Kemp searched and found a piece he had cut in making the tube. It was perfectly round, ideal for the purpose. He sliced off the inner side where it tapered to a cone, then, working only by eye estimate, cut out a hole in which the wedge of fission material would fit. He wasn’t off by a thirty-second of an inch. Skillful application of the torch melted the thorium around the wedge and sealed it tightly. Koa was ready with a sheet of nuclite. Trudeau arrived with a long pole he had made by lashing two crate sticks together. Rip gave directions as they formed a cylinder of nuclite. Kemp spot-welded it, and they pushed it into the hole, forming a lining. Nunez found a small piece of material in one of the earlier craters. It would provide some neutrons to start the chain reaction. Rip added it to the front of the plutonium wedge along with a piece of beryllium from the bomb, and Kemp welded it in place. They put the thorium block which contained the plutonium into the hole, the plutonium facing outward. Trudeau rammed it to the bottom with his pole. The neutron source, the neutron reflector, and one piece of fissionable material were in place. Kemp sliced another round block of thorium out of a near-by crystal and fitted the second wedge of plutonium into it. At first Rip had worried about the two pieces of plutonium making a good enough contact, but Kemp’s skillful hand and precision eye removed that worry. The torchman finished fitting the plutonium and carried the block to the tube opening. He tried it, removed a slight irregularity with his torch, then said quietly, "Finished, sir." Rip took over. He slid the thorium-plutonium block into the tube, took a rocket head from Santos and used it to push the block in farther. When the rocket head was about four inches inside the tube, its wires trailing out, Rip called Kemp. At his direction, the torchman sliced a thin slot up the face of the crystal. Rip fitted the wires into it and held them in place with a small wedge of thorium. Kemp cut a plug, fitted it into the hole, and welded the seams closed. The tube was sealed. When electric current fired the rocket head, the thorium carrying the plutonium wedge would be driven forward to meet the wedge in the back. And, unless Rip had miscalculated the mass of the two pieces, they would have their nuclear blast. Rip surveyed the crystal with some anxiety. It looked right. Dominico already had rigged the timer from the atomic bomb. He connected the wires, then looked at Rip. "Do I set it, sir?" "Load the communicator, the extra bomb parts, the rocket launcher and rockets, the cutting equipment, my instruments, and the tubes of fuel," Rip ordered. "Leave everything else in the cave."