Despite the situation and the time of the year, which was October, the temperature was sticky warm due to the hothouse effect of the carbon dioxide in this Earth's dead atmosphere.

From inside his suit, through the transparent visor, Mishnoff watched it all somberly. If the epicenter of the noise were close by, adjusting the second seismograph a mile or so away would be enough for the fix. If it weren't, they would have to bring in an air scooter. Well, assume the lesser complication to begin with.

Methodically, he made his way up a rocky hillside. Once at the top, he could choose his spot.

Once at the top, puffing and feeling the heat most unpleasantly, he found he didn't have to.

His heart was pounding so that he could scarcely hear his own voice as he yelled into his radio mouthpiece, "Hey, Ching, there's construction going on."

"What?" came back the appalled shout in his ears.

There was no mistake. Ground was being leveled. Machinery was at work. Rock was being blasted out.

Mishnoff shouted, "They're blasting. That's the noise."

Ching called back, "But it's impossible. The computer would never pick the same probability pattern twice. It couldn 't."

"You don't understand-" began Mishnoff.

But Ching was following his own thought processes. "Get over there, Mishnoff. I'm coming out, too."

"No, damn it. You stay there," cried Mishnoff in alarm. "Keep me in radio contact, and for God's sake be ready to leave for Earth proper on wings if I give the word."

"Why?" demanded Ching. "What's going on?"

"I don't know yet," said Mishnoff. "Give me a chance to find out."

To his own surprise, he noticed his teeth were chattering.

Muttering breathless curses at the computer, at probability patterns and at the insatiable need for living space on the part of a trillion human beings expanding in numbers like a puff of smoke, Mishnoff slithered and slipped down the other side of the slope, setting stones to rolling and rousing peculiar echoes.

A man came out to meet him, dressed in a gas-tight suit, different in many details from Mishnoff's own, but obviously intended for the same purpose-to lead oxygen to the lungs.

Mishnoff gasped breathlessly into his mouthpiece, "Hold it, Ching. There's a man coming. Keep in touch." Mishnoff felt his heart pump more easily and the bellows of his lungs labor less.

The two men were staring at one another. The other man was blond and craggy of face. The look of surprise about him was too extreme to be feigned.

He said in a harsh voice, "Wer sind Sie? Was machen Sie hier?"

Mishnoff was thunderstruck. He'd studied ancient German for two years in the days when he expected to be an archeologist and he followed the comment despite the fact that the pronunciation was not what he had been taught. The stranger was asking his identity and his business there.

Stupidly, Mishnoff stammered, "Sprechen Sie Deutsch?"and then had to mutter reassurance to Ching whose agitated voice in his earpiece was demanding to know what the gibberish was all about.

The German-speaking one made no direct answer. He repeated, "Wer sind Sie?" and added impatiently, "Hier ist fiir ein verriickten Spass keine Zeit."

Mishnoff didn't feel like a joke either, particularly not a foolish one, but he continued, "Sprechen Sie Planetisch?"

He did not know the German for "Planetary Standard Language" so he had to guess. Too late, he thought he should have referred to it simply as English.

The other man stared wide-eyed at him. "Sind Sie wahnsinnig?"

Mishnoff was almost willing to settle for that, but in feeble self-defense, he said, "I'm not crazy, damn it. I mean, "AufderErde woher Sie gekom-"

He gave it up for lack of German, but the new idea that was rattling inside his skull would not quit its nagging. He had to find some way of testing it. He said desperately, "Welches fahr ist es jetzt?"

Presumably, the stranger, who was questioning his sanity already, would be convinced of Mishnoff's insanity now that he was being asked what year it was, but it was one question for which Mishnoff had the necessary German.

The other muttered something that sounded suspiciously like good German swearing and then said, "Es ist dock zwei tausend drei hundert vier-und-sechzig, und warum-"

The stream of German that followed was completely incomprehensible to Mishnoff, but in any case he had had enough for the moment. If he translated the German correctly, the year given him was 2364, which was nearly two thousand years in the past. How could that be?

He muttered, "Zwei tausend drei hundert vier-und sechzig?"

"/a, fa," said the other, with deep sarcasm. "Zwei tausend drei hundert vier-und-sechzig. Der ganze fahr long ist es so gewesen."

Mishnoff shrugged. The statement that it had been so all year long was a feeble witticism even in German and it gained nothing in translation. He pondered.

But then the other's ironical tone deepening, the German-speaking one went on, "Zwei tausend drei hundert vier-und-sechzig nach Hitler. Hilft das Ihnen vielleicht? Nach Hitler!"

Mishnoff yelled with delight. "That does help me. Es hilft! Horen Sie, bitte-" He went on in broken German interspersed with scraps of Planetary, "For Heaven's sake, urn Gottes willen-"

Making it 2364 after Hitler was different altogether.

He put German together desperately, trying to explain.

The other frowned and grew thoughtful. He lifted his gloved hand to stroke his chin or make some equivalent gesture, hit the transparent visor that covered his face and left his hand there uselessly, while he thought.

He said, suddenly, "Ich heiss George Fallenby."

To Mishnoff it seemed that the name must be of Anglo-Saxon derivation, although the change in vowel form as pronounced by the other made it seem Teutonic.

"Guten Tag," said Mishnoff awkwardly. "Ich heiss Alec Mishnoff," and was suddenly aware of the Slavic derivation of his own name.

"Kommen Sie mit mir, Hen Mishnoff," said Fallenby.

Mishnoff followed with a strained smile, muttering into his transmitter, "It's all right, Ching. It's all right."

Back on Earth proper, Mishnoff faced the Sector's Bureau Head, who had grown old in the Service; whose every gray hair betokened a problem met and solved; and every missing hair a problem averted. He was a cautious man with eyes still bright and teeth that were still his own. His name was Berg.

He shook his head. "And they speak German: but the German you studied was two thousand years old."

"True," said Mishnoff. "But the English Hemingway used is two thousand years old and Planetary is close enough for anyone to be able to read it."

"Hmp. And who's this Hitler?"

"He was a sort of tribal chief in ancient times. He led the German tribe in one of the wars of the twentieth century, just about the time the Atomic Age started and true history began."

"Before the Devastation, you mean?"

"Right. There was a series of wars then. The Anglo-Saxon countries won out, and I suppose that's why the Earth speaks Planetary."

"And if Hitler and his Germans had won out, the world would speak German instead?"

"They have won out on Fallenby's Earth, sir, and they do speak German."

"And make their dates 'after Hitler' instead of A.D.?"

"Right. And I suppose there's an Earth in which the Slavic tribes won out and everyone speaks Russian."

"Somehow," said Berg, "it seems to me we should have foreseen it, and yet, as far as I know, no one has. After all, there are an infinite number of inhabited Earths, and we can't be the only one that has decided to solve the problem of unlimited population growth by expanding into the worlds of probability."

"Exactly," said Mishnoff earnestly, "and it seems to me that if you think of it, there must be countless inhabited Earths so doing and there must be many multiple occupations in the three hundred billion Earths we ourselves occupy. The only reason we caught this one is that, by sheer chance, they decided to build within a mile of the dwelling we had placed there. This is something we must check."