Free Wizard by John Varley

many seconds. Minutes? Could she possibly have hours to live?
    Growing up in the Coven was a help. She knew about centripetal movement, could work that type of problem more readily than she could have dealt with gravitation. Robin had never been in a gravitational field of any consequence.
    She began with a known factor, which was the one-fortieth gee that prevailed at the hub. When theelevator floor opened under her, she had begun to fall at a velocity of one-quarter meter per second. But she would not accelerate at that rate. A moving body in a spinning object does not fall along a radial line but appears to move against the direction of spin. In effect, she would be moving in a straight line if viewed from the outside, while the wheel turned under her. Her downward acceleration would at first be slight. Only when she had built up a considerable sidewise velocity would the rate of her fall really begin to increase, and she would experience this as wind coming from the direction opposite the spin.
    She looked around quickly. The wind was already strong. She could make out the tops of trees growing from one vertical wall. This was the storied horizontal forest of Gaea. Had Gaea been turning the other way, Robin would have been smashed in seconds or minutes. Since the fall had started at the near wall, she still had time.
    There were a few simplified calculations she could make. She was handicapped by not knowing the precise air density in Gaea. She had read it was high, something like two atmospheres at the rim. But at what rate did it fall off as one approached the hub? It never got too thin to breathe, so she could get an estimate by assuming one atmosphere at the hub.
    It was oddly comforting to lose herself in the math. She didn’t mind having to start over, though she was struck with the futility of the project. She kept at it from a desire to know when death would overtake her. It was important to die right. She gripped the strap of the bag containing Nasu and started again.
    She came up with an answer she didn’t like, tried again, and a third time when the answers didn’t match. Averaging, she got a figure of fifty-nine minutes to impact. As an added bonus there was the impact speed. Three hundred kilometers per hour.
    She was falling with her back to the wind. Since she was moving toward both the rim and the approaching wall, it meant her body was at a slight angle. The hub was not quite under her feet. The receding wall was not quite vertical to her. She looked around.
    It was breathtaking. Too bad she could not appreciate it.
    The Coven, if dropped from her point of departure, would have been a tin can falling down a smokestack. The Rhea Spoke was a hollow tube, flared at the lower end, completely encrusted with trees to dwarf the biggest sequoia. The trees rooted in the walls and grew outward. She could no longer make out even the largest as individual plants; the inner walls were a featureless sea of dark green, all around her. The interior was lit by twin vertical rows of portholes, if one could use that name for openings at least a kilometer in diameter.
    She craned her neck, looking into the blast of wind. Nox looked closer. There was something else, something that hovered at the top of her view.
    It was the vertical Rhea spokes. They fastened to islands in the Midnight Sea and leaped straight up, converging until they met near the bottom of the spoke and entwined themselves in a monumental pigtail.
    She had to see. Twisting in the air, she managed to stabilize herself with her teeth to the gale and opened her eyes. The spokes were in front of her, getting closer by the second.
    “Oh Great Mother, hear me now.” She mumbled her way through the first death incantation, unable to look away from what had become a rushing dark wall before her. The cable seemed to rotate like a barber pole, the result of her rapid progress past the wound strands.
    It took a full minute to sweep past the cables. At the closest