“The pumps for your jets, are they mechanical?” Arnie asked.

“Yes, electrically driven.”

“Can you cut them off completely and still maintain a constant output from your generator? We have voltage regulators, but it would help if you could produce as constant a supply as is possible.”

Henning threw a series of switches. “All motor power off. There is still an instrumentation drain as well as the atmosphere equipment. I can cut them off—for a limited time—if you like?”

“No, this will be fine. I am now activating the drive unit and will rise under minimum power to a height of approximately one hundred meters.”

Nils made an entry in the log and looked at the waves splashing at the porthole nearest him. “You don’t happen to have an altimeter fitted aboard this tub, do you, Henning?”

“Not really.”

“Pity. Have to get one installed. And radar instead of that sonar. I have a feeling that you’re getting out of your depth…”

Henning had a pained look and shook his head dolefully—then glanced at the port as a vibration, more felt than heard, swept through the sub. The surface of the water was dropping at a steady rate.

“Airborne now,” he said, and looked helplessly at his useless instruments. The ascent continued; moments passed.

“One hundred meters,” Nils said, estimating th£ir height above the ship below. Arnie made a slight adjustment and turned to face them.

“There appears to be more than enough power in reserve even while the drive is holding the mass of this submarine at this altitude. The equipment is functioning well and is in no danger of overloading. Are you gentlemen ready?”

“I’m never going to be more ready.”

“Push the button or whatever, Professor. Just hanging here seems to be doing me no good.”

The humming increased and their chairs pressed up against them. Nils and Henning stared through the ports, struck silent by emotion, as the tiny submarine leapt toward the sky. A thin whistle vibrated through the hull as the air rushed past outside, scarcely louder than the sigh of the air-conditioning unit. The engine throbbed steadily. Seemingly without effort, as silendy as a film taken from an ascending rocket, their strange craft was hurling itself into the sky. The sea below seemed to smooth out, their mother ship shrinking to the size of a model, then to a bathtub toy, before the low-lying clouds closed in around them.

“This is worse than flying blind,” Nils said, his great hands clenching and unclenching. “Seat of the pants, not a single instrument other than a compass, it’s just not right.”

Arnie was the calmest of the three, too attentive to his instruments to even take a quick glimpse through one of the ports. “The next flight will have all the instrumentation,” he said. “This is a trial. Just up and down like an elevator. Meanwhile the Daleth unit shows that we are still vertical in relation to the Earth’s gravity, still moving away from it at the same speed.”

The cloud layers were thick, but soon fell away beneath their keel. Then the steady rhythm of the diesel engines changed just as Arnie said, “The current—it is dropping! What is wrong?”

Henning was in the tiny engine compartment, shouting out at them.

“Something, the fuel, I don’t know, they’re losing power.”

“The atmospheric pressure,” Nils said. “We’ve reached our ceiling. The oxygen content of the air is way down!”

The engine coughed, stuttered, almost died, and a shudder went through the submarine. An instant later they started to fall.

“Can’t you do something?” Arnie called out, working desperately at the controls. “The flow—so erratic—the Daleth effect is becoming inoperable. Can’t you stabilize the current?”

“The batteries!” Henning dived for his position as he spoke, almost floating in the air, so quickly was their fall accelerating.

He clutched at the back of his chair, missed, floated up and hit painfully against the periscope housing and bounced back. This time his fingers caught the chair and he pulled himself down into it and strapped in. He reached for the switches.

“Current on—full!”

The fall continued. Arnie glanced quickly at the other two men.

“Get ready. I have cut the drive completely. When I engage it now I am afraid that the reaction will not be gentle because—”

Metal screeched, equipment crashed and broke, and there were hoarse gasps as the sudden deceleration drove the air from their lungs. They were slammed down hard into their chairs, painfully, and for an instant they hovered at the edge of blackout as the blood drained from their brains.

Then it was over and they were gasping for air, dizzily. Henning’s face was a white mask streaked with red, bleeding from an unnoticed scalp wound where his skull had struck the periscope. Outside there were only clouds. The engine ran smoothly and the air hushed from the vents, soft background to their rough breathing.

“Let us not—” Nils said, taking a deep breath. “Let us not… do that again!”

“We are maintaining altitude with no lateral motion/’ Arnie said, his words calm despite the hardness of his breathing. “Do you wish to return—or to complete the test?”

“As long as this doesn’t happen again, I’m for going on,” Nils said.

“Agreed. But I suggest that we operate on the batteries.”

“How is the charge?”

“Excellent. Down less than five percent.”

“We will go back up. Let me know when the charge is down to seventy percent and we will return. That should give us an acceptable safety margin. Plus the fact that engines can be restarted when we are low enough.”

It was smooth, exhilarating. The clouds dropped below them and the engine labored. Henning shut it down and sealed the air intake. They rose.

“Five thousand meters high at least,” Nils said, squinting at the cloud cover below with a pilot’s eye. “Most of the atmosphere is below us now.”

“Then I can step up the acceleration. Please note the time.”

“It’s all in the log. Some of it in a very shaky handwriting, I can tell you.”

The curvature of the Earth was visible, the atmosphere a blue band above it tapering into the black of space. The brighter stars could be seen; the sun burned like a beacon and, shining through the port, threw a patch of eye-hurting brightness onto the deck. The upward pressure ceased.

“Here we are,” Arnie said. “The equipment is functioning well, we are holding our position. Can anyone estimate our altitude?”

“One hundred fifty kilometers,” Nils said. “Ninety or a hundred miles. It looks very much like the pictures shot from the satellites at that altitude.”

“Battery reserve seventy-five percent and dropping slowly.”

“Yes, it takes power to hover, scarcely less than for acceleration.”

“Then we’ve done it!” Nils said and, even louder when the enormity struck him, “We’ve done it! We can go anywhere—do anything. We’ve really done it…”

“Battery reserve nearing seventy percent.”

“We will go down then.”

“A little slower than last time?”

“You can be sure of that.”

More gently than a falling leaf, the submarine dropped. They passed through a silvery layer of high cirrus clouds.

“Won’t we be coming down much further to the west?” Nils asked. “The Earth will have rotated out from under us so we won’t be able to set down in the same spot.”

“No, I have compensated for that motion. We should be no more than a mile or two from the original position.”

“Then I had better get on the radio.” Henning switched it on. “Well be in range soon, and we’ll want to tell them.”

A voice came clearly through the background static, speaking the fast, slang-filled Copenhagen Danish that only a native of that city would be able to understand.

“…dive, daughter, dive, and don’t come up for air. Swim deep, little sister, swim deep…”

“What on earth are they talking about?” Araie asked, looking up, surprised.