"Preposterous, of course," said Davis. But his tone was not at all unbelieving.
"Then suppose something were sent up to the top of the cone, and it projected some kind of a cover of sound on the top of the cone and imprisoned the fish with a lid of sound they couldn't endure. And then suppose that thing sank into the water again. The fish couldn't swim through the walls of noise around them. They couldn't swim through the lid of sound above them. They'd have to swim downward, just as if a hood were closing on them from above."
"Very neat," said Davis. "But of course you don't believe anything of the sort."
"I can't imagine what would produce that sound in that way and send up a cork of sound to take the fish below. And I can't imagine why it would be done. So I can't say I believe it."
Davis said slowly, "I think we begin to understand each other. We'll stay as close to this place as we can until dawn, when we will find nothing to show that anything out of the ordinary happened here."
"Still less," said Terry, "to hint at its meaning. I've been doing sums in my head. That bright water was almost solid with fish. I'd say there was at least a pound of fish to every cubic foot of sea."
"An underestimate," said Davis judicially.
"When the bright patch was a thousand yards across--and it was even more--there'd have been four hundred tons of fish in the top three-foot layer."
Davis seemed to start. But it was true. Terry added, "The water was clear. We could see that the packing went on down a long way. Say fifty yards at least."
"So in the top fifty yards, at one time, there were at least twenty thousand tons of fish gathered together. Probably very much more. What _La Rubia_ carried away couldn't be noticed. All those thousands of tons of fish were pushed straight down. Tell me," said Terry, "what would be the point in all those fish being dragged to the bottom? I can't ask who or what did it, or even why. I'm asking, what results from it?"
"My mind stalls on who or what and why. And I'd rather not mention my guesses. I.... No!"
The _Esperance_ remained under sail near the patch of sea that had glittered earlier and now looked exactly like any other square mile of ocean. The recorder verified the position by giving out, faintly, the same unpleasant humming noise, either louder or fainter. A soft warm wind blew across the waters. The land was somewhere below the horizon. The reel of recorder-tape ran out. It was notable that there were very few fish sounds to be heard, now. Very few. But the hum continued.