'You are alive,' Rodolfo says. 'You have saved our lives. And you are rich.'
'Rich?'
Wing and Rodolfo and Bong look at each other, confused. 'Yes, of course!' Bong says.
Goto Dengo is still looking nonplussed. Reckoning that he has merely gone deaf or daft from the explosions, Bong reaches into his trousers and pulls out a hand-sewn pouch, teases it open, and displays a healthy double handful of diamonds. Wing and Rodolfo scarcely take note.
Goto Dengo looks away despondently. He himself has saved no treasure except these men's lives. But that's not why he feels so bad. He had hoped that being thus saved they would all be noble, and not think of the treasure. But maybe that was too much to hope for.
A distant thump lifts them slightly off the ledge, just for a moment. Goto Dengo feels a strange sensation in his head: the air pressure is beginning to rise. The column of air trapped in the diagonal is being compressed by a piston of water rushing down it from the lake. Captain Noda has dynamited the plug.
Goto Dengo is so excited that he forgets to die.
He is an engineer, trapped inside one of his own machines. The machine was designed to keep him alive, and he will never know whether it worked unless it works. After he has achieved that satisfaction, he supposes, he can always kill himself at leisure.
He pinches his nose shut, presses his lips together, and begins to blow air into his Eustachian tubes, equalizing the pressure. The others follow his lead.
All of Golgotha's traps are basically the same. All of them derive their killing power from the pressure of the water communicated down to this level from the bottom of Lake Yamamoto. In any number of places in the complex, false walls have been constructed, designed to be pierced by greedy thieves, or to collapse of their own accord when thieves dig out the sand that holds them up. Then the water will rush in with explosive force and probably crush them before they have a chance to drown.
At its Golgotha end, the diagonal tunnel forks again and again, like a river breaking up into distributaries. Goto Dengo explained it to inspecting officers by likening it to the plumbing inside a modern hotel, which is supplied by a single main that is pressurized by a distant water tower, but which divides into many different pipes that supply pressurized water to taps all over the structure.
Golgotha seethes, hisses, and moans as every pipe in its ramified system is pressurized by the deluge unleashed by Captain Noda's dynamite charge. The bubbles of air trapped at the ends of those pipes are seeking escape: some are leaking out through cracks in the walls and others are bubbling away into the diagonal. The surface of Lake Yamamoto must be boiling like a cauldron, and Captain Noda must be standing above it, watching the air flee Golgotha, grinning with satisfaction. In moments, the floors of the tunnels are obscured by whirling lagoons of dirty water, and the barrels and railcars that were left there have begun to rise, bobbing like corks and clanging together.
Most of the air trapped in the Golgotha does not, however, come bubbling up out of Lake Yamamoto. Most of it rises towards the Bubble, because that is how Goto Dengo planned it. He knows it's working because his ears begin to pop.
Eventually the water rises up into the Bubble itself, but it rises slowly, because the pressure of the air in here has become quite high already. As the water climbs, it further pressurizes the bubble of air in which Goto Dengo and the others are trapped. The pressure of the air rises steadily until it becomes equal to the pressure of the water. Then balance is achieved, and the water cannot rise any more. Another kind of balance is being reached within their bodies, as the compressed air floods into their chests, and the nitrogen in that air seeps through the membranes of their lungs and dissolves into their bloodstreams.
'Now we wait,' says Goto Dengo, and shuts off his acetylene lamp, leaving them in darkness. 'As long as we do not burn lamps, there is enough air in this chamber to keep us alive for several days. Captain Noda and his men will spend at least that long tidying up the Bundok site, erasing all traces of our work, and killing themselves. So we must wait, or else his men will only kill us when we appear on the shores of Lake Yamamoto. I would like to spend the time educating you on the subject of caisson disease, also known as the bends.'
Two days later they set off one last, relatively small dynamite charge, blowing a hole through the wall of the Bubble that is large enough to admit a human being. On the other side, the diagonal to Lake Yamamoto begins.
Rodolfo is more terrified than anyone else, and so they send him first. Then goes Bong, and then Wing. Finally Goto Dengo leaves the foul, used-up air of the Bubble behind. Within a few moments they have found their way into the ascending diagonal tunnel. They begin to swim uphill through total darkness. All of them are trailing their hands against the tunnel ceiling, feeling for the opening of the first vertical shaft. Rodolfo is supposed to stop when he feels it, but the others must also be alert in case Rodolfo misses.
They thud into one another in the darkness like a loosely connected train bumping to a halt. Rodolfo has stopped-with any luck, he has found the first vertical shaft. Wing finally moves forward, and Goto Dengo follows straight up the vertical shaft and finally into a bulb at its top where a bubble of air has been trapped. The bulb is just barely wide enough to accommodate four men. They pause there, all jammed together in a cluster of bodies, heaving as they exhale the nitrogen— and carbon-dioxide-tainted air that they've been living on for the last sixty seconds, and breathe in fresh lungfuls. Goto Dengo feels his ears popping as pressure is relieved.
They have covered only a small fraction of the four hundred and fifty meters that separate Golgotha from the lake
Goto Dengo is not a diver, and knows very little of diving medicine. But his father used to speak of how caissons were used to send workers deep underwater, to build things or to mine. That is how he learned about caisson disease, and how he learned the rule of thumb that most men will not suffer its symptoms if you have them decompress for a while at half the original air pressure. If they stop and breathe for a while, the nitrogen will come out of the tissues. Once this is done, the air pressure may be halved again.
In the Bubble, the air pressure was nine or ten atmospheres. Here in the first chamber, it's more like five. But there's not much air in this one-just enough to let them breathe for fifteen or twenty minutes, and bleed nitrogen out of their tissues, and get lungfuls of air for the next leg of the swim.
'Okay,' Goto Dengo says, 'we go.' He finds Rodolfo in the darkness and slaps him encouragingly on the shoulder. Rodolfo takes a series of deep breaths, getting ready, and Goto Dengo recites the numbers that they all know by heart: 'Twenty-five strokes straight. Then the tunnel bends up. Forty strokes up a steep hill. Where the tunnel bends again, you go straight up to the next air chamber.'
Rodolfo nods, crosses himself, and then does a somersault in the water and kicks himself downwards. Then goes Bong, then Wing, and finally Goto Dengo.
This leg is very long. The last fifteen meters is a vertical ascent into the air chamber. Goto Dengo had hoped that the natural buoyancy of their bodies would make this easy, even if they were on the verge of drowning. But as he is kicking up the narrow shaft, pushing frantically on the feet of Wing, who is above him and not going as fast as he would like, he feels a growing panic in his lungs. Finally he understands that he must fight the urge to hold his breath-that his lungs are filled with air at a much higher pressure than the water around him, and that if he doesn't let some of that air out, his chest will explode. So against his instinct to save that precious air, he lets it boil out of his mouth. He hopes that the bubbles will pass by the faces of the men above him and give them the idea too. But shortly after he does it, they all stop moving entirely.
For perhaps ten seconds Goto Dengo is trapped in total darkness in a water-filled vertical hole in the rock that is not much wider than his own body. Of all the things he has experienced in the war, this is the worst. But just as he gives up and prepares to die, they begin moving again. They are half dead when they get to the breathing chamber.
If Goto Dengo's calculations were right, then the pressure in here should be no more than two or three atmospheres. But he is beginning to doubt those calculations. When he has breathed in enough air to restore full consciousness, he's aware of sharp pains in his knees, and it's clear from the sounds that the others are making that they are suffering the same way.
