ONCE THE TWENTY had been chosen there was little more time to count the days. They rushed by, packed with new experiences. At first, dressed in their everyday uniforms, they walked the long circular passages of the Ark. The outermost passage was just over three kilomctres in length. Four times around, it had been suggested, might be equivalent to a day's march. It took them a week just to be able to walk the distance.

Then they began to climb the never-used emergency stairs that ran between each floor at the extremity of each of the four quadrants. They learned to walk up the sixteen metres from the generator and water treatment plant past the storage bays, the living quarters, and the manufacturing and food processing floors to the level of the Dome, ground level, and then jog the seven hundred and eighty-five metres to the next stairway and go down again.

They did it, gasping and stopping after every ten stairs. They did it, resting at the end of each flight. Over and over, up the stairs, along the passages and down again, until they could climb up and down all four staircases without losing breath. Their muscles became firm and hard. They felt confident.

Then they were fitted out with boots and rainproof jackets and a fifteen kilo pack and it all began again. Panting up the stairs, resting on the landings, stum bling along the perimeter corridor to the next flight down.

They groaned at the aches and the stiffness. They lay in hot tubs and had the knots massaged out of their painful legs by teams of Healers. They lay under sun lamps slowly accustoming their skins to the sun that, for the last six generations, had reached them only through the plastic of the Dome.

By June even a stranger could have picked out the twenty from the other five thousand inhabitants of Ark Three. They stood taller. Their bodies were muscled and alert and their eyes had a snap to them. Their skins had changed too, to a deep tan on dark haired people like Luke, to a golden hue on the Initiator and many of the others, all the way down to Charity's freckles.

“I look crazy,” wailed Charity, counting the dots across the bridge of her nose in a mirror. “He'll hate me. Do you sup- pose they'll fade when this is all over and we're safely home?'' But she felt better when a new fashion sprang up among the neophytes and younger adults, of penciling dots on their cheek bones with brown crayons.

“HOW MANY PEOPLE live in Ark One?” “Who are their leaders?”

“Can't you give us any more details?”