Terry paced back and forth on the Esperance's deck. In a few minutes Davis and the crew-cuts appeared with Deirdre. But they were not alone. Straggling behind them came nearly all the personnel of the tracking station. There would be somebody on official duty, of course. But here was the bespectacled Dr. Morton; the bald young man who'd offered Terry beer; and the installation cook; a typist, and specialists in radar and other abstruse subjects.
Deirdre said, "I told them about the fish-driving business and they want to see. They stopped arguing about last night's bolide to take ringside seats. All right?"
Terry shrugged. He had the recorder already set up. He'd taken a section of the tape made where the sea was bright, at the place where the loudest of the unpleasant humming noise was recorded. He'd made a loop of it so it would play over and over.
He played the much-amplified sound through the underwater horn held in the air. The result was a raucous bellowing noise. He lowered it into the water. The horn touched the surface and went under.
Instantly, the fish of the lagoon seemed to go crazy. All the surface broke and writhed and splashed. There was an incredible number of fish. Terry turned the horn on one side. In this way, not all the water was filled with the intolerable noise, but only a net-like beam of it raced across the water. Within that line the fish continued to leap frenziedly. The rest of the lagoon suddenly quieted down. In a little while the beam's space, also, grew quiet. But that was because the fish that had been previously caught in it had escaped.
"I'm afraid," said Terry, "that this isn't going to be very entertaining. I'm going to sweep the beam across the lagoon, pushing the fish ahead of it, until I should have them all in one small area."
It was curious that he felt uncomfortable as he set about his task. But he'd experienced the sensation this sound produced. And it was not very pleasant.
He turned the beam around, slightly. Again, there were sudden splashings. They died away. He turned the beam again. It was a nasty, snarling vibration in the water. So far as fish were concerned, it was more like a wall than a net, because not even the tiniest living creature could penetrate it. Not only fish fled before it. Shrimps and crabs and all types of crustaceans jerked and crawled and swam ahead of its motion. Jellyfish writhed when it touched them. Sea cucumbers contorted themselves. Everything that lived in the lagoon and could swim or crawl or writhe moved before the invisible barrier. Presently, the effect of crowding could be seen, and fish began to leap out of water.
"This is a great advance in civilization," said Dr. Morton. "Men invented guns and destroyed the buffalo and the passenger pigeon! You may have made it possible to depopulate the sea!"
Terry did not answer. The morning sun shone brightly, a gentle breeze made ripplings on the lagoon, the palms waved their fronds in languid gestures, and the surf could be heard booming and splashing on the outer reef. And about two dozen people stood on the wharf or on the Esperance's deck and watched a spliced section of recorder-tape go through and through a recorder, which was set to make a sound underwater that could not be heard by the people above.