeah."

"Well, I'm real sorry, excuse me, but I am going to take it seriously because anyone who can't see why it's serious has bad, bad problems and needs to get straightened out. If you think you're doing this because it's natural and fun, you aren't thinking too fucking hard."

"But, Jeez, Sarah," said Mari, hardly believing anyone could be so weird, "it's for the better. We've all been through it together now and we're all sisters. We're all an equal family together. We were just welcoming you in."

"The whole purpose of a fucking university is not so that you can come and be just like everyone else. I'm not equal to you people, never will be, don't want to be, I don't want to be anyone's sister, I don't want your activities, all I want is a decent place to live where I can be Sarah Jane Johnson, and not be equalized… by a mob.. . of little powderpuff terrorists… who just can't stand differentness because they're too stupid to understand it! What goes on in your heads? Haven't you ever seen the diversity of… of nature? Stop laughing. Look, you think this is funny? The next time you do this, someone is going to get hurt very badly." She looked down at the little drops of blood on the floor, dripping from her hand, and suddenly felt cleansed. She clenched the fist and held it up. "Understand?"

They had been smug at her wild anger. Now they were scared and disgusted and their makeup lay on their appalled skin like blood on snow. Most fled, hysterically grossed out.

"Gag me green!"

"Barf me blue!"

Mari averted her gaze from this gore. "Well, that's okay if you want to give all of this up. But I don't think it's like rape. I mean, we all scream a lot and stuff, and we don't really want them to do it, if you know what I mean, but when they do it's fun after all. So for us it's just sort of wild and exciting, and for the guys, it helps them work off steam. You know what I mean?"

"No! Get out! Don't fuck with my life!" That was a lie— she did know exactly what Mari meant. But she had just realized she could never let herself think that way again. Mari sadly floated out, sniffling. Sarah, alone now, washed her hair again (though it had not been a "dirty swirlie") and retreated to her room, a little ill in a gag-me-green sort of way, yet filled with a tingling sense of sureness and power. She was not harassed anymore. Word had gone out. Sarah had gotten additional punishment and was not to be bothered.

The door opened slightly, and a dazzling splinter of fluorescent light shot out across the dusky linoleum. Within the room it was still. The door opened a bit more. "Spike? It's me. Don't try to get out, kittycat."

Now the door opened all the way and a tall skinny figure stepped in quickly, shut the door, and turned on a dim reading lamp. "Spike, are you sleeping? What did you get into this time?" He found the kitten under his bed, next to the overturned rat-poison tray that was not supposed to be there. Spike had only been dead for a few minutes, and his body was still so warm that Casimir thought he could be cuddled back to life. He sat on the floor by his bed and rocked Spike for a while, then stopped and let the tiny corpse down into his lap.

A convulsion took his diaphragm and his lungs emptied themselves in jolts. He twisted around, breathless, hung on his elbows on the bed's edge, finally sucked in a wisp of air and sobbed it out again. He rolled onto the bed and the sobs came faster and louder. He pulled his pillow into his face and screamed and sobbed for longer than he could keep track of. Into his lumpy little standard-issue American Megaversity pillow he shuddered it all out: Sharon, Spike, the desecration of his academic dream, his loneliness.

When he pulled himself together he was drained and queasy but curiously relaxed. He put Spike in a garbage bag and slid him into an empty calculator box, which he taped shut. Cradling it, he stared out the window. Around him in even ranks rose the thousands of windows of the towers, and to his tear-blurred vision it was as though he stood in a forest aflame "Spike," he said, "What the hell should I do with myself?

"Yeah. Okay. That's what it's going to be.

"Well, Spike, now I have to do something unbelievably great. Something impossible. Something these scum are too dumb even to imagine. To hell with grades. There are much fairer ways of showing how smart you are. I'm smarter than all of these fuckers, rules aside."

He cranked his vent window open. Outside a Tower War was raging: students shouting to one another, shining lights and lasers into one another's rooms, blaring their stereos across the gulfs. Now the countertenor cry of Casimir Radon rode in above the tumult.

"You can make it as hard as you want, as hard as you can, but I'm going to be the cleverest bastard this place has ever seen! I can make idiots of you all, damn it!"

"Fuck you!" came a long-drawn-out scream from F Tower. It was precisely what Casimir wanted to hear. He shut his window and sat in darkness to think.

At four in the morning the wing was quiet except for Sarah, who was up, preparing her laundry. It was not necessary to do it at four in the morning— one could find open machines as late as six or seven— but this was Sarah's time of day. At this time she could walk the halls like something supernatural (or as she put it, "something natural, in a place that is sub-natural"). In the corridors she would meet the stupid gotten-up-to-urinate, staggering half-dead for the bathroom, and they'd squint at her— clothed, up and bright— as though she were a moonbeam that had worked its way around their room to splash upon their faces. The ultra-late partiers, crushed by alcohol, floated, belched and slurred along in glitzy boogie dress, and the fresh and sober Sarah, in soft clothes and tennis shoes, could dance through them before they had even recognized her presence. The brightest nerds and premeds riding the elevators home from all-nighters were so thick with sleep they could hardly stand, much less appreciate the time of day. A dozen or so hard-core athletes liked to rise as early as Sarah, and when she encountered them they would nod happily and go their separate ways.

Being up at four in the morning was akin to being in the wilderness. It was as close to the outside world as you could get without leaving the Plex. The rest of the day, the harsh artificiality of the place ruled the atmosphere and the unwitting inhabitants, but the calm purity of the predawn had a way of seeping through the cinderblocks and pervading the place for an hour or so.

"Screw the laundry," is what she finally said. She had plenty of clean clothes.

She was kneeling amid a heap of white cottons, and the grim brackishness of her room was all around her. Suddenly she could not stand it. Laundry would not make the room seem decent, and she had to do something that would.

Out in the wing it was easy to find the leftover paints and brushes. The Castle in the Air paintings were just now getting their finishing touches. She found the supplies in a storage closet and brought them to her room.

Normally this would have been a quick and dirty process, but the spirit of four in the morning made her placid. She moved the furniture away from the walls and in a few minutes had the floor, door, windows and furniture covered with a Sunday New York Times. It looked better already.

The Castle in the Air, as will later be described, was a sickly yellow, floating on white clouds in a blue sky. By mixing cloud-color with Castle-color and a bit of Bambi-color (on the ground under the Castle, Bambis cavorted) she made a mellow creamy paint. This she applied to the walls and ceiling with a roller. It was breakfast-time. She wasn't hungry.

Sky-color and castle-color made green. She splayed open a cardboard box and made it into a giant palette, mixing up every shade of green she could devise and smearing them around to create an infinite variety. Then she began to dab away on one wall with no particular plan or goal.

The light fixture was in the middle of the wall. She paused, thinking of the dire consequences, then sighed blissfully and slapped it all over with thick green daubs.

By noon the wall was covered with pied green splotches ranging from almost-black to yellow. It was not a bad approximation of a forest in the sun, but it lacked fine detail and branches. She had long since decided to cut all her classes. She left her room for the first time since sunrise and started riding the 'vators toward the shopping mall. She felt great.

"Doin' some paintin'?" asked a doe-eyed woman in leg warmers. Plastered with paint, Sarah nodded, beaming. "Doin' your room?"

"Yep."

"Yeah. So did we. We did ours all really high-tech. Lots of glow-colors. How bout you? Lotsa green?"

"Of course," said Sarah, "I'm making it look like the outside. So I don't forget."

At the Sears in the Mall she got matte black paint and smaller brushes. She returned to her room, passing the Cafeteria, where thousands stood in line for something that smelled of onions and salt and hot fat, Sarah had not eaten in twenty-four hours and felt great— it was a day to fast. Back in her room she cleared away a Times page announcing a coup in Africa and sat on her bed to contemplate her forest. Infinitely better than the old wall, yet still just a rude beginning— every patch of color could be subdivided into a hundred shades and crisscrossed with black branches to hold it all up. She knew she'd never finish it, but that was fine. That was the idea.

Casimir immediately went into action. He had already daydreamed up this plan, and to organize the first stages of Project Spike did not take long. Since Sharon had sunk completely into a coma, Casimir had taken over the old professor's lab in the Burrows, spending so much time there that he stored a sleeping bag in the closet so he could stay overnight.

This evening— Day Three— he had found six rats crowded into his box trap near the Cafeteria. Judging from the quantity of poison scattered around this area, they were of a highly resistant strain. In the lab, he donned heavy gloves, opened the trap, forced himself to grab a rat, pulled it out and slammed shut the lid. This was a physics. not a biology, lab and so his methods were crude. He pressed the rat against the counter and stunned it with a piece of copper tubing, then held it underwater until dead.

He laid it on a bare plank and set before him an encyclopedia volume he had stolen from the Library, opened to a page which showed a diagram of the rat's anatomy. Weighing it open with a hunk of lead radiation shield, he took out a single-edged razor and went to work on the little beast. In twenty minutes he had the liver out. In an hour he had six rat livers in a beaker and six liverless rat corpses in the wastebasket, swathed in plastic. He put the livers in a mortar and ground them to a pulp, poured in some alcohol, and filtered the resulting soup until it was clear.

Next morning he visited the Science Shop, where Virgil Gabrielsen was fixing up a chromatograph that would enable Casimir to find out what chemicals were contained in the rat liver extract. "We're ready for your mysterious test," said Virgil. "Hope you don't mind."

"I love working with mad scientists— never dull. What's that?" "Mostly grain alcohol. This machine will answer your question, though, if it's fixed."

A few hours later they had the results: a strip of paper with a line squiggled across it by the machine. Virgil compared this graph with similar ones from a long skinny book.

"Shit," said Virgil, showing rare surprise. "I didn't think anything could live with this much Thalphene in its guts. Thalphene! These things have incredible immunities."

"What is it? I don't know anything about chemistry." "Trade name for thallium phenoxide." Virgil crossed his arms and looked at the ceiling. "Dangerous Properties of Industrial Materials, my favorite bedtime reading, says this about thallium compounds. I abbreviate. 'Used in rat poison and depilatories … results in swelling of feet and legs, arthralgia, vomiting. insomnia, hyperaesthesia and paresthesia of hands and feet, mental confusion, polyneuritis with severe pains in legs and loins, partial paralysis and degeneration of legs, angina, nephritis, wasting, weakness … complete loss of hair . . ha! Fatal poisoning has been known to occur.'"

"No kidding!"

"Under phenols we have.. . 'where death is delayed, damage to kidneys, liver, pancreas, spleen, edema of the lungs, headache, dizziness, weakness, dimness of vision, loss of consciousness, vomiting, severe abdominal pain, corrosion of lips, mouth, throat, esophagus and stomach'."

"Okay, I get the idea."

"And that doesn't account for synergistic effects. These rats eat the stuff all the time."

"So they go through a lot of rat poison, these rats do."

"It looks to me," said Virgil, "as though they live on it. But if you don't mind my prying, why do you care?"

Casimir was slightly embarrassed, but he knew Virgil's secret, so it was only fair to bare his own. "In order for Project Spike to work, they have to be heavy rat-poison eaters. I'm going to collect rat poison off the floors and expose it to the slow neutron source in Sharon's lab. It's a little chunk of a beryllium isotope on a piece of plutonium, heavily shielded in paraffin— looks like a garbage can on wheels. Paraffin stops slow neutrons, see. Anyway, when I expose the rat poison to the neutrons, some of the carbon in the poison will turn to Carbon— 14. Carbon— 14 is used in dating. of course, so there are plenty of machines around to detect small amounts of it. Anyway, I set this tagged poison out near the Cafeteria. Then I analyze samples of Cafeteria food for unusually high levels of Carbon— 14. If I get a high reading. .