words. "You probably know that work on the scientific negation of gravity has been going on since the early 1950's. It was known shortly after experiments had been conducted on atomic and subatomic particles that grounds had at last been found by means of which a counteraction to gravity might be set up. Early subatomic studies showed that such a force was not only theoretically possible, but that certain subparticles actually displayed such tendencies. On the basis of these first discoveries, work has been going on in the development of negative gravitational drive for at least twenty years. As early as 1956, there were not less than fourteen such projects under way in virtually all the leading aircraft industries of the United States, not to mention the rest of the world. In the last few years, at the direction of the Air Force, these projects have been consolidated, placed under one main roof, and brought to its present status, which is, we believe, the one of final triumph."

He glanced at General Shrove, who returned the glance unsmilingly. "After the successful testing of several models, a full-sized craft has been built which utilizes the new method of space drive. One such craft has been built, and only one. This ship, if it works, is at this time the only means by which humanity can hope to make the trips to the other places in the solar system from which the Sun-stealers are working. It is with this one vessel only that we can put their Sun-tap stations out of commission.

"But I emphasize again the experimental nature of this ship. What its capacities are and how well it will work is still a matter of planning-book conjecture. We can prepare the ship to take off in one week's time. I do not think, judging from what Merckmann and Clyde have said, that we can afford to wait any longer. Another such ship cannot be built in less than a year."

General Shrove spoke then. "It is already arranged that this A-G 17 spaceship is going to go. A volunteer crew has been selected; several of them are in this room." He nodded briefly to Clyde and to Lockhart. "But although these volunteers are among the best men in their fields, there isn't one of them who couldn't be replaced by someone equally skilled in the same field. But there is one person on Earth right now who may just possibly be unique. This person may hold, by virtue of an experience not shared by any other human being, a special key that will render easier the task that this spaceship must fulfill."

He turned to Burl, who sat tingling with suspense. "You, Burl Denning, are apparently still carrying some sort of electronic or subelectronic charge which is attuned to the controls of the Sun-tap station. We feel that you should be along on this expedition. It will be long and dangerous, it will involve landings on worlds no man has ever visited or expected to visit for hundreds of years. There is an enemy in the sky who will certainly try to stop our single ship. To be bluntly honest, the voyagers on this ship face such dangers as explorers have not faced since the days of Magellan and Cook. Its chances of return are probably remote. But with the permission of your father, which he has already given, I would like to ask that you volunteer to join its crew."

Burl felt dizzy, his heart thumping painfully within his chest. He took a deep breath, and then carefully, trying to keep his voice from quivering, he said, "Yes, I'll go."

Chapter 4.
The Hidden Skyport

Around the table there was a concerted sigh. Burl, his ears still throbbing from his sudden excitement, realized each of them had been holding his breath. General Shrove smiled and glanced at the elder Denning, who sat expressionless. It is not an easy thing for him, Burl thought.

At that moment, Burl knew that he had come of age. This moment of decision, coming truly and literally like a bolt out of the blue, had thrust him into man's estate before his time. He would show that he was able to carry this burden.

Shrove now spoke to Lockhart. "Colonel, we are holding you to your schedule. According to it, you can take off in five more days. Will you need any more time because of this addition to your crew?"

The stocky air veteran shook his head. "Not at all. We'll be loaded and ready on the hour I set. I'll take Denning in hand and brief him on what he may need to know. Actually, we may even be able to get him a home-leave. After all, his duties won't begin until actual planetfalls are made."

They rose from their seats. Burl stood up, uncertain as to procedure, but Lockhart came over to him and took his arm. "Burl, we're going to have to give you a rundown on the ship and the plans. We've no time to waste if you want to get a chance to say good-by to your folks later on."

"I understand," said Burl. He turned and waved to his father, who was in conversation with the general. "I'll see you at home in a few days, Dad," he called, then followed Lockhart out.

Outside the building they were joined by several other members of the conference and immediately ringed about by a squad of Air Force men wearing sidearms. Burl realized that they were to be thus guarded everywhere they went. Obviously, the possibility that the builders of the Sun-traps might have agents operating on Earth had occurred to the officers.

Russell Clyde, the young astronomer, was among their group. He walked over to Burl and shoved out a hand. "Glad to have you with us, Burl. This is going to be quite a trip!"

Clyde was about Burl's size. He had an engagingly boyish air about him, and Burl took a liking to him. Burl had heard of him before. For the young man, while still a college student, had formulated a remarkable new theory of the composition of galactic formations which had instantly focused the attention of the scientific world upon him. This theory had been taken up by the gray-beards of the scientific world and had survived the test of their debates. Now associated with the great Mount Palomar Observatory, Russell Clyde had continued to build a reputation in astronomical circles.

"You're one of the expedition, then?" asked Burl, shaking his hand.

The redhead nodded. "Yep. They're taking me as their chief astrogator. And don't think it's because I'm any great shakes at it, either! It's just that I'm still young enough to take the kind of shoving around these high brass figure we're going to get. Boy, have they got it figured!"

Burl chuckled. "Ah, you're kidding, Dr. Clyde. You've probably been in on this from the beginning."

The other shook his head vigorously. "Nope. It was going to be Merckmann's baby, but when they realize they have a fight on their hands, they always look for young blood. And, say, cut out this 'Doctor' stuff. Call me Russ. We're going to share quarters, you know."

"How do you know that?" asked a tall, rather sharp-featured man who had overheard them. "The colonel will assign quarters."

"I say he will ... and you can bet on that," snapped Russell Clyde. He waved a hand in introduction. "This is Harvey Caton, one of our electronics wizards."

Caton nodded, but before he could continue the discussion, Lockhart rounded them all up, packed them into a couple of station wagons, guards and all, and they were off.

The next days were hectic ones. By car and plane the group was transferred to the large, closely guarded base in Wyoming where the secret anti-gravity ship was waiting. Burl did not see this ship right away. First, he was introduced to all the other members of the crew, and given a mass of papers to study which outlined the basic means of the new space drive, and which detailed the opinions and suggestions of various experts as to methods of procedure and courses of action. He was subjected to various space medical tests to determine his reactions under differing pressures and gravities. Although it proved a strenuous and exhausting routine, he emerged from the tests with flying