Kath Two walked with only minor unsteadiness toward the top of a moving stairway that would take her down to the mass transit level. The ceiling above was high and arched, like a grand Old Earth train station, and its nickel-iron fretworks were atwitter with birds, a whole society of them going about its internecine trends and controversies while keeping an eye on the human traffic below. Specialized siwis, wrapped around the struts and girders like pythons around tree branches, moved along at a rate too gradual for the birds to notice, cleaning off their shit. The birds were all the same species, called the grizzled crow: a small corvid, half of whose feathers were devoid of pigment, giving it a salt-and-pepper appearance. This feature had been added by its designers simply as a visual flag so that they could be easily distinguished from rootstock crows. They moved in wheeling gray cyclones through the vaulted space overhead, but they were also comfortable shooting up and down the angled shafts that connected it to the transit level below. As Kath Two walked along the platform, a single one of those birds peeled away from a spiraling and squawking murder and dove toward her. As it hied in closer she became more and more certain that it was homing in on her face. It pulled up just short of colliding with her and, lacking a place to perch, hovered before her in ungainly style, treading air and slipping backward to match her pace. “The grove in the temperate rain forest,” it said, or as near as a crow could come to pronouncing those words, and then beat air and took off, rising toward the rafters but then banking hard down the slanted tube that would take it back into the transit. Nor was it the only grizzled crow that was completing such an errand; similar encounters were happening all around her. Perhaps a score of the birds were perched on the safety railing that surrounded the entrance to the moving stair, muttering things that they had heard from humans. One of them, who perhaps had listened to a couple making love, was producing a crow’s approximation of an orgasmic moan. Three of them were singing a popular song in unison. One was barking like a dog. A few were trying to cadge food from people who were carrying snacks. One of them just kept repeating “meet me at the train station at dot sixteen,” another “I’ll be wearing a red scarf.”
At the bottom of the moving stair the crows were flying in and out of snug little rookeries that had been built for them at the ends of the tube cars, so that they wouldn’t foul the seats. Ten minutes on one of those cars took Kath Two to Aldebrandi Gardens. This was a series of six consecutive blocks that had been constructed as botanical preserves. Each consisted of a rectangular slab of ecosystem covered by a lofty arched glass roof under which simulated Earth landforms had been built. The temperature and humidity of each had been tuned to simulate a different part of Old Earth. Plants and other organisms, sequenced from digital records, had been cultivated here, and supplemented later with birds, insects, and small animals. Creatures fostered and studied here had later been disseminated to factories in other parts of the ring where they’d been propagated in vast numbers and used to seed New Earth.
Starting at the hot end, Kath Two walked through a Southeast Asian jungle so humid that moisture condensed on her face before she could even begin to perspire. No sky was visible beneath its triple canopy, but when she stepped through the next airlock into Chihuahuan desert, she was treated to a direct view up through its ceiling into space, and blasted with sunlight bounced in by a robotic mirror mounted outside. Hanging up there in the center of the Great Chain was a little habitat called Surtsey. For during Kath Two’s stay in Quarantine, the Eye had moved on from Akureyri, passed the even larger habitat of Sean Probst at twenty degrees west, and was now entering a sort of boundary zone on the edge of the Cape Verde boneyard. She knew nothing of Surtsey, but it looked like a placeholder habitat, a sort of construction shed that would be used as the basis for something planned a minute or two west of here. Her skin and hair dried out instantly under the sun, and by the time she reached the end of the block, she almost wished she’d stayed below in the tunnels, where she needn’t have worried about cactus spines and rattlesnakes.
The next ecosystem was Fynbos, the characteristic environment of the Cape of Good Hope, cooler but no less sunny, a riot of scrappy flowering plants, a favorite of picnickers and birdwatchers from elsewhere in the Great Chain. It was a little too crowded for her taste, and so she marched straight down its length, trying not to be distracted by its many small charms, and entered the next block. This was almost more aquarium than terrarium, being a simulation of Old Earth Louisiana bayou. A plank walkway snaked among its moss-covered trees, carrying her over teeming reptile-infested waters to the airlock at its far end, where she stopped to pull a jacket out of her knapsack and don a pair of gloves.
Eight-hundred-year-old Douglas firs filled the next block from end to end. This one had been engineered to simulate the temperate rain forest of pre-Zero British Columbia, so its roof had been equipped with filters that damped the sun down to a steady silver glow that seemed to come from all directions. The lack of shadows made it seem brighter, in its way, than the unobstructed sunlight in the Chihuahuan biome. Ferns, moss, and epiphytes grew on fallen logs so thickly that they seemed to have been sprayed from a hose. A skein of faint paths ran through it. Kath Two followed one of them to the Kupol Grove: a relatively open space near the center, ringed by particularly enormous trees, where she found Doc, four of his students, his aide, and his robot sitting on moss-covered rocks and logs.
Dr. Hu Noah and most of his students were Ivyn. In Doc’s case it was difficult to tell, since extreme old age tended to obscure racial differences. He’d lost his hair long ago, and his skin was blotchy from years spent down on the surface doing research in unfiltered sunlight. Limp skin dangled from his sharp cheekbones like wet laundry from the edge of a rock, and eventually joined into a system of wattles mostly concealed by a scarf wrapped around his neck. That, and other touches meant to keep him comfortable, had been seen to by his nurse, a stocky Camite wearing a knapsack full of medical supplies. Curled at Doc’s feet like a sleeping dog was a grabb with a display panel in its back showing live readouts of his vital signs, which it was monitoring through a bundle of wireless connections. A pole projected vertically from its back to about the level of Doc’s waist, where it forked to a pair of handlebars. It was a smart cane. When he grabbed the handlebars it would help him stand up. It would then steady his locomotion even on the roughest terrain, adding its six legs to his two.