Pebble In The Sky - By Isaac Asimov Page 0,1

but crude uranium, and that isn't dangerous. I mean, extreme purity is one of the most important qualifications for fission, isn't it?" He touched his tongue to his lips quickly. "Do you think it was fission, sir? It's not plutonium, and it wasn't being bombarded."

"And," said Dr. Smith thoughtfully, "it was below the critical mass. Or, at least, below the critical masses we think we know." He stared at the soapstone desk, at the bummed and blistered paint of the cabinets and the silvery streaks along the concrete floor. "Yet uranium melts at about 1800 degrees Centigrade, and nuclear phenomena are not so well known that we can afford to talk too glibly. After all, this place must be fairly saturated with stray radiations. When the metal cools, young man, it had better be chipped up, collected, and thoroughly analyzed."

He gazed thoughtfully about him, then stepped to the opposite wall and felt uneasily at a spot about shoulder height.

"What's this?" he said to the chemist. "Has this always been here?"

"What, sir?" The young man stepped up nervously and glanced at the spot the older man indicated. It was a tiny hole, one that might have been made by a thin nail driven into the wall and withdrawn-but driven through plaster and brick for the full thickness of the building's wall, since daylight could be seen through it.

The chemist shook his head, "I never saw that before. But I never looked for it, either, sir."

Dr. Smith said nothing. He stepped back slowly and passed the thermostat, a parallelopiped of a box made out of thin sheet iron. The water in it moved swirlingly as the stirrer turned in motor-driven monomania, while the electric bulbs beneath the water, serving as heaters, flicked on and off distractingly, in time with the clicking of the mercury relay.

"Well, then, was this here?" And Dr. Smith scraped gently with his fingernail at a spot near the top of the wide side of the thermostat. It was a neat, tiny circle drilled through the metal. The water did not quite reach it.

The chemist's eyes widened. "No, sir, that wasn't there ever before. I'll guarantee that."

"Hmm. Is there one on the other side?"

"Well, I'll be damned. I mean, yes, sir!"

"All right, come round here and sight through the holes...Shut the thermostat off, please. Now stay there." He placed his finger on the hole in the wall. "What do you see?" he called out.

"I see your finger, sir. Is that where the hole is?"

Dr. Smith did not answer. He said, with a calmness he was far from feeling, "Sight through in the other direction... Now what do you see?"

"Nothing now."

"But that's the place where the crucible with the uranium was standing. You're looking at the exact place, aren't you?"

Reluctantly, "I think so, sir."

Dr. Smith said frostily, with a quick glance at the name plate on the still-open door, "Mr. Jennings, this is absolutely top-secret. I don't want you ever to speak about this to anyone. Do you understand?"

"Absolutely, sir!"

"Then let's get out of here. We'll send in the radiation men to check the place, and you and I will spend a siege in the infirmary."

"Radiation burns, you mean?" The chemist paled.

"We'll find out."

But there were no serious signs of radiation burns in either. Blood counts were normal and a study of the hair roots revealed nothing. The nausea that developed was eventually tabbed as psychosomatic and no other symptoms appeared.

Nor, in all the Institute, was anyone found, either then or in the future, to explain why a crucible of crude uranium, well below critical size, and under no direct neutronic bombardment, should suddenly melt and radiate that deadly and significant corona.

The only conclusion was that nuclear physics had queer and dangerous crannies left in it.

Yet Dr. Smith never brought himself to tell all the truth in the report he eventually prepared. He made no mention of the holes in the laboratory, no mention of the fact that the one nearest the spot where the crucible had been was barely visible, the one on the other side of the thermostat was a trace larger, while the one in the wall, three times as far away from that fearful spot, could have had a nail thrust through it.

A beam expanding in a straight line could travel several miles before the Earth's curvature made the surface fall away from it sufficiently to prevent further damage, and then it would be ten feet across. After that, flashing emptily into space, expanding and weakening,