"You do say so and shouldn't," agreed Hazel.

"Roger," asked Dr. Stone, "that thing they were living in could it be operated as a ship?"

"I doubt it, not the way they've got it rigged now. I wouldn't call it a ship; I'd call it a raft"

"What do they do when they want to leave?"

"They probably don't want to leave. They'll probably die within hailing distance of Rock City - as Jock nearly did. I suppose they sell their high grade at Ceres, by scooter - circum Ceres, that is. Or maybe the sell it here."

"But the whole town is migratory. They have to move some-time."

"Oh, I imagine you could move that hulk with a few jato units, if you were gentle about it and weren't in any hurry. I think I'd decompress it before I tried it, though."

The Asteroid Belt is a flattened torus ring or doughnut in space encompassing thirteen thousand five hundred thousand million trillion cubic miles. This very conservative figure is arrived at by casting out of the family the vagrant black sheep who wander in down to Mars and farther - even down close, to Sun itself - and by ignoring those which strayed too far out and became slaves to mighty Jove, such as the Trojan Aster­oids which make him a guard of honor sixty degrees ahead and behind him, in orbit. Even those that swing too far north or south are excluded; an arbitrary limit of six degrees deviation from ecliptic has been assumed.

13,500,000,000,000,000,000,000,000 cubic miles of space.

Yet the entire human race could be tucked into one corner of a single cubic mile; the average human body is about two cubic feet in bulk.

Even Hazel's dauntless hero 'Captain John Sterling' would he hard put to police such a beat. He would need to be twins, at least.

Write the figure as 1.35 x 10^25th cubic miles; that makes it easier to see if no easier to grasp. At the time the Rolling Stone arrived among the rolling stones of Rock City the Belt had a population density of one human soul for every two billion trillion cubic miles - read 2 x10²¹. About half of these six thousand-odd lived on the larger planetoids. Ceres, Pallas, Vesta, Juno; one of the few pleasant surprises in the explora­tion of our system was the discovery that the largest Asteroids were unbelievably dense and thus had respectable surface gravitations. Ceres, with a diameter of only 485miles, has an average density five times that of Earth and a surface gravity about the same as Mars. These large planetoids are believed to be mainly core material of lost Lucifer, covered with a few miles of lighter debris.

The other three thousand inhabitants constitute the Belt's floating population in a most literal sense; they live and work in free fall. Almost all of them are gathered into half a dozen loose communities working the nodes or clusters of the Belt. The nodes are several hundred times as dense as the main body of the Belt - if 'dense' is the proper word; a transport for Ganymede could have ploughed through the Hallelujah node and Rock City and never noticed it except by radar. The chance that such a liner would hit anything is extremely small.

The miners worked the nodes for uranium, transuranics, and core material, selling their high grade at the most conveniently positioned large Asteroid and occasionally moving on to some other node. Before the strike in the Hallelujah the group calling themselves Rock City had been working Kaiser Wilhelm node behind Ceres in orbit; at the good news they moved, speeding up a trifle and passing in-orbit of Ceres, a ragtag caravan nudged through the sky by scooters, chemical rocket engines, jato units, and faith. Theirs was the only community well placed to migrate. Grogan's Boys were in the same orbit but in Heartbreak node beyond the Sun, half a billion miles away. New Joburg was not far away but was working the node known as Reynolds Number Two, which rode the Themis orbital pattern, inconveniently far out.

None of these cities in the sky was truly self-supporting, nor perhaps ever would be; but the ravenous appetite of Earth's industries for power metal and for the even more valuable planetary-core materials for such uses as jet throats and radia­tion shields - this insatiable demand for what the Asteroids could yield - made certain that the miners could swap what they had for what they needed Yet in many ways they were almost self-supporting; uranium refined no further away than Ceres gave them heat and light and power; all of their vegetables and much of their protein came from their own hydroponic tanks and yeast vats, Single-H and oxygen came from Ceres or Pallas.

Wherever there is power and mass to manipulate, Man can live.

For almost three days, the Rolling Stone coasted slowly through Rock City. To the naked eye looking out a port or even to a person standing outside on the hull Rock City looked like any other stretch of space - empty, with a backdrop of stars. A sharp-eyed person who knew the constellations well would have noticed far too many planets distorting the classic configurations, planets which did not limit their wanderings to the Zodiac. Still sharper attention would have spotted motion on the part of these 'planets', causing them to open out and draw aft from the direction the Stone was heading.

Just before lunch on the third day Captain Stone slowed his ship still more and corrected her vector by firing a jato unit; City Hall and several other shapes could be seen ahead. Later in the afternoon he fired one more jato unit, leaving the Stone dead in space relative to City Hall and less than an eighth of a mile from it He turned to the phone and called the Mayor.

"Rolling Stone, Luna, Captain Stone speaking."

"We've been watching you come in, Captain," came the voice of the Mayor.

"Good. Mr. Fries, I'm going to try to get a line over to you. With luck. I'll be over to see you in a half-hour or so."

"Using a line-throwing gun? I'll send someone out to pick it up."

"No gun, worse luck. With the best of intentions I forgot to stock one."

Fries hesitated. "Uh, Captain, pardon me, but are you in good practice for free-fall suit work?"

"Truthfully, no."

"Then let me send a boy across to put a line on you. No, no! I insist"

Hazel, the Captain, and the twins suited up, went outside, and waited. They could make out a small figure on the ship across from them; the ship itself looked larger now, larger than the Stone. City Hall was an obsolete space-to-space vessel, globular, and perhaps thirty years old. Roger Stone surmised correctly that she had made a one-way freighter trip after she was retired from a regular run.

In close company with City Hall was a stubby cylinder; it was either smaller than the spherical ship or farther away. Near it was an irregular mass impossible to make out; the sunlight on it was bright enough but the unfilled black shadows gave no clear clues. All around them were other ships or shapes close enough to be distinguished from the stars; Pollux estimated that there must be two dozen within as many miles. While he watched a scooter left a ship a mile or more away and headed toward City Hall.

The figure they had seen launched himself across the gap. He seemed to swell; in half a minute he was close by, checking himself by the line he carried. He dropped to an easy landing near the bow of the Stone; they went to meet him.

"Howdy, Captain. I'm Don Whitsitt, Mr. Fries' bookkeeper."

"Howdy, Don." He introduced the others; the twins helped haul in the light messenger line and coil it; it was followed by a steel line which Don Whitsitt shackled to the ship.