The scientist, a short, wiry man with gray hair cropped crew-cut fashion, waved to the pilot, then motioned the young people back as the pilot turned with a blast of his prop and taxied to take-off position in front of the lab.
Because of the racket, no one tried to talk until the plane was nearly out of earshot. Then Barby spoke for all of them as they walked to the house. "We thought you'd never get here!"
Dr. Gordon smiled his pleasure at being home again. He shook hands with the boys. "You've no idea how nice and green this island looks after the Nevada desert. And you've no idea how hungry I am! Is it too late for lunch?"
Mrs. Brant answered him from the porch. "You have just two minutes to wash up and come to the table, John!"
Hartson Brant appeared behind her. He shook hands with Dr. Gordon as the three young people escorted him to the porch. "Welcome home, John."
"Thanks, Hartson. It's good to be back. Where are the others? Zircon, Weiss, and Winston? I know Tony and Howard are off on an expedition, but I thought the others were home."
"They are. Parnell Winston is probably having lunch at his cottage. Hobart and Julius are in New York, examining some new equipment for the lab. They'll be back tonight."
Rick was dying to ask questions, but he knew this was not the right time. At lunch, perhaps, they might be given some details.
John Gordon looked at him and grinned. "Here's Rick Brant," he declared, "politely holding his tongue when he's about to pop like a firecracker with questions. Your self-control does you credit, Rick. Want one bit of data to chew on while you're waiting?"
Rick gulped, then returned the grin. "Yes, sir!"
John Gordon lowered his voice to a confidential pitch. "We have an enemy," he stated. "What kind of enemy may be seen clearly in the name by which he goes." He paused.
"What name?" Rick asked impatiently.
"Homo Terrestrialis."
John Gordon turned and hurried upstairs to his room to wash up for lunch.
Rick stared after him. What in the name of a simple-minded spacefish did that mean?
Homo Terrestrialis.
Man of Earth.
Earthman!
CHAPTER II
Assignment: Rocket Base
Rick turned the phrase over and over in his head, trying to make sense out of it. Earthman? Who wasn't an earthman? The whole human race was composed of them. Of course ordinary people didn't refer to themselves as homo terrestrialis, but that's what they were just the same.
Scotty was just as puzzled. "Do you make anything out of it?" he inquired.
Rick shook his head mutely.
As Barby made a beeline for the library, Scotty called after her, "Where are you going? It's lunchtime."
She answered without pausing. "I'm going to consult the dictionary before Dr. Gordon comes down."
"Maybe she has something there," Rick said. "Let's go."
But the dictionary gave no clues. Homo was simply "man," and terrestrial was simply "of earth."
"Terrestrial is in here, but not terrestrialis," Barby complained.
"Same thing," Rick said. "Adding 'is' just makes it a Latin form. No, there's nothing strange about the term, except it's strange that anyone should use it."
"We'll find out," Scotty reminded him. "John Gordon was just teasing us. Let's go eat. Maybe he'll break down at lunch."
Rick realized the sense of what Scotty said, but he couldn't stop worrying the problem as his dog, Dismal, might worry a bone. Then, when they all sat down to lunch, his father effectively blocked discussion of it, and their new assignment, by talking with Dr. Gordon about mutual friends out West.
Finally Mrs. Brant came to her son's rescue. "Now, Hartson, and you too, John. You've teased Rick and Scotty enough."
Mr. Brant chuckled. "I wondered how long he was going to put up with our reminiscences before blowing a fuse or something."
Rick grinned sheepishly. He should have guessed that the two scientists were deliberately keeping the conversation off the main subject just as a joke.
John Gordon took a generous helping of salad. "All right. I'll talk, but you'll have to excuse me if I mumble a little. I intend to go right on eating. I've been looking forward to this for months!"
"We'll excuse you," Barby said quickly. "Only please start!"
Gordon smiled at her. "Can you keep secrets?"
"I always have," Barby retorted.
"All right. Then you can listen. But what I say must not be repeated."
The scientist paused long enough to drain his glass of milk and refill it from the pitcher.
"Well, to begin with, we moved from New Mexico to Nevada only a short while ago, in order to separate our work from military research. We created a new test base in Nevada, not too far from the Atomic Energy Commission's Nevada Test Site, although we have no connection with it."
"Then you're not on a military project?" Scotty asked.
"Yes and no. The work is sponsored jointly by the Department of Defense and some other agencies, including the National Science Foundation. However, we are not working on military projects, in the sense that our rockets are not weapons. They're for research purposes. Of course some of the things we're doing will be valuable for military application later, and so our test base is closed to the public and most of our work has a high classification. Usually the work is secret, but sometimes it's top secret. Is that clear?"
Scotty and the Brants agreed that it was.
"Very well. Since we operate under security, every person who works on the base is fully investigated and cleared for top secret. This is an important point. You know how thorough these investigations are. Once a security check for top secret is completed, there is literally nothing of importance that isn't known about a person. But in spite of the most careful security work, there is someone on our base about whom we do not know everything.
"It's absolutely baffling," Gordon continued. "Our first project was a simple one, with a tested rocket system. Actually, we used a modified Aerobee, a rocket of proven dependability. Nothing should have gone wrong. But when we fired, the rocket exploded at the top of the launcher. We investigated thoroughly, of course, and found someone had cleverly sabotaged the shoot."
"The what?" Barby asked.
"The shoot. When we launch a rocket we simply call it a shoot."
"Oh. Now I understand."
"Ask any questions you want. Well, we discovered that someone had rigged a steel bar at the top of the launching tower. It was spring-loaded and triggered to move right across the path of the rocket when we fired."
"What does spring-loaded mean?" Mrs. Brant asked.
"The bar was activated by a spring. The spring was under tension. The steel bar lay along one of the pieces of the frame, and was held by a latch. When the trigger withdrew the latch, the spring pushed the bar across the path of the rocket. That's what spring-loaded means in this case."
"Couldn't anyone have found the steel bar?" Scotty wanted to know.
"Yes, if anyone had looked for it. But once the launching tower was erected, there was no reason for anyone to go to the top for an inspection."
Scotty nodded his understanding.
"To go on, as soon as we found the bar and the spring mechanism we knew we'd been sabotaged. But that wasn't all. Etched on the bar was a rather good picture of a knight in armor, in the process of driving his sword through a rocket. Underneath was the inscription: Homo Terrestrialis."
"I don't get it," Rick complained.
Gordon