"Oh certainly. Your idea is to prepare a sphere that glows with no signal. That can be done with a local signal, which is cut when no-radiation enters. Hard to say in words, isn't it?" Maynard laughed cheerfully. "As long as you get my thought, I don't care how you say it. The barrier-screen absorbs all radiation. Therefore any position holding a sub-ship would produce zero radiation. It would then show on the negative sphere. Right?" "I think that's about it," said Carrington. "Good. We agree on that. Want to work on it?" "Absolutely." "It's yours, then. Go ahead and make it tick." "That I'll do, sir. We'll have it by the time we hit Pluto." "One more thing, Carrington. Keep it under your hat. It's a military secret, you know." "I'll say nothing." "Check. I'll be down and see you later." Carrington left, and as he went back to his quarters, he told several of his contemporaries that the new commander was everything that they had ever heard of him. * * * * * Finding Pluto was a good job of work for the combined efforts of the astrogator and the chief pilot. Pluto was completely hidden just as Ertene was, and Maynard knew the completeness of that shield. It was done gropingly, by sheer hit and miss effort, but finally a black circle in the starry sky established above them. And as the pilot announced his success, it began to spread from a minute spot to mightiness. Then they passed through the barrier, and Pluto was a warm, greenish planet above them, much the same as Terra as seen from Luna. The _Orionad_ dropped onto the Spaceport; the entire trip without incident. Maynard signed his command into the base marshal's office and ordered his chief executive officer to grant planet liberty as he saw fit. Space Marshal Lincoln smiled at the younger man and told him: "I think you'll be interested in the experiments going on in the radiation laboratory." "Yes?" "They're having a bit of trouble on one of your gadgets." "Which one?" "The stellar light-filter. Somehow, it doesn't work as you predicted." "Why didn't they ask for me sooner?" wondered Maynard. "It's been six years since I thought that one up--they've had plenty of time." "It's possible," admitted Lincoln. "But you forget that it was extremely complex and highly theoretical. Also, no good use has ever been found for it. Unlike your other inventions, this seems to be an experiment in pure research. So we didn't start on it until last, and it's been three years in the building." "So long?" "Oh yes. Some of the parts were entirely unheard of before, and many of the major components had to be built of parts that were designed for the job. When you design the minor components to assemble the major components--which also require design--you pyramid the time and difficulty." "I hadn't thought of it that well."