"Did you ever work on Niccolò Tartaglia's puzzle about the three lovely brides, the three jealous husbands, the river and the two-passenger rowboat?"

"Yep," Grampa said. "Too easy."

Four thought a moment. "There's a modern variation with three missionaries and three cannibals. Same river, same rowboat and only one of the cannibals can row. If the cannibals outnumber the missionaries—"

"Sounds good, boy," Grampa said eagerly. "Whip it up for me."

"Okay, Grampa." Four looked at Fweep again. The translucent sphere had paused at Grampa's feet.

Grampa reached down to pat it. For an instant, his hand disappeared into Fweep, and then the alien creature rolled away. This time its path seemed crooked.

Its gelatinous form jiggled. "Hic!" it said.

As if in response, the flivver vibrated. Grampa looked querulously toward the airlock. "Flivver shouldn't shake like that. Not with the polarizer turned on."

The airlock door swung inward. Through the oval doorway walked Fred, followed closely by Junior. They were sweat-stained and weary, scintillation counters dangling heavily from their belts.

"Any luck?" Reba asked brightly.

"Do we look it?" Junior grumbled.

"Where's Joyce?" asked Fred. "Might as well get everybody in on this at once. Joyce!"

The door to his wife's room opened instantly. Behind it, Joyce was regal and slim. The pose was spoiled immediately by her avid question: "Any uranium? Radium? Thorium?"

"No," Fred said slowly, "and no other heavy metals, either. There's a few low-grade iron deposits and that's it."

"Then what makes this planet so heavy?" Reba asked.

Junior shrugged helplessly and collapsed into a chair. "Your guess is as good as anybody's."

"Then we've wasted another week on a worthless rock," Joyce complained. She turned savagely on Fred. "This was going to make us all filthy rich. We were going to find radioactives and retire to Earth like billionaires. And all we've done is spent a year of our lives in this cramped old flivver—and we don't have many of them to spare!" She glared venomously at Grampa.

"We've still got Fweepland," Four said solemnly.

"Fweepland?" Reba repeated.

"This planet. It's not big, but it's fertile and it's harmless. As real estate, it's worth almost as much as if it were solid uranium."

"A good thing, too," Junior said glumly, "because this looks like the end of our search. Short of a miracle, we'll spend the rest of our lives right here—involuntary colonists."

Joyce spun on him. "You're joking!" she screeched.

"I wish I were," Junior said. "But the polarizer won't work. Either it's broken or there's something about the gravity around here that just won't polarize."

"It's these '23 models," Grampa put in disgustedly. "They never were any good."

The land of the Fweep turned slowly on its axis. The orange sun set and rose again and stared down once more at the meadow where the improbable spaceship rested on its improbable stern. The sixteen Earth hours that the rotation had taken had changed nothing inside the ship, either.

Grampa looked up from his pircuit and said, "If I were you, Junior, I would take a good look at the TV repairman when we get back to Earth. If we get back to Earth," he amended. "You can't be Four's father. All over the Universe, gravity is the same, and if it's gravity, the polarizer will polarize it."

"That's just supposition," Junior said stubbornly. "The fact is, it isn't because it doesn't. Q.E.D."

"Maybe the polarizer is broken," Fred suggested.

Grampa snorted. "Broken-shmoken. Nothing to break, Young Fred. Just a few coils of copper wire and they're all right. We checked. We know the power plant is working: the lights are on, the air and water recirculation systems are going, the food resynthesizer is okay. And, anyway, the polarizer could work from the storage battery if it had to."

"Then it goes deeper," Junior