Nolan walked around it. He saw that it could be aimed in almost any direction. But not quite. There was a direction that stops prevented it from pointing to. Nolan said:
"What's in that direction?"
The skipper jumped. When Nolan asked the question he began to suspect many answers. He said in a stricken voice, "That's where the missiles were launched—and where the others are stored."
Nolan stared at the thing. It looked hateful. It had the savage feel of a frozen snarl.
"The power-pile?"
The skipper nodded. He mopped his face again.
"Right alongside. We figured they wanted to shield the rest of the base from radioactives."
Nolan said carefully:
"It could be that they wanted to shield the radioactives from something in the base. Maybe something that would act on radioactives is involved." He said painfully, "Men can't change the rate of fission except by building up a critical mass. But maybe—possibly bug-eyed monsters could."
The skipper perspired. He'd have worked out the same thing in the long run, but Nolan saw it right away. He went away and got the ship's engineers. They brought an X-ray for finding flaws in metal. They took pictures of the inwards of the brass-barreled instrument in its place. They traced two separate, incomprehensible circuits. But they were separate.