Ken felt he had grown 3 inches taller after his father's discussion. As if he had passed some ancient ritual, he could be admitted to the company of adults and his opinions would be heard.

This proved to be true. His father rapidly organized the facilities of the college laboratories and recruited every possible science student in the chemistry and physics departments, as well as many from the high school. As these plans were outlined, Ken made a proposal of his own.

"I believe our first move," he said, "should be to set up a network of amateur radio stations operating in cities where there are other laboratories. If you could be in touch with them, ideas could be exchanged and duplication of work avoided."

"An excellent idea," said Professor Maddox. "You can work it out as we go along."

"No. It ought to be done immediately," Ken said. "If not, it may be almost impossible to find anyone on the air later. There may not be many amateurs who will bother to convert their rigs to battery operation. There may not be many who can get the batteries together."

"Good enough!" his father said. "Let that have priority over everything else until you get it organized. Probably you should find at least two contacts in each of the university centers. Put at the top of your list Berkeley, Pasadena, Chicago, New York, and Washington, D.C.

"See if you can get relay contacts that will put us in touch with Stockholm, Paris, London, Berlin, and Tokyo. If so, we can have contact with the majority of the workers capable of contributing most to this problem."

"I'll do my best," Ken promised.

Someone would be needed to operate the station and spend a good many hours a week listening and recording. He didn't want to spend the time necessary doing that, and he knew none of the other club members would, either. At once he thought of Maria Larsen. She would undoubtedly be happy to take over the job and feel she was doing something useful. On the way home he stopped at her house and told her what he had in mind. She readily agreed.

"I don't know anything about radio," she said. "You'll have to show me what to do."

"We won't expect you to learn code, of course," he said. "When we do handle anything coming in by code one of us will have to take it. We'll try to contact phone stations wherever possible for this program we have in mind. Most of the stuff will be put on tape, and Dad will probably want you to prepare typed copies, too. You can do enough to take a big load off the rest of us."

"I'll be happy to try."

They spent the rest of the day in the radio room of the science shack. Ken taught Maria the simple operations of turning on the transmitter and receiver, of handling the tuning controls, and the proper procedure for making and receiving calls. He supposed there would be some technical objection to her operation of the station without an operator's license, but he was quite sure that such things were not important right now.

It was a new kind of experience for Maria. Her face was alive with excitement as Ken checked several bands to see where amateurs were still operating. The babble of high-frequency code whistles alternated in the room with faint, sometimes muffled voices on the phone band.

"There are more stations than I expected," Ken said. "With luck, we may be able to establish a few of the contacts we need, tonight."

After many tries, he succeeded in raising an operator, W6YRE, in San Francisco. They traded news, and it sounded as if the west coast city was crumbling swiftly. Ken explained what he wanted. W6YRE promised to try to raise someone with a high-powered phone rig in Berkeley, near the university.

They listened to him calling, but could not hear the station he finally raised.

"What good will that do?" Maria asked. "If we can't hear the station in Berkeley...."

"He may be working on a relay deal through the small rig. It's better than nothing, but I'd prefer a station we can contact directly."

In a few minutes, the San Francisco operator called them back. "W6WGU knows a ham with a 1000-watt phone near the university," he said. "He thinks he'll go for your deal, but he's not set up for battery. In fact, he's about ready to evacuate. Maybe he can be persuaded to stay. I'm told he's a guy who will do the noble thing if he sees a reason for it."

"There's plenty of reason for this," said Ken.

"Let's set a schedule for 9 p.m. I ought to have word on it by then."

They agreed and cut off. In another hour they had managed a contact with a Chicago operator, and explained what they wanted.

"You're out of luck here," the ham replied. "This town is falling apart at the seams right now. The whole Loop area has been burned out. There's been rioting for 18 hours straight. The militia have been trying to hold things together, but I don't think they even know whether anybody is still on top giving the orders.

"I'll try to find out what the eggheads at the university are doing, but if they've got any kind of research running in this mess, it'll surprise me. If they are still there, I'll hang on and report to you. Otherwise, I'm heading north. There's not much sense to it, but when something like this happens a guy's got to run or have a good reason for staying put. If he doesn't he'll go nuts."

The Chicago operator agreed to a schedule for the following morning.

Maria and Ken sat in silence, not looking at each other, after they cut off.

"It will be that way in all the big cities, won't it?" Maria asked.

"I'm afraid so. We're luckier than they are," Ken said, "but I wonder how long we'll stay lucky." He was thinking of Frank Meggs, and the people who had swamped his store.

At 9 p.m., W6YRE came back on. The Berkeley 1000-watt phone was enthusiastic about being a contact post with the university people. He had promised to make arrangements with them and to round up enough batteries to convert his transmitter and receiver.

They had no further success that night.

Ken's father shook his head sadly when told of the situation in Chicago. "I had counted on them," he said. "Their people are among the best in the world, and they have the finest equipment. I hope things are not like that everywhere."

Members of the science club took turns at the transmitter the following days for 20-hour stretches, until everything possible had been done to establish the contacts requested by Professor Maddox.

In Chicago there appeared to have been a complete collapse. The operator there reported he was unable to reach any of the scientific personnel at the university. He promised a further contact, but when the time came he could not be reached. There was no voice at all in the Chicago area. Ken wondered what had become of the man whose voice they had heard briefly. He was certain he would never know.

Although there was much disorder on the west coast, the situation was in somewhat better control. The rioting had not yet threatened the universities, and both Berkeley and Pasadena were working frantically on the problem with round-the-clock shifts in their laboratories. They had welcomed wholeheartedly the communication network initiated by the Mayfield group.

In Washington, D.C. tight military control was keeping things somewhat in order. In Stockholm, where contact had been established through a Washington relay after 2 days of steady effort, there was no rioting whatever. Paris and London had suffered, but their leading universities were at work on the problem. Tokyo reported similar conditions.

Ken grinned at Maria as they received the Stockholm report. "Those Swedes," he said. "They're pretty good at keeping their heads."

Maria answered with a faint smile of her own. "Everybody should be Swedes. No?"

The fall winds and the black frost came early that year, as if in fair warning that the winter intended a brutal assault upon the stricken world. The pile of logs in the community woodlot grew steadily. A large crew of men worked to reduce the logs to stove lengths.

They had made a crude attempt to set up a circular saw, using animal power to drive it. The shaft was mounted in hardwood blocks, driven by a complicated arrangement of wooden pulleys and leather belts. The horses worked it through a treadmill.

The apparatus worked part of the time, but it scarcely paid for itself when measured against the efforts of the men who had to keep it in repair.

The food storage program was well underway. Two central warehouses had been prepared from the converted Empire Movie Theater, and the Rainbow Skating Rink.

Ken wished their efforts at the college laboratory were going half as well. As the days passed, it seemed they were getting nowhere. The first effort to identify any foreign substance in the atmospheric dust was a failure. Calculations showed they had probably not allowed sufficient time to sample a large enough volume of air.

It was getting increasingly difficult to keep the blower system going. All of their original supply of small engines had broken down. The town had been scoured for replacements. These, too, were failing.

In the metallurgical department hundreds of tests had been run on samples taken from frozen engines. The photomicrographs all showed a uniform peculiarity, which the scientists could not explain. Embedded in the crystalline structure of the metal were what appeared to be some kind of foreign, amorphous particles which were concentrated near the line of union of the two parts.

Berkeley and Pasadena confirmed these results with their own tests. There was almost unanimous belief that it was in no way connected with the comet. Ken stood almost alone in his dogged conviction that the Earth's presence in the tail of the comet could be responsible for the catastrophe.

Another theory that was gaining increasing acceptance was that this foreign substance was an unexpected by-product of the hydrogen and atomic bomb testing that had been going on for so many years. Ken was forced to admit the possibility of this, inasmuch as radiation products were scattered heavily now throughout the Earth's atmosphere. Both Russia and Britain had conducted extensive tests just before the breakdowns began occurring.

The members of the science club had been allowed to retain complete control of the air-sampling program. They washed the filters carefully at intervals and distilled the solvent to recover the precious residue of dust.

As the small quantity of this grew after another week of collecting, it was treated to remove the ordinary carbon particles and accumulated pollens. When this was done there was very little remaining, but that little something might be ordinary dust carried into the atmosphere from the surface of the Earth. Or it might be out of the tail of the comet. Dust from the stars.

By now, Ken and his companions had learned the use of the electron microscope and how to prepare specimens for it. When their samples of dust had become sufficient they prepared a dozen slides for photographing with the instrument.

As these were at last developed in the darkroom, Ken scanned them eagerly. Actually, he did not know what he was looking for. None of them did. The prints seemed to show little more than shapeless patches. In the light of the laboratory he called Joe Walton's attention to one picture. "Look," he said. "Ever see anything like that before?"

Joe started to shake his head. Then he gave an exclamation. "Hey, they look like the same particles found in the metals, which nobody has been able to identify yet!"

Ken nodded. "It could be. Maybe this will get us only a horselaugh for our trouble, but let's see what they think."

They went into the next laboratory and laid the prints before Ken's father and his associates. Ken knew at once, from the expressions on the men's faces, that they were not going to be laughed at.

"I think there may be something here," said Professor Maddox, trying to suppress his excitement. "It is very difficult to tell in a picture like this whether one particle is similar to any other, but their size and configuration are very much alike."

Professor Douglas grunted disdainfully. "Impossible!" With that dismissal, he moved away.

Professor Larsen looked more carefully. "You could scrape dust from a thousand different sources and get pictures like this from half of them perhaps. Only the chemical tests will show us the nature of this material. I am certain it is very worthwhile following up."

"I feel certain that whatever contaminating agent we are dealing with is airborne," said Professor Maddox. "If this is the same substance it will not tell us its origin, of course, nor will it even prove it is responsible for these effects. However it is a step in the right direction. We can certainly stand that!"

"Couldn't we tell by spectroscopic analysis?" said Ken.

"That would be difficult to say. The commonness of the elements involved might mask what you are looking for. Get John Vickers to help you set up equipment for making some comparisons."

Vickers was the teaching fellow in the chemistry department whom Professor Maddox had planned to assign to help the boys when they first suggested atmospheric analysis. He had become indispensable in the research since then. But he liked helping the boys; it was not too long since he had been at the same stage in his own career. He understood their longing to do something worthwhile, and their embarrassment at their ineptness.

"Sure, Guys," he said, when Professor Maddox called him in. "Let's see if we can find out what this stuff is. Who knows? Maybe we've got a bear by the tail."

It was delicate precision work, preparing specimens and obtaining spectrographs of the lines that represented the elements contained in them. Time after time, their efforts failed. Something went wrong either with their sample preparation, or with their manipulation of the instruments. Ken began to feel as if their hands possessed nothing but thumbs.

"That's the way it goes," John Vickers consoled them. "Half of this business of being a scientist is knowing how to screw a nut on a left-handed bolt in the dark. Unless you're one of these guys who do it all in their heads, like Einstein."

"We're wasting our samples," Ken said. "It's taken two weeks to collect this much."

"Then this is the one that does it," said Vickers. "Try it now."

Ken turned the switch that illuminated the spectrum and exposed the photographic plate. After a moment, he cut it off. "That had better do it!" he said.

After the plates were developed, they had two successful spectrographs for comparison. One was taken from the metal of a failed-engine part. The other was from the atmospheric dust. In the comparator Vickers brought the corresponding standard comparison lines together. For a long time he peered through the eyepiece.

"A lot of lines match up," he said. "I can throw out most of them, though—carbon, oxygen, a faint sodium."

"The stuff that's giving us trouble might be a compound of one of these," said Ken.

"That's right. If so, we ought to find matching lines of other possible elements in the compounds concerned. I don't see any reasonable combination at all." He paused. "Hey, here's something I hadn't noticed."

He shifted the picture to the heavy end of the spectrum. There, a very sharp line matched on both pictures. The boys took a look at it through the viewer. "What is that one?" Ken asked.

"I don't know. I used a carbon standard. I should have used one farther toward the heavy end. This one looks like it would have to be a transuranic element, something entirely new, like plutonium."

"Then it could be from the hydrogen bomb tests," said Joe.

"It could be," said Vickers, "but somehow I've got a feeling it isn't."

"Isn't there a quick way to find out?" said Ken.

"How?"

"If we took a spectrograph of the comet and found this same line strongly present, we would have a good case for proving the comet was the source of this substance."

"Let's have a try," said Vickers. "I don't know how successfully we can get a spectrograph of the comet, but it's worth an attempt."

Their time was short, before the comet vanished below the horizon for the night. They called for help from the other boys and moved the equipment to the roof, using the small, portable 6-inch telescope belonging to the physics department.

There was time for only one exposure. After the sun had set, and the comet had dropped below the horizon, they came out of the darkroom and placed the prints in the viewing instrument.

Vickers moved the adjustments gently. After a time he looked up at the circle of boys. "You were right, Ken," he said. "Your hunch was right. The comet is responsible. Our engines have been stopped by dust from the stars."