Murgatroyd wriggled vigorously under Calhoun's parka. He'd heard the spitting of the blaster and the roaring of exploded steam. He was disturbed. The stocky man stared.
"What's that?" he demanded blankly. "You pick up . . ."
"We're going to pick up your daughter and the man she's with," Calhoun told him crossly. "Dammit, there's an isolation syndrome from what looks like a Crusoe health problem here! It's got to be dealt with! As a matter of public health!"
The stocky Hunt stared at him. Calhoun's intentions were unimaginable to him. He floundered among incredible ideas.
"We medics," said Calhoun, "made it necessary for men to invent interplanetary travel because we kept people from dying and the population on old Earth got too large. Then we made interstellar travel necessary because we continued to keep people from dying and one solar system wasn't big enough. We're responsible for nine-tenths of civilization as it exists today, because we produced the conditions that make civilization necessary! And since on this planet civilization is going downhill and people are dying without necessity, I have the plain obligation to stop it! So let's go pick up your daughter Nym and this sweetheart of hers, and keep them from dying and get civilization on the up-grade again!"
The former leader of the kidnappers said hoarsely, "You mean . . ." Then he stammered, "Th-th-they're heading for the hotlands. No other way to go. Watch for their tracks!"
The drive-engine bellowed. The sledge raced ahead. And now it did not complete the circle that had been begun, to head back to the landing grid. Now it straightened and rushed in a splendid roaring fierceness down between the sides of the valley. It left behind the dark patch with its whirling mists. It flung aside bow-waves of fine snow, which made rainbows in the half-light which was darkness here. It rushed and rushed and rushed, leaving behind a depression which was a singular permanent proof of its passage.
Calhoun cringed a little against the wind. He could see little or nothing of what was ahead. The sprayed wings of upflung snow prevented it. Hunt, standing erect, could do better. Murgatroyd, inside the parka, again wriggled his nose out into the stinging wind and withdrew it precipitously.
Hunt drove as if confident of where to go. Calhoun dourly began to fit things into the standard pattern of how such things went. There were evidently three cities or colonies on this planet. They'd been named and he'd seen three patches of pasture from the stratosphere. One was plainly warmed by power applied underground, electric power from the landing grid's output. The one now falling behind was less likely to be electrically heated. Steam seemed more probable because of the vapor-veil above it. This sledge was surely fuel-powered. At a guess, a ram-jet drove it. Such motors were simple enough to make, once the principle of air inflow at low speeds was known. Two City—somewhere to the rear—might operate on a fuel technology which could be based on fossil oil or gas. The power source for Three City could not now be guessed.
Calhoun scowled as he tried to fill in the picture. His factual data was still limited. There was the misty golden ribbon in space. It was assuredly beyond the technical capacity of cities suffering from an isolation syndrome. He'd guessed at underground hydroponic gardens. There was surely no surface city near the landing grid and the city entrance they'd just left was in the face of a cliff. Such items pointed to a limited technical capacity. Both, also, suggested mining as the original purpose of the human colony or colonies here.
Only mining would make a colony self-supporting in an arctic climate. This world could have been colonized to secure rare metals from it. There could be a pipeline from an oil field or from a gas well field near a landing grid. Local technological use of gas or oil to process ores might produce ingots of rare metal worth interstellar freight charges. One could even guess that metal reduced by heat-chemistry could be transported in oil suspension over terrain and under conditions when other forms of surface transportation were impractical.
If the colony began as a unit of that sort, it would require only very occasional visits of spacecraft to carry away its products. It could be a company planet, colonized and maintained by a single interstellar corporation. It could have been established a hundred and fifty or two hundred years before, when the interstellar service organizations were in their infancy and only operated where they were asked to serve. Such a colony might not even be on record in the Medical Service files.
That would account for everything. When for some reason the mines became unprofitable, this colony would not be maintained. The people who wished to leave would be taken off, of course. However, some would elect to stay behind in the warmed, familiar cities they and their fathers had been born in. They couldn't imagine moving to a strange and unfamiliar world.
So much was normal reasoning. Now the strictly technical logic of the Med Service took over to explain the current state of things. In one century or less an isolated community could lose, absolutely, its defenses against diseases to which it was never exposed. Amerinds were without defense against smallpox, back on Earth. A brown race scattered among thousands of tiny islands was nearly wiped out by measles when it was introduced. Any contact between a long-isolated community and another—perhaps itself long isolated—would bring out violently any kind of contagion that might exist in either.
There was the mechanism of carriers. The real frequency of disease-carriers in the human race had been established less than two generations ago. But a very small, isolated population could easily contain a carrier or carriers of some infection. They could spread it so freely that every member of their group acquired immunity during infancy. A different isolated group might contain a carrier of a different infection and be immune to it but distributive of a second disease.
It was literally true that each of the three cities might have developed in their first century of isolation a separate immunity to one disease and a separate defenselessness against all others. A member of one community might be actually deadly to a member of either of the others whom he met face to face.
With icy wind blowing upon him as the sled rushed on, Calhoun wryly realized that all this was wholly familiar. It was taught, nowadays, that something of the sort had caused the ancient, primitive human belief that women were perilous to men and that a man must exercise great precaution to avoid evil mana emanating from his prospective bride. When wives were acquired by capture and all human communities were small and fiercely self-isolated—why each unsanitary tribal group might easily acquire a condition like that Calhoun now assumed in cities One, Two, and Three. The primitive suspicion of woman would have its basis in reality if the women of one tribe possessed immunity to some deadly microbe their skin or garments harbored, and if their successful abductors had no defense against it.
The speeding sledge swerved. It leaned inward against the turn. It swerved again, throwing monstrous sheets of snow aloft. Then the drive-jet lessened its roar. The shimmering bow-waves ceased. The sledge slowed to a mere headlong glide.
"Their trail!" Hunt cried in Calhoun's ear.
Calhoun saw depressions in the snow. There were two sets of pear-shaped dents in the otherwise virgin surface. Two human beings, wearing oblong frames on their feet, crisscrossed with cordage to support them atop the snow, had trudged ahead, here, through the gold-blue night.
Calhoun knew exactly what had happened. He could make the modifications the local situation imposed upon a standard pattern, and reconstitute a complete experience leading up to now.