"Safe at last." They sat for a while and watched the passing buildings. A few minutes later she pushed an elbow in his ribs. "Look over to your left." She whispered. The purple and white robe was some yards away moving along the strip towards them. "I think she's looking for us. Come along. Here's where we get off." They threaded quickly through the crowd toward the outer strip and were shortly on the stationary walk. "That was close."

"Why was she looking for us?"

"Maybe she wasn't, but I took no chances. I can't stand to be slobbered over."

"What do we do now?" They were standing by the entrance of a large squat building of synthetic marble. Over the entrance Perry read UNITED STATS POST OFIS, Tub Stashon A. Diana followed his glance.

"Want to see how the tubes work?"

"Sure." They went inside, across a broad foyer and mounted a flight of stairs to a mezzanine. Diana led to the far side of the balcony. They leaned over a rail and looked down into a broad deep room whose floor level Perry judged to be below the street. Diana pointed down, and to the right.

"See them coming in there. Then they go on the belt and are sorted." Canisters of various lengths but of a uniform thickness, about eighteen inches, streamed out of a round hole and were deposited one after the other on a conveyor belt. Every few feet a mechanism leaned over the belt. Occasionally relays would click and a broad hook would roll a canister off the belt and pull it onto another belt running crosswise underneath the first. The crosswise belts then carried the canisters off to the right and left...

"Who operates the selectors?"

"They are automatic. An electric eye scans the destination tag. If the appropriate symbol corresponds, the grabber swings out and hooks off the can. See that first selector that is so busy? The one with three arms? That takes all the San Francisco traffic. Its belts unload in another room about as big as this where they are sorted for the local stations."

"I suppose the tubes run on compressed air."

"Only on short jumps. On the trunk lines they shoot along in a partial vacuum floating in a magnetic field that pulls them along. They make tremendous speeds on the long jumps."

"Suppose I wanted to mail a letter to New York. Would it ride in one of those cans all by itself?"

"Yes, but there isn't much sense in writing a letter when you can call up on the visiphone, or write on the telautograph."

"No, I suppose not. Say, I'd like to take one of those selectors to pieces."

"Perhaps you can if you care to apply for permission. But there is nothing fancy about them. Seen enough?"

"I guess so. What now?"

Diana glanced at a chronometer on the wall. "It's ten minutes past thirteen. We could run out to the rocket port if you like."

"Say, that's fine. Let's go!" They went back to street level and rode the first strip to an intersection where they dropped down one flight to the crosstown shuttle. This they took to a station marked TUB EKSPRES TU ROKET PORT. An attendant sealed them in a cylinder containing heavily cushioned chairs. Diana sat down and laid her head back against a head rest and told Perry to do likewise. A light glowed above them for a few seconds, then cut off. Perry suddenly felt very heavy and was pressed into the cushions. Then he was suddenly normal weight again.

"Brace your feet, Perry." The sudden increase in weight pressed him forward this time. Then normal weight returned and the door opened.

"Where are we?"

"At the port, about fifteen kilometers south of town."

"San Mateo?"

"No, west of there near Pillar Point." They climbed out and proceeded up a ramp to a waiting room, where swarms of people moved about and clustered at the far end. Diana glanced at an illuminated notice board and then at the chronometer beside it. "Hurry, Perry. We are just in time."

"For what?"

"The Antipodes Express. It arrives from New Zealand in four minutes. Hurry." He followed her up a ramp into a gallery with windows facing the field. Several sightseers were already there. Diana turned to one of them, a boy about twelve. "Is she in sight yet?"

"Uh huh, she's circling. See?" He pointed for them. Diana and Perry squinted at the sky.

"I'm afraid I can't make her out."

"She's there all right. There go the field lights. The screens'll be up any minute now."

"What kind of screens?" Perry inquired. The boy looked at him curiously.

"Say, you haven't been around much, have you? These kind of screens." Dark amber glass shutters were settling over the view windows. "You look at a rocket blast with your naked eyes and you'll wish you hadn't."

"Thanks, son. I don't know much about rockets."

"I do. I'm going to be a rocket pilot when I grow up. There she comes. She's the good old Southern Cross. See how pretty she rides? That's old Marko himself. He don't bounce 'em." The ship, a faint silvery sliver, circled toward the earth. She rode with her bow lifted perhaps twenty degrees, and her tail jets streaming behind her.

"Looks as if she were climbing."

"No, no." Superior Knowledge was faintly scornful. "He's riding her in on her tail. Old Marko don't pull out the plug till he's ready." The ship circled again lower down and on a narrower course. The tail jets snuffed out, then a brilliant light flared from her keel. "There goes her belly blast. Oh boy!" The youngster's eyes shone. The blast reached down toward the earth. Soon it splashed around the field. Steadily the ship lowered until the blast was almost point blank and the splash filled the halfmole landing circle and concealed the ship. Then the blast ceased and the ship lay before them. The boy chortled. "Did you see that? Just as steady as a rock on her good old gyros. And he just slid her down like sliding down a rope. Not even a side jet. Not once! What he aims at, he hits. Marko's going to drive one to the Moon someday; you wait and see. And I bet I'll go along, too."

A little cart was rolling out toward the ship and unfurling a long matting as it went. Perry asked the lad about it.

"That's the asbestos rug. You wouldn't want to walk on that field in those sandals after the belly blast hits it. You'd fry. The cart's just the baggage cart." They watched the passengers debark,then strolled about the station for a few minutes.

"Any place else you want to go, Perry?" Diana presently inquired.

"Have you any suggestion?"

"I'm getting a little weary of the crowds. Let's get back." Fifteen minutes later they were on the platform where they had left the Cloud Horse. Diana surrendered her receipt and her car was run out onto the take-off flat. Inside, she shucked off her tunic and tossed it on the bench and had the car in the air before Perry was out of his belt and comfortably settled. Once seated he lit a cigarette and handed it to her. "Where are we going?"

"Would you like to go swimming?"

"Swell. Where?"

"I know a little cove down near Monterey that is sheltered from the wind. The water may be a bit chilly."

"Let's try it."

Diana switched to 'plane' combination and gave it the gun. In fifteen minutes they were over Monterey Bay. Diana continued past Point Pinos for a few miles, circled, changed to helico, and settled down in a little cove which faced southwest. The waves broke gently on a narrow ribbon of beach. On each side shoulders of granite jutted out onto the sea. They opened the door and stepped out. The air was almost still and the afternoon sun beat down on them. The sand was warm underfoot. The sea smell, ripe and tangy, stirred in their nostrils. They walked toward the water but soon the joy of being alive lifted them up and they felt compelled to run. They splashed into the water, yelling and laughing. Perry charged along and dived head first onto the face of a breaker. He came up and dog-paddled in the back wash. Diana's head broke beside him.