Cradle

by Arthur C. Clarke

  ‘As I understand it,’ Carol continued as both men stayed glued in fascination to the monitor, ‘the telescope system then does the rest, following a planned set of observations stored in its software. Obviously we see what it sees here on this monitor. At least we see the visual image. The simultaneous infrared and sonar pictures are stored on the recorder. My friend at MOI’ (she didn’t want to alert them even more by using Dale’s name) ‘tried to explain how I could change between the visual and infrared and sonar images, but it wasn’t simple. You’d think it would be as easy as pushing an “I” for infrared or an “S” for sonar. Nope. You have to input as many as a dozen commands just to change which output signal is fed into the monitor.’

  Troy was impressed. Not just by the ocean telescope system, but also by the way Carol, a woman admittedly not educated in engineering or electronics, had clearly grasped the essentials of it. ‘The infrared part of the telescope must measure thermal radiation,’ he said slowly, ‘if I remember my high school physics correctly. But how would underwater thermal variations tell you anything about whales?’

  At this point Nick Williams shook his head and turned away from the screen. He recognized that he was hopelessly out of his intellectual element with all these engineering terms and he was more than a little embarrassed to admit his total ignorance in front of Carol and Troy. Nick also didn’t believe for an instant that Carol had brought all this electronic wizardry on board to find whales that had strayed from their migration route. He walked over to the small refrigerator and pulled out another beer. ‘And what we’re going to do for the next two hours, if I understand it correctly, is ride around in the boat while you look for whales on that screen?’.

  Nick’s derisive comment carried with it an unmistakable challenge. It intruded upon the warm and friendly rapport that had been created between Carol and Troy. She allowed herself to become irritated again by Nick’s attitude and fired back her own verbal fusillade. ‘That was the plan, Mister Williams, as I told you when we left Key West. But Troy tells me that you’re something of a treasure hunter. Or at least were some years ago. And since you seem to have convinced yourself that treasure is really what I’m after, perhaps you’d like to sit here next to me and look at the same pictures to make sure I don’t miss any whales. Or treasure, as the case may be.’

  Nick and Carol glared at each other for a few moments. Then Troy stepped between them. ‘Look, Professor… and you too, angel… I don’t pretend to understand why you two insist on pissing each other off. But it’s a pain in the ass for me. Can’t you just cool it for a while? After all,’ Troy added, looking first at Nick and then at Carol, ‘if you two go for a dive, you’re partners. Your lives may depend on one another. So knock it off.’

  Carol shrugged her shoulders and nodded. ‘Okay by me,’ she said. But seeing no immediate response from Nick, she couldn’t resist another shot. ‘Provided that Mr. Williams recognizes his responsibility as a PADI member and stays sober enough to dive.’

  Nick’s eyes flashed angrily. Then he walked over to the deck railing and dramatically poured his new beer into the ocean. ‘Don’t worry about me, sweetheart,’ he said, forcing a smile, ‘I can take care of myself. You just worry about what you do.’

  The ocean telescope microprocessor contained a special alarm subroutine that sounded a noise like a telephone ring whenever the programmed alarm conditions were triggered. At Carol’s request, Dale Michaels had personally adapted the normal alarming algorithm just before she left for Key West so that it would react to either a large creature moving across the field of view or a stationary unknown object of significant size. After he had finished the logic design for the small change and sent it to his software department for top priority coding and testing, Dale had smiled to himself. He was amused by his complicity with Carol. This piece of technological subterfuge would certainly convince Carol’s companions, whoever they might be, that she was earnest in her search for whales. At the same time, the alarm would also sound if what Carol was really seeking, supposedly an errant (and secret) Navy missile currently under development, appeared on the ocean floor underneath the boat.

  The basic structure for both alarm algorithms was easy to understand. To identify a moving animal, it was sufficient to overlay two or three images taken less than a second apart (at any wavelength, although there was greater accuracy in the process with the sharper visual images), and then compare the data using the knowledge that most of the scene should be unchanged. Significant miscompares (connected areas in the overlay that differed from image to image) would suggest the presence of a large moving creature.

  To identify foreign objects in the field of view, the alarm algorithm took advantage of the tremendous storage capacity of the memory unit in the telescope data processing system. The near simultaneous infrared and visual images were fed into the memory unit and then crudely analysed against a data set that contained chains of pattern recognition parameters over both wavelength regions. These pattern parameters had been developed through years of careful research and had been recently expanded by MOI to include virtually everything normal (plants, animals, reef structures, etc.) that might be seen on the ocean floor around the Florida Keys. Any large object that didn’t correlate in real-time with this existing data base would be flagged and the alarm would sound.

  The alarms made it unnecessary to sit patiently in front of the screen and study the thousands of frames of data as they were received on the boat. Even Troy, a confessed ‘knowledge junkie’ whose interest in everything was almost insatiable, grew tired of staring at the monitor after about ten minutes, particularly when the boat entered into deeper water and very little could be seen in the visual images.

  A couple of solitary sharks triggered alarms and created momentary excitement about twenty minutes after the telescope was activated, but a long period void of any discoveries followed. As the afternoon waned Nick became more and more impatient. ‘I don’t know why I allowed myself to be talked into this wild goose chase,’ he grumbled to nobody in particular. ‘We could have been preparing the boat for the weekend charter.’

  Carol ignored Nick’s comment and studied the map one more time. They had traversed from south to north the region she and Dale had defined and were now moving slowly east along the northern periphery. Dale had constructed the search area based upon his own inferences from the questions asked him by the Navy. He could probably have pinned down the area of interest with greater certainty with a few more questions of his own, but he hadn’t wanted to arouse any suspicions.

  Carol knew that the search was a little like finding a needle in a haystack, but she had thought it would be worthwhile because of the potential payoff. If she could somehow find and photograph a secret Navy missile that had crashed near a populated area… What a scoop that would be! But now she too was growing a little impatient and it was hard for her to revive her earlier excitement after the long afternoon in the sun. They would have to head back to Key West soon to ensure arrival by nightfall. Oh well, she thought to herself with resignation, at least I gave it a shot. And as my father used to say, nothing ventured, nothing gained.

  She was standing at the prow of the boat when suddenly alarms started coming from the memory unit next to the monitor. One ring, then two, followed by a brief silence. A third ring then sounded and was rapidly joined by a fourth. Carol rushed excitedly toward the monitor. ‘Stop the boat,’ she shouted imperiously at Nick. But she was too late. By the time she reached the monitor, the alarms had stopped and she could not see anything on the screen.

  ‘Turn around, turn around,’ a frustrated Carol hollered immediately, not noticing that Nick was again glaring at her.

  ‘Aye, aye, Cap-i-tan,’ Nick said, jerking on the wheel with such force that Carol lost her balance. The monitor and other electronic equipment started to slide off their flimsy mountings on the top of the footlocker; they were rescued at the last minute by Troy. The Florida Queen veered sharply in the water. Despite t
he quietness of the ocean, a small wave came over the railing on the low side of the deck, catching Carol from the knees down. The bottoms of her cotton slacks were left clinging to her calves. Her white tennis shoes and socks were drenched. Nick made no effort to hide his amusement.

  Carol was about to joust with him again when the renewed ringing of the alarms diverted her attention. Regaining her footing as the boat levelled off, she saw in the monitor that they were above a coral reef. And deep beneath the boat, barely discernible on the screen, were three whales of the same kind that she had seen on the beach that morning at Deer Key. They were swimming together in what appeared to be an aimless pattern. But there was more. The special alarm message code indicated that there was also a foreign object in or near to the same field of view as the desultory whales. Carol could not contain her excitement. She clapped her hands. ‘Anchor, please,’ she shouted, and then she laughed. She saw that Troy had already thrown the anchor overboard.

  A few minutes later Carol was hurriedly putting on her buoyancy vest in the aft portion of the boat behind the canopy. Her mask and her flippers had already been adjusted and were beside her on the deck. Troy was helping her by holding up the air bottle that was built into the back of the bulky vest. ‘Don’t worry about Nick,’ Troy said. ‘He may be grumpy today for some reason, maybe because Harvard lost the basketball game, but he’s a fabulous diver. And he has the reputation of being the best dive teacher in the Keys.’ He grinned. ‘After all, he taught me a couple of months ago and we’re not even supposed to be able to swim.’

  Carol smiled and shook her head at Troy. ‘Don’t you ever stop joking?’ she said. She slid her free arm through the second opening and the vest fell into place. ‘By the way,’ she continued softly, ‘for an expert diver your friend certainly uses antiquated equipment.’ At this moment she regretted her decision to leave her customized diving vest in the station wagon. She always used it when she dived with Dale and it had all the latest advances, such as ABC (Automatic Buoyancy Compensation) and a perfect pocket for her underwater camera. But after all the brouhaha when she came through the marina headquarters with her footlocker of electronic equipment, Carol had decided not to attract further attention by bringing in a state-of-the-art diving vest.

  ‘Nick thinks the new vests make it too easy for the diver. He wants them to have to adjust their buoyancy manually—so that they are more conscious of how far down they are.’ Troy looked Carol over. ‘You’re pretty light. This belt may be enough by itself. Do you normally use any weights?’

  Carol shook her head and pulled the belt around her waist. Nick came around the canopy carrying his mask and flippers. He had already put on his diving vest with air bottle and his weighted belt. ‘Those whales of yours are still in the same spot down there,’ he said. ‘I’ve never seen whales hang around like that.’ He handed her a piece of chewing tobacco. She rubbed the tobacco on the inside of her mask to prevent fogging, while Nick walked around behind her. He looked at her air gauge and checked both her regulator and the secondary mouthpiece that he might have to use to share her air in the event of an emergency.

  Nick talked to Carol while he was making her final equipment checks. ‘This is your charter,’ he began in what sounded like a friendly tone, ‘so we can go almost anywhere you want while we are down there. The dive will not be too difficult, since it’s only thirty-five feet or so to the floor. However,’ Nick moved around in front of Carol and looked directly in her eyes, ‘I want one thing thoroughly understood. This is my boat and I am responsible for the safety of the people on it. Including you, whether you like it or not. Before we dive, I want to make certain that you will follow my lead under the water.’

  Carol recognized that Nick was trying to be diplomatic. It even flashed through her mind that he looked quite attractive standing there in front of her in his diving gear. She decided to be gracious. ‘Agreed,’ she said. ‘But one thing before we descend. Remember that I’m a reporter. I will have a camera with me and may want you to move from time to time. So don’t get angry if I motion you out of the way.’

  Nick smiled. ‘Okay,’ he said, ‘I’ll try to remember.’

  Carol put on her flippers and mask. Then she picked up her underwater camera by the strap and threw it over her neck and shoulder. Troy helped her tighten the strap in the back. Nick was sitting on the side of the boat at a break in the railing, right next to a crude ladder that Troy had just dropped overboard. ‘I’ve checked the water already,’ Nick said, ‘and there’s quite a current up here. Let’s go down the anchor rope until we reach the ocean floor. Then you can pick the direction from there.’

  Nick rolled backward off the boat. In a moment he surfaced, treading water. Carol returned his thumbs-up sign (the signal between divers that everything’s all right) and sat down herself on the side of the boat. Troy helped her make one last comfort adjustment to her vest. ‘Good luck, angel,’ Troy said. ‘I hope you find what you’re looking for. And be careful.’

  Carol put the regulator in her mouth, took a breath, and then repeated Nick’s backward roll manoeuvre. The ocean water felt cool against her sunbaked back. In a few seconds she joined Nick over at the anchor rope and the two of them repeated the thumbs-up sign. Nick led the way down. He went hand over hand, cautiously, never completely releasing the rope. Carol followed carefully. She could feel the strong current that Nick had mentioned. It pulled at her, trying to take her away from the rope, but she managed to hold on. Every six to eight feet in the descent, Nick stopped to equalize the pressure in his ears and looked up to see both that Carol was following and that she was all right. Then he continued his descent.

  There was nothing much to see until they reached the reef beneath them. The telescope pictures had been so sharp that they had been misleading. The reef with its riot of colour and its surfeit of plant and animal life had seemed to be right underneath them because of the automatic focusing action of the optical system. But thirty-five feet is a long way down. Any normal three-storey building could have been sitting on the ocean floor underneath the Florida Queen and it would not have touched her hull.

  When they finally reached the top of the reef where the anchor was implanted, Carol realized she had made a mistake. She did not recognize her surroundings and therefore did not know which direction to take to find the whales. She reproached herself briefly for not having spent a few more moments studying the monitor to make sure that she knew where all the landmarks were. Oh well, Carol thought, it’s too late for that now. I’ll just pick a direction and go. Besides, I don’t have any idea where the alarm object is anyway.

  Visibility in the water was fair to good, maybe fifty to sixty feet in all directions. Carol adjusted her buoyancy slightly and then pointed to a gap between two reef structures, both of which were covered with kelp, sea anemones, and the ubiquitous coral. Nick nodded his head. Tucking her arms to her side to streamline her movement, Carol kicked up and down with her flippers and swam toward the gap.

  Behind her, Nick watched Carol swim with appreciation and admiration. She moved through the water as gracefully as the school of yellow and black angelfish beside her. Nick had not interrogated Carol very much about her diving experience and had not known exactly what to expect. He had suspected from her ease and familiarity with the equipment that she was a seasoned diver; but he had not prepared himself for an underwater peer. Except for Greta, Nick had not encountered a woman before who was as comfortable under the water as he was.

  Nick absolutely loved the peace and serenity of the rich and vibrant world beneath the ocean surface. The only sound he ever heard down there was his own breathing. All around him the coral reefs teemed with life of unimaginable beauty and complexity. There, underneath him now, was a grouper taking a bath by sitting at the bottom of a natural hole and letting dozens of tiny cleaner fish eat away all the accumulated parasites. A moment earlier, Nick’s downward excursion toward the ocean floor had disturbed a manta hidden in the sand. This large ray,
called a devilfish by the cognoscenti, had undulated out of its hiding place at the last moment and just missed Nick with its powerful and dangerous tail.

  Nick Williams felt at home down in this watery world at the bottom of the Gulf of Mexico. It was his recreation and his refuge. Whenever he was distressed or disturbed by events on the surface, he knew that he could dive and find relaxation and escape. Except on this particular dive he was aware of an ineffable emotion, a beginning perhaps, a longing that was barely defined, possibly mixed up with a memory of years ago. He was following a beautiful mermaid as she swam along the reef and the sight stirred him. I have acted like a schoolboy, he thought, and a bore. Or worse. And why? Because she is pretty? No. Because she is so alive. So much more alive than I am.

  Carol and Nick made two different excursions, each time starting from the anchor rope, without finding the whales or anything else unusual. When they returned to the anchor after the second unsuccessful foray, Nick pointed at his watch. They had been under the water for almost half an hour already. Carol wagged her head up and down and then held up her index finger, indicating that she would try one more direction.

  They found the whales immediately after they crossed over a big upward bulge in the reef that came within fifteen feet of the surface. Nick saw them first and pointed down. The three whales were about twenty feet below them and maybe thirty yards ahead. They were still swimming slowly, more or less together, in the same directionless, near circular pattern that Nick and Carol had watched on the screen. Carol waved Nick out of the way and pointed at her camera. She then swam toward the whales, taking pictures as she approached them, while carefully monitoring her depth and equalizing the pressure in her ears.