Rick sighed and let out his belt. "Well, that's our story. What's yours?"
Steve stirred his coffee thoughtfully. "I can make it short. We don't know the whole story yet, but we will by the time I get back to St. Thomas. Have you two any idea what these brass-ball gadgets are?"
"We decided that they were probably sonar equipment of some type," Scotty said. "But we couldn't figure out what they were for."
"Easy," Steve said. "Although you couldn't know, of course. They were for spotting submarines."
Rick stared. Submarines?
Steve saw his look of bewilderment. "It happens that our new atomic-powered submarines are conducting manuevers in this area. Does that help?"
It did! Light slowly dawned. "Then these were scanning our subs! But I still don't see why it would be any problem to find them. The subs must have equipment that will tell when sonar beams hit them."
"They do. And that's a big part of the story."
Steve sipped his coffee for a moment. "These sonar devices are a new type, and very cleverly designed. They don't send out a continuous beam. Instead, they operate in bursts, in a random pattern. They might send out a beam twice in a minute, or wait an hour between bursts. The beam is a powerful one. It's effective for an extraordinary distance."
"The wail, of course, was the beam operating," Zircon interjected. "You didn't hear the beam itself, since that's ultrasonic. But you did hear the mechanical vibration of the brass ball. It had a kind of sub-harmonic effect that was audible."