Tunnels 03, Freefall

then what about the gravity? Go on -- try it."
    "All right, I will," Will replied, taking up the challenge. He bounded up and down several times, reaching unfeasible heights above the ground with each successive jump. As he stopped jumping, he seemed undecided. "Feels lower than normal."
    "Thank you," Dr. Burrows said a little scornfully. "In fact, it's much lower. And that's because it's mainly centrifugal force keeping you on the inside of this rotating space, which is less than the force of gravity we're used to back on the surface." Dr. Burrows stopped speaking as they heard a twittering noise and a flock of flame-red birds swooped past. They were the size of pigeons, but far more refined in appearance, with long tail feathers and, most remarkably, they had two pairs of wings, and fine, curving beaks almost ten centimeters in length. One of the birds dipped down to the blue beach ball flower and , hovering by it like a humming bird, poked its beak deep inside the bloom to collect nectar.
    "Ever seen anything like that before?" Dr. Burrows asked his son.
    "Can't say I have," Will conceded reluctantly.
    As they turned to begin the journey towards the mountains, Bartleby sprang up and grabbed the flame-red bird in his jaws.
    "Bartleby! No!" Will shouted, but it was too late.

    * * * * *

    Elliott led them towards a V she'd spotted in the hills, which turned out to be the right decision because a pass lay there. Although this meant they hadn't had to do any more climbing, the 'woodland or forest' Will had referred to was the thickest jungle imaginable, and it took them many hours to push their way through the tangle of vegetation and go even a short distance. But as they finally emerged from it, they found they were at the edge of an area of scrubland, perhaps a kilometer square. It was bordered by more jungle, which rose to an incredible height and looked even more dense than the stretch they'd just come through.
    "I wonder why this area isn't overgrown too," Dr. Burrows pondered, as he went down on one knee and began to poke around in the grass, muttering something about 'pioneer colonies' of plants.
    "Hey," Will said to his father as he spied several herds of animals grazing on the distant reaches of the clearing.
    In an instant Dr. Burrows was up and peering through his binoculars. "Buffalo," he said. "But see over there." He pointed to a far corner of the scrub land.
    "Zebra?" Will suggested, just able to make out their black and white markings.
    "They're like zebra, but the stripes stop behind their forelegs... Will... I don believe they're quagga!" Dr. Burrows exclaimed, then gave a slightly hysterical giggle.
    "Nah. Quagga are extinct," Dad," Will said dismissively. "The last one died in a zoo in--"
    "I know, I know -- the eighteen-eighties... a zoo in Amsterdam." Dr. Burrows lowered his binoculars. "But they haven't been hunted to extinction here. It's as though they've been given a second chance!"
    "You mean we've been given a second chance," Will contradicted him.
    Dr. Burrows was silent as something else caught his eye and he passed the binoculars to his son. "Just above the tree-line -- tell me what you see."
    "Looks like smoke -- a big cloud of it," Will answered.
    "Yes, I saw that," Dr. Burrows said. "A bushfire, I'd say. The foliage probably gets so overheated that fires break out spontaneously. From a quick examination of the ground round here, there appears to be a thick layer of ash under the new raft of vegetation." He paused dramatically. "But I wasn't talking about the smoke. Take another look, Will."
    Will adjusted the binoculars. He didn't say anything, but then lowered them and met his father's eyes. "Pyramids.... two of them."
    "Yes," Dr. Burrows said, "and they're--"
    "-- look like Mayan pyramids," Will interrupted him. The tops are flattened, just like them."
    "Yes... Mayan pyramids," Dr. Burrows agreed. "But I counted three of them. We should head for the nearest." Dr. Burrows decided on the spot.
    As they trekked across the clearing, the herds of grazing animals seemed not to take the slightest notice of them, as if they held no fear of human beings. But Will was feeling more and more uncomfortable. He held out his forearm to examine it.
    "What's the matter?" Dr. Burrows asked him.
    "It's the sun -- I can't stay in this much longer. It's burning me to hell," Will said.
    Fortunately, they were close to the perimeter of the scrub land and Will was soon able to take shelter under the thick