Dead Giveaway by Randall Garrett (best manga ereader .TXT) 📕

Well, that was that, Turnbull thought. It galled him a little to think that he'd been offered a chance to do research with Scholar Duckworth and hadn't been able to take it. But if the research hadn't panned out.... He frowned and turned back to the first letter.

A theory that would "literally kick the supports right out from under every theory that's been evolved for the existence of that city," he'd said. Odd. It was unlike Duckworth to be so positive about anything until he could support his own theory without much fear of having it pulled to pieces.

Turnbull poured himself a second glass of sherry, took a sip, and rolled it carefully over his tongue.

The Centaurus Mystery. That's what the explorers had called it back in 2041, nearly a century and a half before, when they'd found the great city on one of the planets of the Alpha Centaurus system. Man's first interstellar trip had taken nearly five years at sublight velocities, and bing!—right off the bat, they'd found something that made interstellar travel worthwhile, even though they'd found no planet in the Alpha Centaurus system that was really habitable for man.

They'd seen it from space—a huge domed city gleaming like a great gem from the center of the huge desert that covered most of the planet. The planet itself was Marslike—flat and arid over most of its surface, with a thin atmosphere high in CO_2 and very short on oxygen. The city showed up very well through the cloudless air.

From the very beginning, it had been obvious that whoever or whatever had built that city had not evolved on the planet where it had been built. Nothing more complex than the lichens had ever evolved there, as thousands of drillings into the crust of the planet had shown.

Certainly nothing of near-humanoid construction could ever have come into being on that planet without leaving some trace of themselves or their genetic forebears except for that single huge city.

How long the city had been there was anyone's guess. A thousand years? A million? There was no way of telling. It had been sealed tightly, so none of the sand that blew across the planet's surface could get in. It had been set on a high plateau of rock, far enough above the desert level to keep it from being buried, and the transparent dome was made of an aluminum oxide glass that was hard enough to resist the slight erosion of its surface that might have been caused by the gentle, thin winds dashing microscopic particles of sand against its smooth surface.

Inside, the dry air had preserved nearly every artifact, leaving them as they had been when the city was deserted by its inhabitants at an unknown time in the past.

That's right—deserted. There were no signs of any remains of living things. They'd all simply packed up and left, leaving everything behind.

Dating by the radiocarbon method was useless. Some of the carbon compounds in the various artifacts showed a faint trace of radiocarbon, others showed none. But since the method depends on a knowledge of the amount of nitrogen in the atmosphere of the planet of origin, the rate of bombardment of that atmosphere by high-velocity particles, and several other factors, the information on the radioactivity of the specimens meant nothing. There was also the likelihood that the carbon in the various polymer resins came from oil or coal, and fossil carbon is useless for radio-dating.

Nor did any of the more modern methods show any greater success.

It had taken Man centuries of careful comparison and cross-checking to read the evolutionary history written in the depths of his own planet's crust—to try to date the city was impossible. It was like trying to guess the time by looking at a faceless clock with no hands.

There the city stood—a hundred miles across, ten thousand square miles of complex enigma.

It had given Man his first step into the ever-widening field of Cultural Xenology.

Dave Turnbull finished his sherry, got up from the breakfast nook, and walked into the living room, where his reference books were shelved. The copy of Kleistmeistenoppolous' "City of Centaurus" hadn't been opened in years, but he took it down and flipped it open to within three pages of the section he was looking for.

"It is obvious, therefore, that every one of the indicators points in the same direction. The City was not—could not have been—self-supporting. There is no source of organic material on the planet great enough to support such a city; therefore, foodstuffs must have been imported. On the other hand, it is necessary to postulate some reason for establishing a city on an otherwise barren planet and populating it with an estimated six hundred thousand individuals.

"There can be only one answer: The race that built the City did so for the same reason that human beings built such megalopolises as New York, Los Angeles, Tokyo, and London—because it was a focal point for important trade routes. Only such trade routes could support such a city; only such trade routes give reason for the City's very existence.

"And when those trade routes changed or were supplanted by others in the course of time, the reason for the City's existence vanished."

Turnbull closed the book and shoved it back into place. Certainly the theory made sense, and had for a century. Had Duckworth come across information that would seem to smash that theory?

The planet itself seemed to be perfectly constructed for a gigantic landing field for interstellar ships. It was almost flat, and if the transhipping between the interstellar vessels had been done by air, there would be no need to build a hard surface for the field. And there were other indications. Every fact that had come to light in the ensuing century had been in support of the Greek-German xenologist's theory.

Had Duckworth come up with something new?

If so, why had he decided to discard it and forget his new theory?

If not, why had he formulated the new theory, and on what grounds?

Turnbull lit a cigarette and looked sourly at the smoke that drifted up from its tip. What the devil was eating him? He'd spent too much time away from Earth, that was the trouble. He'd been too deeply immersed in his study of Lobon for the past year. Now all he had to do was get a little hint of something connected with cultural xenology, and his mind went off on dizzy tizzies.

Forget it. Duckworth had thought he was on to something, found out that he wasn't, and discarded the whole idea. And if someone like Scholar James Duckworth had decided it wasn't worth fooling with, then why was a common Ph. D. like Turnbull worrying about it? Especially when he had no idea what had started Duckworth off in the first place.

And his thoughts came back around to that again. If Duckworth had thought enough of the idea to get excited over it, what had set him off? Even if it had later proved to be a bad lead, Turnbull felt he'd like to know what had made Duckworth think—even for a short time—that there was some other explanation for the City.

Ah, hell! He'd ask Duckworth some day. There was plenty of time.

He went over to the phone, dialed a number, and sat down comfortably in his fat blue overstuffed chair. It buzzed for half a minute, then the telltale lit up, but the screen remained dark.