The stock of flat cats in deep freeze steadily melted. Their stock of high grade grew.

Roger Stone received their suggestion that they save out a few for breeding stock with one of his more emphatic refu­sals; once, he declaimed, was enough to be swamped in flat cats. Fuzzy Britches could stay, safely on short rations - but one was enough.

They had reached the last few at the back of the hold and were thinking about going out of business when a tired-looking, grey-haired man showed up after their broadcast. There were several other customers; he hung back and let the twins sell flat cats to the others. He had with him a girl child, little older than Lowell. Castor had not seen him before but he guessed that he might be Mr. Erska; bachelors far out-numbered families in the node and families with children were very rare. The Erskas picked up a precarious living down orbit and north; they were seldom seen at City Hall. Mr. Erska spoke Basic with some difficulty; Mrs Erska spoke it not at all. The family used some one of the little lingos - Icelandic, it might have been.

When the other customers had left the Stone Castor put on his professional grin and introduced himself. Yes, it was Mr. Erska. "And what can I do for you today, sir? A flat cat?"

"I'm afraid not"

"How about a projector? With a dozen tapes thrown in? Just the thing for a family evening."

Mr. Erska seemed nervous. "Uh, very nice, I'm sure. No." He tugged at the little girl's hand. "We better go now, babykin."

"Don't rush off. My baby brother is around somewhere - or was. He'd like to meet your kid. Maybe he's wandered over into the store. I'll look for him"

"We better go."

"What's the rush? He can't be far."

Mr. Erska swallowed in embarrassment 'My little girl. She heard your program and she wanted to see a flat cat. Now she's seen one, so we go."

"Oh-" Castor brought himself face to face with the child. "Would you like to hold one, honey?" She did not answer, but nodded solemnly. "Mr. P.,. bring up the Duchess."

"Right, Mr. C." Pollux went aft and fetched the Duchess - the first flat cat that came to hand, of course. He came back, warming it against his belly to revive it quickly.

Castor took it and massaged it until it flattened out and opened its eyes. "Here, honeybunch. Don't be afraid"

Still silent, the child took it, cuddled it The small furry bundle sighed and began to purr. Castor turned to her father. "Don't you want to get it for her?"

The man turned red. "No, no!"

"Why not? They're no trouble. She'll love it. So will you."

"No!" He reached out and tried to take the flat cat from his daughter, speaking to her in another language.

She clung to it, replying in what was clearly the negative. Castor looked at them thoughtfully. "You would like to buy it for her, wouldn't you?"

The man looked away. "I can't buy it."

"But you want to." Castor glanced at Pollux. "Do you know what you are, Mr. Erska. You are the five hundredth cus­tomer of Flat Cat Alley."

"Uh?"

"Didn't you hear our grand offer? You must have missed one of our programs. The five hundredth flat cat is absolutely free."

The little girl looked puzzled but clung to the flat cat Her father looked doubtful. "You're fooling?"

Castor laughed. "Ask Mr. P."

Pollux nodded solemnly. "The bare truth, Mr. Erska. It's a celebration of a successful season. One flat cat, absolutely free with the compliments of the management And with it goes either one pin-up, or two candy bars - your choice."

Mr. Erska seemed only half convinced, but they left with the child clinging to 'Duchess' and the candy bars. When the door was closed behind them Castor said fretfully, "You didn't need to chuck in the candy bars They were the last; I didn't mean us to sell them"

"Well, we didn't sell them; we gave 'em away."

Castor grinned and shrugged. "Okay, I hope they don't make her sick. What was her name?"

"I didn't get it."

"No matter. Our Mrs Fries will know." He turned around, saw Hazel behind them in the hatch. "What are you grinning about?"

"Nothing, nothing. I just enjoy seeing a couple of cold-cash businessmen at work."

"Money isn't everything!"

"Besides," added Pollux, "it's good advertising."

"Advertising? With your stock practically gone?" She snick­ered. "There wasn't any "grand offer" - and I'll give you six to one it wasn't your five hundredth sale."

Castor looked embarrassed. "Aw, she wanted it! What would you have done?"

Hazel moved up to them, put an arm around the neck of each. "My boys! I'm beginning to think you may grow up yet. In thirty, forty, fifty more years you may be ready to join the human race."

"Aw, lay off it!"

XVIII - THE WORM IN THE MUD

Cost-accounting on the flat-cat deal turned out to be complicated. The creatures were all descendants of Fuzzy Britches, chattel of Lowell. But the increase was directly attributable to food fed to them by everyone - which in turn had forced them to eat most of the luxury foods stocked by the twins for trade. But it had been the twins' imaginative initiative which had turned a liability into an asset. On the other hand they had used freely the capital goods (ship and electronic equipment) belonging to the entire family. But how to figure the probable worth of the consumed luxury foods? Whatever the figure was, it was not just original cost plus lift fuel.

Roger Stone handed down a Solomon's decision. From the gross proceeds would be subtracted Meade's percentage for singing; the twins would be reimbursed for the trade goods that had been commandeered; the balance would be split three ways among the twins and Lowell - all to be settled after they had traded high grade for refined metal at Ceres, then sold their load at Luna.

In the meantime he agreed to advance the twins' money to operate further. Fries having promised to honor his sight draft on Luna City National.

But for once the twins found no immediate way to invest money. They toyed with the idea of using their time to pros­pect on their own, but a few trips out in the scooter con­vinced them that it was a game for experts and one in which even the experts usually made only a bare living. It was the fixed illusion that the next mass would be 'the glory rock' - the one that would pay for years of toil - that kept the old rockmen going. The twins knew too much about statistics now, and they believed in their ability rather than their luck. Finding a glory rock was sheer gamble.

"They made one fairly long trip into the thickest part of the node, fifteen hundred miles out and back taking all one day and the following night to do it. They got the scooter up to a dawdling hundred and fifty miles per hour and let it coast, planning to stop and investigate if they found promising masses having borrowed a stake-out beacon from Fries with the promise that they would pay for it they kept it

They did notneed it. Time after time they would spot a major blip in the stereo radar, only to have someone else's beacon wink on when they got within thirty miles of the mass. At the far end they did find a considerable collection of rock travelling loosely in company; they matched, shackled on their longest lines (their father had emphatically forbidden free jumping) and investigated. Having neither experience nor a centrifuge, their only way of checking on specific gravity was by grasping a mass and clutching it to them vigorously, then getting a rough notion of its inertia by its resistance to being shoved around. A Geiger counter (borrowed) had shown no radioactivity; they were searching for the more valuable core material.