As in Manhattan, the discretization of the space imposed form on how it had developed, with each link of the chain—each city block—acquiring its own skyline and identity. Groups of consecutive blocks had long since coalesced into neighborhoods. Each block was, in effect, a fully independent space vehicle with its own system for keeping the air from leaking out. But each was connected to its two neighbors by a bundle of passageways routed through its foundation slab, which made it possible to move easily from one to the next in the same way that the Londoners of Old Earth had used underground passages—“subways” in the London sense of that word—to cut beneath crowded intersections. Some of the subways were sized for human pedestrians. Four of them carried trains: locals and express service running both directions around the full circuit of the Great Chain. Still others were reserved for robotic vehicles programmed to carry cargo. Beyond that was a wide range of smaller conduits carrying air, water, power, and information. All of them went by the name of subways—this was a conflation of the old London and New York senses of the word. At each end of each block was a system of airlocks; these would seal themselves off in the event that a block were to depressurize. People ran marathons through them—four consecutive marathons made up about one circuit around the entire Chain.
Every fifth link in the Chain was public property. These tended to be parks, though some served as cultural facilities. So you were never more than two links away from green, or at least open, space. The other 576 links were privately owned, and constituted a commercial and residential real estate market that would have been easily recognizable to any pre-Zero property magnate. The Great Chain had been likened more than once to the ancient board game of Monopoly. Some stretches of the loop were more high-rent, others less so. The pattern was interrupted in several places by special links, or short series of links, placed there to serve industrial and civic requirements, such as making the transit system work.
One of those was the Ramp Link, whose purpose was to make connections, every five minutes, with the On Ramp and the Off Ramp. Since the Great Chain was moving at about five hundred meters per second with respect to the nonrotating frame of the Eye, persons wishing to get from the latter to the former needed to be accelerated to a fairly spectacular velocity—almost Mach 1.5—before they could set foot on the Ramp, or any other, Link. And those wishing to dechain, as the expression had it, needed to be decelerated by the same amount. The acceleration and the deceleration were handled by machines built into a place on the rim of the “iris” of the Eye. Though some efforts had been made to camouflage their essential nature, they were really just guns for shooting humans, albeit humans strapped into comfortable, pressurized bullets.
Outside of the Great Chain, the rest of the Eye was lightly infested with human beings, heavily so with robots. Most of it existed in microgravity, since the entire contraption—Great Chain, tethers, and all—was in geosynchronous orbit, hence free fall, around Earth. As you moved away from its center, toward the two extremities of the Eye where the tethers emerged, you might begin to notice tidal forces, which would show up as very mild gravity-like tugs. These shifted whenever the Eye adjusted its orbit to move around the habitat ring, and people who spent a lot of time there could always feel in their bones when a move was under way, like Old Earthers predicting the weather in their knees.
The skeleton of the Eye was a simple space frame built in the Amalthean style, which was to say that it had been carved and shaped from existing material (Cleft) as opposed to fabricated from scratch. Aesthetically, it meant that the big structural elements had a rough-hewn, space-battered look about them, a bit like a log cabin with all the knots and bark still visible. Vacancies between the big structural elements had been filled in with giant machines, most notably several immense rotating masses whose purpose was to stabilize the whole Eye gyroscopically. The nooks and crannies between the machines had been caulked with pressurized spaces where humans could move about. Some of those rotated to produce simulated gravity; they were like miniature, torus-shaped space colonies pinned to a much bigger structure. Docking ports tended to cluster near those.
As Kath Two’s eyes closed into sleep, she was gazing at the usual ring-shaped formation of iridescent sparkles, so densely packed that they blended into each other on the varp. The Eye was a slightly larger white dot between twelve and one o’clock; it would have been difficult to see were it not for the long white line representing its tether system, which ran from just above Earth’s surface all the way through the big white dot and beyond to the Big Rock.
Their flivver’s trajectory, a sharp green ellipse, projected from where they were now (near Earth) all the way out to slightly beyond the ring before curving back in to intersect the Eye.
Through her eyelids she could see indistinct patterns, reminding her a little of the first thing she’d seen this morning: the flickering lights on the walls of her tent. But then the varp figured out that her eyes were closed and shut off the display.