Norby said, "I thought I had antigrav, but you can never tell. I suppose I can remember how to work it."

Central Park was beneath them now. Behind them, low in the east, the sky showed a diffuse light behind the skyscrapers even though the sun was not yet up. Beneath them the park was still in the deep shadow of night.

"I've always wondered what personal antigrav would be like," said Jeff, excited and breathless. The wind whipped his curly brown hair back from his forehead.

"It's hard work, if you want to know, and I don't know when my next electric bath will come."

"It seems easy to me. Easy and delightful, like swimming in an ocean of water you can't feel, like swooping through-"

"That's because you're not the one who's producing the antigrav field, so it's no work to you," grumbled Norby. "Don't get so stuck up about how it feels that you forget to hang on. Hold more tightly! Also, tell me where I'm supposed to go for this solstice celebration of yours."

"It's in the Ramble-that wooded section beyond the boathouse, with the boating pond circling 'round to the other side. Go down-now."

"Not so fast. I've got to figure out how. We can't just drop. You'll dent a bone or something. Besides, it's dark, and I can't make my internal light bright enough to show the ground without running out of power. I can't do antigrav and bright light both. What do you think I am? A nuclear powerhouse?" Norby circled, and they sank downward, then up again with a jerk.

"Hey," shouted Jeff, "watch out!"

"Look, I've got to get this right, don't I?" said Norby. "It's not easy to ease into the gravitational field and let yourself sink just right." He grunted. "Okay-now-now. I wish I breathed so I could hold my breath."

"I'll hold mine," said Jeff.

"Good! That helps psychologically. It's hard to make out the ground from the shadow in this dark."

With a thump that rattled his teeth, Jeff found himself on his knees and elbows, which were dug well into moist dirt. His head stuck out over a pool of goldfish in the center of the small grassy clearing. They were lucky-it was the very place Jeff would have had Norby aim for if it had been light enough to see.

Jeff could see the goldfish despite the dark. The pool seemed to be lighted from within, which was odd, because Manhattan was usually too broke for fancy lighting in public parks.

"Norby! Where are you?" Jeff called, trying to shout in a whisper.

The light in the pool brightened, and slowly a shape rose up and out of the water. It was a barrel shape, draped in water lilies. It continued to rise until it was suspended a foot over the water, and then it spun rapidly in the air, scattering drops, as a dog shaking itself would do.

Jeff received some of the spray and shouted, "Hey!"

The barrel slowly stopped spinning. Two legs emerged from the bottom and started a good try at a dignified walk-in the air-down to Jeff.

Norby's hat popped up. "I didn't judge it quite right. I turned on illumination just a little too late. Still, that was an excellent landing, if I do say so myself."

"You'll have to say so yourself," said Jeff, brushing at himself without much effect. "I've got mud allover me, and you've managed to make me good and wet, too."

"You'll dry," said Norby. "The mud will dry, too, and then you can shake it off."

"How about you?" said Jeff. "Are you waterlogged? You won't turn rusty, will you?"

"Nothing damages me," said Norby. "Stainless steel outside; and better than that inside." He carefully untwined a water-lily frond from around his middle and dropped it in the pond with a finicky gesture.

Norby put out his illumination, but it was getting light enough for Jeff to be able to see him even in its absence. "Now I know why a simple judo throw landed you on the dome of your hat," he said.

"You charged before I was ready," Norby said.

"I did no such thing. You charged," Jeff said.

"I mean you defended yourself before I was ready."

"No such thing, either. You just can't manage your own technology. You said so yourself when we were antigravving."

"It was hard, I admit, but I managed," Norby said. "Look at that landing."

"You managed imperfectly," Jeff insisted. "That landing nearly drove us through to China."

"Well, I try," said Norby in an aggrieved voice. "You couldn't get any other robot to do this for what you paid for me. Besides, it's not my fault. I was damaged in a spaceship crash, and then Mac fixed me so that I would be undamageable, you see. He used salvaged equipment for that and-"

"What salvaged equipment?" demanded Jeff.

"Oh, well, if you're going to disbelieve everything I tell you, I've got nothing more to say."

"What salvaged equipment? Darn it, you've got to answer my questions sometimes. You're a robot, aren't you?"

"Yes, I'm a robot, so why don't you understand I've got to tell the truth?"

Jeff took a deep breath. "You're right. If I sounded incredulous, I apologize. What salvaged equipment, Norby?"

"Salvaged equipment from an old spaceship we found on an asteroid."

"That's impossible-I believe you, Norby, I believe you. I know you wouldn't lie, but that's impossible. Nobody's ever found a ship on an asteroid just lying around. Wrecks are always salvaged at once by Space Command. In this computerized age, Space Command always knows when a wreck takes place, and exactly where, too."

"Well, this one wasn't salvaged by Space Command. It was just lying there, and it was salvaged by us. And how can I tell you which asteroid it was? There are a hundred thousand of them. It was a small asteroid that looked exactly like all the other small asteroids."

"What happened when he repaired you?"

"He just kept chuckling all the time. He seemed very pleased with himself and kept saying, 'Oh boy, oh boy, wait till they see this.' He was a genius, you know. I asked him what it was all about, but he wouldn't tell me. He said he wanted me to be surprised. And then he died, and I never found out."

"Never found out what?"

"About the things I could do. Like antigrav. And how to do it. Sometimes I can't get things sorted out in time, and that's why you could throw me. And then I don't land right because I don't have enough time to make the judgments I need. Please don't tell anyone about this."

"Are you kidding? Of course not."

"The scientists would take me apart, or try to, in order to find out how I do the things I do, and I don't want them to…to try to take me apart, I mean. I'd be glad to tell them if I only knew myself."

Jeff sat back, his arms wrapped around his muddy knees. He looked up at the sky, which was reddening now in the onrush of morning. "You know, I'll bet it was an alien spaceship. It would be the first real proof that there is alien intelligence out beyond our Solar System. In fact, Norby, if that were so, you would be the first real proof of that."

"But you won't tell. You promised." Norby's voice sounded panicky.

"Never! I won't tell-Friend." Jeff reached out and shook Norby's hand. "But we've got to get on with the solstice celebration."

"All right," said Norby, "but that might not be easy. It seems to me that there's a herd of elephants somewhere."

Footsteps were indeed approaching. Lots of them.

Jeff seized Norby and scuttled behind a bush. Down the path between the trees came a group of people. Each person was holding binoculars.

"Bird-watchers," whispered Jeff.

"What are those?" Norby asked. " A new species of human being? I haven't seen anything like that before."

"That's because you spent too much time in space with McGillicuddy watching asteroids. Human beings like to observe the activities of other animals. These people watch birds, not asteroids."

"You mean they pry into the privacy of birds?"