The frogmen

  The horns were the only things Amos understood about this mine.

  And he wasn't going to understand anything more unless he could examine that pulsing diaphragm. To do that he had to get the top plate off.

  Amos lay still in the water for a long time, remembering his first day in Death Row and the little plunger in the bolthole.

  Was there a plunger in one of these four posts?

  Hingman and his stupid remarks! "Remember, somebody had to put the mine together when it was alive and hot. So take it apart the way he put it together and you 11 live one more day."

  Amos circled the mine slowly, studying the plate, the posts, the welding, the bolts.

  There was no way to get that plate off without taking all four bolts completely out.

  There could be a pressure switch under one of the bolts. But how could a man activate it after the plate was on? There wasn't room enough to reach down into the mine, once the plate was on the posts.

  And the posts were so small. Half an inch of metal tapped out for a bolt didn't leave much room for switches.

  As he moved in close to the mine, he knew that he was breaking all of Hingman's rules by assuming, but not knowing, that these posts were harmless.

  Holding on to the rim with one hand and keeping

  his body away from the mine with his fins, he picked a wrench to fit the aluminum bolts holding the top metal plate to the support posts and slowly lowered the jaws around the first bolt. He screwed the wrench down as tightly as he could and then stopped to set in his mind exactly where the four horns were, and where, when the bolt turned, the end of the wrench handle would go.

  Ready, he began to apply a slow, steady pressure on the wrench.

  The bolt would not move, and as he applied more pressure he could see the sharp corners of the aluminum beginning to round off, letting the wrench slip a little.

  He could not permit the wrench accidentally to slip off the bolt, and the pressure could not be so great that it broke the head off the bolt, for there was not enough room between the wrench handle and the Hertz horn for him to stop any such sudden and unexpected movement before something hit the horn and broke that thin-walled vial of acid inside it.

  What he needed was a socket wrench, which would grip all sides of the bolt, not just the two that the adjustable wrench lay against.

  The sockets he had were too big, designed for casing bolts.

  Amos opened the wrench jaws a little and lifted it straight up and away from the mine. Then he swam back to the tool bag and got the stainless-steel hammer with the ball-peen head.

  In a different position above the mine, he lay a

  moment, trying to stop a shaking that had started in his arms and hands. There seemed to be something wrong with his vision, too; everything was a little blurred.

  When he was ready, he rested the flat head of the hammer on top of the bolt and studied the position of his hand and arm and the distance between all parts of the hammer and the horns.

  He raised the hammer an inch or so and brought it slowly down to the bolt head.

  Then he raised it higher and brought it down again, watching all his movements.

  He practiced several times, moving slowly, and then, his eyes fixed on the bolt head, he brought the hammer down hard, feeling the strong resistance of the water.

  Out of the corner of his eye he saw the red flash of some fish, frightened by the sudden movement.

  And then the hammer struck the head of the bolt.

  There was no time to spare for this sudden trembling, but he could not go on until he got it stopped and was again ready to move against the mine.

  The hammer blow had broken the oxidation on the screw threads, and the bolt turned without burring.

  He turned it only a little way, then got the hammer and beat on the other three until the bolts came off easily. He lifted the top plate, which was made of thick bronze, and set it aside. Next, he removed

  the four screens and laid a wrench on them to keep the current from moving them.

  Now he could look directly down on that pulsing thing set into the top of the can.

  The little wire in the center was held there by some sort of glue, not solder.

  So far, this mine had been so honest that Amos felt almost certain that the little wire was honest too. It had some vital role to play in firing the mine, and that was all; it was not there solely as a trick.

  If it killed you, it would be only because you did not understand why it was there, what its function was.

  Amos didn't understand.

  Not far from the wire, but clear of the area of hardened glue, there was a small hole in the diaphragm.

  Amos held himself poised over the Hertz horns and looked at the little hole. Perhaps it was only a flaw in the rubber or whatever the stuff was.

  Or perhaps it had some function.

  He swam down to the bottom of the mine, studying the casing where it disappeared into the sand.

  How deep into the sand did it go? What held it there?

  He started digging very carefully, moving the sand away from the side of the mine.

  Underneath the mine there was a thick, heavy, concrete slab that anchored the mine in place.

  Set into the concrete was a metal ringbolt.

  Attached to the bottom of the mine was a pelican

  hook, the hook going through the ringbolt and securing the mine to its anchor.

  All very logical and simple.

  When Amos got the flashlight and put his head a little way into the hole he had dug, he saw that the bale shackle, which held the pelican closed, had a heavy-gauge wire or rod that went up through a hole in the bottom of the mine.

  That, too, was simple. A pull on the wire would yank the bale shackle off, letting the hook open and detach itself from the ringbolt in the concrete so that the mine could float straight up.

  The thing that was not simple was: what device pulled the bale shackle off? What impulse made by a passing ship triggered this thing? Was it sound, or magnetism, or some vibration?

  As Amos backed away, he realized that it would take a powerful jerk to pull the shackle off.

  The answer was somewhere inside the mine, somewhere between that rubber diaphragm and the bale shackle.

  The metal cylinder was in one piece, with a welded seam. The top had been welded to the cylinder, and as Amos studied it more closely now, he didn't think that the lifting belt bolted to the case hid any separation in the mine cylinder. Perhaps on the bottom there was a plate that could be removed, but he could not reach it.

  The only way he could get into the mine was to remove the rubber diaphragm.

  As though solving a problem in Death Row, Amos

  thought: The only thing I know is that as long as that little, sharp-pointed piece of wire doesn't move, nothing happens. And I'm pretty sure that if it does move, a lot happens.

  Amos unscrewed two of the posts that supported the bronze top plate, leaving the two others diametrically across the diaphragm. They came loose easily, and he dropped them into the tool bag he had clipped to the rim of the mine; then he took out one of the copper probes, a pair of needle-nose pliers, and the diagonal cutters.

  The probe was just a length of stiff copper wire. Measuring carefully, he cut off a length of it with the diagonals and laid it on the mine.

  He measured the rest of the probe, and then with dykes and the round-nose pliers, formed two loops that fitted exactly over the boltholes in the two support posts still standing.

  Using the bolts that had held the plate, he screwed the piece of rod down securely to the posts so that it stretched straight and rigid above and across the diaphragm.

  With the length of probe he had cut, he measured again, making a loop in one end of it and, with the other end, formed another loop to fit over the probe that was now a crossbar between the posts.

  Putting this looped piece in place, he was pleased to see that it hung nicely, the bottom loop about a quarter of an
inch below the top of the can. He slid the hanging piece out of his way, but left the crossbar where it was.

  Amos found it hard to keep his mind on getting the stainless-steel knife out of the tool bag, opening the smallest blade, and then finding the smallest needle-nose pliers he had and placing them exactly where he wanted them beside the round-nose pliers already in place near the base of the can.

  He knew that for a long time he would have to control the muscles in his left hand so that, although his body might be washed by wave motion and moved by his breathing, his hand did not move at all. A movement of only a fraction of an inch would, he knew, loll him.

  The hand holding the needle-nose pliers must not move vertically, although, as the process went on, it would have to move horizontally.

  He forced himself to stop thinking about it and not go on to wonder what would happen if an unexpectedly strong wave swept against him or if the prop turbulence from a ship forced his hand to move.

  When he was breathing slowly, he took off his fins, looped the tool-bag lashing through them, and let them sink straight down to the bottom.

  Next he wrapped his legs around the mine, adjusting himself until he was at the right height and felt comfortable.

  He rested there for a moment and then picked up the sharp, needle-nose pliers in his left hand. He let his elbow slide carefully across the mine top until it rested against one of the Hertz horns. He could put

  almost no pressure against the soft, lead horn, but the touch of it helped to steady him.

  He reached out slowly with the pliers, sliding them over the diaphragm but not touching it until the tips were just over the short, sharp end of the wire glued to the rubber.

  Then he lowered the pliers and slowly closed them around the end of the wire, making sure that they exerted no pressure either up or down.

  Amos wanted to take a little while to test his immobility but was afraid that time would run out on him; that, if his cutting took too long, this rigidity might start an involuntary muscular reaction, a trembling or shaking he could not control.

  He picked up the small knife and put the point of the blade down at the outer edge of the diaphragm exactly opposite the tips of the pliers, which were held slightly open by the wire between them.

  As he was about to apply pressure to the knife, he thought: This is what John was talking about, the point of no return. At the instant he punctured the diaphragm and released its pressure, the hand with the pliers would have to take control of the little wire. After that, he could not turn loose, or allow the wire to move, until he was finished. No matter how long it took, he would be committed to the control of the wire.

  The black stuff seemed to be rubber and was far tougher than he had thought it would be. It took great and controlled strength to make a small puncture in it with the point of the knife.

  The unexpected resistance forced him to readjust the muscles in his left hand. Now, in addition to holding perfectly steady, he had to resist, and resist exacdy and at exactly the instant that the knife blade changed the pressure on the diaphragm.

  He began to feel an almost personal hatred of the black rubber as the knife sawed at the tough, unco-operative stuff. There were apparently strong reinforcing threads in it, each one changing the pressure he had to exert both on the knife and in his left hand.

  The water around him seemed to be growing warmer, and he could feel sweat inside the face mask as he saw with dismay that he was not cutting straight toward the tips of the pliers, the reinforcing threads curving his cut to the left.

  He need not have worried about it. The small, flat area of glue that held the wire to the diaphragm extended out a good quarter of an inch beyond the tips of the pliers, and when the knife blade reached the glue, it felt as hard as rock.

  He stroked the blade down against the glue and could hear it grating, the knife making no mark on the hard, grayish material.

  His left arm was tiring. There was a vagueness of touch now; he was not sure exactly how much pressure his elbow was putting against the horn, and even when he concentrated on that area, he could not drive off the vagueness.

  He put the knife down and picked up the diagonal cutters.

  In order to get the lower blade of the cutters down into the slit he had cut in the diaphragm, he had to change his position, forcing him to rest awkwardly above the mine, his right arm now also touching one of the horns.

  He slid the cutters into the patch of glue until the curved end of the top blade just cleared the tips of the pliers.

  He knew that the four fingers on the handle of one blade of the cutter, and his thumb on the other, must move with exactly equal pressure so that neither blade would force his left hand, holding the wire, up or down.

  Something was fluttering in his throat as he closed his hand on the handles and watched the blades sliding together.

  It took a lot of pressure to cut through the glue, but at last it snapped, a section of it popping loose and sliding across the diaphragm.

  The wire held in the tips of the pliers was free of the rubber, and the diaphragm sagged down a little way, still pulsing faintly as the waves swept across the channel.

  Moving with infinite care, Amos put the diagonals down and picked up the round-nose pliers.

  His left hand was growing numb, his fingers beginning to lose their sense of touch. The tips of the pliers were shaking.

  Pushing the round-nose tips down through the slit he had cut, he felt blindly until he touched the wire and could get a new grip on it.

  He steadied his right hand as he had his left, positioning it so that the wire would not move up or down, and then let go with the pliers in his left hand.

  He changed his grip on the needle-nose pliers and touched the little wire again.

  Holding it absolutely still with the round-nose, he bent the tip over into a small U.

  Putting the needle-nose pliers down, he slid the looped wire along the crossbar until it hung down beside the mine's wire.

  He fitted the U of one wire into the U of the other and clamped the two wires together with the tips of the needle-nose pliers.

  Then he clamped the top loop of the vertical wire to the crossbar, twisting it until the wire of the mine was held exactly where it had been and could not move up or down.

  Finally he was able to turn loose with the round-nose pliers. And yet, when he decided to do it, he suddenly found that he was too afraid.

  With the pliers in place around the wire, the mine had remained silent, motionless, safe.

  His right hand was hurting badly now, his fingers feeling nothing except pains shooting along the nerves.

  At last he withdrew the pliers slowly and was surprised to see them drop out of his hand, striking the edge of the can and falling onto the top of the mine.

  He lifted his arms straight up from the area of

  the horns, let go with his legs, and slid slowly down the cylindrical walls of the mine until he reached the bottom.

  He stayed there for a long time, his face against the mine, his arms half around it. When he opened his eyes, he saw that the light had grown very dim, the colors around him slowly fading.

  He pulled himself up the mine to the top and got the knife, feeling a little surge of pride as he saw how well he had fastened the lethal wire in place.

  Somehow, it seemed that the stuff cut easily now, and he soon had the diaphragm completely free of the clamp at the edge of the can. He put it inside his wet suit.

  There was a dark opening going down into the heart of the mine, and as Amos hung motionless above it, looking into it but unable to see anything in the darkness, he had a strange feeling.

  He loved this mine. It was so honest, so straightforward. No secrets within secrets, just an honest mechanism, designed only to destroy ships.

  Getting the flashlight, he beamed it down into the hole.

  The wire in the diaphragm triggered a device almost like a rat trap. It was a spring-loaded release that tripped a pla
te when the tiny wire moved, letting the powerful spring jerk the bale shackle off.

  The mine was armed.

  He hurried now, putting the posts back in place, sliding the screens in and then laying the top plate down on the posts. His wires prevented the plate

  from fitting exactly, but he bolted the two corners down firmly enough to hold it in place and provide some protection.

  As he got the tool bag and put his fins on again, Amos felt good.

  Then the truth hit him in the face.

  All he knew was how the mine worked; he did not know what made it work.

  Magnetism did not. A magnetic firing mechanism was a delicate device with magnetic bars finely balanced on a knife edge so that the slightest movement of a magnetic field around them would trigger the mine. There was nothing like that in this mine.

  Acoustics did not. There was nothing down in that black hole that he could not account for. There was no microphone in there.

  There was no physical thing, like an antenna brushing against a ship's hull. There were no wires from a shore control station.

  There was nothing.

  It was late now, the shadows very long on the bottom, the light growing dim, as Amos swam slowly toward the entrance to the cave.

  He couldn't seem to keep his mind on the problem.

  Instead he thought about his best blue uniform with the gold ensign stripes lying at the bottom of the Pacific Ocean near that beat-up island.

  He had bought the suit when he'd been accepted in the NROTC. He'd been pretty proud of it.

  Amos stopped swimming entirely.

  Rotcy class. One day they had been taken to hear

  a lecture at the Bureau of Ships testing-tank laboratory . . . huge tanks, like enormous swimming pools, with catwalks over them and beautiful ship models floating in them. . . .

  They could do anything in those tanks, create any kind of wave form, varying them from the long, slow, crestless waves of a ground sea, to the furious waves of hurricanes.