insisted. "It goes right to the principle of polarization itself. For some reason, it doesn't work here. Why? Before we can discover the answer to that, we'll have to know more about polarization itself. How does it work, Grampa?"

Grampa gave him a sarcastic grin. "Now you're curious, eh? Couldn't be bothered with Grampa's invention before. Oh, no! Too busy. Accept without question the blessings that the Good Lord provideth—"

"Let's not get up on any pulpits," Fred growled. "Come on, Grampa, what's the theory behind polarization?"

Grampa looked at the four faces staring at him hopefully and the jeering grin turned to a smile. "Well," he said, "at last. You know how light is polarized, eh?" The smile faded. "No, I guess you don't."

He cleared his throat professorially. "Well, now, in ordinary light the vibrations are perpendicular to the ray in all directions. When light is polarized by passing through crystals or by reflection or refraction at non-metallic surfaces, the paths of the vibrations are still perpendicular to the ray, but they're in straight lines, circles or ellipses."

The faces were still blank and unillumined.

"Gravity is similar to light," he pressed on. "In the absence of matter, gravity is non-polarized. Matter polarizes gravity in a circle around itself. That's how we've always known it until the invention of spaceships and later the polarizer. The polarizer polarizes gravity into a straight line. That makes the ship take off and continue accelerating until the polarizer is shut off or its angle is shifted."

The faces looked at him silently. Finally Joyce could endure it no longer. "That's just nonsense! You all know it. Grampa's no genius. He's just a tinkerer. One day he happened to tinker out the polarizer. He doesn't know how it works any more than I do."

"Now wait a minute!" Grampa protested. "That's not fair. Maybe I didn't figure out the theory myself, but I read everything the scientists ever wrote about it. Wanted to know myself what made the blamed thing work. What I told you is what the scientists said, near as I remember. Now me—I'm like Edison. I do it and let everybody else worry over 'why.'"

"The only thing you ever did was the polarizer," Joyce snapped. "And then you spent everything you got from it on those fool perpetual-motion machines and those crazy longevity schemes when any moron would know they were impossible."

Grampa squinted at her sagely. "That's what they said about the gravity polarizer before I invented it."

"But you don't really know why it works," Junior persisted.

"Well, no," Grampa admitted. "Actually I was just fiddling around with some coils when one of them took off. Went right through the ceiling, dragging a battery behind it. I guess it's still going. Ought to be out near the Horsehead Nebula by now. Luckily, I remembered how I'd wound it."

"Why won't the ship work then, if you know so much?" Joyce demanded ironically.

"Well, now," Grampa said in bafflement, "it rightly should, you know."

"We're stuck," Reba said softly. "We might as well admit it. All we can do is set the transmitter to send out an automatic distress call—"

"Which," Joyce interrupted, "might get picked up in a few centuries."

"And make the best of what we've got," Reba went on, unheeding. "If we look at it the right way, it's quite a lot. A beautiful, fertile world. Earth gravity. The flivver—even if the polarizer won't work, there's the resynthesizer; it will keep us in food and clothes for years. By then, we should have a good-sized community built up, because out here we won't have to stop with one child. We can have all the babies we want."

"You know the law: one child per couple," Joyce reminded her frigidly. "You can condemn yourself to exile from civilization if you wish. Not me."

Junior frowned at his wife. "I believe you're actually glad it happened."

"I could think of worse things," Reba said.

"I like