Terry listened critically, and Tony with interest. Then Terry brought out the fish-driving paddle. He turned on the tape, now, to have a record of the sound the paddle made.
“Whack this on the water,” he suggested, “and we’ll hear how it sounds.”
Tony went down the ladder and gave the water surface a few resounding whacks. There were tiny, violent swirlings. For thirty or forty feet from the Esperance’s side there were isolated, minute turmoils in the water. Three or four fish actually leaped clear of the surface.
“Not bad!” said Tony. “Shall I whack some more?”
Terry reeled back a few feet of the tape which contained the whacking sounds. He re-played them, listening critically as before. Tony had returned to the deck. The whackings, as heard underwater, were not merely impacts. There was a resonance to them. Almost a hum. Rather grimly, Terry substituted this tape-reel with the recording he’d made the night before. He started the instrument and found the exact spot where the object from the depths had fallen back into the sea. He stopped the recorder right there. He hauled up the submarine ear and plugged in the horn to the audio-amplifier, as yet untested, which should multiply the volume of sound from the tape. Then he put the horn overside.
He switched on the recorder again. The tape-reel began to spin. The sound went out underwater from the horn. Underwater it was much louder than when it had been received by the Esperance’s microphone. Here it was confined by the surface above and the harbor-bottom beneath. It must have been the equivalent of a loud shout in a closed room—only worse.
The fish in the harbor of Barca went mad. All the harbor-surface turned to spray. Creatures of all sizes leaped crazily above the surface, their fins flapping, only to leap again, more frantically still, when they fell back. A totally unsuspected school of very small flying fish flashed upward in such frenzied haste that some tried to climb too steeply and fell back and instantly flung themselves into the air again.
Terry turned off the playing recorder. The disorder at the top of the water ceased immediately. But he heard shrill outcries. Children had been wading at the edge of the shore. They stampeded for solid ground, shrieking. Where their feet and legs had been underwater they felt as if a million pins and needles had pricked them.
Something flapped heavily on the Esperance’s deck. Tony went to see. It was a three-pound fish which had leaped clear of the water and over the yacht’s rail to the deck.
Tony threw it back into the water.
“I guess there’s not much doubt,” he said painfully.
“Of what?” demanded Terry.
“Of what… I had guessed,” said Tony.
“And what did you guess?”
Tony hesitated.
“I guess,” he said unhappily, “that I’d better not say.”
He watched with a startled, uneasy expression on his face as Tony put the apparatus away.
Time passed. Davis and Deirdre had been ashore over an hour. Then Terry saw the small boat leave the shore and approach. It came deftly alongside, the two passengers climbed up to the deck, and all four crew-cuts hauled the boat back inboard and lashed it fast.
“Our dredge isn’t ready yet,” said Davis. “It looks good, but there’ll be a delay of a few days.” Deirdre examined Terry’s expression. “Something’s happened. What?”
Terry told her. Davis listened. Tony added what he’d seen, including the fish that had leaped high enough out of the water to land on the Esperance’s deck.
“After the fact,” said Davis, “I can see how it could happen. But… “ He hesitated for a long time and then said, “This is another case where I’ve been making guesses and hoping I was wrong. And like the others, proof that my early guess was wrong makes another guess necessary. And I dislike the later guess much more than the first.”
He moved restlessly.
“I’m glad you only tried it once, here,” he said unhappily. “We’re due up at Thrawn Island anyhow. You can work this trick out in the lagoon up there. If there’s no reaction to the dredge when we try it, we can try this. But it might be a very violent poke at something we don’t quite believe in. I’d rather try a gentle poke first.”
He turned away. In minutes Nick was belowdecks starting the yacht’s engine, two others of the crew-cuts were hauling up the anchor, and the fourth was at the wheel. Without haste, but with celerity, the Esperance headed for the harbor-mouth and the open sea.
They had their midday meal heading north by west. Late in the afternoon Deirdre found occasion to talk to Terry about Thrawn Island.
“It’s the China Sea tracking station for satellites,” she told him. “Some of the staff are friends of my father’s. It’s right on the edge of the Luzon Deep, and the island’s actually an underwater mountain that just barely protrudes above the surface. There are some hills, a coral reef and a lagoon. It’s also terrifically steep, and you can use the fish-driving device as much as you please without startling any Filipino fishermen.”
“You’ve been there before,” said Terry.
“Oh, yes! I told you a fish wearing a plastic object was caught in the lagoon there. That was when the station was being built. The men at the tracking station fish in the lagoon for fun, and now they’re naturally watching out for more… oddities.”
The Esperance sailed on. The crew-cuts went about their various chores and talked endlessly, among themselves and with Deirdre, when she joined in. Terry felt useless. He trailed the submarine ear overboard and set the recorder to work as an amplifier only. At low volume it played the sounds of things below. He kept half an ear cocked toward it for the mooing sound he’d picked up at the place where the ocean glittered. He heard it again now, and again found it difficult to imagine any cause for it. The sounds uttered by noise-making fish are usually produced in their swim-bladders. The purpose of fish cries is as obscure as the reason for some insect stridulations, or the song of many birds. But a long-continued fish noise would involve a swim-bladder of large size. At great depths, if a considerable cavity were filled with gas, under pressures running into tons to the square inch … Terry could not quite believe it.
He did not hear the mooing sound any more, as the yacht went on its way. Other underwater sounds became commonplace, and he tended not to hear them. From the deck around him, though, he heard arguments about wave mechanics, prospects in the World Series, the virtues of Dixieland jazz, ichthyology, Cope-land’s contribution to modern music, the possibility of life on other planets, and kindred topics. The crew-cuts were taking their summer vacations as able seamen on board the Esperance, but they had as many and as voluble opinions as any other undergraduates. They aired them on each other.
The afternoon passed. Night fell, and dinner was a session of learned discussion of different subjects, always vehemently argued. Later Terry took the yacht’s wheel, Deirdre sat comfortably nearby, and they discussed matters suitable to their more mature status. They were much less intellectual than the crew-cuts. In a few days they developed an interest in each other, but each of them believed this was just a very pleasant friendship.
Eventually, the moon rose. It was close to midnight when Nick bobbed belowdecks and came up with a report that they’d been picked up by the Thrawn Island radar and were proceeding exactly on course. Half an hour later a tiny light appeared at the edge of the sea. The Esperance headed for it, and presently there were breakers to port and starboard, the engine rumbled, down below, and the yacht lifted and fell more violently than ordinary. Then once more she was in glassy-smooth water; the air was very heavy with the smell of green vegetation. Certain rectangles of light became visible. They were the windows of the Thrawn Island satellite-tracking installation.