After pausing for a few minutes to allow his rattling heart to rest, Rees rolled on down the shallow, curving slope; Nebula light faded, to be replaced by the white glow of a chain of well-spaced lamps. Rees peered up at them as he passed. No one knew how the fist-sized globes worked. Apparently the lamps had glowed here unattended for centuries — most of them, anyway; here and there the chain was broken by the dimness of a failed lamp. Rees passed through the pools of darkness with a shudder; typically his mind raced through the years to a future in which miners would have to function without the ancient lamps.

After fifty yards of passageway — a third of the way around the circumference of the star — the light of the Nebula and the noise of the rain had disappeared. He reached a wide, cylindrical chamber, its roof about ten yards beneath the surface of the star. Rust-free walls gleamed in the lamplight. This was the entrance to the mine proper; the walls of the chamber were broken by the mouths of five circular passageways which led on into the heart of the star. The Moles — the digging machines — cut and refined the iron in the passageways, returning it in manageable nodules to the surface.

The real function of humans down here was to supplement the limited decision-making capabilities of the digging machines — to adjust their quota, perhaps, or to direct the gouging of fresh passageways around broken-down wheelchairs. Few people were capable of more… although some miners, like Roch, were full of drunken stories about their prowess under the extreme gravity conditions.

From one passageway came a grumbling, scraping sound. Rees turned the chair. After some minutes a blunt prow nosed into the light of the chamber, and — with painful slowness — one of the machines the miners called the Moles worked its way over the lip of the tunnel.

The Mole was a cylinder of dull metal, some five yards long. It moved on six fat wheels. The prow of the Mole was studded with a series of cutting devices and with handlike claws which worked the star iron. The machine's back bore a wide pannier containing several nodules of freshly cut iron.